4 replies to this topic

[domiBod]

Dear all,

 

I have a question concerning the volumetric rate Q (L/min) while sizing for liquid or subcooled liquid cases.

A volumetric rate being pressure and temperature dependent, it is important to associate to a flow rate these two variables.

In the API 520, the sizing for liquid or subcooled liquid cases consider a volumetric rate Q without mentioning whether this rate is the one at the PRV inlet or outlet (or elsewhere).

Hence my question: at which location is considered the volumetric rate Q for the liquid and subcooled liquid case?

 

Hoping this question is not too silly ...

 

Regards

Dominique

[domiBod]

I guess the flow rate is considered at the PRV inlet, at least for the subcooled liquid case where the fluid is 100% liquid.

[latexman]

Where the fluid remains 100% liquid at the inlet and  outlet conditions, it really doesn't matter, because the density doesn't change significantly from inlet to outlet.  That is why API 520 does not distinguish between inlet or outlet in this case.

Edited by latexman, 27 August 2015 - 08:34 AM.

[domiBod]

and where the fluid is two-phase, we rather consider mass rate, so that we can probably conclude that the volumetric flow rate is always assumed at the PRV inlet. On the top of this, liquid density at PRV inlet intervenes in the rate formula.

[fallah]

domiBod,

 

The volumetric flowrate for liquid relief is normally considered at relieving pressure and temperature...