Ground Key Cocks

May be either stop cocks for controlling water in a pipe, or faucets for drawing water at a fixture. The only difference is in their exterior appearance, the principles of construction and operation being the same for both patterns. Ground key cocks can be had for lead pipe, for iron pipe, and, in the case of stop cocks, they may be had with one end threaded for iron pipe and the other end prepared for lead pipe. Cocks for iron pipe can be had tapped with female threads or threaded to screw in a fitting. A sectional illustration of a ground key cock is shown in Fig. 85. The plug, a, is ground to a watertight fit in the cock, b, and water is turned on and off by giving a one-quarter turn to the lever, c. The principal objection to this kind of a cock is that the constant wearing of the plug and cock every time the water is turned on or off, soon causes the cock to leak, and the leak can only be repaired by regrinding the plug, which is a tedious and rather expensive undertaking, sometimes costing more than would a new cock. Another objection that should not be overlooked, is the quickness with which this type of cock shuts off the water.

Fig. 85

Fig. 86

Where the water pressure is high, this might cause serious damage to pipes and fixtures.

Compression

Cocks

A compression cock such as is used at kitchen sinks is shown in section in Fig. 86. In construction it is quite similar to a globe valve and, like one, it closes against the pressure. The core, a, of a compression cock is fitted with a soft disk packing, b, which can be easily renewed when the cock leaks. They are also fitted with a rubber packing, c, or in some cases with a ground joint to prevent water spouting out around the compression stem. Compression stop cocks should be fitted with an auxiliary stuffing box around the stem to withstand the back pressure they are subjected to.