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A flush toilet is a toilet that disposes of human liquid and solid waste, by using water to flush it through a drainpipe to another location for disposal, thus maintaining a separation between humans and their excreta. Flush toilets can be designed for sitting (in which case they are also called "Western" toilets) or for squatting, in the case of squat toilets. The opposite of a flush toilet is a dry toilet which uses no water for flushing. Flush toilets usually incorporate an "S", "U", "J", or "P" shaped bend that causes the water in the toilet bowl to collect and act as a seal against sewer gases. Since flush toilets are typically not designed to handle waste on site, their drain pipes must be connected to waste conveyance and waste treatment systems. When a toilet is flushed, the wastewater flows into a septic tank or sewage system and from there to a sewage treatment plant.〔Kagan, Mya. "Where Does the Water Go When I Flush the Toilet?" Kids' Why Questions. Whyzz. Publications LLC, 2011. Web. 28 Nov. 2011.〕 A flush toilet may be colloquially called a lavatory, a water closet (abbreviated W.C.), a loo, a comfort room (abbreviated "C.R.") and many other names. A flush toilet is different from a urinal, which is designed to handle only liquid waste; or from a bidet which can be used for cleaning after toilet use. ==Operation== A typical flush toilet is a vitreous, ceramic bowl containing water, plus plumbing to rapidly fill it with more water. The water in the toilet bowl is connected to a hollow drain pipe shaped like an upside-down U connecting the drain. One side of the U channel is arranged as a hollow siphon tube longer than the water in the bowl is high. The siphon tube connects to the drain. The top of the upside-down U-shaped drain pipe limits the height of the water in the bowl before it flows down the drain. If water is poured slowly into the bowl it simply flows over the rim of the upside-down U and pours slowly down the drain — thus the toilet does not flush. The standing water in the bowl acts as a barrier to sewer gas coming out of the sewer through the drain, and also as a receptacle for waste. Sewer gas is vented through a separate vent pipe attached to the sewer line. When a user flushes a toilet, a "toilet flapper valve" (not to be confused with a type of check valve) opens and allows water from a reservoir tank to quickly enter the toilet bowl. This rapid influx from the tank causes the swirling water in the bowl to rapidly rise and fill the U-shaped inverted siphon tube mounted in the back of the toilet. This full siphon tube starts the toilet's siphonic action. The siphon action quickly (4–7 seconds) “pulls” nearly all of the water and waste in the bowl and the on-rushing tank water down the drain — it flushes. When most of the water has drained out of the bowl, the continuous column of water up and over the bottom of the upside-down U-shaped drain pipe (the siphon) is broken when air enters the siphon tube. The toilet then gives its characteristic gurgle as the siphonic action ceases and no more water flows out of the toilet. After flushing, the flapper valve in the water tank closes; water lines and valves connected to the water supply refill the toilet tank and bowl. Then the toilet is again ready for use. At the top of the toilet bowl is a rim with many angled drain holes that are fed from the tank, which fill, rinse, and induce swirling in the bowl when it is flushed. Mounted above the toilet is a large holding tank with approximately of water in modern designs. This tank is built with a large drain diameter hole at its bottom covered by a flapper valve that allows the water to rapidly leave the holding tank. The plumbing is built to allow entry of the tank’s water into the toilet in a very short period. This water pours through the holes in the rim and a siphon jet hole about diameter in the bottom of the toilet. Some designs use a large hole in the front of the rim to allow faster filling of the bowl. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「flush toilet」の詳細全文を読む スポンサード リンク
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