ISO 1219-1:2012 is a sub-division of the ISO 14617 series, which lays down the basic elements required to produce universally recognised standard symbols. In ISO 1219-1, rules are established for devising symbols specifically related to fluid power systems.

Pneumatic Air Supply and Distribution Symbols

Symbols are used in pneumatic air supply and distribution to illustrate the function of valves and other necessary devices in the system. They are used on the components themselves as well as in the circuit design diagrams. The fixed dimension ratios may vary, as they are intended for direct use in data processing.

Pneumatic Circuit

Compressor

The symbol is the same as the Main Air symbol, as this is normally supplied by a compressor. High pressure air can be produced using piston, screw or vane compressors.

Compressor Symbol

Receiver

Main Air is stored in a receiver or reservoir for future use, to smooth uneven pressure and separate out water for drainage.

Receiver Symbol


Filters

Compressed air filters move moisture and contamination particles from the compressed air systems. Particles are retained or collected by a sintered filter, depending upon the grade of filtration particles between 40…5 μm can be removed. Liquids and moisture are separated using centrifugal force, the condensate that accumulates in the filter bowl must then be emptied or else the moisture will be pulled through by the drawn in air flow.

Filters

Filters Without drain Symbol

Without drain

Filters With manual drain Symbol

With manual drain

Filters With automatic drain Symbol

With automatic drain

Coalescing Filters

Coalescing Filters Without drain Symbol

Without drain

Coalescing Filters With manual drain Symbol

With manual drain

Coalescing Filters With automatic drain Symbol

With automatic drain


Regulators

Main air is usually at a higher pressure than is required for the distribution system, so a regulator is used to reduce it.

Regulators Without relieving Symbol

Without relieving

Regulators With relieving Symbol

With relieving

Pressure Regulator With Pressure Gauge

Pressure Regulator With Pressure Gauge

Differential Pressure Regulator

Differential Pressure Regulator

Lubricators

Lubricate the compressed air after it has been filtered and regulated.

Lubricators Symbol

Soft Start Valve

Soft start valves emulate a 3/2 manual valve function, that limits the amount of air input directly to the valve, allowing pressure to build up gradually and venting excess air from the exhaust port.

Soft Start Valve Symbol

Lockable Isolation Valves

An isolation lock that will block the input air flow to the valve for greater safety when servicing pneumatic equipment. With the valve locked, all the downstream pressure will be vented, and no output device can function. These valves are often positioned before the FRL unit.

Lockable Isolation Valves Symbol

Manifold

Allows connection and switching of several components in a circuit.

Manifold Symbol

Air Pipes Connected/Not Connected

The compressed air distribution system via connected lines or pipes to operating equipment, or not connected and crossing over. Pneumatic pipes running in a factory are installed running downhill in a further attempt for excess water to run off.

Air Pipes Connected/Not Connected Symbol


Pneumatic Valve Symbols

Most valve symbols are drawn in three parts, number of ports, number of positions and type of actuation. Pneumatic valve symbols are always drawn in their unactuated state. The arrows on the valve indicate the direction flow of the air.

Each box gives an indication of how many ports the valve has, so if each box shows two ports (top and bottom centre) then it is a 2-port valve. If there are only two boxes in the symbol this indicates a valve with only two positions, called a 2-stage valve. So a valve with two ports in each of two boxes is a 2-port, 2-stage valve (2/2 Valve).This indicates its two positions or operating states (Input and Output : Open or Closed).

In the box on the left, the directional arrow indicates that each of the two ports is open, so that air may flow through the valve. In the box on the right, those two ports are both depicted as blocked, so that no air may pass through.

Ports

Ports are the valve openings where pipes or hoses can be connected. They are usually numbered. In the case of a valve conforming to ISO 5599 they have up to five ports:

Port 1: Main Air

Main Air is the input air supplied from a compressor or other similar device.

Port 1: Main Air Symbol

Port 2: Output Connection

The output is where other components are connected, usually cylinders. On a 5-port valve, commonly used with a Double-Acting Cylinder, the output is usually connected to the in-stroke, with Port 4 usually connected to the out-stroke.

Port 2: Output Connection Symbol

Port 3: Exhaust

Exhaust is the waste or trapped compressed air that is vented into the atmosphere after the actuation of the valve. On the 5-port valves used for Double-Acting Cylinders, there is a second Exhaust outlet, at Port 5.

Port 3: Exhaust Symbol


Pneumatic Actuator Symbols

Control valves can be actuated in several ways, including Diaphragm, Pilot, Solenoid or Mechanical.

Pilot Air

A Pilot can operate a switch or send signals to an actuator which will set its working pressure.

Pilot Air Symbol

Solenoid Actuator

Solenoids change a valve's state with an electrical pulse. Solenoid control combines pneumatics with electrical or, more recently, electronic governance systems, using a computer or PLC (progammable logic control).

Solenoid Actuator Symbol

Mechanical Actuators

Mechanical Actuators Push Button Symbol

Push Button

Toggle Symbol

Toggle

Mechanical Actuators Roller Symbol

Roller

Mechanical Actuators Key Switch Symbol

Key Switch


Pneumatic Cylinder Symbols

Pneumatic cylinders can use piston rod or rodless actuation. Double-acting cylinders drive the rod back and forth, allowing a push-pull load motion, while single-acting cylinders use a return spring with only the outstroke moving the load.

Single-Acting Cylinder (front spring)

In a single-acting cylinder, compressed air is used to push the piston rod out and a spring to return it (instroke).

Single-Acting Cylinder (front spring) Symbol

Double-Acting Cylinder

Double-acting cylinders use compressed air for the out-stroke and also for the in-stroke by reversing the air flow direction.

Double-Acting Cylinder Symbol

Pneumatic Cylinder Cushioning Diagrams

Cushions can be applied to the cylinder in a variety of configurations, to absorb impact and prevent unnecessary wear.

Fixed Mechanical

Double-Acting Cylinders, Fixed Cushions Symbol

Double-Acting Cylinders, Fixed Cushions

Double-Acting Cylinders, Cushioned Symbol

Double-Acting Cylinders, Cushioned Magnet

Double-Acting Cylinders, Through Rod, Fixed Symbol

Double-Acting Cylinders, Through Rod, Fixed

Double-Acting Cylinders – Magnetic, Through Rod Fixed Cushions Symbol

Double-Acting Cylinders – Magnetic, Through Rod Fixed Cushions

Adjustable Cushioning

Double-Acting Cylinders – Magnetic, Adjustable Cushions in both directions Symbol

Double-Acting Cylinders – Magnetic, Adjustable Cushions in both directions

Double-Acting Cylinders – Magnetic, Through Rod, Adjustable Cushions in both directions Symbol

Double-Acting Cylinders – Magnetic, Through Rod, Adjustable Cushions in both directions

PSS

A self-adjusting cushioning for optimal cushioning even with varying loads and speeds

PSS Symbol

Other types of pneumatic cylinders

Tandem Cylinder Symbol

Tandem Cylinder

Single-Acting Rotary Cylinder Symbol

Single-Acting Rotary Cylinder

Double-Acting Rotary Cylinder Symbol

Double-Acting Rotary Cylinder

Rotary Indexing Table

Rotary Indexing Table


Control Valves

3/2 Valve

A 3/2 valve is commonly used for Single-Acting Cylinders. It has three ports and two states or positions. 3/2 Valves can be normally open or normally closed allowing air to either flow or stop the flow of air when actuated. In the case of a NO (normally open valve):

State 1 – Off (unactuated state)

The main air input to the valve is blocked, so the air in the valve is unable to reach the output connection. Any air remaining in the cylinder can be dispelled through the Exhaust, allowing the cylinder to revert to its original position.

State 1 – Off (unactuated state) 3/2 Valve Symbol

State 2 – On (actuated state)

The main air input flows freely through the valve, supplying output connections. A 3-port valve symbol depicts both states or positions side by side, generally in the Off (unactuated) state.

State 2 – On (actuated state) 3/2 Valve Symbol

5/2 Valve

This valve has five ports depicted in each of two boxes, indicating that it has two stages of operation. 5-port valves have one Main Air, two Output Connection and two Exhaust ports, and are commonly used for Double-Acting Cylinders. The 5-port valve is then operated by signals from an actuator.

5/2 Valve Symbol

5/3 Valve

This valve has five ports in three boxes, indicating that it has three stages of operation. 5-port valves have one Main Air, two Output Connection and two Exhaust ports, and are commonly used for Double-Acting Cylinders. The 5-port valve is then operated by signals from an actuator. 5/3 Valves can have the centre position either blocked, open to exhaust or pressurised.

5/3 Valve Symbol


Flow Control Valves

Unidirectional Flow Control

Unidirectional flow control valves are used to limit the speed of the cylinder's operation by controlling the flow direction of compressed air. The symbol depicts a non-return or check valve, which restricts the air supply so that it air is restricted in one direction and free flowing in the other direction.

Unidirectional Flow Control Symbol

Bidirectional Flow Control

Bidirectional control valve symbols are the same as unidirectional, but without the check valve, indicating that the air is restricted in either direction.

Bidirectional Flow Control Symbol

Non Return Valve

Non-return valves allow compressed air flow in one direction only, flow in the other direction is blocked.

Non Return Valve Symbol


Pneumatic Logic

The logic symbols for some valve types are more complex than the valves themselves, such as these:

Shuttle Valve (‘OR’ valve)

A shuttle valve allows air flow to pass through it from either or both of two input sources. The higher of the two inlet pressures forces a small ball or blocking element inside the valve from that end to the other, blocking it off, but leaving a central port open for the air to flow through.

Shuttle Valve (‘OR’ valve) Symbol

'AND' Valve

An AND valve has two input signals which it must receive simultaneously in order to permit an output signal. AND valves can be connected together in a series, with the output of the first unit forming one of the inputs on a second AND valve.

'AND' Valve Symbol


Vacuum Pneumatic Symbols

These symbols pertain to any items used in a pneumatically driven vacuum system.

In-line Ejector Symbol

In-line Ejector

Suction Pad/Cup Symbol

Suction Pad/Cup

Suction Cup Filter Symbol

Suction Cup Filter


Silencer Pneumatic Symbols

Compression systems can be loud, particularly when the exhaust air is vented, so a silencer is often fitted to reduced operational noise.

Silencer Symbol

Silencer

Silencer with Exhaust Control Symbol

Silencer with Exhaust Control