The flush valve is a comparatively recent device, introduced for the purpose of flushing the water closet without the use of the flush tank.

Urinals and slop sinks may also be flushed by the same device.

The advantages of the flush valve are many. It may be operated on direct or tank pressure, on high and low pressure; it is noiseless; it may easily be concealed; it may be made to work automatically; and it may be used in many places and under many conditions where it would be very difficult and unsatisfactory to use a tank closet.

It is used very extensively in public buildings, in marine work, and in high-class residence work.

The subject of the application of the flush valve is considered further under Plate 42.