When choosing a Air Control Valve for a process, there are many things that must be considered, including the valve’s flow characteristic, its size, noise, the potential for cavitation or flashing damage, body and trim materials, actuator size and type, and its dynamic response to changes in the control signal.
The selection primarily depends upon the application and the pressure and temperature conditions.
The first and most obvious question is—what gas (or liquid) will be controlled by this valve, and at what input pressure? Compressed Air? Water? Negative Pressure? Gas? Before checking for any additional factors, ensure that the valve is compatible with the media and pressure passing through.
Method of Valve Actuation
There are a variety of methods available to open or close a valve. The four most common are Solenoid operated (via electrical current), Manually operated (by skilled labor and via a lever, pushbutton, foot peddle, etc.), Mechanically operated (via tooling or work pieces in contact with a cam, ball or plunger), or Remote Air operated (from an output signal of another valve).
Spring-Return or Detented Actuation
This is the return method the valve will take “back” to its original, un-actuated state. Typically, this is either a mechanical spring, or a separate form of the same actuation method described above. Manufacturers call these methods “spring return” and “detented” valve types. Said another way, are you looking for a “momentary contact, momentary output” or “momentary contact, maintained output”? Decide whether you want your valve to return to its initial position or stay in its last position after actuation.
Most pneumatic directional control valves are 2-way, 3-Way or 4-Way and, as a rule of thumb, it is a count of their active media ports.
2-Way valves have one INLET and one OUTLET port and, upon actuation, allow media to pass through (known as a 2-way Normally Closed), or to stop flow (2-way Normally Open)
3-Way valves add a third port to allow for venting (EXHAUST port) of pressure at the OUTLET port, when the INLET port is blocked. 3-Way valves are offered Normally Closed or Normally Open, as well.
4-Way valves add a second OUTLET and corresponding second EXHAUST port to the 3-Way function, and are most commonly used for control of double acting pneumatic cylinders and actuators. Upon 4-Way Valve actuation, INLET pressure switches from one OUTLET port to the other.
Note: As an option, 4-way valves can be configured with 3 positions, where the center position is forms a “neutral” position choice of three options (either all OUTLET ports exhausted, pressurized, or checked).
Flow Capacity (Valve Size)
Flow capacity is a fifth factor to address in valve selection. An undersized valve will slow down fill time or cause other forms of inefficiency in the system while an oversized valve can be classified as a form of waste in the system. It’s important to estimate a maximum flow capacity for your application and select the valve size with enough capacity. All valve suppliers provide a flow capacity, and have easy reference material to assist you, but essentially your valve will need to fill a specific downstream volume within your acceptable period of time.
In addition to the above-discussed tips, you can discuss your requirements with the manufacturer. Whenever you are considering these valves for your project, ensure that they are sourced from a reliable supplier like Ningbo Lida Pneumatic Complete Sets Co., Ltd, you can click https://www.nblida.com/ to learn more information about Pneumatic Control Solenoid Valve