Flush Valve Types

• Flush valves carry away waste for sanitary purposes. Toilet bowl and bidet in a toilet image by terex from Fotolia.com

  Flush valves, in three primary designs, are essential to the operation of a toilet. The valve allows water to pass through the bowl from the tank once the lever is switched on the outside of the tank. Flushing the toilet carries away waste, which is what makes the toilet a sanitary and necessary invention from thousands of years of history and adaptation.

Standard Flush Valve

• The standard flush valve is designed with an external lever that a person will activate to rid the toilet of waste water. The lever lifts a chain on the inside of the toilet tank, thus pulling up the flapper (plastic or rubber seal) so the water is exchanged. This motion also uses water pressure to "flush" out the water in the bowl until it drains out through the waste pipe beneath the toilet. The water level inside the toilet is preset and dependent on the balloon, attached to the chain and lever, that rises within the tank.

Sensor Flush Valve

• The sensor flush valve is often seen in public restrooms to eliminate the hazards of germ transfer from person to person. Instead of flushing with an external lever, the toilet "senses" when the person stands from the seat, and an internal mechanism activates a hydraulic flush system and the water rushes away. The sensor flush valve also has an external button in case the mechanism is not automatically activated.

Hydraulic Flush Valve

• The hydraulic valve is well known in public places, mostly due to the durability and long life of the mechanism. The hydraulic valve is activated with an external lever, which in turn causes a fast flow of water to be rushed from the water pipes into the toilet bowl. The hydraulic valve uses water pressure and air pressure, by forcing both into the bowl at the same time. This eliminates the need for a toilet tank, since the water is purged from the water pipe, and not dropped by gravity like the traditional toilet.