Key switch with make contact for surface mounting. The key can be removed in the centre position when the switch is on or off.
The key switch with 1-pole contact and three keys is used to manually override the airflow monitor in order to be able to maintain kitchen operation in the event of a defect in the airflow monitor. The person in charge must then ensure himself that the exhaust air system is switched on safely so that there is no poisoning of the personnel due to excessively high CO concentrations.