Combi-Siphon Plus trap vents available from Studor Australia Studor Australia Available from Studor Australia , Combi-Siphon Plus is a washbasin trap vent featuring a 50mm seal. They have an integrated air admittance valve that removes the need of secondary ventilation. Combi-Siphon Plus trap vents are compliant with new European Standard EN12380 requirements and are suitable for venting small groups of appliances and problem solving in buildings. Combi-Siphon Plus trap vents replace conventional S and P traps and are simple to maintain as the base easily screws off. These washbasin traps can be supplied in a white ABS version and also in chrome. They are compact and can be installed in practically any situation. When a siphonage action takes place in the discharge pipe the Combi-Siphon Plus acts as a one-way valve and allows air into the waste system.