The ATH-Exx series from Jumo are used to control and monitor thermal processes. They can be used directly in the zone 1 and zone 21 hazardous areas.
The thermostats are available in manual and automatic reset versions. In manual reset thermostats a reset pushbutton must be pressed once the set temperature has been reached and the thermostat has tripped.
ATH-Exx thermostats operate on the principle of liquid or gas expansion. The electrical switching device is a microswitch inside a flameproof enclosure.
ATH-Exx thermostats can be supplied in "fail safe" configuration. In the event of a failure of the measurement system, for example, the expansion liquid escapes due to a capillary fracture, the electrical circuit will open permanently and cannot be reset.