Humidity Alarm Manual
Model HCLS 20/99-AL
Ohmic model HCLS 20/99-AL Air Line Humidity Alarm is designed to monitor the relative humidity in a pressurized air system and provide alarm output conditions when the air line humidity exceeds a preset humidity level. The unit is constructed in a weather-tight NEMA 12 enclosure. The humidity level in the air line is sensed by an Ohmic weatherproofed humidity sensor model UPS-600RS, which is mounted using a model HPM-350 high pressure mount. This high pressure mount is installed into the pressurized environment using 1″ NPT fittings. A 12′ sensor cable model CH-12 is used to connect the humidity sensor to the alarm system.
Model HCLS 20/99-AL provides a direct indication of humidity in the pressurized environment on a color-zoned analog meter on the front panel. The color zones apply to a typical 85% setpoint application, but the setpoint may be adjusted for any humidity value between 20% and 99%. The setpoint is adjusted from the front panel by simply depressing the push-to-read button and turning the alarm setpoint adjustment until the desired humidity alarm level is indicated on the meter. The setpoint adjustment has a locking nut which should be tightened after the desired setpoint is obtained to minimize tampering. The unit is factory set to activate the alarm conditions when the humidity rises above the alarm setpoint. An alarm condition will be indicated by a flashing LED on the front panel, a pulsed (or continuous) audible alarm, and contact closures on humidity rise above or below the setpoint value. These contact closures can be used for external humidity control of the pressurized air.
The unit is powered from a 12 VDC power source which can be supplied either through the 25-pin D-type output connector, or by using the included plug-in 120 VAC to 12 VDC power supply which supplies power through a 1/8″ jack on the bottom of the enclosure. The accuracy of the model HCLS 20/99-AL is ±1% relative humidity at an operating temperature of 80°F. A negative temperature coefficient of -3% relative humidity per +20°F change from 80°F can be used to correct measurements at other operating temperatures.