5 replies to this topic

[manchester]

Dear Sirs,

I found in some reference that NPSHR for hydrocarbon such as propane, butane, etc are less than that NPSHR of water at the same temperature.

However, still I don't understand the reasons. Would you like to teach and explain to me what is the reasons?

Thanks in advance

Edited by manchester, 05 August 2012 - 07:53 PM.

[Art Montemayor]

Manchester:

Your first sentence doesn't make any sense. Do you mean to say that the hydrocarbon Required NPSH is less than that for (water?) at the same temperature? I am guessing and trying to read your mind....

[fallah]

manchester,

Because at ambient temperatures, HC's are closer to their critical pressures than cold water. Then, for the same drop in pump's suction pressure lesser volume of HC gas would be liberated ; means lower NPSH is required. Of course, API 610 don't permit any NPSHR correction due to this matter.

Fallah

[manchester]

Dear Art,
I apologize for my miss type. You are right. I mean "...... less than that NPSHR of water at the same temperature."
@Fallah,
Thank you very much.

[kkala]

http://www.pump-zone...npshr-different presents actually same explanation as post No 3.

Note: In the local Process Dept we do not consider any "discount" in liquid hydrocarbon pumps NPSHr in centrifugal pump data sheets.

[manchester]

kkala,

Thank you very much.