The form of urinal shown in Plate 6 is the Bedfordshire lip urinal with flat back. This is undoubtedly the urinal most commonly in use. This fixture is made in a great variety of forms, several of which are shown in Plate 43.

The waste of the lip urinal should be not less than 1 1/2 in. in size, although a waste 2 in. in size is now sometimes used.

The vent should be 1 1/2 in. in size.

The urinal should be set so that the lip comes about 24 in. from the floor. This height should be less when the urinal is used in toilet rooms for small boys.

All lip urinals should be of the flushing rim type. The flushing rim allows the entire surface of the interior to be thoroughly cleansed at each flush. The lip urinal may be flushed as shown in Plate 6, the flush being under direct pressure, and operated by means of a urinal cock attached to the top of the urinal. It may also be flushed from a tank serving a single fixture or a group. This flush tank may be of the automatic type, flushing the group of urinals at regular intervals.

Owing to the conditions surrounding the use of the urinal, the known carelessness of many of the people using it, and the character of the waste entering it, the partitions, backs, and flooring should never be of wood or of any material which may corrode. When wood is used for these purposes it soon absorbs moisture with its impurities, and in a short time becomes very unsanitary. Slate is the proper and commonly used material for this purpose. A form of urinal, which is not shown in Plate 43, is the waste-preventive urinal, which works in a manner similar to that of the waste-preventive slop hopper. The fixture is of such sensitive action that the entrance of urine into the trap acts to form a vacuum which produces siphonage and the immediate operation of the flush. This fixture is not in extensive use, however, although an excellent device.