Explosion-Proof Wireless Proximity Sensor

I was wondering if anyone knows of an industrial wireless proximity sensor (e.g., inductive sensor) with a transmitter and a receiver that are all rated to operate in hazardous areas. The sensor will be used to detect whether a piece of machinery is retracted or extended (up to 10 cm).

Steute—a manufacturer of industrial automation equipment—has an explosion-proof wireless proximity sensor and a transmitter, that are both certified for zone 1 hazardous areas, but not their receivers.

Thank you for any help you could provide on this including any idea or alternative solution for explosion-proof wireless proximity measurement.