Contact pressure gauges with electrical alarm contacts are suitable for controlling or regulating process sequences. The contacts open or close electrical circuits in relation to the position of the pointer on the pressure gauge.
Contact pressure gauges with the Bourdon tube system are used at process pressures of approximately 1 bar and upwards. The media (gases or liquids) may not attack the copper alloy materials used. Liquids may not be too viscous or be susceptible to crystallization. The inexpensive and tried and tested Bourdon tube system coupled with a modern modular priniciple provides a very reliable yet inexpensive contact pressure gauge.
Electrical alarm contacts are used as magnetic snap-action contacts, especially in harsh industrial conditions. The high contact pressure and the choice of different electrical contact materials enable high currents to be switched reliably. If the electrical switching capacities of the alarm contacts are exceeded or not reached (see DE 1231), a relay is to be used to provide an appropriate current rating (see DE 1230).
Inductive alarm contacts operate without physical contact and thus have no unfavourable effects on the pressure measuring system while having an unlimited service life. A control unit is always needed to operate these contacts. An integrated switch amplifier (SVA) allows direct connection of the contact to a PLC system. Contact pressure gauges with inductive alarm contacts can be used in potentially explosive atmospheres, provided that the appropriate regulations are complied with.