FEMA vacuum pressure switches detect the pressure difference relative to atmospheric pressure. All switching pressure ranges and scale markings on the switching devices therefore refer to the pressure difference between the respective atmospheric pressure and the set switching pressure. The zero reference point on the device scale corresponds to the respective atmospheric pressure. Type VCM4156 with setting range -15…+6 mbar, switching differential 2 mbar and maximum permissible pressure 1 bar.

The FEMA vacuum pressure switch VCM4156 is suitable for detecting pressure differences relative to atmospheric pressure. The setting range is -15…+6 mbar. The switching differential is 2 mbar. The maximum permissible pressure is 1 bar. The pressure sensor materials are Perbunan diaphragm; sensor housing made of 1.4301. The zero reference point on the device scale corresponds to the respective atmospheric pressure.

Technical data
Pressure connection: external G 1/2 pressure gauge connection according to DIN 16288 and internal G 1/4 thread according to ISO 228 Part 1
Switching device: robust housing 200 made of seawater-resistant die-cast aluminium GD Al Si 12
Degree of protection: IP54 in vertical mounting position
Pressure sensor materials: VNM111 and VNM301 metal bellows made of 1.4571, sensor housing made of 1.4104; VCM095, VCM101 and VCM301 metal bellows made of CuZn, sensor housing made of CuZn; VCM4156 Perbunan diaphragm, sensor housing made of 1.4301
Mounting position: vertically upwards and horizontal
Ambient temperature at the switching device: -25…+70 °C
Max. media temperature: the maximum media temperature at the pressure sensor must not exceed the permissible ambient temperature at the switching device. Short-term temperatures up to 85 °C are permissible. Higher media temperatures are possible if suitable measures, such as a siphon, ensure the above limit values at the switching device.
Mounting: directly on the pressure line pressure gauge connection or on a flat surface with two screws, 4 mm diameter
Switching pressure: externally adjustable with a screwdriver
Switching differential: not adjustable
Contact arrangement: single-pole changeover contact
Switching capacity normal: 250 V AC resistive 8 A, 250 V AC inductive 5 A, 250 V DC resistive 0.3 A, 24 V DC resistive 8 A
Setting range: -15…+6 mbar
Switching differential: 2 mbar
Maximum permissible pressure: 1 bar
Pressure sensor materials for type VCM4156: Perbunan diaphragm; sensor housing made of 1.4301
Dimensional drawing: 1 + 15

Applications
Detection of pressure differences relative to atmospheric pressure. Monitoring of vacuum and pressure conditions in industrial applications. The zero reference point on the device scale corresponds to the respective atmospheric pressure.