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Desiccant Breathers

There are two ways to deal with contamination: prevent it or remove it. While in most cases it may be important to do both, there is no doubt that removing contaminants is significantly more costly than preventing them to begin with. As nearly all gearboxes, reservoirs and storage tanks are designed to breathe, allowing only clean, dry air to enter the system is one of the best measures to prevent contamination. Simply replacing standard breather/filler caps or vents (that provide minimal or no contamination control) with a desiccant breather immediately prevents moisture contamination and moves particle filtration from 40 micron to 2 micron.

Desiccant breathers are quite literally the first line of defense against contamination and should be an integral part of any proactive maintenance and reliability program. Watchdog® desiccant breathers are designed to replace the breather cap or air filter on gear boxes, hydraulic fluid reservoirs, bulk storage tanks, oil drums, oil-filled transformers, and other fluid reservoirs. The breathers adsorb water and filter particulate contaminants from the atmosphere before they enter your fluid system. Watchdog® desiccant breathers utilize patented designs and feature color indicating silica gel and self-cleaning 2-micron filtration.

U.S. Lubricants has assembled a comprehensive range of desiccant breathers to address most applications. It is part of our customer promise of Assuring Machine Health™. And since new products are added regularly, be sure to check with us if you don’t see the solution to your needs here.

  • Essential Desiccant Breathers
  • Extreme Humidity Desiccant Breathers
  • Extreme Vibration Desiccant Breathers
  • Passive Oil Dryers
  • Hydraulic Reservoir Breather Kits

Desiccant breathers may be used across a wide range of industries and applications:

  • On fluid storage containers and holding tanks
  • On wind turbines and power transformers
  • On mobile and stationary mining machinery, gear boxes and hydraulic reservoirs
  • On heavy equipment, conveyor systems, pumps and gearboxes
  • In cement and aggregate facilities
  • In power generations, steel production, and waste treatment plants
  • On heavy mobile equipment and bulk material handling systems
  • And more

How Desiccant Breathers Work

Diagram 1 indicates how the patented design allows outside air to enter through the 360° opening in the breather’s top cap. The top cap design overhangs the body of the breather helping protect the breather from rain, sleet, snow, as well as most equipment wash-down procedures.

When contaminated air enters the top of the breather, it passes through a self-cleaning solid particle filter. This filter traps solid particles greater than 2 micron and keeps them from entering the breather and ultimately to wear surfaces on your equipment. The filtered air then passes through a bed of silica gel that adsorbs moisture in the air. Up to 95% of the water vapor in the air is filtered out in this step.

Finally, the filtered air passes through an additional 2 micron filter in the bottom of the breather to ensure that no harmful particles will enter the tank or reservoir. This three stage filtration design ensures your equipment gets clean, dry air.

As the color indicating silica gel adsorbs moisture, it changes from gold to dark green. When the silica gel is adsorbed to its capacity (approximately 40% of its original weight), the breather has fully turned dark green. This color change is easy to observe and serves as the visual indication that it is time to remove and replace the disposable breather.

Diagram 2 indicates air being expelled back through the desiccant breather from the equipment the breather is mounted on. As contaminated air travels this reverse path, expelled water vapors are absorbed by the silica gel. During this reverse air flow process, the silica gel indicates the presence of excessive moisture inside the reservoir as the gold silica gel turns to dark green from the bottom of the breather, rather than from the top.

Located in the bottom is a layer of carbon impregnated foam. This carbon pad absorbs small amounts of oil vapor exhaled from the tank and protects the silica gel from minor oil mist contamination. In some cases, excessive oil mist control may be required and adapters are available for such applications.

As the exhausted air passes back through the self-cleaning 2-micron filter, (located in the top cap of the breather) any particles that were trapped as air and entered the system are now back-flushed from the filter.

Desiccant Breathers - Specifications, Options, Selection Charts

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