Marine Pump Selection & Specification Guide

Marine pumps are specified by duty rather than by name. Two pumps of the same physical size can be entirely different products once flow, head, fluid and material are considered. Define the duty point The core specification is flow rate (m3/h) and total head (metres or bar) at the operating speed. Give the fluid handled — sea water, fresh water, fuel oil, lubricating oil, bilge water, ballast, cargo or chemical — with temperature and viscosity where relevant. Suction conditions matter too: static lift, NPSH available, and whether the pump must be self-priming. Pump type follows the duty Centrifugal pumps suit high-flow, low-viscosity services such as ballast, cooling and fire duties. Positive-displacement types — gear, screw and vane pumps — suit viscous services such as lube oil and heavy fuel oil transfer. Reciprocating and diaphragm pumps appear in dosing and bilge services. Specifying the wrong family produces a unit that will not hold its duty. Materials and construction State the required casing and impeller materials (cast iron, bronze, stainless steel, duplex), shaft seal type (gland packing or mechanical seal), and any coating requirement. Sea-water service in particular is material-critical; a freshwater pump in the same frame size is not a substitute. Drive and electrical details For motor-driven pumps, give voltage, frequency, phase, rated power, insulation class and enclosure rating. Marine supplies vary widely — 380V/50Hz, 440V/60Hz and 690V systems are all common — and a motor mismatch is the most frequent cause of a pump being unusable on arrival. For engine-driven and hydraulic pumps, give the drive arrangement, mounting and shaft or flange details. Interfaces Flange standards and sizes, connection orientation, base or bracket arrangement, and overall footprint decide whether a unit can be installed without modification. Include a photograph and, where available, the original drawing. Compressors and valves Air compressors are specified by delivery pressure, free air delivery, cooling arrangement and drive. Valves are specified by type, size, pressure class, body and trim material, end connection and actuation. Condition terminology Used pumps are listed with their reported condition. Refurbished is used only where restoration work is confirmed, and any test data available is shared as received. What to send Fluid, flow, head, speed, materials, seal type, motor electrical data, flange details, condition accepted, quantity, delivery point and required date.

Marine Pump Selection and Specification Guide