2 replies to this topic

[vsnlbom]

We have chemical injection system which is used for chemical dosing in gas at pressure of around 120 barg. All piping upto suction of pump is designed for shutoff pressure of pump. In case of stoppage of flow gas may back flow from piping to tank which is atmospheric day tank with vent.

 

We need to check capacity of existing vent on tank, for probable case of back (reverse flow) scenario. Can we install two check valve in series  of similar type but different manufacturer to take credit of reduce back flow  (10% of choked flow) as advise in API 521.

 

request forum view. Thanks

Edited by vsnlbom, 22 December 2023 - 06:20 AM.

[latexman]

Can you put up a snippet of that API 521 language. Include Edition, page number, section number so we can EASILY identify and find it. Thank you!

[vsnlbom]

Can you put up a snippet of that API 521 language. Include Edition, page number, section number so we can EASILY identify and find it. Thank you!

 

API 521 4.4.9.3.3 Calculation of Reverse Flow Through Failed Check Valves. This section gives methodology to calculate reverse flow for sizing PSV. 

 

In my case we have change of reverse flow in atmospheric tank and I need to take credit of vent on tank for release. I am taking credit of above mention clause to estimate reverse flow. However, instead of having dissimilar check valve (NRV) want to use similar type of NRV from different manufacturer.