Siphon is an hydraulic element inserted in a pipe and realized through a "u" shaped curve pipe. It's useful to create an obstacle (an "hydraulic top") against bad smell thanks to the presence of residual water in its owbow, water that occupies the transit section of smell. There are several types of siphon used in hydraulic establishments: goose-neck ( "P" or "S" shaped and space-saving model), bottle shaped, ecc.. Every single siphon is characterized by the voluntary stagnation zone of the washing fluid of the sanitary device, formed by a tank or an oxbow.