All About the Marine Water PumpAll About the Marine Water Pump The primary purpose of the pump is to supply and pressurise the water from the tank. A pump is selected based on the number of outlets to be supplied and the flow rate required. If the pump is incorrectly rated for the system the flow will drop off when another outlet is opened. A significant pump development is the Sensor-Max VSD (Variable Speed Drive) water pump from Jabsco. The pump unit has a Hall Effect pressure sensor for the water flow and varies the motor speed to maintain constant pressure. This dispenses with the requirement for an accumulator and pressure switches. The VSD controls the motor speed using a PWM DC motor controller. Diaphragm Pump. These units are the most robust and are designed for multi-outlet systems. They are more tolerant to dry running conditions, self-priming, relatively quiet in operation and have inbuilt hydraulic pulsation dampening. Impeller Pump. These units normally have a pump with bronze casing and nitrile or neoprene impeller. They are less tolerant to running dry and they are self-priming. All About the Marine Water Pump Wiring There a couple of installation points to observe when installing water pumps. Cable Sizes Ensure that the cable is rated for maximum current draw and voltage drop. Voltage drop problems are very common, and over sizing the cable is a good practice. Connections Connections directly on to pumps is common, and ensure the crimps are done properly. Also put some Vaseline over the connection to stop moisture getting to the connection lugs. Where wire tails require a butt splice, ensure that they are crimped properly. Some pumps with integral pressure switches require connection directly to one side so ensure this is properly done. Bonding Some metal cased pumps, such as wash down pumps must be bonded. This should be taken to the negative polarity of the supply. In the even of a positive short to the case, this will ensure circuit breaker trips
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