Combination Air Valves are also known as Double Orifice Air Valves and are designed to provide the functions of both Air Release (Small Orifice) Air Valves and Air Vacuum (Large Orifice) Air Valves in a single valve body.
A Small Orifice, opened and closed by the rising and falling movement of a float, lever mechanism and button seal, releases accumulated gas whilst the system is under pressure. The Large Orifice function, located in the same valve, can be of a piston design or through the use of a second float.
The Large Orifice guided piston in a Combination Valve design includes the Small Orifice through its centre and offers a significantly more compact, economical, lighter and shorter construction, ideal for valve chambers with height restrictions.
Initially closed by the rising of the Small Orifice float and lever mechanism, the Large Orifice piston seats against an O-ring and remains in place whilst the system is under pressure. As with the Air Vacuum (Large Orifice) valve, when there is negative pressure as a result of emptying the pipework and in presence of a surge event, the piston rapidly drops allowing large volumes of air into the system, equalising pressure.
Combination Air Valves are available in a range of materials such as Cast Iron, Ductile Iron and Stainless Steel to suit a varied range of applications in the Water & Wastewater and Construction Industries. Our technical team are on hand to offer any information regarding our range of combination air valves. We would be happy to hear from you on +44 (0)1704 898980 or alternatively, email [email protected].