They look like "completely normal" compact position switches with standard dimensions according to DIN EN 50047. But the construction details of the light and robust Ex 97 switching devices with plastic housings now available from the steute business unit "Extreme" make these devices unique.
The switches are tested and certified according to ATEX and IECEx for use in Gas Ex zones 1 and 2, as well as dust Ex zones 21 and 22. They can also be used in temperatures down to -60°C, which is a terribly demanding, most particularly for the construction and sealing of the housings. For example, the high protection class (IP 66) has to remain guaranteed at such low temperatures, even during a 7-Joule impact test.
For this reason the robust housings are manufactured from high-quality plastic with a glass fibre reinforcement which is partly textile in structure. In addition, the housing covers are completely vulcanised, guaranteeing that they remain sealed even upon impact. To seal the plungers, the steute developers have implemented a redundant sealing system comprising an external sealing cuff suitable for low temperatures and an internal Teflon sealing ring.
The sealing materials used have been classified by their own manufacturers for temperatures down to -95°C, and the lubricants used for temperatures down to -75°C. There is thus sufficient "safety clearance" before the -60°C certified for the Ex 97 switches is reached. This means that users, e.g. in the offshore oil and gas industry, can be certain that the new position switches will work reliably even in their truly extreme environments.
Due to their comprehensive range of actuators (plungers, roller levers, turning levers, push buttons) and compact dimensions, the Ex norm switches, available as snap action or slow action, are very versatile and can easily be integrated in an existing construction. Their protectively insulated plastic design also makes earthing and potential equalisation unnecessary.
With their unique set of features – in particular their enormous temperature range – they are suited to the position monitoring of flaps, valves, covers and other moving components, for example in plants within the oil and gas industry (onshore and offshore) or in shipbuilding and ports. Other application areas include handling systems on oil rigs, as well as position monitoring on crane booms. Safety applications, e.g. on maintenance flaps and guard doors, are a further possibility.