Horizontal pump unit with primary stage unit and separate stage unit with pressure on the suction side of the pump (NPSH)

摘要

A horizontal pumping system has a motor, a suction chamber and a pump driven by the motor. The pump includes a primary stage assembly and a low NPSH stage assembly connected between the primary stage assembly and the suction chamber. The low NPSH stage assembly is external to the primary stage assembly. The low NPSH stage assembly includes a diffuser connected to the pump housing and a low NPSH impeller contained within the diffuser. The diameter of the low NPSH stage assembly is optionally larger than the diameter of the primary stage assembly.