D4-A Dryer-Filter-Regulator

Model 4076
Expanded view of the D4-A
to clearly show components

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. Most air supplies contain substantial amounts of oil, water, and particulates. Water will accumulate in receiver tanks, even in dry climates. Centrifugal separators and coalescing filters can remove water droplets, but can not reduce the relative humidity below 100%.

Refrigerative and regenerative (twin tower) dryers can get the air very dry, but they tend to fail suddenly and catastrophically from power failures, shuttle valves sticking, etc. Deliquescent dryers, like our D4-A, have the best reliability record, and do not depend on an electrical supply. The deliquescent tablets in the dryer combine with water vapor to form a liquid which is drained daily. Saturated air is reduced to about 60% relative humidity at pressure. This is equivalent to reducing the dew point from 72°F to about 56°F.

The D4-A requires little maintenance, providing economical, effective, continuous drying and filtering with no moving parts and no electrical energy use. It produces clean, dry air from readily available shop air supplies, and is suitable for use in laboratories.

All D4-A Systems Include:

  • A pre-filter to remove large particles and droplets.
  • A coalescing filter to remove almost all of the oil droplets and free water.
  • A deliquescent dryer with a capacity of 15 standard cubic feet per minute (SCFM) at 150 psi.
  • A regulator/filter downstream from the dryer and upstream from a carbon cartridge.
  • An activated carbon cartridge to adsorb residual oil vapor and other organic contaminants such as tars and resins from cigarette smoke. THIS IS IMPORTANT. It is required even if an “oil-free” air compressor is used. The cartridge can be removed for periodic replacement.
  • A final filter rated at 5 microns.

The D4-A Dryer-Filter-Regulator, when used in conjunction with a Humidity Alarm, provides a reliable, efficient, and inexpensive air-treating station.

D4-A Operator’s Manual

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