The 110mm Push-Fit Soil Vent Air Admittance Valve (Grey) (often referred to as a Durgo valve) is an essential, one-way pressure-relief valve designed to allow negative air pressure within a soil stack to balance without permitting foul sewer gases to escape into the building or surrounding area. It provides a localized venting solution that eliminates the need to route the 110mm soil stack through the roofline.
 
When fixtures like toilets, baths, or showers are flushed, a vacuum is created in the soil stack. The valve's internal, spring-loaded or rubber-diaphragm mechanism opens under this negative pressure to draw ambient air into the system, protecting trap seals throughout the building. Once the pressure equalizes, gravity and air pressure force the internal rubber seal closed to maintain a gastight barrier against sewer odours.
 
Featuring a push-fit socket base with an integrated rubber ring seal, the valve mounts directly over the plain spigot end of a 110mm grey uPVC soil pipe. It is typically installed vertically at least 200mm above the highest wet entry point on the stack (such as the spillover level of the highest basin or toilet) inside loft spaces, ducting voids, or boxing. Manufactured from high-impact uPVC in compliance with UK standards (BS EN 12380 / BS EN 1329-1), it provides a maintenance-friendly solution that satisfies UK Building Regulations (Approved Document H).