Adjustable overpressure valve

This adjustable overpressure valve is a one way check valve that installs on the outflow vent pipe of your shelter or safe room. It only allows air to flow out of, not into your protected space.

It can be adjusted to increase the positive pressure inside your protected space. The positive air pressure is what resists airborne toxins from migrating into your protected space through cracks or holes in the shelter.

It can be attached directly to the inside wall or ceiling or on a blast valve.

Pressure and flow have an inverse relationship. More pressure equals less airflow, and vice versa. If you have the maximum number of occupants rated for the Safe Cell, you need to have this valve wide open. If you have well under the rated occupants, you can increase the pressure in your shelter while staying within the safe airflow rating.

The adjustment cap is located at the bottom of the valve assembly. Tightening this cap increases the pressure in the protected space. This allows you to compensate for a shelter that is not entirely sealed up - within reason. This valve should be used with the differential pressure gauge. so you can see the difference in pressure as you adjust it.

This is the adjustable overpressure valve mounted on a blast valve with a differential pressure gauge.

It is normally closed and will not open unless the air pressure inside the shelter is slightly greater than the outside air pressure. It opens when the Safe Cell is turned on and gives a little back pressure to the Safe Cell to help it create and maintain the positive pressure.

In other words, it gives the Safe Cell something to push against, helping it maintain overpressure and it won't let any contaminated air back up through the outflow pipe into your shelter.

The Safe Cell draws air down the intake ventilation pipe, through the intake blast valve, through the filter bank, and then expels the filtered air into the shelter at a slightly higher pressure than the air outside the shelter (positive pressure or overpressure).

This gives you true ventilation - air in through the Safe Cell and out through this valve. This replenishes the oxygen and removes the carbon dioxide exhaled by the occupants.

The overpressure valve must be oriented so it points at the floor because it partially uses gravity to keep the synthetic rubber diaphragm closed. We include both wall and ceiling adapters. All joints between the overpressure valve, the adapters, and the blast valve are slip fit so they can be assembled or disassembled for cleaning or servicing without tools.

This valve mounts exactly like the preset overpressure valve.

 

What's included with this item

One adjustable overpressure valve (center item above)
One wall mount flange and gasket (items on right)
One 90 degree wall mount adapter (top left)
One ceiling adapter (bottom left)
One hard copy of the manual.

Due to the variety of walls this item can be mounted on, fasteners are not included.

 

American Safe Room provides free air filtration and component blast protection shelter consultations. Contact our Sales Manager at 541-459-1806 or send a plan view drawing of your shelter to sales@AmericanSafeRoom.com or FAX it to 503-212-6695.