Glove Valves are made with solid and re newable discs ; in the former case they are of brass and in the latter of soft metal, asbestos or packing of some kind. Fig. 9 represents the most common type of globe valve, It is pro vided with a vulcanized asbestos disc ring. The ring is composed of the fibre of asbestos, to which is added a waterproof vulcanizing mate rial, making a very durable packing, which will the fluid has raised and passed the gate, the pressure being removed from the face of the gate it closes thereby checking or stopping the fluid from flowing in the reverse direction. Fig. 11 represents the foot valve, its use and operation being similar to the check valve. It is used, however, in a vertical pipe and at the end of the suction pipe of a pump.
Air Valves are made for two common pur poses, namely: To he placed on mains at high points where air accumulates and obstructs the flow of water and for use on pipe lines to per mit air to enter when water is drawn off, and to allow 'air to escape when pipes are being refilled. The former, the lever-and-float air valves, are shown in Fig. 12. When air takes the place of water about the float in the valve chamber, the float which is attached to the bronze lever drops, thus opening the small valve and allowing the air to escape. As the water returns it lifts the float, thereby closing the valve. Fig. 13 represents the poppet air valve; when filling a line of pipe the gate remains open until the water reaches and lifts the cop per float, thereby closing the gate, which re mains closed while the pressure is on. Fig. 14 is an external view of a common lever safety valve. The valve consists of a gate with a not crack or flake off. It is held centrally on its seat by guides cast on the body of the valve. It is also secured to the spindle without the use of nuts, screws, pins or wires. The vul canized asbestos ring is forced into a brass holder and the metal is spun or turned over the of the ring, so that it cannot drop out. This valve has a raised round seat, upon which scale, grit or sediment is less likely to lodge than on the broad flat seats sometimes used. On account of the construction of the valve seat, as will be noted in the cut, globe valves do not permit of a clear and unobstructed pas sageway. Fig. 10 shows the check stop, or as it is sometimes called back-pressure valve. This valve is used in a horizontal pipe, to pre vent the backward movement of a fluid. After conical edge, resting on a conical seat, and is held to its seat by the pressure of a weight act ing on a lever as shown. The spring safety valve is shown in Fig. 15, the spring taking the place of the lever and weight; this style of safety valve is known as the pop safety. Fig. 16 represents a relief valve, similar in con struction to the pop safety valve, but instead of being used for steam is intended for use on water mains, for the purpose of relieving the pipes of water hammer, to which they may bg subjected. The gate as in the pop safety valve,
is held to its seat by the pressure of a spring, which is protected, as shown in the cut, by a control or reduce pressure in street mains and pipe lines or to regulate the flow of water be tween reservoirs located at different levels. This valve can be placed in any position. Ow ing to the manner of packing, the friction is but trifling, as can be readily understood by exam ining the cut.
Valves also form the principal part of hydrants or fire plugs, and are of two dis tinct types: slide gate and compression, accord ing to the valve motion.
Gate Fig. 18 represents the gate hydrant, which is absolutely non-freezing, owing to the fact that the drip is positive and being in the bottom of the hydrant it drains it completely, no water being left in the barrel when the hydrant is closed, to freeze; therefore, no outer jacket, or frost case, is necessary.
cast jacket, having an outlet of the same size as the inlet. The operation of the valve is as follows: When the valve is set at the pressure desired, which is done by adjusting the wheel, any excess of pressure over this opens the valve, thus relieving the mains and joints of any extra strain, and doing away with the breaking of pipes or blowing out of joints. The regulating valve, as shown in Fig. 17, is used to The working parts are so arranged, that by tak ing off the dome and packing plate, all the work ing parts can be removed without disturbing the barrel of the hydrant, or doing any digging. All the working parts are of solid bronze, thus preventing rust, and the gate is rubber-faced. The operation of the hydrant is as follows: In closing, the gate is moved downward by the action of the stem through the threaded bronze wedge nut in the back of the gate, until it strikes a stop at the bottom of the projection in the back of the hydrant, when by the action of the bronze wedge nut, moving along the incline on the back of the gate, it is forced squarely against its seat without any grinding movement on either the rubber gasket, with which the gate is faced, or on the bronze seat ring against which it closes, the projection at the top and bottom of the gate keeping the rubber gasket away from the seat ring until it is forcerd squarely against it by the action of the wedge nut. The final turn of the stem, after the gate is closed and wedged, opens the drip valve. In opening the hydrant, the first turn of the stem closes the drip valve, after which the bronze wedge nut in back of gate is loosened, thus relieving the gate from its seat.