anti-syphonage pipe/trap

Anti-syphonage pipe 是反虹吸管

Difference :
Syphonage is an suction inside waste or soil pipes. An anti-syphonage system could avoid the suction. It could be a anti-syphonage trap, a vent pipe or any ventilation system inside the drains. On the other hand, u-trap is only a gully with water trapped to ensure smell and insert would not transferred between the two end of the traps. As a conclusion, u-trap and anti-syphonage pipe are two different systems.

U-trap refers to only the trap. It provides a water seal under a sanitary fitment in order to prevent foul gas entering the interior of a building through the drain pipe.

2014-01-10 10:53:53 補充：
There are occasions that the water seal inside a trap will disappear due to imbalance of air pressure in the drainage system. An anti-siphon pipe is provided near the trap to balance the air pressure, so to prevent loss of water seal.

2014-01-10 10:57:13 補充：
The anti-siphon pipe can sometimes be omitted. We may instead use an anti-siphon trap which is able to release the difference in air pressure through a small device attached to it (looks like a small umbrella). Where circumstances permit, an anti-siphon trap can replace the anti-siphon pipe.