PB 2013-010 NPSH Margin Ratio is Not Being Applied to the NPSH Required by Centrifugal Pumps

Bulletin: 2013-010

Date: 06-25-2013

Category: 2

Program affected: PIPE-FLO Professional 12

Build numbers affected: 12.0.19520

Approved by: RL

If the calculated NPSHa < NPSHr x margin ratio, then message 150 should be provided and the Centrifugal Pump will be colored on the FLO-Sheet to indicate there is a calcualtion warning. The margin ratio is not being applied to the pump's NPSHr, so the message will only be provided if NPSHa < NPSHr.

Both conditions must be met:

System model contains a Centrifugal Pump with a specified NPSH margin ratio.

NPSHr ≤ NPSHa < NPSHr x margin ratio

For a manually entered pump curve, the NPSHr values can be adjusted to include the desired margin ratio. For catalog pumps, the performance data cannot be edited and the only recourse is to enter the curve manually and adjust the NPSHr values. If you do not wish to modify the NPSHr values then the condition will need to be checked manually to ensure your NPSH requirements are met.