Pneumatic logic is a system that is generally used for controlling industrial processes, and is often times referred to as air logic. Pneumatic logic can perform any function that is traditionally handled through relays, pressure or vacuum switches, time delays, limit switches, and counters. Controls are relayed through a medium of compressed air instead of electrical current.
Pneumatic logic removes the potential for internal and external explosions, electrical shocks, and water damage doesn't affect the operation of the circuit or controls. Electricity is not necessary in pneumatic equipment. Air logic circuits can tend to be slower than electrical controls especially in long conductor lines.
The way an air logic or pneumatic system works can involve various logic elements. A signal at either input port of an OR element can produce an output signal. A shuttle valve can serve the same purpose as an OR element, and pilot signals from two different sources can pass through the OR to start the next function. The system can also rely on an AND element, which requires two input signals simultaneously before it passes an output signal. When there are more than two inputs in use, AND elements become connected in a series, and this requires the first AND to receive the first two signals, and the other input of the second AND receives a third signal.
