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[Sara Owens]

I am filling out physical properties of a liquid for control valve. One of the fields requested is vapor pressure. How is vapor pressure determined on HYSYS. is that reid or true vapor pressure? i understand reid and true are taken from 37.8 C (100 F). is this the correct value used for the vapor pressure and reported for control valve data. In some instances, the reid and true vapor pressure is not calculated in HYSYS and is left blank even though i have 100% liquid. Can this value be manually calculated in HYSYS? i know my inlet pressure has to be greater than my vapor pressure to ensure there are no bubbles at the inlet of the control valve. Anyhow, i don't understand the reference of 100 F. shouldn't vapor pressure be addressed based on the inlet temperature of the control valve?

[Bobby Strain]

You should use the vapor pressure at valve inlet conditions. Are you still viewing stream properties in HYSYS and entering them in your datasheets? I automated that task more than a decade ago. Did you get the HEM file?

 

Bobby