In any system, valves are a necessary component that control a fluid’s pressure, flow rate and direction. Pneumatically controlled valves direct the flow of pressurized air which is crucial to your system’s success. Although the medium flowing through the system is fluid (the same as hydraulic or process water systems), how control is executed differs in many more ways than with a liquid.
Pressure Relief Valves
Pressure relief valves control pressure at the inlet port by releasing pressure into the atmosphere. Typically you can find relief valves in receivers or in air storage devices. Suitably, relief valves can also be called safety valves as they are put in place to prevent excessive pressurization. By adding a pressure regulator in your pneumatic system, you will limit the downstream pressure of the unit. A pressure regulator is especially helpful in a large centralized compressor that feeds to various workstations. You may find a pressure regulator as a stand-alone unit, or with a filter attached. Regardless of your selection, your regulator will most likely feature an inlet port, outlet port, and a port for the pressure gauge.
Flow Control and Directional Control Valves
Valves that control flow are commonly found in pneumatic systems. Flow control valves are available in two configurations and are used in two different ways. The first is a variable restriction with a component that opens or closes the valve. This type of valve could be called a needle or a choke valve. The other type is a check valve which allows flow in one direction, but restricts flow in the opposite direction.
Pneumatic systems can also feature directional valves in many sizes, styles or configurations. These types of valves can vary from a simple check valve to a more complex valve with varying positional envelopes and work ports in the valve. The directional valve features an operator which provides the force to shift the valve between its positions. The operator can be controlled by a variety of mechanisms including a manual lever, electric solenoid, air pilot, cam mechanism or others.
Other Considerations for Pneumatic Valves
While pressure relief, flow control and directional control valves may be the most popular pneumatic valves, these valves can come in all kind of varieties. Another common pneumatic valve is a poppet valve which uses a spring to push a face of the poppet down on its seat. These valves typically flow in one direction, similar to a check valve, but are energized to flow in reverse. Spool valves are another pneumatic valve you may come across in your search. Spool valves have a notched metal cylinder that slides within a precisely machined body that is drilled anywhere from three to seven ports.
When you are choosing your pneumatic valve, you will notice that most directional valves come in both standard and non-standard mounting configurations. The non-standard configuration is constructed at the notion of the manufacturer. Port positioning, operator style and mounting options will be exclusive depending on where the valve is from. Due to the inconsistencies between manufacturers and their mounting preferences, it is best to research the product most suitable for your system.
However, there are also lines of standardized valves that may suit one or more specifications. If your valve is particular to a certain specification it means that one manufacturer’s valve will fit the sub plate or manifold of another manufacturer’s. Additionally, port and electrical connections are standardized with most valves to aid in your decision.