Brownell Hydraulic Reservoir Breathers protect the contents of reservoir and storage vessels against water contamination. Water contamination of hydraulic oil can cause the failure of hydraulic systems.


These rechargeable units also minimise pressure differentials and odour emissions. The design of the dryers incorporates excellent weather protection, making them suitable for external applications.


An active desiccant bed retains the moisture before it enters the vessel. Field trials have proven that most existing water vapour contained within a vessel is quickly removed when these vent dryers are fitted.

Brownell’s range of products designed to keep Hydraulic oil operating at its optimum include:

  • Vent Dryers - Gear boxes, hydraulic reservoirs
  • Tank Vent Dryers - Large hydraulic reservoirs
  • Pipe line Dryers - For air airline protection
  • In Line Dryers - For fluid product protection

Many applications involve storage of volatile and flammable liquids which pose a real risk to safety. In such environments, where there is a serious risk of explosions, overpressure and vacuum conditions generated inside the tank by warming/cooling cycles of the fluid and emptying/filling operations tend to increase the exposure to this hazard.  This can be prevented by expelling the excess air through a venting port or vent pipe. Tank Vent Dryer operates as a breather and can be simply installed with a direct connection to an existing breather or vent pipe. The absence of moving parts or electrical components in the Tank Vent Dryer minimises the possible causes of ignition. Tank Vent Dryer complies with the directive 94/9/EC (ATEX) and therefore is suited for applications where there is a high exposure to hazards such as potential explosions.

On the other hand, when the direction of the flow is inverted (negative pressure) and air is pushed inside the tank, it is extremely important that external contaminating agents and moisture laden air do not enter the container. Tank Vent Dryer is the ideal solution to protect any volatile fluid from moisture. Industrial fluids in general are affected by water vapour contamination, which modifies the fluid properties. F or example, biofuels are particularly sensitive to moisture due to their nature. Presence of water in this type of fuel can potentially cause bacteria growth which will decrease the performance of the fuel. In addition, depending on the fluid chemical composition and on the ambient temperature, moisture can also cause corrosion problems and formation of ice.

Tank Vent Dryer is available in various configurations, materials and sizes, it can be wall mounted (models 605, 610 and 615) or floor mounted (models 620, 630). This product is suitable for tanks of a considerable size, with a capacity of up to 500,000 litres. Extra precaution might be observed in order to achieve pressure equalisation by installing pressure relief valves on the connecting pipe. The main body is available in mild steel or stainless steel indicated for more aggressive environments.

Tank Vent Dryer can be filled with a variety of adsorbent products according to the customer requirements. Silica gel Envirogel can adsorb moisture up to 30% of its weight and the desiccant colour change from orange to green is a clear indication that the desiccant is saturated and needs to be replaced. A UV stabilised polycarbonate clear window installed on the body allows visual reading of the saturation level of the desiccant.

Molecular sieves are a suitable alternative for those applications in which very low dewpoints are required. It adsorbs moisture up to 20% of its weight and has high adsorption efficiency at high temperatures.

When the desiccant is saturated, it can be easily replaced by simply removing the desiccant holder. Refills Packages are available for every model.