Air bearings require clean, dry, oil-free air. The air supply must be maintained at less than 85% relative humidity, and it must be free of oil and of particles larger than 5 microns. One of the major causes of air bearing failure is corrosion from condensation of water vapor inside the bearing. These bearing failures are costly in terms of down-time and repair charges.

The Humidity Alarm, manufactured for Professional Instruments by Ohmic Instruments, continuously monitors the humidity level in a compressed air supply. Relative humidity above 20% will be constantly displayed on an analog meter. If the moisture content of your air supply rises above an adjustable setpoint (factory set at 85% relative humidity), a piercing alarm will sound and a light will flash.


Audible alarm and LED
Large analog meter with color-coded scale
Alarm setpoint adjustment (factory set at 85% relative humidity)
Humidity sensor installed in 1” NPT fitting
Custom-made union to mate sensor with the D4-A Dryer-Filter-Regulator
Watertight NEMA 12-gage steel enclosure
12 VDC power input jack
110V UL listed external power supply
12’ cable for humidity sensor
25 pin D-type output connector for remote alarm signal
The Humidity Alarm, when used in conjunction with a D4-A Dryer-Filter-Regulator, provides a reliable, efficient, and inexpensive air-treating station.