#  > Petroleum Industry Zone >  > Safety And Environment >  >  >  Modeling explosion in PHAST 6.54

## nmerzak

Hi
 I would modeling explosion in PHAST
How i can calculate "confined volume"?


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## safetyuser

> Hi
> I would modeling explosion in PHAST
> How i can calculate "confined volume"?
> thanks



first you should identify the areas in your plant where confinement may occur e.g. by the presence of parallel planes, barriers, physical obstructions to ventilation. These may be the air coolers, heavy loaded piperacks, elevated platforms, etc...

Then, a guidance of the fraction of flammable cloud to be considered as "confined" to give explosion can be found in the CPR 14E "methods for calculation of physical effects" (yellow book)

There are link somewhere in this forum where you can take this book.

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## nmerzak

deep thanks safetyuser
the broblem is:
there is a leak in compressor station
if i take total volume "the building volume of the compresssor station"
how i can calculate  
1/ confined volume
2/flammable mass in the cloud

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## safetyuser

> "the building volume of the compresssor station"
> how i can calculate 
> 1/ confined volume
> 2/flammable mass in the cloud



Well, I don't know exactly your problem anyway from your few words I can suppose:
1- confinement is 100% if your compressor is totally enclosed in a building/box-shaped shelter and similar
2- the flammable volume in the cloud may be estimated in the worst case as the Upper Flammable Limit (UFL) of the congested gas, times the total confined volume. Use the gas density to turn into mass.

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## Dushmen

> 2- the flammable volume in the cloud may be estimated in the worst case as the Upper Flammable Limit (UFL) of the congested gas, times the total confined volume. Use the gas density to turn into mass.



It would be more correctly to use the difference between UFL and LFL.

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## nmerzak

thanks for all
for worst case we can use :
confined volume =9,5 % total volume confinned
total volume confinned=total volume of building-volume obsructin if exist.
 "9,5% total volume confinned" for a stoichiometric combustion.

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## Itzvinodwagh

Check Chapter 17 of LOSS PREVENTION IN PROCESS INDUSTRIES - LEE VOLUME 2, It may help you. Book is availabe in the forum.

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## raj_lodha1

I understand from the discussion that you are trying to use the MultiEnergy model in Phast. 

PHAST needs 3 inputs for VCE, flammable mass, confined volume and blast strength. 

However in PHAST once you determine the confined volume, it considers that the entire confined volume is filled with stochiometric concentration and is available for explosion. Thus put flammable mass as say 1000kg. ( Otherwise based on the volume calculate the stochiometric flammable mass, but you will get the same results at the end , so as long as you are putting any value greater than stochiometric mass results are same). 

Identify the confined area within the plant, the congested volume is typically the volume of the congestion minus the volume of the equipment located within the congestion. e.g. if there is a structure supporting 2-3 process equipment, then confined volume is structure volume ( L*B*H) - VOlume of the process equiment. ( Explosion happens due to flame acceleration i.e. due to congestion, flammable gas cloud from any source can lead to flammable gas to reside within the congested area. Assuming entire congested volume as described is worse case but widely used in Industry ) 

For the blast strength, use Kinsella method available in Yellow Book. DOnt use too much coservative values without any basis as the resultant peak overpressure will be much higer. 

If you need any further help, you can contact me on

rajkumarlodha@hotmail.com

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## rimk23

Please i need help 

i don't understand the concept related the Averaging-Time . Could someone provide  me basic documentary  tools.
I tried some books (too specialisied) but i find it difficult to understand.
tHANKS

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## Itzvinodwagh

Hello,
Can we model dust explosion scenarion in phast.
What i have done,
Converted mass of sulphur to TNT equivalence mass and used TNTmodel. Have anybody tried this earlier?????

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## Dushmen

Using TNT equivalence for dust explosion is not a good idea for 2 reasons (you are trying to use some correlations with VCE, for which TNT equivalence method widely applicable):
1) mechanism of burning of dust and vapor is very different - for dust explosion you may see up to 8 explosions for same mixture (coal, for example) - relay mechanism. As a result of this, dynamic of pressure generation and its max value for dust exp. and VCE are different.
2) you have no correlations for calculation of flammable mass of dust, because in different conditions the difference between flammable mass of dust in the same dust cloud may be up to 10 times.

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## nilamabar

please give the link if anybody having PHAST software ......

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## hamidkeng

> It would be more correctly to use the difference between UFL and LFL.



Why difference? Did you mean average?

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## noiha

for flammable mass, can we just multiply initial mass flow rate and release duration? (it's in discharge report from source)

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## rean

Hi, does anyone know a good software for dust explosion modeling ? In air, in building , in equipment

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## ravisasi

Thanks for the very useful information.
Can you also explain about Explosion modelling using GAME methos

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## swan123

> deep thanks safetyuser
> the broblem is:
> there is a leak in compressor station
> if i take total volume "the building volume of the compresssor station"
> how i can calculate  
> 1/ confined volume
> 2/flammable mass in the cloud



ppppp

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## akbavra

Hello All ,

I had found a useful link to download the PHAST . It is working well & no key is required.

To download this, below is the link -

**[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]

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## sumairkhalid

i could't download it from here.... google drive doest nothing ... might be some error

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## peter_v

I choose volumen equivalent

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## huge1000

Thank you for the information

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## patsyconnelly

Sonu-Exchange is captivated to advance specific online coin exchange advantages despite dis*****ing a respectable and centered rates of exchange.. **[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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## hantana

Hi all,

******** for my Phast 6.54 has stopped working since 31 Jan 2015. Could anybody help me solve it. 
Thanks and Regards

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## marianogru

Can we do the  domino effect analysis with phast or safety 6.54? 
please help me.

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## f81aa

Hi marianogru:



I have not seen the possibility of performing domino effects analysis with PhastRisk 6.53.1. I even searched for the phrase "domino effects" in Help and found nothing.

Regards





> Can we do the  domino effect analysis with phast or safety 6.54? 
> please help me.



See More: Modeling explosion in PHAST 6.54

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## sushantchaturvedi

The concept of averaging time is basivally related to the time considered for the scenario for consequence calculation. PHAST considers 18 secs for flammability and 600 seconds for toxic release. To understand the concept you may refer to technical document available in phast. 

You can also refer to BEVI manual and purple book by TNO.

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