引言油船的泵浦、管路以及阀系统必须设计得使船的周转尽可能快,而且使装卸所用的劳动最少。当操纵和控制都很方便时,则压载和清舱也使用这些系统。由于原油和成品油船上的阀门比例数增大,而且由于下述两个原因或其中一个原因,阀门需用动力操纵: 1) 因阀门的尺寸和在装卸期内通过阀门的流体降增大,从而打开和关闭阀门所要的功率超过了人力; INTRODUCTION The tanker pumps, piping and valve systems must be designed to keep the ship’s turnaround as fast as possible and to minimize the labor involved in handling. These systems are also used for ballast and tank cleaning when handling and control are easy. Due to the increased number of valves on crude oil and product tankers, and the need for power-operated valves for either or both of the following two reasons: 1) Due to the size of the valve and increased fluid flow through the valve during loading and unloading, So the power required to open and close the valve exceeds the manpower;