Safety precautions that make it possible to use electrical apparatus in explosion-hazard zones.
SIGRIST process photometers use one of the following types of protection:
- Encapsulate enclosure EEx d is based on a housing resisting an internal explosion, without a spark escaping.
- Pressurized enclosure, complying with protection type EEx p. The electrical apparatus is housed in an enclosure that is slightly pressurized with either air or an inert gas. This prevents the potentially explosive gases surrounding the enclosure from coming into contact with the electrical components. Whenever the enclosure pressure drops below a certain level, an automatic monitor cuts off the power supply. Prior to start-up, the enclosure is purged with fresh air for a prescribed period of time.