2 replies to this topic

[zaifull]

hi there,
hope someone can help me.

1. How to calculate the maximum suction pressure by data given as follows:

atmospheric pressure - 98kpa
resistance suction valva - 2kpa
pipe resistance - 8kpa


2. What is permissible wear ring clearance in impeller with diameter of 150mm in a two stage pump at operating temperature 225 degree C


Please help me. Thanks in advance

[akslzf]

Vapor pressure at pumping temp is crucial.
NPSHA = Vessel pressure+head-VP at PT - friction loss.
Compare this with the NPSHR state in the pump spec.
Presuming this is a small pump running at 3000/3600 rpm, a margin of at least 1m is required.
For high speed pumps, the margin evealuated as a ratio. Dont want to confuse you.

Again, refer to Heinz Bloch's book in Google books.

WR clearance of 0.5mm should be good for 150mm. Refer API610 on min running clearance.

[zaifull]

thank you sir, it's helping me a lot