You did not describe what type of pump you were considering. Overhung pumps have an axial thrust produced by the suction pressure acting over the area of the mechanical seal For a Sundyne pump, this produces a very high up-thrust until the pump is up to speed and pressure. The upper thrust bearing must be designed to accommodate this thrust. The standard bearing in a Sundyne is only rated for a maximum of 200 psi. They use a Kingsbury style bearing for suction pressures up to 400 psi. Also, in order to start-up with proper bearing lubrication, Sundyne would require a pre-lube pump for these suction conditions. For a standard, horizontal overhung pump, you may also have thrust problems. We have one Boiler Circulating pump that has suction pressure above 400 psi and uses three angular contact thrust bearings; with two oriented for normal thrust and one oriented for reverse thrust. BigInch and Artisi covered all of the other points that I would be concerned with.
Johnny Pellin
