A valve which is fitted to a reactor or pipeline to allow small sample of a fluid to be withdrawn for further testing. In simple cases a standard gate or needle valve, for example, may be used. The disadvantage is, that inappropriate use may result in spillage. As an alternative, valves are available which ‘trap’ a small quantity of fluid in a chamber, and only this small amount of fluid is released when the valve is operated.
Solenoid valves, typically of the needle globe type, are operated by an electrical solenoid. They are often deployed as pilot valves, i.e., fitted to actuators which in turn control larger valves.
See Pneumatic actuator.
A valve which is designed for use in sea water. For example, installed in a pipeline on the sea bed.
This non-return valve has a hinged disk as the closing element.