From all points above, i gathered the normal practices is just to take the npshr tested with water by Vendor.
Npsh margin = npsha in meter of pumping fluid - npshr value provided by Vendor (tested using water).
There is no need to express the npsha to equivalent head in water column.
What i gathered from the material is that npsha in m of pumping liquid is used for margin calculation, even if npshr is given in m of liquid water. This is what i have always seen in all engineering datasheets.
Just something i thought about this approach - what if your pumping liquid has a...
Pump manufacturer npshr curve are always given in absolute meter of water column.
Question: npsha is always calculated or expressed in meter of pumping liquid. When calculating npsh margin, do you convert your npsha from meter of pumping liquid to meter of water?
