FEMA / Honeywell negative pressure switches Ex-VCM and Ex-VNM detect the pressure difference relative to atmospheric pressure. All data relating to the switching pressure ranges and thus also the scal...
FEMA / Honeywell negative pressure switches Ex-VCM and Ex-VNM detect the pressure difference relative to atmospheric pressure. All data relating to the switching pressure ranges and thus also the scale divisions on the switching devices are to be understood as the difference in pressure between the releant atmospheric pressure and the set switching pressure.
|Type||Setting range||Switching differential
|Ex-VCM095||-0,9…+0,5 bar||50 mbar||3 bar|
|Ex-VCM101||-1…+0,1 bar||50 mbar||3 bar|
|Ex-VCM301||-250…+100 mbar||25 mbar||1.5 bar|
|Ex-VCM4156||-15…+6 mbar||2 mbar||1 bar|
|Ex-VNM111||-1…+0,1 mbar||50 mbar||6 bar|
|Ex-VNM301||-250…+100 mbar||45 mbar||3 bar|
* At very high vacuums, close to the theoretical maximum of –1 bar, the switch may not be usable in view of the special conditions of vacuum engineering. However, the pressure switch itself will not be damaged at maximum vacuum.
The “zero” reference point on the scale of the unit corresponds to the relevant atmospheric pressure.
The maximum medium temperature at the pressure sensor must not exceed the permitted ambient temperature at the switching device. Higher medium temperatures are possible provided the above limit values for the switching device are ensured by suitable measures (e.g. siphon).
The Ex-VCM and Ex-VNM Honeywell / FEMA series are calibrated for falling pressure. This means that the adjustable switching pressure on the scale corresponds to the switching point at falling pressure. The reset point is higher by the amount of the switching differential.
• IBExU12ATEX1040 according to ATEX 94/9/EC
• IECEx IBE 14.0077