To order handwheel or chainwheel actuators, add the appropriate order code to the basic valve order code. 订购手轮或链轮执行器时，要在主阀门订购代码基础上增加适当的执行器订购代码。
For snap action, the main valve opens rapidly at set pressure and achieves rated relieving capacity at relieving pressure. 对于快动式先导器，主阀门在达到设定压力时快速打开并且在泄放压力时达到额定排放量。
