Breather Valves

Breather Valves, also known as Pressure Relief Valves, prevent excessive pressure or vacuum buildup in sealed containers, which reduces container weight, cube, and cost. AGM manufactures a variety of Breather Valves, which include valves that keep dust, water, and blowing sand from entering containers. These Breather Valves meet SAE AS27166 (replaces cancelled MIL-V-27166) and MIL-DTL-27166 which is the re-instated version of MIL-V-27166. Products include: One-Way Pressure Relief Valves; Two-Way Pressure Relief Valves; Breathing Desiccators; Filler Valves; RFI/EMI Shielded Nut Assemblies; Screened Drain Vents; and Mounting Flanges. AGM also offers a full line of Immersion Proof Breathers.

Please Note: Unless otherwise specified in AGM's catalog, all valves are supplied with a nut, washer and gasket for mounting through a hole on a flat, smooth surface. Valve gaskets may not provide a proper seal if the mounting surface is curved or rough. Valves can also be installed in a mounting flange or a threaded boss when a suitable counterbore has been provided for thread relief.

Breather Valves Frequently Asked Questions

Do these breather valves work automatically?

Yes, but valves with a manual release button can also be opened manually to equalize pressure.

Do the valves completely equalize the pressure between the interior and the exterior of my container?

No, not unless you push the manual release button (only on those valves that have a manual release button). In automatic mode, they will equalize only to the level of the reseal pressure. That is, a TA333-05-05-R breather valve will only equalize to within 0.5 psid because below that the valve will be closed.

Will the breather valve allow water to enter my container?

Not under normal circumstances. There are two cases to consider: submersion and wind driven rain. For submersion, as long as the pressure at the submersion depth is not sufficient to cause the valve to open, it will prevent water from entering through the valve. For wind driven rain, this will normally not make it inside the valve due to AGM’s unique cover design which forces the airstream through two 180° turns, thereby causing most particulates to fall out of the air stream. (Airborne water droplets, sometimes called atomized water, are not the same as water vapor, in the physical sense. Airborne water droplets are actual particles, agglomerations of thousands of water molecules, whereas water vapor is individual water molecules mixed in with the air.)

Are the opening and closing pressures the same?

No. AGM breather valves are small mechanical systems where a spring pushes a seal onto a seat. Due to the surface energy forces of the elastomeric seals, it will always require slightly more force to open the valve than to close it. Therefore, the opening pressure will be slightly higher than the reseal pressure. Also, the higher the setting of the valve, the greater the difference between the opening and closing pressures.

What is the highest setting that I can get?

We have made valves with reseal pressures as high as 10 psid. However, these valves are difficult to work with and the settings may tend to shift after long periods of time and large temperature changes, but they will continue to perform their basic function.

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