The valve pit provides the interface between the vacuum system and the house. The 1-piece valve pit is rotationally molded and made entirely of PE. It consists of two (2) separate chambers; an upper chamber that houses the vacuum valve and a lower chamber that is the sump into which the building sewer is connected. These two chambers are sealed from each other. The 1-piece AIRVAC valve pit includes an integral anti-buoyancy collar and has an H-20 traffic load rating.
Each valve pit can accommodate sewage from up to four homes, although the most common configuration is one valve pit serving two adjacent houses. Houses connected to the vacuum sewers do not need any special plumbing fixtures.
Located in the upper chamber is a vacuum interface valve, which is pneumatically controlled and operated. Vacuum from the sewer line opens the valve and outside air from a breather pipe closes it. The interface valve is a full-port 3” (75 mm) valve and designed for handling 3” (75 mm) solids.
The upper chamber, made of a PE material, houses the vacuum valve and controller and is suitable for H-20 traffic loading..
The sump portion of the valve pit is used to accept the wastes from the house. Elastomer connections are used for the entry of the building sewer. Holes for the building sewers are field cut by the contractor at the position directed by the engineer.
The AIRVAC controller requires a source of atmospheric air to the actuator chamber permitting spring assisted closing of the vacuum valve. Without this air, the valve will remain in the open position.
Early vacuum systems used an external breather for this source of air. This has been replaced by the in-sump breather, which uses atmospheric air from the sump. In the event of low vacuum conditions where the valve would not open, floats in the in-sump breather protect the controller from unwanted liquid.
Atmospheric air used for transport enters through the 4” (100 mm) screened air-intake on the homeowner’s gravity line. The possibility of odors at this air-inlet is minimized due to the small volumes of sewage and short detention time in the sump.