The pneumatic systems make use of different components to control or manage the amount of media like liquids and air which flow through a system. It also controls the pressure with which the media pass through the system.
Pneumatic systems are usually used in industries that are powered by compressed air, fluid gases. It is composed of a centrally located compressor powers cylinders, air motors, and other pneumatic devices that are electrically powered. But those ones controlled manually or through automatic solenoid valves are more cost effective, more flexible and safer when compared to the ones with electric motors and actuators.
The main component used in this pneumatic control system is the pneumatic valves and they made in various incarnations. Another distinction within the various types of pneumatic valves available in the market is the porting configuration. Putting this into consideration, there are three major classifications, and these are the port size, the port style and, the port valves ways.
Based on the port sizing, pneumatic valves have port sizes that can be less than 0.00625inch and could be greater than 48 inches in diameter. Selection is made based on the need.
And using port style as a means of distinguishing between the various configurations of pneumatic valves, there are socket, flare, compression tube, sanitary, threaded which could be NPT, BIS, JIS, DIN and so on, and other unique port styles and arrangements.
Based on the port ways,
Pneumatic Valves can be designed and manufactured as:
(i) Two-way Pneumatic Valve:
It is the most simple inlet and outlet valve. It is two-position valves consisting of two ports which are connected with a passage which can be opened or closed to control any flow through the valve. Normally, an electrically activated solenoid shifts the valve poppet or spool to direct the flow and the valve provides an easy on and off function, which many systems employ in interlocking, isolating and connecting various system parts.
(ii) Three-way Pneumatic Valve:
It consists of three ports which are connected through passages a valve system. It directs pressurized air to the cap-end side of the cylinder and by shifting the spool to the other extreme position, it blocks or stops flow and pressure to the actuator which is connected to the exhaust passage. This makes the spring force or gravity to return the rod to its original position.
(iii) Four-way Pneumatic Valve:
These are the most commonly used type in which two of the ports are attached to actuators. While one is mainly for airflow, and the other for exhaust. The two-position valve has two flow paths in each position used to actuate and reverse cylinders or rotary actuators. The spool directs flow from the pressure port while the other, which is the actuator port exhausts to atmosphere.
It should be noted that there is four-way valves can be configured, as another option, with three positions, where the center part is a neutral position.