Want to install a limit switch in explosive area but temperature is 250 C. Did not find any switch in this temp range.

Any expert advice, please.

 

1) Thermocouple or RTD wired with an IS barrier to an electronic high limit controller in the safe area. Too many vendors to list.

2) temperature switch
United Electric Series 120 EXP rated temperature switch

http://www.lesman.com/unleashd/catalog/switches/ue120.pdf

Temperature switch specs start on page 13.

It isn't clear if you need to switch at 250°C or if the ambient is 250°C. Switching at 250°C is just a matter of range selection in the model number.

Ambient conditions at 250° require remote mounting with a remote capillary bulb:
Bulb and capillary: 6 feet (2m) 304 stainless steel (standard) or optional 10 feet 3m);
Ambient limits: -50 to 71°C

For latching high limit with manual reset, the 1530 option is an external manual reset, 15 amp 125/250/480 VAC resistive; latches on rise only.

 

Since the test environment is Hi temp & explosive, install optical, IR or proximity out side the hi temp & explosive area. This is an idea only.

 

Sorry for confusion

Need limit switch on control valve but ambient temp is 200- 250C and also explosive environment.