(7) The pan breaks the force of the water flush, and the trap is usually not completely emptied.
Valve and Plunger Closets are an improvement upon the pan closets, but are not free from several objections enumerated above. As a rule, all water-closets with mechanical parts are objectionable.
Hopper Closets are made of iron or earthenware. Iron hopper closets easily corrode; they are usually enameled on the inside. Earthenware hoppers are preferable to iron ones. Hopper closets are either long or short; when long, they expose a very large surface to be fouled, require a trap below the floor, and are, as a rule, very difficult to clean or to keep clean. Short hopper closets are preferable, as they are easily kept clean and are well flushed. When provided with flushing rim, and with a good water-supply cistern and large supply pipe, the short hopper closet is a good form of water-closet.
The washout and washdown water-closets are an improvement upon the hopper closets. They are manufactured from earthenware or porcelain, and are so shaped that they contain a water seal, obviating the necessity of a separate trap under the closet.
Fig. 25.
LONG HOPPER WATER-CLOSET. (Gerhard.)
Fig. 26.
SHORT HOPPER WATER-CLOSET. (Gerhard.)