What are Proportional Valves?
Essentially proportional valves are electronic flow controllers. Users can vary the input current to the solenoid, and the output flow of the valve will vary accordingly. The greater the input current, the greater the flow through the valve.

Typical applications for proportional Humphrey valves are:

• dynamically dispensing controlled amounts of air or gas
• controlling downstream pressures
• accelerating/decelerating air cylinders.

Humphrey proportional valves come in two-port, normally closed, direct acting, spring return type flow controllers.

Use Caution in Sizing Proportional Valves

In the pneumatic valve world, we often oversize valves for applications. Many times we size the valve strictly off of the port size that the customer wants to use, which can make the valve significantly higher in flow than is needed.

While over-sizing is not usually an issue with on/off type valves, it is important to size correctly with proportional valves. Keep in mind that a proportional valve allows the control of flow based on the electrical input signal. Over-sizing of a proportional valve can cause loss of fine control in the output of the valve.

With a valve properly sized to the system requirements, the system will have the full range of adjustment that the valve will allow, making the system it is working in much more responsive and accurate. So, when specifying a proportional valve for a system, take the extra time to determine what is really needed and avoid the oversize dilemma.

For more information on sizing a proportional valve, please contact Diffley-Wright Corporation at (800) 282-4886.