Desiccant Breather Theory and Characteristics

Drum Desiccant Breather

Many fluids, semi-solids and powders stored in 55-gallon drums will adsorb water vapor when exposed to normal atmospheric humidity. This water vapor will condense, causing these substances to become contaminated and permanently damaged from the resulting chemical changes.

A Drum Desiccant Breather installed onto a 55-gallon drum, which will prevent contamination during storage and use.

Drum Desiccant Breathers, also known as Drum Vent Dryers, prevent this contamination, which occurs during storage and use. Changes in temperature, barometric pressure, and fluid pumping will result in air entering the drum. This air passes through a column of blue indicating silica gel, which removes and retains the water vapor. The silica gel changes from blue to pink when the desiccant is saturated and requires replacement. The units can also be filled with orange silica gel, which is acceptable for use in the European Union. The Drum Desiccant Breather is reusable — saturated desiccant can easily be replaced by removing the access port plug.

The Drum Desiccant Breather begins to work from the moment it is installed. Field testing has demonstrated that when a Drum Desiccant Breather is fitted to a new drum of uncontaminated fluid, the air space above the fluid is made safe from condensation within a few hours.

Contaminated Substances Can Result In:

  • Alteration of Active Properties;
  • Increased Corrositivity;
  • Loss in Dialectric Properties;
  • Viscosity Variation;
  • Chemical Instability; and
  • Coagulation and Sedimentation.

Tank Desiccant Breather

The reusable Tank Desiccant Breather offers an innovative solution to the desiccant breather industry. Instead of wasting yet another traditional breather, now all you have to do is attach a Tank Desiccant Breather to your industrial storage tanks (up to 132,000 gallons) and simply change the desiccant when needed.

Tank Desiccant Breather can attach directly to an industrial storage tank.

Each Tank Desiccant Breather can be filled with a variety of desiccant products, including blue or orange indicating silica gel, molecular sieve, activated alumina and activated carbon. The standard desiccant fill is blue silica gel.

AGM also has the technical expertise to help you select the right Tank Desiccant Breather product, located in our Tank Vent Dryer selection guide.

Typical materials which can be readily protected:

  • acetic acid;
  • arklone;
  • brake fluid;
  • ethanolamine;
  • glycerol;
  • monomethylemethacrylate;
  • perklone;
  • polyalcohols;
  • polyethers;
  • sulphuric acid;
  • transformer oils;
  • trichloroethylene; and
  • triklone


In addition to water vapor, other contaminants may be removed, including:

  • acetone;
  • acid;
  • ammonia;
  • carbon dioxide;
  • carbon monoxide;
  • ethylene;
  • formaldehyde;
  • freon;
  • hydrogen;
  • oil vapors;
  • oxides of nitrogen;
  • sulphide;
  • sulphur dioxide; and
  • toluene

Transformer Desiccant Breather

The failure or malfunction of many transformers or similar equipment can be directly attributed to the lack of proper control of the level of water vapor entering the equipment. It is essential, therefore, that a very low level of humidity is maintained in the airspace of the conservator tank to avoid deterioration in the insulating properties of the cooling medium.

A transformer desiccant breather installed onto industrial equipment to control the level of moisture entering and prevent contamination.

Transformer Desiccant Breathers provide an economic and efficient means of controlling the level of moisture entering equipment during the change in volume of the cooling medium and/or airspace caused by temperature gradients.

All Transformer Desiccant Breathers (except Re-Actrans) are filled with self-indicating silica gel. This desiccant is blue when active and turns pink when saturated.This allows a visible assessment of the condition of the desiccant. Various sizes and types of packs of this desiccant are available for recharging the desiccant containers.

Transformer Desiccant Breathers provide clear visibility of the desiccant charge through a clear, shatter-proof, UV stabilized polycarbonate cylinder or window, depending upon the size of the unit. Two-way, low pressure valves are fitted in the base of the breather to ensure that atmospheric air enters the desiccant charge when a negative pressure differential occurs within the equipment being protected.

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