Not sure if an IP67 switch would necessarily be OK in this application as it says nothing about its' susceptibility to vapour, which would be the hazard here. Unless the contacts are sealed such as in a reed switch type of design, vapour could find its' way to the contacts and be ignited by a spark.
You could take an IP67 rated pushbutton with a rubber sealed button, put it in a suitably sealed enclosure and hope for the best. I personally would also ensure that it's only switching a low energy control signal.
To make a design intrinsically safe you really want to take the switching function that presents a hazard out of the hazardous environment completely. I'm assuming you're talking about switching motors and valves in the presence of fuel vapour, so high currents, inductive loads and the potential for sparks.
You need to perform the load switching and any protection, circuit breakers, etc elsewhere, and ideally with a solid state relay, and switch only a low energy control signal in the hazardous environment, with a protection circuit that ensures that a fault can't cause a large enough current to cause an arc to flow in the circuit.
You can take this as far as you like. Hot tubs and spa baths, for example, often have pneumatically actuated switches that are operated by plungers mounted on the bath via a length of air line.
Author
Topic: Looking for specialist switches (Read 3661 times)