The steute business unit “Extreme” has developed the position switches in its Ex 97 series for precisely this requirement profile.
These position switches, with dimensions to DIN EN 50047, have been tested and approved 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 be used in temperatures as low as -60°C, which is very demanding on housing construction and sealing. For example, it must be guaranteed that the switchgear’s high protection class (IP 66) will be maintained in these subzero conditions at all times, even after a 7-Joule impact test.
For this reason, the stable housing is manufactured from high-quality fibreglass-reinforced plastic. The sealing of the housing cover is completely vulcanised, while the sealing of the plunger features a redundant sealing system, comprising an external sealing cuff able to withstand low temperatures and an internal Teflon sealing ring.
The sealing materials have been cleared by their manufacturers for temperatures down to -95°C, and the lubricants down to -75°C. There is therefore a sufficient “tolerance” to the steute-approved temperature of -60°C. This gives users the certainty that the new position switches will work reliably even in truly extreme ambient conditions.
Due to a comprehensive range of actuators (plunger, roller plunger, roller lever, parallel lever, turning lever, adjustable turning lever, push button…) and their compact dimensions, the Ex norm switches are very versatile and easy to integrate in a surrounding construction. They are available with slow-action or snap-action and, as an added bonus, earthing and potential equalisation are superfluous because of the protection-insulated plastic.
