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Condensate vapor and critical pressures

Condensate vapor and critical pressures

Condensate vapor and critical pressures

Every time I size a control valve on condensate I have to go back to the customer and ask for the vapor and critical pressures. Does anyone know where I can find a chart that I can go by?

Colorado Valve And Controls

RE: Condensate vapor and critical pressures

If you have access to a copy of Perry's Chemical Engineers' Handbook, the necessary charts are in Chapter 2.  I would also imagine that they would be available in the CRC Handbook of Chemistry and Physics, but I don't have my copy handy to check.  Both are widely available and very heavy books.

Note: The charts require a basic knowledge of organic chemistry in order to be able to calculate the critical pressures.

RE: Condensate vapor and critical pressures

there are charts in API TDB etc. but values differ depending from compositions, when the customer gives the composition I calculate the (pseudo) critical pressure (required by ISA formulation) and vapor pressure with a software (Prode Properties), since critical pressure and vapor pressure are required in case of liquid flashing with the same tool I can evaluate that condition.
If the customer doesn't provide data about composition I prefer to ask.

RE: Condensate vapor and critical pressures

I guess it is best to ask. Some of my customers are not providing enough info and I was hoping there was an easy fix to this. I know some of my compeditors quote the valves without the complete info and that makes my customers feel like I'm asking for more than they feel they should have to supply. Thanks for the help!

RE: Condensate vapor and critical pressures


Your competition is either too lazy to ask, or they have done this so many times that they know approximately what the critical properties of hydrocarbon condensate are.  They may have completed a study to compare the control valve sizes for various critical properties and have found that there is not much difference.

Most of your clients will not have the critical properties.  Many of your clients will not even know what critical properties are.  At the very least, the client should provide you a composition of the condensate, or you could ask for it as apetri suggested.  You could then assume the critical properties of the mixture.  Many times you could use your best engineering judgment to assume a value within a range of known critical properties for similar substances.

As a client, I prefer my contractors to ask something similar to "If you do not have the exact data, then give me some general information about the fluid."  I prefer that because I am paying the contractor for their expertise.  

I wish you success with your valve sales.


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