invented various contrivances for this purpose, e.g. in "Jenning's valve closet the overflow is trapped by means of an india rubber ball, the ball allowing water to pass it in one direction, but any pressure of gas in the other only causes the ball to fit more closely to the end of the pipe. In Dent and Hillyer's valve closet, the overflow pipe is made larger than usual, so that the water seal is of greater bulk, besides which pressure in the valve box is rendered impossible, for a ventilating pipe is inserted into the valve box and continued into the open air. A better way to deal with the overflow pipe is to disconnect it from the valve box and carry it into the open air similarly to the warning pipe of a cistern, or to let it deliver it on the safe tray of the closet, and thus any waste will go down the waste pipe of the safe tray. The hopper closet differs from either of the two previous closets in having no mechanical parts; it is simply a funnel terminating in a syphon, all that is required is a good flush of water and the contents pass away (Fig. 43). An improved form of the hopper closet is what is known as the "wash-out closet;" this again has no mechanical parts, it is often made of glazed stoneware cast in a single piece, the closet is simply cleansed after use by a good flush of water (Fig. 44). It is the custom to place a lead tray beneath closet pans on the floor, to prevent any overflow soaking through into the ceiling below. This is called a "safe;" there is a waste pipe from the safe, sometimes carried into the soil pipe, and sometimes into the D-trap it ought of course to be carried into the open air direct. The safe is usually boxed in together with the lower part of the closet by wood casing, and the whole space is not unfrequently a receptacle of dirt and filth and a cause of air contamination. The most modern closets have no safe, nor wood casing; the best form of all is without doubt of the wash-out type, the basin and syphon of which are freely exposed to view, in which mechanical parts are absent, and in which deposits in the syphon or around the pan are rare. The supply pipe to all the closets mentioned should be of sufficient size, 1 inch is the least admissible diameter for the supply pipe of a closet; the supply pipe should under no circumstances be directly connected with the drinking water cistern, nor what is still worse, with the service pipe of a constant supply system. Closets should have a separate cistern, or what is called a water waste preventing cistern. This holds a charge of two gallons, the whole of which runs into the closet when the valve is pulled. The mechanical arrangement of this cistern is usually as follows: a spindle valve guards the opening of the flushing pipe going to the pan, the spindle valve is connected with a lever to which is attached a chain and ring; on pulling the chain, the spindle valve is raised and the water rushes out. The supply pipe is connected with the usual floating ball cock arrangement; when the cistern is full the ball cock floats up and shuts off the supply, when the cistern is empty the ball falls and the supply is opened. It must also be noted, that the apparatus connected with the spindle valve, by which the cistern is emptied is so arranged, that when the chain. is pulled, the ball is also lifted and prevented from descending, so that until all the water is run out of the small cistern, water from the supply pipe does not enter. In this way also there is no chance of contamination by any foul gas which has made its way into the waste preventer. It may be necessary to observe that the waste preventer cistern must be a sufficient height above the closet to ensure a good flush, the writer has known them placed almost at the seat level. (173) Soil Pipes. The best material for soil pipes is lead. Lead soil pipes used formerly to be seamed, that is to say, each piece of the pipe was made by taking a long strip of lead, rolling it into a cylinder and joining the two edges by a seam. In this way there were not alone the usual transverse joints between the different portions of the soil pipe but also a seam or joint down the middle. Experience has amply shown that seamed pipes are liable to open, and they are now replaced by "drawn pipes" in which there are no longitudinal seams. The diameter of a soil pipe should be at least 4 inches; its best position is outside the house, not inside; nevertheless a pipe carried inside is not a source of injury providing the joints are tight; in many instances the soil pipe must be carried inside. The next best material for a soil pipe is iron, but this is not suitable for inside pipes from the difficulty in making the joints absolutely perfect. Zinc soil pipes rapidly corrode and are therefore undesirable. The soil pipe should be ventilated; this is best done by carrying or rather continuing the soil pipe full bore without curves or bends to a few inches above the roof-ridge. It may be protected from the entrance of dirt by a perforated conical cap fixed by wires so as to stand well off the mouth, otherwise if placed close to the opening of the pipe, there will be obstruction of air current. |