Valve number 2 is awkward to maintain, as its spring return actuator is heavy and causes unnecessary strain on the pipe elbow just above it before the pipe turns downward through the floor.

• 2号阀门也很难进行维护，因为它的弹簧复位执行器非常重，而且正好位于管道转向地面的弯管上，因此管道承受着很大的压力。