RS PRO 687 Series Panel Mounted Latching Air Switch

Double-pole momentary or latching air-operated switch elements with two SPDT microswitches acting simultaneously
The contacts are rated at 15A 250 Vac./30Vdc and connection is via 250 ( 1/4 in) terminals
Through panel fixture is by means of a 9/16 UNF nut (supplied) or may be surface mounted using the additional 3.2 mm fixing holes, suitable for M3 screws or No. 6 self tapping screws
Operating temperature range -10°C to +60°C (subject to tube length limitations - see additional data tables)

The air operated switch system offers enhanced safety in hazardous areas by allowing remote operation of electrical circuits.
The actuator is a bellows which, when compressed moves air down the air tubing to the switch element. This compressed air then expands a bellows in the switch, which operates the electrical contacts.
When used in wet environments or where electrical switching would be dangerous due to arcing, the switch and all electrical wiring can be located outside the hazardous area giving the operator total electrical isolation for the equipment.
Such applications include: Battery charging rooms, laboratories, garages, or wherever explosive gases, vapours or powders may exist.

When assembled the air switch and actuator form a sealed system, therefore temperature variation will cause pressure changes, which can in extreme cases affect the performance of the switch. To prevent this the total volume of the system must be kept below a critical value for a given temperature range and, to this end, a maximum length of air tubing (and hence volume) can be given for any combination of switch and actuator.
The additional data tables give these lengths in metres; for moderate and extreme temperatures.