Watchdog Desiccant Breathers

Watchdog Desiccant Breathers

Watchdog Desiccant Breathers are a unique particle filtration and water removal system. They prevent destructive contaminants from entering industrial equipment as air is breathed in and out due to thermal expansion or fluid level changes. They feature visual indication of the silica for replacement, which turns from orange to dark green.

By allowing only clean, dry air into industrial equipment, the Watchdog Desiccant Breathers prolong fluid life, reduce abrasive wear, downtime, and repair costs.


  • Water Vapor Adsorbent – the silica gel used adsorbs up to 40% of its own weight.
  • Color Indicator – When maximum adsorption is reached the silica gel turns from orange to dark green, indicating replacement is needed. The silica gel used is chemically inert, non-corrosive, and does not contain cobalt chloride, a heavy metal. The color changing dye used is environmentally safe and meets all health and safety requirements.
  • Dual Filtration System – A two micron filter (99% efficiency) is located at the top and bottom of the silica gel bed. The top filter removes particle contamination from atmospheric air and the bottom helps with dust created by the silica gel beads contacting each other.
  • Activated Carbon – As air is expelled, it passes through activated carbon which removes oil vapors, fumes, and odors (except for part numbers 39131, 39132, 39133, and 39134).
  • Bi-directional air flow – A 360º air flow allows air to be breathed in and out as fluid level changes or differential pressures occur. Expelled air “backflushes” the particulate filter to prolong the life of the breather.
  • Durable construction – Watchdog Desiccant Breathers are manufactured from rugged ABS plastic and impact modified acrylic.
  • To install Watchdog Desiccant Breathers use one of several Watchdog Breather Adapters.

Do you have a suggestion to improve this product? If so, you can submit your idea here. For special quote requests, please use our quote request form or contact our customer service team at 262.691.9336.



SDS Sheets



Model No.DescriptionHeightDiaConnectionAir FlowFluid Volume ExchangeSilica Gel VolumeWater Capacity
39101Breather6.25 in5 in1" Male Friction Fit20 CFM150 gpm1.4 lb.4 lb
39102Breather9.25 in5 in1" Male Friction Fit20 CFM150 gpm2.7 lb.9 lb
39108Breather11.25 in5 in2" Male NPT20 CFM150 gpm3.5 lb1.3 lb
39131Breather2 in2 in1/2" Female NPT5 CFM37 gpm.08 lb.032 lb
39132Breather3.25 in2 in1/2" Female NPT5 CFM37 gpm.1 lb.056 lb
39133Breather2 in3.25 in1/2" Female NPT5 CFM37 gpm.3 lb.104 lb
39134Breather3.25 in3.25 in1/2" Female NPT5 CFM37 gpm.5 lb.18 lb
Nominal Air Flow Rate 20 CFM (150 gpm of fluid volume change)
5 CFM (37 gpm of fluid volume change)
Particulate Filtration Level 2 micron absolute (99% efficiency)
Operating Temperature Range -20º to 200ºF / -28 to 93ºC
Silica Gel Adsorption Up to 40% of its weight of water
Material ABS plastic and impact-modified acrylic

Listed below is the maximum water capacity for the Watchdog Desiccant Breathers by part number.

Model No. Silica Gel Content Max. Water Capacity
39100 0.8 lbs 4.91 fl oz
39101 1.4 lbs 8.6 fl oz
39102 2.7 lbs 16.56 fl oz
39108 3.5 lbs 21.47 fl oz
39131 0.08 lbs 0.49 fl oz
39132 0.1 lbs 0.92 fl oz
39133 0.3 lbs 1.84 fl oz
39134 0.5 lbs 3.06 fl oz

Note: Water capacity is a function of relative humidity. At higher humidity levels, the silica gel adsorbs (holds) a larger amount of water. The maximum is approximately 40% of the weight of the silica gel at about 90% humidity.

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