Rugged Breathers Offer Multi-layer Filtration

Reservoir breathers provide a path for air to enter and leave a tank as its fluid level rises and lowers during system operation. They let the reservoir inhale and exhale. Many breathers also include filters to exclude solid contaminant particles, oil mist, and water vapor from the hydraulic fluid.

Richard Schneider

Sept. 19, 2006

2 min read

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Hydraulic reservoir breathers provide a path for air to enter and leave a tank as its fluid level rises and lowers during system operation. They let the reservoir inhale and exhale. Many breathers also include filters to exclude solid contaminant particles, oil mist, and water vapor from the hydraulic fluid.

The disposable DC/DS-6 breather from Des-Case has a rugged metal housing that survives in harsh environments — such as mobile and nautical applications — and withstands temperatures as high as 250° F. The base plate and central standpipe are stainless steel; the housing is molded aluminum, powder-coated with epoxy. The base is fitted with eight vent plugs that can be selectively removed to match inlet-air flow to the system's requirement. Ambient air enters through the vents, passes through a multi-tiered filter, and flows into (and out of) the reservoir via the standpipe. The standpipe channels all air flow through the filter; there is no bypass.

The filter consists of an initial foam layer that diffuses the incoming air and captures any ambient oil mist, a layer of microglass to capture incoming particulate, a large bed of silica-gel desiccant to adsorb water, a second microglass layer to block migration of desiccant particles,and a final foam layer that captures any oil mist exiting from the tank. As the silica gel becomes saturated, its color changes from blue to pink, signaling that it should be replaced. A pair of visual indicator windows — diametrically opposite on the breather housing — simplify monitoring the silica gel's condition.

Spec sheet: DC/DS-6 breather

Height: 6.5 in.
Diameter: 5.0 in.
Filtration area: 38 in. ²
Filtration level: 1 µm absolute
Maximum flow rate: 20 cfm @ 1.5 psid
Amount of silica gel: 24 oz
Adsorption capacity: 9 fl. oz

Make contact:
Des-Case Corp.
White House, Tenn.
(615) 672-8800
www.des-case.com

About the Author

Richard Schneider

Contributing Editor

Contributing Editor, has been affiliated with Hydraulics & Pneumatics for more than 30 years and served as chief editor from 1987 through 2000. He received a BSME from Cornell University and also completed additional courses at the Milwaukee School of Engineering. His diverse background in industry includes ten years with a fluid power distributor and a variety of other professional positions. He has also been active with the National Fluid Power Association and Fluid Power Society.