Anti-syphon traps, or anti vac traps as they are sometimes called, are used to avoid the possibility of the trap seal being drawn away by siphonage within the waste system. Siphonage generally occurs where there is a long run of waste pipe particularly if there is a steeper than normal fall on the pipe. It can also occur when the trap is positioned very near to the connection with the soil pipe.Our anti-syphon traps have a 76mm seal. It is available in a 32mm or 40mm size option.This trap is manufactured by FloPlast, one of the UKandrsquo;s leading suppliers of above and below ground drainage systems. It can be connected to most UK manufacturersandrsquo; push fit and solvent weld waste pipes.To connect the trap, always start at the top with the connection to the waste fitting. If the installation is particularly tight we suggest assembling all connections loosely before finally tightening all nuts once the trap is in position.First you should ensure that the O ring is correctly seated