Installation Instructions Types 1920E, 1921E and 1924E Automatic Dehydrators

Bulletin 237041

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Description These automatically operated dehyrdrators are designed to supply dry air under pressure to the transmission line of an antenna system. The dehydrator (Figures 1 and 2) basically consists of a motor-compressor unit and a dryer unit. They start operation when transmission line pressure decreases to a preset level and stop when pressure increases to a preset level. The motor-compressor unit is shock-mounted to reduce vibration. The compressor has two single-stage cylinders. The dehyrdrator is designed to produce a maximum outlet pressure of 9 psi (62 kPa) with a maximum dew point (the temperature at which air becomes saturated and moisture condenses) of -40°F (-40°C) at the outlet. Since the compressor has low-friction piston rings and the motor has sealed bearings, no lubrication is required. The two air intake filter assemblies at the slides of the compressor

should be replaced at least once a year to ensure efficient operation. Two adsorption cylinders in the dryer unit hold the desiccant in which air drying takes place. During operation, a timing motor controls two input solenoid valves for the alternate drying of air in one cylinder and purging of moisture from the other cylinder. The front panel controls and indictors include a humidity indicator, illuminated circuit breaker, and pressure gauge. The humidity indicator contains a visible layer of silica gel style desiccant that changes color according to the relative humidity in the outlet line of the dehydrator. A deep blue color indicates 10% relative humidity or less, lavender indicates 30%, and pink indicates 50% or more.

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