#  > Petroleum Industry Zone >  > Mechanical Engineering >  >  >  Pump and pump system glossary

## Esam

[h=PUMP AND PUMP SYSTEM  GLOSSARY]1[/h] 
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 					[TD]*Absolute pressure*:  					pressure is measured in psi (pounds per square inch) in the imperial system and kPa  					(kiloPascal or bar) in the metric system. Most pressure measurements are made relative  					to the local atmospheric pressure. In that case we add a "g" to the pressure measurement  					unit such as psig or kPag. The value of the local atmospheric pressure varies with elevation  It is not the same if you are at sea level (14.7 psia) or at  					4000 feet elevation (12.7 psia). In certain cases it is necessary to measure pressure values  					that are less then the local atmospheric pressure and in those cases we use the absolute unit  					of pressure, the psia or kPa a.


 					pa(psia) = pr(psig) + patm(psia), patm = 14.7 psia at sea level.

					 					where pa is the absolute pressure, pr the relative pressure and patm 					 the absolute pressure value of the local atmospheric pressure.

 					and in the metric system

 					pa(kPa a) = pr(kPag) + patm(kPa a), patm = 100 kPa a at sea level.
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 					[TD]*Accumulator*: used in domestic water applications to  					stabilize the pressure in the system and avoid the pump cycling on and off every time a tap  					is opened somewhere in the house. The flexible bladder is pressurized with air at the pressure  					desired for acheiving the correct flow rate at the furthest point of the house or system. As  					water is pulled from the tank the bladder expands to fill the volume and maintain the pressure.  					When the bladder can no longer expand the water pressure drops, the pressure switch of the pump  					is activated on low pressure, and the pump starts and fills the water volume of the accumulator.  					The bladder keeps the air from entering into solution with the water resulting in less frequent  					re-pressurisation of the accumulator.
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 			Pumps are often sold as a package with an accumulator.
 			[hr][/hr] 			 						*Affinity laws*: the affinity laws are  used to predict the change in diameter required to increase the flow or  total head of a pump. They can also predict the change in speed required  to achieve a different flow and total head. The affinity laws can only  be applied in circumstances where the system has a high friction head  compared to the static head and this is because the affinity laws can  only be applied between performance points that are at the same  efficiency. see **[link Point to another website Only the registered members can access]
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<![CDATA[[Only Registered And Activated Users Can See Links]**[link Point to another website Only the registered members can access]
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<![CDATA[[Only Registered And Activated Users Can See Links]

						The following figure shows a system that has a friction head  (curve A) higher than its static head for which the affinity laws apply,  as compared to curve B, a system with a high static head as compared to  the friction head where the affinity laws do not apply.

 			Domain of application of the affinity laws for an axial flow pump.

 			The affinity laws are expressed by the three following  relationships where Q is the flow rate, n the pump rpm, H the total head  and P the power. You can predict the operating condition for point 2  based on the knowledge of the conditions at point 1 and vice versa.



 			The process of arriving at the affinity laws assumes that the two  operating points that are being compared are at the same efficiency. The  relationship between two operating points, say 1 and 2, depends on the  shape of the system curve (see next Figure). The points that lie on  system curve A will all be approximately at the same efficiency. Whereas  the points that lie on system curve B are not. The affinity laws do not  apply to points that belong to system curve B. System curve B describes  a system with a relatively high static head vs. system curve A which  has a low static head.
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## Esam

*Diameter reduction* To reduce costs pump casings are  designed to accommodate several different impellers. Also, a variety of  operating requirements can be met by changing the outside diameter of a  given radial impeller. Euler's equation shows that the head should be  proportional to (nD)2 provided that the exit velocity triangles remain the same before and after cutting. This is the usual assumption and leads to:
   				 			 			which apply only to a given impeller with altered D and constant efficiency but  			not a geometrically similar series of impellers.If that is the case then the affinity  			laws can be used to predict the performance of the pump at different diameters for the  			same speed or different speed for the same diameter. Since in practice impellers of  			different diameters are not geometrically identical, the author's of the section called  			Performance Parameters in the Pump Handbook recommend to limit the use of this technique  			to a change of impeller diameter no greater than 10 to 20%. In order to avoid over  			cutting the impeller, it is recommended that the trimming be done in steps with careful  			measurement of the results. At each step compare your predicted performance with the  			measured one and adjust as necessary. 



 			[hr][/hr] 			 			 			*Air entrainment (ingestion)*: air in the pump suction can  reduce the performance of a pump considerably. The following chart from  Goulds shows that even 2% air by volume in the liquid can have an effect  on performance.

 			Performance reduction due to air in the pump

 			There are many causes of air entrainment, the air may be coming in at the suction tank due to improper piping

 			or due to leakage iin the pump suction line (assuming that  conditions are such that low pressure is produced in the suction line).

 			Leakage in a suction pipe under low pressure will cause air to enter the pump.
 			Centrifugal pumps can be designed to handle more air if required. Viscous drag pumps can handle large quantities of air.

 			[hr][/hr] 			*ALLOWABLE PIPE STRESS*: the allowable  or maximum pipe stress can be calculated using the ASME Power Piping  Code B33.1. The allowable pipe stress is fixed by the code for a given  material, construction and temperature from which one can calculate the  allowable or maximum pressure permitted by code. 

[hr][/hr] 			*ANSI*: American National Standards  Institute.  A term often used in connection with the classification of  flanges, ANSI class 150, 300, etc. See this **[link Point to another website Only the registered members can access]
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<![CDATA[[Only Registered And Activated Users Can See Links] for the pressure rating of ANSI class flanges. 
 			[hr][/hr] 			*ANSI B73.1*: this is a standard that  applies to the construction of end-suction pumps. It is the intent of  this standard that pumps of all sources of supply shall be  dimensionnally interchangeable with respect to mounting dimensions, size  and location of suction and discharge nozzles, input shafts,  baseplates, and foundation bolts.
 			This next image shows the dimensions that have been standardized (source: the Pump Handbook by McGraw-Hill)

 			This next image shows a cross-section of an end-suction  pump  built to the B73.1standard (source: the Pump Handbook by McGraw-Hill).

 			This **[link Point to another website Only the registered members can access]
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<![CDATA[[Only Registered And Activated Users Can See Links]  gives comments on the scope of pump standards and recommends various  changes to apply  to pumps prior to ordering and modifications that will  increase the operating life after receipt of a pump.

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## Esam

*Anti Vortex Plate*: An anti vortex plate prevents the formation of a vortex and 			and therefore air entrainment into the pump by forcing any emerging vortex to go around a plate  			and then into the suction pipe. The swirling motion cannot be maintained and the vortex dissipates and cannot form 			if the path is too long and contorted. _Source: NFPA 22, Standard for water tanks for private fire protection 			2008 edition_. You can find the entire code **[link Point to another website Only the registered members can access]
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<![CDATA[[Only Registered And Activated Users Can See Links] 			 			[hr][/hr] 			*API 610*: American Petroleum Industry, a  pump standard adopted by the petroleum industry. The intent being to  make pumps more robust, leak-free and reliable.
 			[hr][/hr] 			*ASME*: American Society of Mechanical  Engineers. The Boiler pressure power piping code B31.3 is a code that is  often used in connection with the term ASME, the maximum pressure  safely allowable can be calculated using this code.



[hr][/hr] 			*Atmospheric pressure*: usually refers to  the pressure in the local environment of the pump. Atmospheric pressure  varies with elevation, it is 14.7 psia at sea level and decreases with  rising elevation. The value of the local atmospheric pressure is  required for calculating the NPSHA of the pump and avoiding cavitation. 

 			Ta

 			The variation of atmospheric pressure with elevation.



 			 			[hr][/hr] 			*Axial flow pump*: refers to a design of a centrifugal pump  for high flow and low head. The impeller shape is similar to a  propeller. The value of the **[link Point to another website Only the registered members can access]
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<![CDATA[[Only Registered And Activated Users Can See Links] will provide an indication whether an axial flow pump design is suitable for your application. see **[link Point to another website Only the registered members can access]
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<![CDATA[[Only Registered And Activated Users Can See Links]

 			They are used extensively in the state of Florida to control the  water level in the canals of low lying farming areas. The water is  pumped over low earthen walls called burms into the **[link Point to another website Only the registered members can access]
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<![CDATA[[Only Registered And Activated Users Can See Links] main collecting canals.

**[link Point to another website Only the registered members can access]
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<![CDATA[[Only Registered And Activated Users Can See Links] is a reputable supplier of these pumps.


 			[hr][/hr] 			
*Barometric pressure*: the same as atmospheric pressure, the pressure in the local environment. Barometric pressure is a term used in meteorology and is often expressed in inches of Mercury.

 			[hr][/hr] 			*Baseplate*: all pumps require some sort of steel base that holds the pump and motor and is  anchored to a concrete base.

 			 these baseplates are built to the ANSI standard B73.1 and will therefore accomodate any pump built to the same standard.

 			[hr][/hr] 			*Best Efficiency Point (B.E.P.)*: The point  on a pump's performance curve that corresponds to the highest  efficiency. At this point, the impeller is subjected to minimum radial  force promoting a smooth operation with low vibration and noise.


 			Figure 1 Important points of the pump characteristic curve.

 			Radial force on the impeller vs. the flow rate (source: the Pump Handbook by McGrawhill).
 			When selecting a  centrifugal pump it is important that the design  operating point lie within the desirable selection area shown in the  next figure.




 			 			[hr][/hr] 			 			*Bingham plastic*: A fluid that behaves in a  Newtonian fashion (i.e. constant viscosity) but requires a certain  level of stress to set it in motion.
 			 				For more information see **[link Point to another website Only the registered members can access]
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<![CDATA[[Only Registered And Activated Users Can See Links]

 				[hr][/hr] 			 			*Bourdon pressure gauge*: the Bourdon tube  is a sealed tube that deflects in response to applied pressure and is  the most common type of pressure sensing mechanism.

 			[hr][/hr] 			*Bowl (vertical turbine pump)*: the casing of one stage a multi-stage vertical turbine pump.

 			[hr][/hr] 			*Bypass line*: a line used to connect the discharge side of the pump to a  			low pressure area, often the pump's suction tank, for the purpose of moderating the flow in the system  			and/or to bring the pump's operating point within a favorable area of the pump's performance curve.  			

 			To find out more about control systems, this is an excellent treatment of **[link Point to another website Only the registered members can access]
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<![CDATA[[Only Registered And Activated Users Can See Links].  Thanks to Walter ******** of Colt Engineering a  			consulting engineering firm for the petro-chemical industry in Alberta, Canada.
 			 			[hr][/hr] 			*Calculation software*: doing pump system calculations and pump  			selection can be a long manual process with opportunities for many errors. Help yourself  			produce accurate, consistent and error free total head calculation results with PIPE-FLO software.  			This sofware can resolve complicated systems with multiple branches, handle control valves and  			other equipment and help you do the final pump selection with the manufacturer's electronic  			pump performance curves providing you with customizable search features to obtain the  			optimum selection. **[link Point to another website Only the registered members can access]
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<![CDATA[[Only Registered And Activated Users Can See Links]
 			[hr][/hr] 			*Capacity*: refers to a pump's flow rate capacity. Often expressed in USgpm  			(US gallons per minute) or l/min (litre per minutre) or m^3/h (meter cube per hour).
 			[hr][/hr] 			*Casing*: The body of the pump, which encloses the impeller, syn. volute.

 			[hr][/hr] 			*Cavitation*: the  collapse of bubbles that are formed in the eye of the impeller due to  low pressure. The implosion of the bubbles on the inside of the vanes  creates pitting and erosion that damages the impeller. The design of the  pump, the pressure and temperature of the liquid that enters the pump  suction determines whether the fluid will cavitate or not.

 			Figure 2 Pressure profile inside a centrifugal pump.

 			as the liquid travels through the pump the pressure drops, if it  is sufficiently low the liquid will vaporize and produce small bubbles.  These bubbles will be rapidly compressed by the pressure created by the  fast moving impeller vane. The compression creates the characteristic  noise of **[link Point to another website Only the registered members can access]
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<![CDATA[[Only Registered And Activated Users Can See Links].   Along with the noise, the shock of the imploding bubbles on the  surface of the vane produces a gradual erosion and pitting which damages  the impeller.


 			Cavitation damage on an impeller of a Robot BW5000 pump (image provided by my pump friend Bart Duijvelaar).

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## Esam

*Centrifugal force*: A force associated with a rotating body. In  the case of a pump, the rotating impeller pushes fluid on the back of  the impeller blade, imparting circular and radial motion. A body that  moves in a circular path has a centrifugal force associated with it . 			Try this experiment, find a plastic cup or other container that  you can poke a small pinhole in the bottom. Fill it with water and  attach a string to it, and now you guessed it, start spinning it.

 			Figure 3 An experiment with centrifugal force.

			 			The faster you spin, the more water comes out the small hole, you  have pressurized the water contained in the cup using centrifugal force,  just like a pump.

*A CENTRIFUGAL PUMP ANIMATION*
**[link Point to another website Only the registered members can access]
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<![CDATA[[Only Registered And Activated Users Can See Links] 				This animation shows my interpretation of what happens to fluid particles  				(represented by gray balls) once they enter the eye of the impeller and after they turn 90 degrees.  				At this point they are at the entrance of the volume formed by two adjacent impeller vanes.  				The rapid rotation of the vanes (impeller blades) displaces the fluid particles by moving them in a  				radial direction where they come into contact with the pump  volute and are decelerated and pressurized.  				Check out the direction of rotation, not what one would expect at first glance.



		For those of you who would like to have this image for your presentation here is  		
 		an **[link Point to another website Only the registered members can access]
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<![CDATA[[Only Registered And Activated Users Can See Links]
 		 			[hr][/hr] 			*Characteristic curve*: same as **[link Point to another website Only the registered members can access]
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<![CDATA[[Only Registered And Activated Users Can See Links].
 			[hr][/hr] 			*Check valve*: a device for preventing  flow in the reverse direction. The pump should not be allowed to turn in  the reverse direction as damage and spillage may occur. Check valves  are not used in certain applications where the fluid contains solids  such as pulp suspensions or slurries as the check valve tends to jam. A  check valve with a rapid closing feature is also used as a preventative  for water hammer. **[link Point to another website Only the registered members can access]
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<![CDATA[[Only Registered And Activated Users Can See Links]

 			Various check valves (source: The Crane Technical Paper no 410)
 			do your own calculation of **[link Point to another website Only the registered members can access]
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<![CDATA[[Only Registered And Activated Users Can See Links] 			[hr][/hr] 			*Colebrook equation*: an equation for calculating the friction factor f of fluid flow in a pipe for **[link Point to another website Only the registered members can access]
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<![CDATA[[Only Registered And Activated Users Can See Links] of any viscosity. see also the **[link Point to another website Only the registered members can access]
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<![CDATA[[Only Registered And Activated Users Can See Links] figure 9. 			This factor is then used to calculate the friction loss for a straight length of pipe.  			Do your own calculation of **[link Point to another website Only the registered members can access]
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<![CDATA[[Only Registered And Activated Users Can See Links]

 			To understand how to solve the Colebrook equation for the friction factor f using the Newton-Raphson iteration technique, **[link Point to another website Only the registered members can access]
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<![CDATA[[Only Registered And Activated Users Can See Links]

			Here is an interesting article on **[link Point to another website Only the registered members can access]
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<![CDATA[[Only Registered And Activated Users Can See Links] and very precise version of the Colebrook equation. 
 			[hr][/hr] 			*Chopper pump*: a pump with a serrated impeller edge which can cut large solids and prevent clogging.

 			Chopper pump
 			 			see **[link Point to another website Only the registered members can access]
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<![CDATA[[Only Registered And Activated Users Can See Links] for more information
 			[hr][/hr] 			*Closed or open impeller*: the impeller  vanes are sandwiched within a shroud which keeps the fluid in contact  with the impeller vanes at all times. This type of impeller is more  efficient than an open type impeller. The disadvantage is that the fluid  passages are narrower and could get plugged if the fluid contains  impurities or solids.


 			In the case of an open impeller, the impeller vanes are open and the edges are not  			constrained by a shroud. This type of impeller is less efficient than a closed type impeller.  			The disadvantage is mainly the loss of efficiency as compared to the closed type of impeller  			and the advantage is the increased clearance available which will help any impurities or  			solids get through the pump and prevent plugging. 
 			[hr][/hr] 			
 			also read this article on **[link Point to another website Only the registered members can access]
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<![CDATA[[Only Registered And Activated Users Can See Links]  by John Kozel, president of the Sims Pump Valve Company re-printed with  his permission. You can view the Sims company web site at **[link Point to another website Only the registered members can access]
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<![CDATA[[Only Registered And Activated Users Can See Links]

 			[hr][/hr] 			*CV coefficient*: a coefficient developed  by control valve manufacturers that provides an indication of how much  flow the valve can handle for a 1 psi pressure drop. For example, a  control valve that has a CV of 500 will be able to pass 500 gpm with a  pressure drop of 1 psi. CV coefficients are sometimes used for other  devices such as check valves. 


 			CV coefficients for a wafer style check valve.
 			[hr][/hr] 			*Cutwater:* the narrow space between the impeller and the casing in the discharge area of the casing.

 			this is the area where pressure pulsations are created, each vane  that crosses the cutwater produces a pulse. To reduce pulsations in  critical process', more vanes are added.
 			[hr][/hr] 			*Darcy-Weisbach equation*: an equation used for calculating the friction head loss for fluids in pipes, the friction **[link Point to another website Only the registered members can access]
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<![CDATA[[Only Registered And Activated Users Can See Links] must be known and can be calculated by the Colebrook, the Swamee-Jain equations or the Moody diagram.

 			[hr][/hr] 			*Dead head*: a situation that occurs when the pump's discharge is closed either due 			to a blocage in the line or an inadvertently closed valve. At this point, the pump will go to it's maximum 			shut-off head, the fluid will be recirculated within the pump resulting in overheating and possible damage. 			
 			[hr][/hr] 			*Diffuser:* located in the discharge area  of the pump, the diffuser is a set of fixed vanes often an integral  part of the casing that reduces turbulence by promoting a more gradual  reduction in velocity.
 			 				The following image comes from this web site **[link Point to another website Only the registered members can access]
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<![CDATA[[Only Registered And Activated Users Can See Links]

 				[hr][/hr] 			*Diaphragm pump*: a positive  displacement pump. Double Diaphragm pumps offer smooth flow, reliable  operation, and the ability to pump a wide variety of viscous, chemically  aggressive, abrasive and impure liquids. They are used in many  industries such as mining, petro-chemical, pulp and paper and others.
 			An air valve directs pressurized air to one of the chambers, this  pushes the diaphragm across the chamber and fluid on the other side of  the diaphragm is forced out. The diaphragm in the opposite chamber is  pulled towards the centre by the connecting rod. This creates suction of  liquid in chamber, when the diaphragm plate reaches the centre of the  pump it pushes across the Pilot Valve rod diverting a pulse of air to  the Air Valve. This moves across and diverts air to the opposite side of  the pump reversing the operation. It also opens the air chamber to the  exhaust.


 			this type of diaphragm pump is driven by pneumatic air so these  can be used where electric drives are not preferred, is self priming and  can run dry for brief periods, an handle hazardous liquids with almost  any viscosity, can pump solids up to certain sizes.

 			Wilden is a major manufacturer of such pumps **[link Point to another website Only the registered members can access]
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<![CDATA[[Only Registered And Activated Users Can See Links]
 			[hr][/hr] 			*Dilatant*: The property of a fluid whose viscosity increases with strain or displacement.

 			For more information see **[link Point to another website Only the registered members can access]
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<![CDATA[[Only Registered And Activated Users Can See Links]
 			[hr][/hr] 			*Discharge Static Head*: The difference in  elevation between the liquid level of the discharge tank if the pipe  end is submerged and the centerline of the pump. If the discharge pipe  end is open to atmosphere than it is the difference between the pipe end  elevation and the suction tank fluid surface elevation. This head also  includes any additional pressure head that may be present at the  discharge tank fluid surface, for example as in a pressurized tank.


 			Figure 4 Discharge, suction and total static head.
 			See this tutorial for **[link Point to another website Only the registered members can access]
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<![CDATA[[Only Registered And Activated Users Can See Links].

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## Esam

*Double suction pump*: the liquid is channeled inside the pump  casing to both sides of the impeller. This provides a very stable  hydraulic performance because the hydraulic forces are balanced. The  impeller sits in the middle of the shaft which is supported on each end  by a bearing. Also the N.P.S.H.R. of this type of pump will be less than  an equivalent end-suction pump. They are used in a wide variety of  industries because of their reliabilty. Another important feature is  that access to the impeller shaft and bearings is available by removing  the top cover while all the piping can remain in place. This type of  pump typically has a **[link Point to another website Only the registered members can access]
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<![CDATA[[Only Registered And Activated Users Can See Links]. 			
			The following **[link Point to another website Only the registered members can access]
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<![CDATA[[Only Registered And Activated Users Can See Links].

 			 			This sketch will help visualize the flow inside the pump.

 			[hr][/hr] 			*Double volute pump*:  a pump where the immediate volute of the impeller is separated by a  partition from the main body of the casing. This design reduces the  radial load on the impeller making the pump run smoother and vibration  free.


 			Double volute pump (source of image the Pump Handbook by McGraw-Hill).
 			see **[link Point to another website Only the registered members can access]
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<![CDATA[[Only Registered And Activated Users Can See Links] for more information

			For more information see this pdf file **[link Point to another website Only the registered members can access]
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<![CDATA[[Only Registered And Activated Users Can See Links]
 						[hr][/hr] 			*Drooping curve*: similar to the normal  profile except at the low flow end where the head rises then drops as it  gets to the shut-off head point. see **[link Point to another website Only the registered members can access]
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<![CDATA[[Only Registered And Activated Users Can See Links]
 			[hr][/hr]*Efficiency:*:  			the efficiency of a pump can be determined by measuring the torque at the pump shaft with a torque  			meter and then calculating the efficiency based on the speed of the pump, the pressure or total head  			and flow produced by the pump. The standard equation for torque and speed provides power.
 			The power consumed by the pump is proportional to total head, flow, specific gravity and efficiency.
 
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<![CDATA[[Only Registered And Activated Users Can See Links]

 			Flow and total head are measured and then the efficiency can be determined.

 			The efficiency is calculated for various flow rates and plotted on the same curve as the pump  			performance or **[link Point to another website Only the registered members can access]
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<![CDATA[[Only Registered And Activated Users Can See Links]. When several performance curves are plotted, the equal efficiency  			values are linked to provide lines of equal efficiency. This is a useful visual aide as it points out  			areas of the various pump curves that are at high efficiency, which will be the preferred areas or  			areas that the selected pump should operate within. The highest efficiency on a given pump curve is  			known as the B.E.P. (best efficiency point), **[link Point to another website Only the registered members can access]
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<![CDATA[[Only Registered And Activated Users Can See Links].

 			Centrifugal pumps come in many designs and some are more suitable for low-flow high-head applications  			and others for high-flow low-head and some in between. They are designed to achieve their maximum  			efficiency to accommodate a particular application.

 			The specific speed number gives an indication of what type of pump is more suited to your application.  			The effect of specific speed on pump design and how to calculate this number is **[link Point to another website Only the registered members can access]
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<![CDATA[[Only Registered And Activated Users Can See Links].

 			It is possible to predict efficiency. Some years ago, a survey of typical industrial pumps was made.  			The average efficiency was plotted against the specific speed and it shows what the ultimate efficiency  			limits are for pumps under various operating conditions. **[link Point to another website Only the registered members can access]
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<![CDATA[[Only Registered And Activated Users Can See Links].

 			Suction specific speed is another parameter that can affect efficiency. This number is a measure of  			how much flow can be put through a pump before it starts to choke (reaches it's upper flow limit)  			and cavitates (the pressure at the suction becomes low enough that the fluid vaporizes). **[link Point to another website Only the registered members can access]
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<![CDATA[[Only Registered And Activated Users Can See Links].
  			[hr][/hr] 			*End suction pump*: a typical  centrifugal pump, the workhorse of industry. Also known as volute pump,  standard pump, horizontal suction pump. The back pull out design is a  standard feature and allows easy removal of the impeller and shaft with  the complete drive and bearing assembly while keeping the piping and  motor in place.
 			Some of its components are:
 			[table]
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 					[TD]1.Casing, volute

						 						2. Impeller, vanes, vane tips, backplate, frontplate (shroud), back vanes, pressure equalising passages or balancing holes

 						3. Back cover parallel to Plane of the impeller intake

 						4. Stuffing Box - Gland/mechanical seal housing or packing/lantern ring 

 						5. Pump shaft

 						6. Pump casing

 						7. Bearing housing

 						8. Bearings

 						9. Bearing seals

 						11. Back pull out

 						12. Bearings
 						13. Bearing seals
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 			Balancing holes

 			Backvanes

*Equivalent length*:  a method used to establish the friction loss of fittings (see next  figure). The equivalent length of the fitting can be found using the  nomograph below. The equivalent length is then added to the pipe length,  and with this new pipe length the overall pipe friction loss is  calculated. This method is rarely used today. See **[link Point to another website Only the registered members can access]
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<![CDATA[[Only Registered And Activated Users Can See Links] for the current method for calculating fittings friction head loss.

 			[hr][/hr] 			*Energy gradient*: see **[link Point to another website Only the registered members can access]
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<![CDATA[[Only Registered And Activated Users Can See Links].
 			[hr][/hr] 			*Expeller*: a hydro-dynamic seal that provides a seal without addition of water to the gland, specially useful for liquid slurries.

 			(image source: Worthington Pumpworld article, see below)


 			see an article on the expeller seal on this web page: **[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links] 			
 			[hr][/hr] 			*External* *Gear pump*: a positive  displacement pump. Two spur gears are housed in one casing with close  clearance. Liquid is trapped between the gear tooth spaces and the  casing, the rotation of the gears pumps the liquid. They are also used  for high pressure industrial transfer and metering applications on  clean, filtered, lubricating fluids.


 				Viking Pumps is a major supplier of these pumps **[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links]
 				[hr][/hr] 				*Flat curve*: head decreases very slowly as flow increases, see **[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links]
 				[hr][/hr] 				 				*Flow splitter*: **[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links].
 			[hr][/hr] 			*Foot valve*: a check valve that is put on the end of the pump suction pipe, often accompanied with an integrated strainer. **[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links] 
 
[hr][/hr] 			*Forum*: the pumpfundamentals forum is a place where you can ask questions on centrifugal pumps and other 			types and also share you knowledge with others. A valuable resource. **[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links]
  			 			[hr][/hr] 			*Friction loss (pump)*: the following chart shows the distribution of friction losses and their relative size that occur in a pump. 						
 
 			Source: Centrifugal and Axial Flow Pumps by A.J. Stepanoff published by John Wiley and Sons 1957. 			
 			[hr][/hr] 			*Friction (pipe)*: The force produced as  reaction to movement. All fluids are subject to friction when they are  in motion. The higher the fluid viscosity, the higher the friction force  for the same flow rate. Friction is produced internally as one layer of  fluid moves with respect to another and also at the fluid wall  interface. Rough pipes will also produce high friction. 

[hr][/hr] 			*Friction head loss (pipe)*: the friction head loss is given by the **[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links] and in many tables such as provided by the **[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links]. It is normally given in feet of fluid per 100 feet of pipe.

 			Table of head loss factors for water from the Cameron Hydraulic data book.


 			For **[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links] .
 			[hr][/hr]

----------


## Esam

*Friction factor f (pipe)*: the friction factor f is required for the calculation of the friction head loss. It is given by the **[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links], or the **[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links] or the **[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links].  The value of the friction factor will depend on whether the fluid flow  is laminar or turbulent. These flow regimes can be determined by the   value of the **[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links]. 			[hr][/hr] 			

 			[hr][/hr] 			*Front plate*: see **[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links].
 			[hr][/hr] 			*Gland*: see **[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links].
 			[hr][/hr] 			*Glandless pumps*: see **[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links].
 			[hr][/hr] 			*Hazen-Williams equation*: this equation is now rarely used but has been much used in the  			past and does yield good results although it has many limitations, one being that it does not consider viscosity.  			It therefore can only be applied to fluids with a similar viscosity to water at 60F. It has been replaced by the  			Darcy-Weisbach and the Colebrook equation. Interestingly the NFPA (National Fire Protection Association) mandates  			that the Hazen-Williams equation be used to do the friction calculations on sprinkler systems for example.

 			The C coefficients use in the above Hazen-Williams equation are given in the table below. 				
				The source of this equation is the **[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links]. 			

 			Hazen-Williams equation C coefficients.
 			[hr][/hr] 			*Head:*  the height at which a pump can displace a liquid to. Head is also a  form of energy. In pump systems there are 4 different types of head:  elevation head or static head, pressure head, velocity head and friction  head loss. For **[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links] see this tutorial.

 			Also known as specific energy or energy per unit weight of fluid, the unit of head is expressed in feet or meters. **[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links]

 			Try this **[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links]
 			[hr][/hr] 			*Hydraulic gradient:*  All the energy terms of the system ( for example velocity head and  piping and fitting friction loss) are converted to head and graphed  above an elevation drawing of the installation. It helps to visualize  where all the energy terms are located and ensure that nothing is  missed.

 			[hr][/hr] 			*Impeller:* The rotating element of a pump  which consists of a disk with curved vanes. The impeller imparts  movement and pressure to the fluid.

			See this paper on impellers by the **[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links].


 			Figure 5 Major pump parts and terminology.

 			The impeller consists of a back plate, vanes and for closed  impellers a front plate or shroud. It may be equipped with wear rings,  back vanes and balancing holes.

 			for more on the different impeller types see **[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links].
 			[hr][/hr] 			*Impeller eye:* that area of the  centrifugal pump that channels fluid into the vane area of the impeller.  The diameter of the eye will control how much fluid can get into the  pump at a given flow rate without causing excessive pressure drop and  cavitation. The velocity within the eye will control the NPSHR, **[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links].
 			see also **[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links]

 			For **[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links] see this web page.
 			[hr][/hr] 			*Inducer:* an inducer is a device attached  to the impeller eye that is usually shaped like a screw that helps  increase the pressure at the impeller vane entrance and make viscous or  liquids with high solids pumpable. It can also be used to reduce the  NPSHR.


 			(image source: The Worthington Pump Co. - Pumpworld). 			

 			see articles on inducers on this web page: **[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links]

----------


## Esam

*Internal gear pump*: a positive displacement pump. 
 			The internal gear pumping principle was invented by Jens Nielsen, one of the founders of  **[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links].   It uses two rotating gears which un-mesh at the suction side of the  pump to create voids which allow atmospheric pressure to force fluid  into the pump.  The spaces between the gear teeth transport the fluid on  either side of a crescent to the discharge side, and then the gears  re-mesh to discharge the fluid.  Viking's internal gear design has an  outer drive gear (rotor- shown in orange) which turns the inner, driven  gear (idler-shown in white).  


 			Viking Pumps is a major supplier of these pumps **[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links]
 			[hr][/hr] 			*Jet pump*: a jet pump is a commonly  available residential water supply pump. It has an interesting clever  design that can lift water from a well (up to 25 feet) and allow it to  function without a check valve on the suction and furthermore does not  require priming. The heart of the design is a **[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links]  (source of water is from the discharge side of the impeller) that  creates low pressure providing a vacuum at the suction and allowing the  pump to lift fluids.

 			see this article for **[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links]
**[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links]
**[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links]
 			[hr][/hr] 			*K factor*: a factor that provides the head loss for fittings. It is used with the following equation


 			The K factor for various fittings can he found in many  publications. As an example, Figure 6 depicts the relationship between  the K factor of a 90 screwed elbow and the diameter (D). The type of  fitting dictates the relationship between the friction loss and the pipe  size.

 			Note: this method assumes that the flow is fully turbulent (see the demarcation line on the Moody diagram of **[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links]).


 			Figure 6 K factor vs. diameter of fitting (source: Hydraulic Institute Engineering data book)
 			Another good source for fitting K factors is the Crane Technical Data Brochure. 

 			Figure 7 Values for the K factor with respect to the friction factor for a standard tee.


 			The Crane technical paper gives the K value for a fitting in terms of the term fT as in this example for a standard tee.



 			As is the case for the data shown in Figure 6,  the friction loss for fittings is based on the assumption that the flow  is highly turbulent, in fact that it is so turbulent that the Reynolds  number is no longer a factor and pipe roughness is the main parameter  affecting friction. This can be seen in the **[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links]. There is a line in the diagram that locates the position where full turbulence starts.


 			The term fT used by Crane is the friction factor and is the same as that given by the Colebrook or the Swamee-Jain equation.


			 			When the Reynolds number becomes large the value of fT (using the **[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links]) becomes:



 			furthermore the **[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links]  assumes that the roughness of the material will correspond to new steel  whose value is 0.00015 ft. Therefore, the previous equation for fT becomes:



 			Therefore the value of the K factor is easily calculated based on the diameter of the fitting, the friction factor fT and the multiplication factor for each type of fitting.

 			[hr][/hr] 			*Laminar*: A distinct flow regime that occurs at low **[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links] (Re <2000). It is characterized by fluid particles in layers moving past one another without mixing.


 			Figure 8 Laminar flow velocity profile.
 			[hr][/hr] 			*Lobe pump*:  a positive displacement  pump. Primarily used in food applications because they handle solids  without damaging them. Lobes are driven by external timing gears as a  result the lobes do not make contact. Liquid travels around the interior  of the casing in the pockets between the lobes and the casing, meshing  of the lobes forces liquid through the outlet port under pressure. They  also offer continuous and intermittent reversible flows and can operate  dry for brief periods of time. Typical applications are in following  industries: food, pharmaceuticals, paper & pulp, beverages, chemical  and biotechnology.



 			 			Viking Pumps is a major supplier of these pumps **[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links]
 			[hr][/hr] 			*Low NPSH pump*: a pump designed for application with a low **[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links], usually has an inducer. **[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links]
 			see **[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links] for more information
 			[hr][/hr] 			*Mechanical seal*: a name for the joint  that seals the fluid in the pump stopping it from coming out at the  joint between the casing and the pump shaft. The following image  (source: the Pump Handbook by McGraw-Hill) shows a typical mechanical  seal. A mechanical seal is a sealing device which forms a running seal  between rotating and stationary parts. They were developed to overcome  the disadvantages of compression packing. Leakage can be reduced to a  level meeting environmental standards of government regulating agencies  and maintenance costs can be lower. 
**[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links].

 			[hr][/hr] 			*Mercury (Hg)*: A metal that remains  liquid at room temperature. This property makes it useful when used in a  thin vertical glass tube since small changes in pressure can be  measured as changes in the mercury column height. The inch of mercury is  often used as a unit for measuring vacuum level or pressures below  atmospheric pressure.


 			The relationship between inches of mercury, psi and psia units of pressure.
 			[hr][/hr] 			 *Minimum flow rate*
 			Most centrifugal pumps should not be  used at a flow rate less than 50% of the B.E.P. (best efficiency point)  flow rate without a recirculation line. (**[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links])  If your system requires a flow rate of 50% or less then use a  recirculation line to increase the flow through the pump keeping the  flow low in the system, or install a variable speed drive.
 			see also the**[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links]

 			How is the minimum flow of a centrifugal pump established (answer from the Hydraulic Institute **[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links])
 			The factors which determine minimum allowable rate of flow include the following:

 			* Temperature rise of the liquid -- This is usually established as  15F and results in a very low limit. However, if a pump operates at  shut off, it could overheat badly.

 			* Radial hydraulic thrust on impellers -- This is most serious  with single volute pumps and, even at flow rates as high as 50% of BEP  could cause reduced bearing life, excessive shaft deflection, seal  failures, impeller rubbing and shaft breakage.

 			* Flow re-circulation in the pump impeller -- This can also occur  below 50% of BEP causing noise, vibration, cavitation and mechanical  damage.

 			* Total head characteristic curve - Some pump curves droop toward  shut off, and some VTP curves show a dip in the curve. Operation in such  regions should be avoided.


 			There is no standard which establishes precise limits for minimum  flow in pumps, but "ANSI/HI 9.6.3-1997 Centrifugal and Vertical Pumps -  Allowable Operating Region" discusses all of the factors involved and  provides recommendations for the "Preferred Operating Region".

----------


## Esam

*Minimum NPSHA*: the margin of safety or minimum NPSHA that  should be available depends in part on the amount of suction energy of  the pump. The suction energy level of the pump increases with: 			
The casing suction diameterThe pump speedThe suction specific speedThe specific gravity of the fluid
 				Anything that increases the velocity of the pump impeller eye,  the rate of flow of the pump, or the specific gravity, increases the  suction energy of the pump.

 			The **[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links] has offered these guidelines for minimum NPSHA depending on the level of suction energy.
 			 			[table]
 				[TR]
 					[TD="colspan: 4"] 						 							Minimum NPSH Margin Ratio Guidelines NPSHA/NPSHR 					[/TD]
 				[/TR]
 				[TR]
 					[TD][/TD]
 					[TD="colspan: 3"] 						 							Suction energy levels 					[/TD]
 				[/TR]
 				[TR]
 					[TD]*Application*[/TD]
 					[TD]Low[/TD]
 					[TD]Medium[/TD]
 					[TD]High[/TD]
 				[/TR]
 				[TR]
 					[TD]Petroleum[/TD]
 					[TD]1.1-a[/TD]
 					[TD]1.3-a[/TD]
 					[TD][/TD]
 				[/TR]
 				[TR]
 					[TD]Chemical[/TD]
 					[TD]1.1-a[/TD]
 					[TD]1.3-a[/TD]
 					[TD][/TD]
 				[/TR]
 				[TR]
 					[TD]Electrical power[/TD]
 					[TD]1.1-a[/TD]
 					[TD]1.5-a[/TD]
 					[TD]2.0-a[/TD]
 				[/TR]
 				[TR]
 					[TD]Nuclear power[/TD]
 					[TD]1.5-b[/TD]
 					[TD]2.-a[/TD]
 					[TD]2.5-a[/TD]
 				[/TR]
 				[TR]
 					[TD]Cooling towers[/TD]
 					[TD]1.3-b[/TD]
 					[TD]1.5-a[/TD]
 					[TD]2.0-a[/TD]
 				[/TR]
 				[TR]
 					[TD]Water/Waste water[/TD]
 					[TD]1.1-a[/TD]
 					[TD]1.3-a[/TD]
 					[TD]2.0-a[/TD]
 				[/TR]
 				[TR]
 					[TD]General industry[/TD]
 					[TD]1.1-a[/TD]
 					[TD]1.2-a[/TD]
 					[TD][/TD]
 				[/TR]
 				[TR]
 					[TD]Pulp and paper[/TD]
 					[TD]1.1-a[/TD]
 					[TD]1.3-a[/TD]
 					[TD][/TD]
 				[/TR]
 				[TR]
 					[TD]Building services[/TD]
 					[TD]1.1-a[/TD]
 					[TD]1.3-a[/TD]
 					[TD][/TD]
 				[/TR]
 				[TR]
 					[TD]Slurry[/TD]
 					[TD]1.1-a[/TD]
 					[TD][/TD]
 					[TD][/TD]
 				[/TR]
 				[TR]
 					[TD]Pipeline[/TD]
 					[TD]1.3-a[/TD]
 					[TD]1.7-a[/TD]
 					[TD]2.0-a[/TD]
 				[/TR]
 				[TR]
 					[TD]Water/Food[/TD]
 					[TD]1.2-a[/TD]
 					[TD]1.5-a[/TD]
 					[TD]2.0-a[/TD]
 				[/TR]
 			[/table]
 			"a" - or 0.6 m (2 feet) whichever is greater
 			"b" - or 0.9 m (3 feet) whichever is greater
 			"a" - or 1.5 m (5 feet) whichever is greater

 			see articles on NPSH guidelines on this web page: **[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links] 			
 			[hr][/hr] 			 *Motor frame*:NEMA (National electrical  Manufacturers Association) provides standards to which electric  induction motors are built. Each frame size (for example frame 254T) is  built to specified dimensions. The amount of room required for the pump  assembly will depend on the size and construction of the motor. It is  easy to find a chart that provides the motor dimensions vs. the frame  size (see following chart).


 			but I looked long and hard to find a chart that provides the frame size vs. the rpm and hp, and here it is:

 			 			[hr][/hr] 			*Moody diagram*: A graphical representation of the laminar and turbulent (Colebrook) flow equations.


 			Figure 9 the Moody diagram, a graphical representation of the  laminar flow equation and the Colebrook equation for the friction factor  f.
 			[hr][/hr] 			*Net Positive Suction Head Available (N.P.S.H.A.)*:  Net positive suction head available. The head or specific energy at the  pump suction flange less the vapor pressure head of the fluid. see **[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links]

 			See this **[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links]
 			Also for those **[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links].
 			[hr][/hr] 			*Net Positive Suction Head Required (N.P.S.H.R.)*:  Net positive suction head required. The manufacturers estimate on the  NPSH required for the pump at a specific flow, total head, speed and  impeller diameter. This is determined my measurement. see also **[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links]

 			This next figure provides an estimate for NPSHR for centrifugal  pumps (source: Centrifugal Pump Design & Application by  Val.S.Labanoff and Robert R Ross, contributed by a pump forum friend,  Ravi Sankar.

 			You can join the centrifugal pump discussion forum at **[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links]
 			For a larger scale image download **[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links]

----------


## Esam

*Newtonian fluid*: A fluid whose viscosity is constant and  independent of the rate of shear (strain). For Newtonian fluids, there  is a linear relationship between the rate of shear and the tangential  stress between layers. 			For more information see **[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links]

 			Figure 10 Shear/strain relationship for a Newtonian fluid.

 			If you want to understand what a non-Newtonian fluid feels like  and what it means for viscosity to change with the rate of shear, try  this experiment.

 			In a large shallow bowl make a solution of approximately 1 part  water and 2 parts corn starch, try moving this fluid rapidly around with  your fingers. When the fingers are moved slowly, the solution behaves  as expected, offering little resistance. The faster you try to move  through the fluid, the higher the resistance. At that rate of shear, the  solution almost behaves as a solid, If you move your fingers fast  enough they will skip over the surface. This is what is meant by  viscosity being dependent on rate of shear. Compare this behavior to  that of molasses; you will find that even though molasses is viscous its  viscosity changes very little with the shear rate. Molasses flows  readily no matter how fast the movement. 
 			See a**[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links].
 			[hr][/hr] 			 			*Operating point*: The point (flow rate and total head) at which the pump operates. It is located at the intersection of the **[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links] and the performance curve of a pump. It corresponds to the flow and head required for the process.


 			Figure 11 Operating point on a pump performance curve.
 			[hr][/hr] 			*Packing*: see **[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links].
 			[hr][/hr] 			*Partial emission pump*: see **[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links].
 			[hr][/hr] 			*Peripheral pump*: also known as  regenerative or regenerative turbine pump. These are low capacity (150  gpm or 34 m3/h) high head (5400 ft or 1645 m) pumps. The impeller has  short vanes at the periphery and these vanes pass through an annular  channel. The fluid enters between two impeller vanes and is set into a  circular motion, this adds energy to the fluid particles which travel in  a spiral like path from the inlet to the outlet. Each set of vanes  continuously adds energy to the fluid particles.  
 			Peripheral pumps are more efficient at these low flow high head  conditions than centrifugal pumps, they also require much less NPSHA  than an equivalent centrifugal pump. They can also handle liquids with  up to 20% entrained gases.

 			They are used in a wide range of domestic and industrial applications.
 			[table]
 				[TR]
 					[TD][/TD]
 					[TD][/TD]
 				[/TR]
 			[/table]

 			For a good explanation of the principal of operation see this **[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links] 			
			and also from the **[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links].

			see also **[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links] from Lawrence Pumps. 			
[hr][/hr] 			*Performance curve*: A plot of Total Head  vs. flow for a specific pump model, impeller diameter and speed (syn  characteristic curve, water performance curve). **[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links]

 			For **[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links] see this tutorial

----------


## Esam

*Pipe roughness*: A measurement of the average height of peaks  producing roughness on the internal surface of pipes. Roughness is  measured in many locations and then averaged, it is usually defined in  micro-inches RMS (root mean square). **[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links]

 			[hr][/hr] 			*Piping pressure (maximum)*: it may be  necessary in certain applications to check the maximum rating of your  pipes to avoid bursting due to excessive pressure. The ASME pressure  piping code B31.3 provides the maximum stress for pipes of various  materials. Also the pipe flange rating will have to be checked.
 			for more information see **[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links]

 			Table of allowable piping stress from the ASME pressure piping code B31.3
 			[hr][/hr] 			*Pitot pump*: also know as rotating  casing pump. This pumps specialty is low to medium flow rates at high  pressures.  It is frequently used for high pressure shower supply on  paper machines. 

 			Pitot (Roto-jet ) pump
 			see **[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links] for more information
 			see also **[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links] from Lawrence Pumps. 			
 			[hr][/hr] 			*Pressure*: The application of a force to a  body producing more or less compression within the liquid. In a static  fluid pressure varies with height.
 			Fluid weight is the cause of hydrostatic pressure. A thin slice of  fluid is isolated so that the forces surrounding it can be visualized.  If we make the slice very thin, the pressure at the top and bottom of  the slice will be the same. The slice is compressed top and bottom by  force vectors opposing each other. The fluid in the slice also exerts  pressure in the horizontal direction against the pipe walls. These  forces are balanced by stress within the pipe wall. The pressure at the  bottom of the slice will be equal to the weight of fluid above it  divided by the area.


 			The weight of a fluid column of height (z) is:

 			The pressure (p) is equal to the fluid weight (F) divided by the  cross-sectional area (A) at the point where the pressure is calculated :

 			where F : force due to fluid weight

 			          V  : volume

 			g : acceleration due to gravity (32.17 ft/s2)

  : fluid density in pound mass per unit volume

   : fluid density or specific weight in pound force per unit volume        
 			[hr][/hr] 			*Pressure head*: an expression of energy, specifically it is energy per unit weight of fluid displaced. **[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links].
 			We often need to calculate the pressure head that corresponds to  the pressure. Pressure can be converted to pressure head or fluid column  height for any fluid. However, not all fluids have the same density.  Water for example has a density of 62.34 pounds per cubic foot whereas  gasoline has a density of 46.75 pounds per cubic foot. **[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links]  is the ratio of the fluid density to water density at standard  conditions. By definition water has a specific gravity (SG) of 1. To  convert pressure to pressure head, the specific gravity SG of the fluid  must be known. The specific gravity of a fluid is:
 

 			where  is the fluid density and  is water density at standard conditions. Since
 
 			where   is the fluid density in terms of weight per unit volume. The constant  gc is required to provide a relationship between mass in lbm and force  in lbf . 


 			The quantity  ( = 62.34 lbm/ft3 for water at 60 F) is:


 			After simplification, the relationship between the fluid column height and the pressure at the bottom of the column is:

----------


## Esam

s the Suction Inlet under pressure or by gravity and as the ROTOR 1  turns within the flexible rubber STATOR 2 forming tightly sealed  cavities 3 which moves the Liquid toward the Discharge Outlet. Pumping  action starts the instant the ROTOR turns. Liquid acts as the lubricant  between the pumping elements.
			 			[hr][/hr] 			*Pseudoplastic*: The property of a fluid whose viscosity increases slowly with rate of shear.

 			For more information see **[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links]
 			[hr][/hr] 			*Pumps as turbines (PAT)*: Pumps used in reverse to act as turbines.

 			For more information see **[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links]
**[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links]*Radial flow pump*: refers to the design of a centrifugal pump for medium head and medium flow or high head and low flow. The value of the **[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links] will provide an indication whether a radial pump design is suitable for your application. see **[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links]
 			[hr][/hr] 			*Radial vane pump*: also known as partial  emission pump or vane pump. A frame mounted, end suction, top  centerline discharge, ANSI pump designed specifically to handle  corrosive chemicals at low flows. 

 			Vane pump
 			see **[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links] for more information
 			 			see also **[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links] from Lawrence Pumps 			
[hr][/hr] 			*Recessed impeller pump*: sometimes known  as vortex pump. This is a frame-mounted, back pull-out, end suction,  recessed impeller, tangential discharge pump designed specifically to  handle certain bulky or fibrous solids, air or gas entrained liquids or  shear sensitive liquids.

 			Recessed impeller pump
 			see **[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links] for more information

			see also **[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links] from the Lawrence pump company. 			
 			[hr][/hr] 				 			*Recirculation*: at low flow and  high flow compared to the flow at the B.E.P. the fluid will start to  recirculate or move in a reverse direction at the suction and at the  discharge.

 			 			 				It is well established that cavitation type of damage seen on the  inlet vanes and not associated with inadequate NPSH can be directly  linked to the pump operating in the suction recirculation zone. Similar  damage seen on the discharge vane tips can also be associated with pump  operation in the discharge recirculation zone.

 				The suction and discharge recirculation may occur at different points as shown on the characteristic curve below.



 				[hr][/hr] 				*Regenerative pump*: see **[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links], also known as regenerative turbine pump.
 			[hr][/hr] 				*Reynolds number*: the Reynolds number  is proportional to the ratio of velocity and viscosity, the higher the  number (higher than 4000 for turbulent flow) the more turbulent the flow  and the less **[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links] has an effect. At high Reynolds numbers (see the transition line to complete turbulence in the **[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links]) the **[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links]  becomes the controlling factor for friction loss. The lower the  Reynolds number (less then 2000 for laminar flow) the more the viscosity  of the fluid is relevant. Most applications are in the turbulent flow  regime mode unless the fluid is very viscous (for example 300 cSt and  up), the velocity has to be very low to produce the laminar flow regime.

 			[hr][/hr] 			*Rheopectic*: The property of a fluid whose viscosity increases with time.

 			For more information see **[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links]
 			 			[hr][/hr] 			*Rubber pump liner*: see **[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links].
 			[hr][/hr] 			 			*Screw impeller*: The screw centrifugal impeller is shaped like a tapered Archimedes screw.  			Originally developped for pumping live fish, the screw centrifugal pump has become popular for 
			many solids handling applications. 			
 
			for more information see **[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links] from Lawrence pumps. 			
 			see also **[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links] from the Hayward Gordon  pump company. 			 			
 			[hr][/hr] 			 			*Sealless pump*: see **[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links] for more information, images and references on sealless pumps.

----------


## Esam

see **[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links] for more information
 			[hr][/hr] 			*Shroud*: see **[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links].
 			[hr][/hr] 			*Shut-off head*: The Total Head corresponding to zero flow on the pump performance curve.


 			Figure 12 Shut-off head and other points on a centrifugal pump performance curve.
 			The shut-off head is the Total Head that the pump can deliver at  zero flow (see next Figure). The shut-off head is important for 2  reasons.


 			1. In certain systems (admittedly unusual), the pump discharge  line may have to run at a much higher elevation than the final discharge  point. The fluid must first reach the higher elevation in the system.  If the shut-off head is smaller than the static head corresponding to  the high point, then flow will not be established in the system.


 			2. During start-up and checkout of the pump, a quick way to  determine if the pump has the potential capacity to deliver the head and  flow required, is to measure the shut-off head. This value can be  compared to the shut-off head predicted by the performance curve of the  pump.



 			[hr][/hr] 			*Side channel pump*: is a pump that provides high head at  			low flows with the added benefit of being able to handle gases. The principle of the pump  			is well explained on the  **[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links]  			web site. I have included a **[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links] (as is) just in case one day the Sero web page is changed or disappears,  			my thanks to Sero for making this available.The principal of the side channel is similar  			to the **[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links] pump.
 
 
 
			You will find other examples and suppliers of side channel pumps in the **[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links]  			using pump type: side channel.
 			[hr][/hr] 			*Siphon*: A system of piping or tubing  where the exit point is lower than the entry point and where some part  of the piping is above the free surface of the fluid source.


 			Figure 14 A siphon.
 				See this article for **[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links].
 				[hr][/hr] 				*Sludge pump*: certain types of sludges tend to settle very  				quickly and are hard to keep in suspension. The Lawrence pump company has solved this  				problem by putting an agitator in front of the pump suction.

 			Sludge pump
 			see **[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links] for more information
 			[hr][/hr] 			*Slurry pump*: a rugged heavy duty pump  intended for aggressive or abrasive slurry solutions typically found in  the mining industry with particles of various sizes.  It achieves this  by lining the inside of the pump casing as well as the impeller with  rubber.

 			Slurry pump
 			see **[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links] for more information

			and also **[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links]

 			[hr][/hr] 			*Specific gravity (SG)*: the ratio of the  density of a fluid to that of water at standard conditions. If the SG is  1 then the density is the same as water, if it is less than 1 then the  fluid is less dense than water and heavier than water if the SG is  bigger than 1. Mercury has an SG of 14, gasoline has an SG of 0.8.  The  usefulness of specific gravity is that it has no units since it is a  comparative measure of density or a ratio of densities therefore  specific gravity will have the same value no matter what system of units  we are using, Imperial or metric.
 			For more information see **[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links]

 			 			See this **[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links].

 			 			the above image is from the Cameron Hydraulic data book which  contains a great deal of information on fluid properties. To purchase go  to the **[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links].
 			[hr][/hr] 			*Specific speed*: a number that provides an indication what type of pump (for example radial,  			mixed flow or axial) is suitable for the application. The figure below is know as the Balje diagram.

 			Specific speed is calculated with this formula:
 

The conversion from metric to imperial specific speed NSm is given below:

 
			see also **[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links]
 			for an article on this topic see **[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links]
 			and here is a **[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links].
 			[hr][/hr] 			*Standard volute pump close coupled*:  The volute is the casing which has a spiral shape. The  			motor shaft is connected to the impeller without an intermediate  coupling providing a compact arrangement. The flow range is typically  less than 300 gpm. 			
 
			The picture for this pump is provided courtesy of **[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links]. 			 			
[hr][/hr] 			*Standard volute pump separately coupled*: The volute is the casing which has a spiral shape. The  			motor shaft is connected to the impeller with an intermediate shaft with two couplings. 			
 
			The picture for this pump is provided courtesy of **[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links]. 			 			
[hr][/hr] 			*Strain*: The ratio between the absolute displacement of a reference point within a body to a characteristic length of the body.**[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links].

----------


## Esam

*Stress*: In this case refers to tangential stress or the force between the layers of fluid divided by the surface area between them.
			 			[hr][/hr] 			*Stuffing box*: the joint that seals the  fluid in the pump stopping it from coming out between the casing and the  pump shaft. The following image (source: the Pump Handbook by  McGraw-Hill) shows a typical stuffing box with gland packing. The  function of packing is to control leakage and not to eliminate it  completely. The packing must be lubricated, and a flow from 40 to 60  drops per minute out of the stuffing box must be maintained for proper  lubrication. This makes this type of seal unfit for situations where  leakage is unacceptable but they are very common in large primary sector  industries such a mining and pulp and paper. 

**[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links] 




 			[hr][/hr] 			*Submersion*: Submersion as used here is the height between the free surface of a suction tank and the pump intake pipe.

**[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links]
 			Figure 13 Minimum submersion to avoid vortex formation.
 			Try this **[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links]
 			Here's a nice picture of an axial flow pump with an suction intake submersion problem.

 			see this **[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links]**[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links]
 			and for more information on this web site see this **[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links].
 			The **[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links] publishes a guide on Pump Intake Design that provides detail recommendations.
 			The Goulds pump company provides similar **[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links]s at no cost.
 			[hr][/hr] 			 			*Suction flow splitter*: a rib  of metal across the pump suction that is installed on certain pumps. 			It's purpose is to remove  large scale vortexes so that the stream  lines are as parallel as possible as the fluid enters the impeller eye.
 			[hr][/hr] 			 			 			*Suction guide*: a device that helps straighten the flow ahead of a pump that has a 90 degree elbow immediately ahead of it. 

 			There are two types of suction gudes as far as I know.



 			Suction guide by Armstrong, see **[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links]
 			The other type of suction guide is the Cheng vane system


 			The Cheng vane, see **[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links]

			Another manufacturer of standard suction guide components from 2" to 14" diameter is **[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links]. 			Bell Gossett produce a suction guide they call a suction diffuser  			
**[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links] 			
			see the Bell Gossett **[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links] 			
 			[hr][/hr]See More: Pump and pump system glossary

----------


## Esam

*Suction specific speed*: a number that indicates whether the  suction conditions are sufficient to prevent cavitation. According to  the Hydraulic Institute the suction specific speed should be less than  8500. Other experiments have shown that the suction specific speed could  be as high as 11000. 			When a pump has a high suction specific speed value, it will also  mean that the impeller inlet area has to be large to reduce the inlet  velocity which is needed to enable a low NPSHR. However, if you continue  to increase the impeller inlet area (to reduce NPSHR), you will reach a  point where the inlet area is too large resulting in suction  recirculation (hydraulically unstable causing vibration, cavitation,  erosion etc..). The recommended maximum suction specifc speed  value is  to avoid reaching that point. (paragraph contributed by Mike Tan of the**[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links]).

 			Keeping the suction  specific speed below 8500 is also a way of determining the maximum speed of a pump and avoiding cavitation.

 			For a double suction pump, half the value of Q is used for calculating the suction specific speed.
 			Suction specific speed is calculated with this formula:
see also **[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links]

			The conversion from metric to imperial suction specific speed Sm is given below:

 


The term NSS is also used to represent the suction specific speed.

 			According to the **[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links]  the efficiency of the pump is maximum when the suction specific speed  is between 2000 and 4000. When S lies outside this range the efficiency  must be derated according to the following figure.

 			source: Pump & Systems magazine August 2005
 			for an article on this topic see **[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links]
 				 					and here is a **[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links].

				The following chart provides some more precise guidelines on desirable suction specific speed operating ranges. 				 				
 
				Source: Process Industry Practices RESP 001 Design of Pumping Systems that use Centrifugal Pumps. 				
 				[hr][/hr] 				*Suction Static Head*: The difference in elevation between the liquid level of the fluid source and the centerline of the pump (**[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links]).  This head also includes any additional pressure head that may be  present at the suction tank fluid surface, for example as in the case of  a pressurized suction tank.

 			 			[hr][/hr] 			*Suction Static Lift*: The same definition  as the Suction Static head. This term is only used when the pump  centerline is above the suction tank fluid surface.

 			[hr][/hr] 			*System*: as in pump system. The system  includes all the piping, including the equipment, starting at the inlet  point (often the fluid surface of the suction tank) and ending at the  outlet point (often the fluid surface of the discharge tank).

 			[hr][/hr] 			*System Curve*: A graphical representation  the pump Total Head vs. flow. Calculations are done for the total head  at different flow rates, these points are linked and form a curve called  the system curve. It can be used to predict how the pump will perform  at different flow rates. The Total head includes the static head which  is constant and the friction head and velocity head difference which  depends on the flow rate (**[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links]). The intersection of the system curve with the pump characteristic curve defines the operating point of the pump.  

 			Changes to the system such as opening or closing valves or making  the discharge pipe longer or shorter will change the friction head which  will change the shape of the system curve and therefore the operating  point. In the following figure there is a system which has a static head  of 100 feet and a total system resistance of approximately 20 feet  shown by curve A. There is a valve at the pumpdischarge which is  partially closed. If the friction head is increased (i.e. valve is  closed) then the operating point will shift from A to point B and the  flow will drop. If the friction head is decreased (i.e. valve is opened)  then the operating point will shift to point C and the flow increases.

 			[hr][/hr] 			*System requirements*: Those elements that  determine Total Head: friction and the system inlet and outlet  conditions (for example velocity, elevation and pressure).

 			[hr][/hr] 			*Swamee-Jain equation*: an equation that can be used as a substitute for the Colebrook equation for calculating the friction factor f.

 			[hr][/hr] 			*Thixotropic*: The property of a fluid whose viscosity decreases with time.

 			[hr][/hr] 			*Total Dynamic Head*: Identical to Total Head. This term is no longer used and has been replaced by the shorter Total Head.

 			[hr][/hr] 			*Total Head*: The difference between the pressure head at the discharge and suction flange of the pump ( syn Total Dynamic Head. **[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links], system head). see also **[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links]

 			[hr][/hr] 			*Total Static Head*: The difference  between the discharge and suction static head including the difference  between the surface pressure of the discharge and suction tanks if the  tanks are pressurized (**[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links]). See also**[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links]

----------


## Esam

*Turbulent*: The behavior of fluid articles within a flow stream  characterized by the rapid movement of particles in many directions as  well as the general direction of the overall fluid flow.

 			[hr][/hr] 			*Vacuum*: pressure less than atmospheric pressure.

 			[hr][/hr] 			*Vanes (no.of)*: see **[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links].

 			[hr][/hr] 			*Vane pass frequency*: when doing a  vibration analysis this frequency (no. of vanes times the shaft speed)  and it's even multiples shows up as a peak which can indicate a damaged  or imbalanced impeller.

 			Figure 15 Noise vibration spectra showing vane pass frequency (source: The Pump Handbook publ. by McGrawHill)

 			see articles on pump vibration sources on this web page: **[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links] 			
 			[hr][/hr] 			*Vane pump*: **[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links].
 			[hr][/hr] 			*Vane pump (hydraulic)*: a positive  displacement pump. Vane pumps are used successfully in a wide variety of  applications (see below). Because of vane strength and the absence of  metal-to-metal contact, vane pumps are ideally suited for low-viscosity,  non lubricating liquids up to 2,200 cSt / 10,000 SSU. Such liquids  include LPG, ammonia, solvents, alcohol, fuel oils, gasoline, and  refrigerants.



 			1.  A slotted rotor or impeller is eccentrically supported in a  cycloidal cam. The rotor is located close to the wall of the cam so a  crescent-shaped cavity is formed. The rotor is sealed into the cam by  two sideplates. Vanes or blades fit within the slots of the impeller. As  the impeller rotates (yellow arrow) and fluid enters the pump,  centrifugal force, hydraulic pressure, and/or pushrods push the vanes to  the walls of the housing. The tight seal among the vanes, rotor, cam,  and sideplate is the key to the good suction characteristics common to  the Vane pumping principle.


 			2.  The housing and cam force fluid into the pumping chamber  through holes in the cam (small red arrow on the bottom of the pump).  Fluid enters the pockets created by the vanes, rotor, cam, and  sideplate.


 			3.  As the impeller continues around, the vanes sweep the fluid to  the opposite side of the crescent where it is squeezed through  discharge holes of the cam as the vane approaches the point of the  crescent (small red arrow on the side of the pump).   Fluid then exits  the discharge port.

 			Rexroth is a major manufacturer of vane pumps  **[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links]
 			see also **[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links]
 			[hr][/hr] 			*Vapor pressure*: The pressure at which a liquid boils for a specific temperature.


 			Figure 16 The boundary between liquid and vapor phase of a fluid. A  fluid can be vaporized by increasing the temperature or decreasing the  pressure.

 			Figure 17 Vapor pressure vs. temperature for various fluids.
**[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links] is available in the Goulds pump catalogue.
 			[hr][/hr] 			*Venturi (Bernoulli's law)*: a venturi is a pipe that has a gradual restriction  			that opens up into a gradual enlargement. The area of the restriction will have a lower pressure than the  			enlarged area ahead of it. If the difference in diameters is large you can even  			produce a very high vacuum (-28 feet of water). I use a cheap plastic venturi made by Fisher or Cole Palmer  			for an experiment that I do to demonstrate vapor pressure during my training seminars and it is very  			easy to create very high absolute vacuum. 
 			 			In certain locations I can't do this experiment, because hey don't have a source of water in hotel suites,  			too bad because it's always a winner, so I have to revert to a **[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links] 			**[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links].  			It's a 14 Meg download so you better have a fast connection to view it. If you want to purchase this nifty plastic  			venturi you can get it **[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links] it only costs $10, and no, I don't  get a commission.

 			It is not easy to understand why low pressure occurs in the small  diameter area of the venturi. I have come up with this explanation that  seems to help.

 			It is clear that all the flow must pass from the larger section to the smaller section. Or in other  			words, the flow rate will remain the same in the large and small portions of the tube. The flow rate  			is the same, but the velocity changes. The velocity is greater in the small portion of the tube. There  			is a relationship between the pressure energy and the velocity energy, if velocity increases the pressure  			energy must decrease. This is the principle of conservation of energy at work which is also Bernoulli's law.  			This is similar to a bicycle rider at the top of a hill. At the top or point 1 (see Figure 18 below), the  			elevation of the cyclist is high and the velocity low. At the bottom (point 2) the elevation is low and the  			velocity is high,	elevation (potential) energy has been converted to velocity (kinetic) energy. Pressure  			and velocity energies	behave in the same way. In the large part of the pipe the pressure is high and velocity is low, in the  			small part, pressure is low and velocity high.


 			Figure 18 The venturi effect.

 			Bernoulli's law is a relationship between two points within a system that states that the sum of the  			energies that correspond to pressure, velocity and elevation must be conserved. 

 			The general form of the law  (neglecting friction) is:

 
 		where p1 is the pressure, v1 the velocity  and h1 the elevation  		at point 1 and the same parameters are used at point 2. Gamma  is the fluid density and g  		the acceleration due to gravity.


 		In the case of the cyclist there is no pressure and only the velocity and elevation can vary, so that  		Bernoulli's law becomes:

 
		as the cyclist goes down the hill h2 becomes smaller than h1 and to  		balance the equation then v2 must be larger than v1.

 		 In the case of the venturi tube there is no elevation change and only the velocity and pressure can vary,  		 so that Bernoulli's law becomes:

 
			We can clearly see that if v2 is greater than v1 then p2 must be smaller than v1 to balance the equation.

 			for an article on this and related subjects see**[link Point to another website Only the registered members can access]
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<![CDATA[[Only Registered And Activated Users Can See Links]
 			[hr][/hr] 			*Viscosity*: A property from which a  fluid's resistance to movement can be evaluated. The resistance is  caused by friction between the fluid and the boundary wall and  internally by the fluid layers moving at different velocities. The more  viscous the fluid the higher the friction loss in the system.  Centrifugal pumps are affected by viscosity and for fluids with a  viscosity  higher than 10 cSt, the performance of the pump must be  corrected. **[link Point to another website Only the registered members can access]
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<![CDATA[[Only Registered And Activated Users Can See Links] to determine the correction for viscosity to the water performance curve of the pump.

 			The following figure which you can find in the Goulds pump  catalogue in the Technical Section shows the effect of viscosity on pump  performance.

 			This next figure is a chart of values for viscosity for different liquids which you can find in the Cameron Hydraulic data book.

 			The basic unit of viscosity is known as the Poise or centiPoise  (cP) named after the French scientist Poiseuille who discovered a  practical method of measuring viscosity. The greek letter   is used to represent viscosity. There are two types of viscosity, the  first just mentioned is known as absolute viscosity and the other for  which the greek letter nu   is used is called the kinematic viscosity. The unit of kinematic  viscosity is the centiStoke (cSt) named after the English scientist  Stokes.
 			The relationship between the two is:

**[link Point to another website Only the registered members can access]
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<![CDATA[[Only Registered And Activated Users Can See Links] can also be found in the Goulds pump catalogue.
 			[hr][/hr] 			*Viscosity correction*: **[link Point to another website Only the registered members can access]
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<![CDATA[[Only Registered And Activated Users Can See Links].
 			[hr][/hr] 			*Viscous drag pump*: a pump whose  impeller has no vanes but relies on fluid contact with a flat rotating  plate turning at high speed to move the liquid.

 			Viscous drag pump
 			see **[link Point to another website Only the registered members can access]
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<![CDATA[[Only Registered And Activated Users Can See Links] for more information
 			[hr][/hr] 			*Volute*: syn casing.

 			[hr][/hr] 			*Vortex*: see **[link Point to another website Only the registered members can access]
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<![CDATA[[Only Registered And Activated Users Can See Links].
 			[hr][/hr] 			*Vortex pump*: see **[link Point to another website Only the registered members can access]
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<![CDATA[[Only Registered And Activated Users Can See Links].
 			[hr][/hr] 			*Water hammer (pressure surge)*: If in  systems with long discharge lines,(e.g. in industrial and municipal  water supply systems ,in refineries and power stations) the pumped fluid  is accelerated or decelerated, pressure fluctuations occur owing to the  changes in velocity. If these velocity changes occur rapidly , they  propagate a pressure surge in the piping system, originating from the  point of disturbance ; propagation takes place in both directions  (direct waves),and these waves are reflected (indirect waves) at points  of discontinuity ,e.g. changes of the cross sectional area ,pipe  branches, control or isolating valves, pumps or reservoir. The boundary  conditions decide whether these reflections cause negative or positive  surges. The summation of all direct and indirect waves at a given point  at a given time produces the conditions present at this point.


 			These pressure surges, in addition to the normal working pressure  ,can lead to excessive pressure and stresses in components of the  installation . In severe cases such pressure surges may lead to failure  of pipe work, of fittings or of the pump casings. The minimum pressure  surge may, particularly at the highest point of the installation ,reach  the vapor pressure of the pumped liquid and cause vaporization leading  to separation of the liquid column. The ensuing pressure increase and  collision of the separated liquid column can lead to considerable water  hammer .The pressure surges occurring under these conditions can also  lead to the failure or collapse of components in the installation.


 			For the maximum pressure fluctuation the JOUKOWSKY pressure surge formula can be used:

 			                                Δp = ρ . a . Δv


 			                                Where   ρ = density of the pumped liquid

 			                                              a = velocity of wave propagation 

 			                                              Δv = change of velocity of the flow in the pipe.


 			The full pressure fluctuation corresponding to the change of  velocity Δv occurs only if the change of velocity Δv takes place during  the period.


 			                                   t ≤  reflection time  tr = 2.l /a

 			                                   where l = distance between the  nearest discontinuity (point of   reflection ) and the point of  disturbance .  


 			A contribution from Moshe Shayan of the pump discussion forum.

			This article titled **[link Point to another website Only the registered members can access]
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<![CDATA[[Only Registered And Activated Users Can See Links] by Val-Matic Valve appeared in the Pumps & Systems magazine of March 2007,  			it's a very good description of how water hammer occurs and how it can be controlled.
 			[hr][/hr]

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## Abdel Halim Galala

Find all prescribed definitions at that book "Pump and Pump System Glossary": 
Link: **[link Point to another website Only the registered members can access]
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<![CDATA[[Only Registered And Activated Users Can See Links]

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