Allows the free entry of air into the sanitary pipework system without the foul gasses escaping into the building. Avoids the need to penetrate outer roof shell. It is recommended that air admittance valves are not used externally as environmental debris will affect the air tightness performance of the valve. Tested and approved for use in installation varying between -20° and +60°C (no insulation required). A1 approved in accordance with BS EN 12380, can be installed below the flood level of connected appliances. FloPlast are the first company in the world to be awarded the Kitemark for Air Admittance Valves in accordance with BS EN 12380:2002, licence number KM512474. Specifications: BS EN 12380: 2002