Barske was a German Engineer who defied the conventional way designing an impeller ( like francis etc ) The impeller is an open type impeller having low specific speed thus making it useful in area of Low flow and High Head. One particular pump manufacturer using this impeller is Sundyne...
I would like to add abt the NPSHr effect on polish material. It is indeed true that well polish or buff finish inducer ( as being termed widely in this industries ) as an example would reduce the NPSHr further as compared to normal finishing. It is related to friction factor. The fluid need to...
Depending on your suction pressure, you may wish to consider using Non Pressurize Tandem Seal. Since ethylene S.G is around 0.5 you may opt to use gas seal as a secondary seal and keep the liquid seal as a primary one. With this arrangement you can make do without the barrier vessel and only N2...
When the pump manufacturer uses feet, it is because they use water to test the pump and NPSHr 3% suppression test.
By rule of thumb you can take the suction pressure and subsract the fluid vapour pressur @ PTempt but the gauge location has to be as closed as possible to the pump suction flange...