Chapter 16 - Pump-Driver Specifications

Abstract

Two approaches to writing specifications for pumps and drivers are investing “unit responsibility” for the complete pumping unit with a single manufacturer and separating the driver, shafting, and pump so that each could be furnished by a different supplier and assembled at the jobsite by the general contractor. This chapter two independent example specification sections based on actual project documents. All pumping units must operate at speeds sufficiently removed from critical speeds that could cause destructive vibration and fatigue failure. The true test of pump performance is satisfactory operation in the intended installation, and it might be desirable or necessary to test a pump in the factory or in the field (or both) to provide assurance of the pump's capacity to meet project requirements. At the outset, the designer should identify two or more manufacturers with the capability of conducting full-scale tests. Mid-sized equipment (up to 500 hp, 480 V, and 15,000 gal/min capacity) could be tested by most manufacturers. Many specifications require that the intended field drive equipment be used in the tests of variable-speed pumps, which doubles or triples the cost of the tests. The perceived benefits include the evaluation of the pump's ability to perform at specified conditions, the determination of wire-to-water power efficiency, the determination of the compatibility of all components, and the discovery of objectionable vibration.