限制开关
LIMIT SWITCHES

　　在阀门的轭架上，可以容易的附加限制开关。转距臂会将开关设置在开启和关闭的位置。
　　Limit switches can easily be attached to the yoke of the valve. The torque arm will actuate the switches in open and closed positions.

无泄漏
LEAK-OFFS

　　对于Velan所有150至1500磅级的闸阀和截止阀，可选择无泄漏管道或DN8 NPT螺纹塞。所有配置无泄漏的阀门都相应配置一个高质量的套环。
　　Optional leak-off pipe or 1/4 NPT threaded plug available on all Velan Class 150-1500 gate and globe valves. All valves supplied with a leak-off are furnished with a high quality lantern ring.

联动装置
INTERLOCKS

　　可以为阀门配置一个联动装置系统。这种系统用于这样的安全需要，如果另一个阀门没有先关闭，则这个阀门不得开启。这种功能是靠有两个锁但只有一把钥匙来实现的。
　　Valves can be supplied with an interlock system. This system is used for safety reasons when one valve must not be opened without a second valve first being closed. This is accomplished by having two locks with only one key.

• 阀门A处于开启状态，钥匙在它的锁上，除非它关闭，否则钥匙无法取下来。
  Valve "A" is open and the key in its lock cannot be removed until the valve is closed.
• 阀门B处于关闭状态，只有等到从阀门A上取来钥匙后，才能够打开。
  Valve "B" is closed and cannot be opened until the key from valve "A" is used on its lock.
• 在阀门B关闭之前，阀门A无法打开。
  Now valve "A" cannot be opened until valve "B" is closed.