Pneumatic Components and Symbols
From DT Online
Pneumatic symbols are used to describe the function of the various valves and other devices which are connected together to form circuits and sub circuits.
Symbols for valves are shown as boxes representing the dfferent operating positions - the symbol shown for example is based on two boxes so it is a two position, or 2-stage, valve. Looking at any one of the boxes gives an indication of the number of ports on the valve - in this case there are 2 ports in each box (i.e. at centre top and bottom) so it would be a 2-port, 2-stage valve (2/2 Valve).
In the left-hand box, the arrow indicates that both ports are open and air would be allowed to pass through the valve in this position. In the right-hand box, the same two ports are shown as blocked. In this position, air is not allowed to pass.
| Component | Name and Description | Symbol | |||
|---|---|---|---|---|---|
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Compressor | The symbol shown is that for the Main Air Supply which is normally supplied by a compressor. High pressure air can be produced using piston, screw or vane compressors. |  | ||
| Exhaust | The symbol shown is used to indicate when compressed air is released to the atmosphere - e.g. following the operation of a valve. |  | |||
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Receiver | The air produced by the compressor is stored in a vessel called the receiver or reservoir. The function of the receiver is to store the air for future use, to smooth pressure spikes and to allow water to fall out of the air to the bottom of the tank where it can be drained. |  | ||
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Air Bleed | This is simply an open pipe that allows the air in the circuit to escape once pressure is reduced by a diaphragm valve. |  | ||
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Air Pipes Connected | The air produced by the compressor is distributed by air lines or pipe-work to the points where it is required. |  | ||
| Air Pipes Not Connected | In a factory the pipe-work is run downhill in a further attempt to remove excess water from the system. |  | |||
| Pilot Air | Pilot signals can be used to monitor the output pressure of a valve for example and supply a pressure which acts against a regulator spring to set the working pressure. |  | |||