Valve Actuators ..continued

Valve Actuators; continued. On the first page about compressed air valve actuators, I wrote about the valve internal spring actuator and the external valve actuator known as an air pilot.

On this page I will review additional common compressed air valve actuators.

Solenoid Valve Actuators

A solenoid , in terms of compressed air valves, is a device that allows the actuation of the air valve with an electrical signal, or a combination of an electrical signal and compressed air signal to actuate the air valve.

When an air valve is actuated solely by the electrical signal, that solenoid valve is defined as being one that is direct acting.

When a solenoid valve uses both electricity and compressed air to shift that air valve, that type is deemed to be a solenoid pilot valve.

The difference between the two is a page unto itself, which I have yet to add to this site. It is coming.

Solenoid Valve Actuator

Fig. 44 shows a double solenoid pilot operated air valve.

A compressed air circuit may be controlled entirely by electricity, and all the compressed air valves, the proximity switches, temperature sensors, E-stops, they all can receive signals from, and in many cases send signals back to the brain of the air circuit, the PLC. (Programmable Logic Controller)

When the solenoid valve actuator gets an incoming electrical signal, and assuming that the valve is in good shape, then the valve will shift and air will flow to the application. For your interest, here is you wish information on how water in the lines negatively affects compressed air valves.

Solenoid actuators usually come from the factory already attached to their air valve. It is necessary to bring a power supply to each of the solenoid valve actuators.

DIN Connectors

One way to accomplish this is through the DIN type electrical connector , the type shown in Fig. 44.

Rather than hard wiring directly to the air valve, and having to undo the wiring each time the valve is disconnected from the air circuit, the hard wiring need only go to the DIN connector cap once. Then, it is the DIN that is connected to the solenoid via an internal plug. Using a DIN connector allows the non-electrical-skilled maintenance person to disconnect and re-connect the wiring to the valve quickly and safely when that valve needs to be changed out.

Lighted DIN

If you opt for the DIN type of electrical quick connect to accomplish a one-time wire connection, do purchase a DIN connector that contains an LED. The LED will light up when the valve solenoid is energized. You will be able to tell at a glance if power is getting to the solenoid. Now, if the valve is not working, it is either the valve that has failed, or perhaps it is a piece of air equipment downstream from that valve that has failed. One less time consuming diagnostic, for sure.

There is more information on compressed air valve actuators coming soon.