Mechanical Hygrostat
MFR 012

  • Efficient condensation control
  • Adjustable relative humidity range
  • High switching capacity
  • DIN rail mountable

The MFR 012 electromechanical hygrostat is designed to control the relative humidity inside enclosures. When connected to an enclosure heater (dehumidifier), it will energize the heater at the humidity set point in order to raise the dew point. This helps prevent damage and malfunction of electronic components caused by condensation and corrosion.¹

The MFR 012 can also be used to control cooling fans, warning lights or other devices.

¹ The critical relative humidity level for most components is 65%. Above 65% RH, condensation can form and cause malfunctions of electronic equipment. Long term, this can lead to corrosion and permanent damage of electronic components and systems.

Switching difference4 %RH (± 3 % tolerance) - at 50 %RH
Permissible air velocity50 ft/sec (15 m/s)
Contact typeSPDT / change-over contact
Service life> 50,000 cycles
Min. Switching capacity100 mA @ AC/DC 20 V
Max. Switching capacity5 A resistive @ AC 250 V
DC 20 W
Connection3-pole terminal, clamping torque 0.5 Nm max.:
solid wire - AWG 14 max. (2.5 mm²)
stranded wire² - AWG 16 max. (1.5 mm²)
Housingplastic, UL 94V-0, light grey
Mountingclip for 35 mm DIN rail, EN 60715
Mounting positionvariable
Operating / Storage temperature+32 to +140 °F (0 to +60 °C) / -40 to +140 °F (-40 to +60 °C)
Operating / Storage humiditymax. 95 %RH (non-condensing)
Dimensions2.64 x 1.97 x 1.5” (67 x 50 x 38 mm)
Weightapprox. 2 oz. (60 g)
Protection typeIP20
ApprovalsUL File No. E164102, EAC

² When connecting with stranded wires, wire end ferrules must be used.

Part. No.Setting range
01220.0-0035 to 95 %RH

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Dimensioned Drawing

Mechanical Hygrostat MFR 012

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