Some Control Valve Accessories

Control valve fittings are many, some of them are extremely critical for the functioning of the whole machine. Positioners are chief accessories. Pneumatically operated valves rely upon a positioner to take a input signal from an activity control and convert it to valve travel. Solenoid valve manifold is likewise an important type of controller valve attachment. The actuator type as well as the desired fail safe operation determine the choice of the suitable solenoid valve.

Limit switches also have intimate relationship with control valves. Limit switches operate discrete input signal to a distributed control system, signal lights, small solenoid valves, electric relays, or alarms. Even the cam-operated type is typically used using two to four separate switches run by movement of the valve stem. A meeting which mounts on the face of this actuator houses the switches. Each switch adjusts individually and can be supplied for either alternating current or direct current methods. Other forms of valve-mounted limitation switches will also be available.

Supply pressure regulators typically known as airsets, which can reduce plant air supply to valve positioners and other control equipment. Common reduced-air-supply pressures are 20, 35 and 60 psig.

Pneumatic lock-up systems are used with control valves to lock in existing actuator loading pressure in the eventuality of supply pressure collapse. They can be used with volume tanks to move the valve to the fully open or closed position on loss of pneumatic air supply. Normal operation resumes mechanically with restored supply pressure. Functionally similar agreements are available for control valves using diaphragm actuators.

Electro-pneumatic transducer KP-LOK receives a direct current input and works on the torque motor, nozzle-flapper, and pneumatic relay to automatically convert the electric signal to a proportional pneumatic output . Nozzle pressure functions the relay and is piped into the torque motor feedback bellows to provide a contrast between input signal and nozzle pressure. As shown, the transducer may be mounted directly on a control valve and operate the valve without need for additional boosters or positioners. And the electro-pneumatic positioners are used in electric control loops to work pneumatic diaphragm control valve actuators.

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