I have been asked to investigate what NPSH margin should be applied to power plant boiler feed pumps. I have discovered that ANSI/HI 9.6.1 addressed this particular matter. However, although this standard was re-confirmed in 2000, it appears that it was withdrawn in 2003.As far as I can tell this is the only standard that has addressed the issue of NPSH margins and I want to use the limits within this standard. But before doing so, I want to understand why it was withdrawn.If anyone can explain why it was withdrawn or advise of any other applicable standard I would be grateful.
I agree with you and have emailed the Hydraulic Institute accordingly, awaiting a response.I am trying to obtain a copy of standard ANSI/HI 9.6.1 even though it has been withdrawn. I am also trying to obtain a copy of ANSI/HI 1.3 just in case it offers advise on NPSH margins. Looking at the contents list, I am not hopeful that this matter will be covered in the same detail as in ANSI/HI 9.6.1. At the moment I understand that the sales of this standard ANSI/HI 1.3 have been suspended because of errors in the formulae in the standard.The reason for posting my original question was Vacuum pumps to obtain advice from engineeers working in the pump field and I would still welcome any response to my original post.
It will be interesting to know why this was withdrawn but anyway the NPSH margins seem to be acceptable for many people and manufacturers. However, if you are talking about high flow / high head BFP's I would certainly opt for the higher figure that was in 9.6.1., of course there may well be others with actual field experience for the same equipment you are considering in similar installations and this could be your guide to establishing margins. A check with manufactureres and or users would be well worth while if you do not get any good response here. 

2011-08-15

Back