On Automatic Running Equipment of Cargo Oil Pump

Abstract

According to the research concerning pumping work and inclination of automation on cargo-handling equipment of oil tankers, this paper made clear that any automatic device must prevent pumps from cavitation in cargo-handling. Cavitation in pumping, as well known, can be prevented if only the following inequality is satisfied : available-N.P.S.H.>required-N.P.S.H. +l/g((dv)/(dt)). Taking suction pressure as available-N.P.S.H., which is a function of suction pressure, velocity head and vapour pressure of the liquid, velocity head naturally makes allowance for the value. Therefore, the pumps can be run without causing cavitation by controlling the rotation and capacity of the pumps in response to the suction pressure computed from oil level and suction friction loss. The ORION MARU delivered to O.S.K. is equipped with such automatic devices as to satisfy the abovestated principle in order to nationalize cargo-handling. The equipment with low suction pressure trip and emergency manual trip carries out cargo-handling work with a steam turbine speed governor in combination with the suction pressure control device. By shop-test, the equipment is certified to be quite fitted to required-N.P.S.H. according to the variation of suction pressure.