2 replies to this topic

[wojtar]

Dear all.

 

Is it reasonable to put flame arrestor at the end of psv discharge pipe? The psv is placed at the top of spherical tank with hydrogen. The hydrogen is under pressure and psv is set at 26 bar g. Now, the user/owner of that tank wants to install end-of-line deflagration flame arrestor at the end of psv discharge pipe. The problem is: psv capacity is so big that possible flame arrestor is extremely huge. Diameter of discharge pipe (existing) is DN80 and selected flame arrestor has DN800 inlet!! Isn't it something strange? Does it protect us against something or maybe it's even dangerous to do such thing?

 

on one hand: we want to prevent possible fire to get into the tank

on the other hand: is it really possible during discharge of psv? Discharge velocity is high and after that psv closes. Any flow restrictions at psv discharge are rather not desirable. Flame arrestor could be blocked.

 

What do you think?

I couldn't find anything about such case in the internet. Are there any codes or standards? All manufacturers provide such flame arrestors only for low pressure storage tanks. So, maybe in that case it is not applicable?

[fallah]

 

Is it reasonable to put flame arrestor at the end of psv discharge pipe? The psv is placed at the top of spherical tank with hydrogen. The hydrogen is under pressure and psv is set at 26 bar g. Now, the user/owner of that tank wants to install end-of-line deflagration flame arrestor at the end of psv discharge pipe. The problem is: psv capacity is so big that possible flame arrestor is extremely huge. Diameter of discharge pipe (existing) is DN80 and selected flame arrestor has DN800 inlet!! Isn't it something strange? Does it protect us against something or maybe it's even dangerous to do such thing?

 

on one hand: we want to prevent possible fire to get into the tank

on the other hand: is it really possible during discharge of psv? Discharge velocity is high and after that psv closes. Any flow restrictions at psv discharge are rather not desirable. Flame arrestor could be blocked.

 

What do you think?

I couldn't find anything about such case in the internet. Are there any codes or standards? All manufacturers provide such flame arrestors only for low pressure storage tanks. So, maybe in that case it is not applicable?

 

Wojtar,

 

It's not common to consider FA at the end of PSV tail pipe discharges the hydrogen gas to the atmosphere which is followed by rapid dispersion caused by the turbulent mixing...but considering FA would imply a relatively high back pressure preventing such rapid dispersion...

[fallah]

Moreover, as per API 2000,open PSV discharges to atmosphere, shall be fitted with FA just on atmospheric tanks in

which petroleum products with a flash point below 38 °C are stored and where the fluid temperature may exceed the flash point.

Edited by fallah, 09 November 2018 - 01:47 PM.