#  > Petroleum Industry Zone >  > Oil And Gas Process >  >  >  Reading  flow on recording charts

## ali

how i can read Barton Gas Measurement Chart in log reading ?
and what the the differnace between Linear charts & Square Root (L-10)?
and how convert chart differential reading to actual differential pressure


for example in case i have chart reading 5.8 and maxmuium reading differential pressure 100 inch water what will be the actual differential pressureSee More: Reading  flow on recording charts

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## kochichiro

Well its pretty simple to read actual pressure differential. The chart shows pressure differential in percents. For example 100 % of full scale is equal to 100 inch of water.  That means 5.8 % is equal to (5.8*100)/100 or 5.8 inches of water. One inch of water equals to  0.0361144 psia, so 5.8 inches would be equal to 5.8*0.0361144 or 0.20946352 psia. But I think these values are too small maybe you should check maximum reading value (maybe it is not 100 inches of water, but 100 inches of mercury).

Such flow recorders show not only pressure differential, but also pressure in the system before flow recorder. In many cases thick and noisy line is pressure differential and thin and straight is pressure in the system. When you are shutting some valve there is no flow in the system and pressure differential line goes to zero, but pressure line is remaining on some level, because there is always pressure in the system.

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## kochichiro

What Ive wrote before applies to linear charts, to calculate actual pressure differential on square root charts you need to use following equation: 

Actual pressure differential = ((chart reading/10)^2)*meter range

For your example it would be: ((5.8/10)^2)*100 in. of water = 33.64 in. of water or 1.215 psia

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## kochichiro

You may read more on the subject here - **[link Point to another website Only the registered members can access]
*link*




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

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## ali

> What Ive wrote before applies to linear charts, to calculate actual pressure differential on square root charts you need to use following equation: 
> 
> Actual pressure differential = ((chart reading/10)^2)*meter range
> 
> For your example it would be: ((5.8/10)^2)*100 in. of water = 33.64 in. of water or 1.215 psia







> You may read more on the subject here - **[link Point to another website Only the registered members can access]
> *link*
> 
> 
> 
> 
> <![CDATA[[Only Registered And Activated Users Can See Links]



*very very tahnks , it is very help for me and ask all my questions *

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