API 620, Vapor Discharge Momentum effects

[tr6]

I know you are not supposed to double post, but after sitting on the PSV Relief valve forum for a week, with no responses, I will try here.

API 620, 4.4.1.1 Vapor Discharge: The discussion of the reaction force (F): "includes the effects of both momentum and static pressure".

Question: Does the momentum effect include the forces exerted at the elbow due to change in direction, or just downward impulse force as the vapor leaves the vent pipe?

Since there is no accounting for the size of the discharge pipe in the first part of the formula, my guess is that the momentum effect at the elbow is not included in the reaction force (F). ???

Thanks for your input.

 

[JStephen]

Check the code reference, you seem to be looking at something different from what I am.

 

[tr6]

Maybe that was my problem. It is API 520 part II.

I hate it when that happens.