Hydrocarbon Vapor Pressure

Question

Hydrocarbon Vapor Pressure

Rabisaab (Mechanical)

(OP)

7 Jul 07 15:26

Can somebody assist me in getting a hydrocarbon vapor pressure chart? Mainly I need to get the vapor pressure for gas oil and gasoline. I need this information to compare between the factory NPSH required and the NPSH available physically.

For more clarification, The minimum NPSH available is zero meters while the Facotry NPSH required is 2.2meters (Of course this is tested on water).

The product we are using is gasoline & gas oil, so I need to get the physical NPSH required in order to know if the pump can operate without cavitation when the NPSH available is zero meters.

BigInch (Petroleum) · Answer 1 · 2007-07-07 17:43:33

Diesel is essentially 0 to 0.4 psia.

Here's the rest. Gas-Oil won't be higher than the kero curve (lowest curve on the chart)

http://virtualpipeline.spaces.msn.com

Rabisaab (Mechanical) · Answer 2 · 2007-07-08 04:31:27

RE: Hydrocarbon Vapor Pressure

Rabisaab (Mechanical)

(OP)

8 Jul 07 04:31

BigInch.
Thanks for your reply.

BigInch (Petroleum) · Answer 3 · 2007-07-08 15:12:52

Rabisaab,

Just saw the graph says psia, but its Reid Vapor Pressure that is plotted. It can be correlated to psia by looking at the table on page 76 here,

http://www.epa.gov/ttn/chief/old/ap42/ch07/s01/final/c07s01_feb1996.pdf

http://virtualpipeline.spaces.msn.com

quark (Mechanical) · Answer 4 · 2007-07-08 23:26:11

mcnallyinstitute webpage is a good resource on pumps.

You can get vapor pressure data for most of the liquids at http://www.mcnallyinstitute.com/Charts/Vapor_Pressure_Chart.html

This is a chart for NPSH reduction
http://www.mcnallyinstitute.com/Charts/NPSH_reduction_chart.html

Thumb rules for NPSH reduction.
http://www.pumps.org/content_detail.aspx?id=998

PS: Just check whether you can apply this particularly for gasoline.

BigInch (Petroleum) · Answer 5 · 2007-07-09 03:02:25

It can be applied to gasoline.

http://virtualpipeline.spaces.msn.com

quark (Mechanical) · Answer 6 · 2007-07-09 04:36:39

BigInch,

Thanks for the confirmation. I wanted to be extra cautious as I don't have experience with pumping gasoline. I think I have seen some previous posts by experts (of this or chemical engineering forum) suggesting not to bank on this extra advantage.

BigInch (Petroleum) · Answer 7 · 2007-07-09 07:56:42

It works for me.

http://virtualpipeline.spaces.msn.com

dcasto (Chemical) · Answer 8 · 2007-07-09 11:57:36

The GPSA Databook has a chart that goes from -320F to 600F for HC's from methane to 400 degree F fraction in gasoline and .01 psia to 800 psia. Fig 23-19 to 20.

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Hydrocarbon Vapor Pressure