Pressure monitoring in explosion-endangered areas
Pressure switches with special equipment can also be used in the Ex area Zone 1, 2 and 21, 22. |
Product pages in the E-Catalog Ex-DCM (Mechanical Pressure Switch) |
1. Pressure switch with flame-proof enclosure,degree of protection EX II 2G/D EEx de IIC T6 IP65 T80°C
The pressure switch in flame-proof enclosure can be used directly in the Ex area (Zone 1 and 2 resp. 21 and 22). Maximum switching voltage, switching capacity, and ambient temperature must be taken into account and the rules for the installation in the Ex area must be observed. All pressure switches can be equipped with Ex switching mechanisms. Special circuits as well as versions with adjustable switching differences are not possible.
2. Pressure switches in EEx-i-version
All pressure switches in normal version can be used in the Ex area Zone 1 and 2 resp. 21 and 22, if they are incorporated in an “intrinsically safe circuit”. In principle, the intrinsic safety is based on, that fact that the control circuit run in the Ex area carries only a small amount of energy, which is not able to generate ignitable sparks.
Isolating switching amplifiers, e. g. Type Ex 011 or Ex 041 must be tested by the PTB and approved for Ex-installations. Isolating switching amplifiers must in any event be installed outside the Ex zone. Pressure switches which are intended for EEx-ia installations can be equipped with blue terminals and cable entries. Because of the low voltages and currents which are carried by the contacts of the microswitch, gold plated contacts are recommended (optional function ZF 513).
3. Pressure switches with microswitch and series resistor for wire breakage and short circuit monitoring
A combination of pressure switch with mechanical microswitch connected with a 1.5 k series resistor and a 10 k parallel resistor and an isolating switching amplifier in safety technology (Type Ex 041) can also be used for Ex zone 1, 2 and 21, 22 (degree of protection EEx-ia). The isolating switching amplifier in safety technology generates an intrinsically safe control circuit and simultaneously monitors the supply line between the isolating switching amplifier and pressure switch for short circuit and line break. Please refer to the chapter on pressure switches in safety technology and data sheet Ex 041.
