II. PRESSURE PEGULATORS.—The Foster Pressure Reducing Valve is shown in Fig. 4. The principle of operation is as follows : Steam is admitted at A and delivered at B, at a pressure dependent upon the open ing of valve, D, which may be regulated by turning spindle, P. to the right to diminish the pressure, or the left to increase the pressure. The delivery pressure, en tering chamber, /17, tends to raise the diaphragm, and draw valve, D, toward its seat ; in opposition to this, the spring, with its lower end bearing on winged nut, E. tends to open the valve until there is an equilibrium established between these two forces. Under this condition, if the delivery pressure fails, the pressure on the diaphragm is diminished, and the spring, overcoming the lighter re sistance, opens the valve until the equilibrium is again established and the pressure restored ; on the other hand, any increased delivery pressure bearing on the diaphragm overcomes the resistance of the spring and draws the valve toward its seat in proportion to the increased pressure. When the tension of the spring is proportioned to the pressure bearing on the diaphragm, a constant and uniform discharge is insured. The spring nut, E, is threaded on the spindle, and, having wins which extend into the hexagon spring chamber, H, it is prevented from turning with the spindle, but is free to move longitudi nally with it, as the valve is opened or closed by reason of variation of pressure on the diaphragm. The flange on lower side of spring nut, E, is used as a stop to prevent an excessive lift and possible bulge of the diaphragm.
The Ross Pressure-regulating Valve is shown in Fig. 5. It is used to control or reduce pressure in street mains and pipe lines ; or to regulate the flow of water be tween reservoirs located at different levels. In the sectional view, A is the inler to high-pressure side; B, the outlet or low-pressure side. The operation of this valve is as follows : The small regulator valve, 1, has been set to close at, say, 40 lbs.; relief valve, 0, to open at as nearly as possible the same pressure. This can be. readily adjusted when the valve is working. It is preferable to have relief valve, 0, open a little in advance of the closing of the regulating valve, as this keeps a circulation constantly through the chamber, K, and valve, _land 0. This maintains a very even pressure in the chamber, K. The urein chamber, K. determines the pressure on out let side of valve, B. For illustration, assume that piston, h, is one-half the area of F. (It can be more or less, as desired; the practice is to make it less.) Water is turned on the system. and passes freely through the valve until the pressure, necumu int ing in the pipes on the outlet side, is exerted on the full area of the valve beneath N. \Vhen 20 lbs. is reached an equilibrium exists, and any further rise of pressure at 11 will increase the pressure twice as much in chamber. K. This decreases the flow of water through 1, and in crease3 the quantity discharged through 0, allow ing the pistons, F' and 7', with valve, N, to slowly close until only enough water pass es to maintain 20 lbs. !west:tire at out let B. Should an extra demand on the system cause the pressure to fall below 20 lbs. on the outlet side, B,
relief valve, 0. would close and regulating valve, 1, would (mem thus allowing pistons, Fand 7'. with valve, M, to open, and allowing sufficient water to pass to keep t he pressure at 20 Ills.
Any rise or fall of pressure will eontinue to repeat this operation.
The Union, Gas Pressure Regulator. made by the Union Water Meter Co_ Worcester, Mass., is shown in Figs. 6, 7, and 8. It is built on the tank or gasometer principle.
Fig. 6 is a sectional view of the tank and piston connected with the valve by rack and segment. Pig. 7 is a view of the valve with cap removed, showing the valve-stem and V-shaped ports. Fig. 8 shows the valve-stem detached from the valve with the four ports which open and close over four alternate parts in the valve-seat The operation is as follows : The gas is taken from the low-press ure side of the valve by the pipe, shown in Fig. 7, to the under side of piston in the dia phragm case in Pig. 6. Then any increase of pressure itnme diately raises the piston and closes the rotary valve by means of the rack, A, and segment, F; any decrease of pressure opens the valve. The rotary valve with V-shaped ports is operated by a piston with a rolling diaphragm. thus giving a long stroke and graduating the flow of gas with the greatest accuracy. The conical form of valve admits of its being ground to a gas-tight joint, not affected by contraction or expansion, and requiring no packing around the valve-stein. The ports have cutting edges and a shearing motion, thus effectually preventing the formation of ice or the accumulation of foreign matter on the valve seats, which so often prevents the closing of other forms of valves.
By the rotary motion of the valve, and its opening and clos ing both ways from the center, a positive cut-off is effected without extra mechanism, the weight of the piston closing the valve whenever the supply of gas fails. Nor can any leak around the piston or diaphragm, or increased pressure of gas, force the valve open and allow the gas to blow through.
The Curtis Pressure Regulator, made by the Curtis Regulator Co., of Boston, shown in Fig. 9, has a main valve, operated by a loose-fitting piston ; a secondary valve in the top of the chamber over the piston ; a metallic diaphragm (performing the double office of oper ating the secondary valve, and making a joint to the cap which contains it); and a side passage, connecting the chamber under the diaphragm with the outlet. When the spring over the diaphragm is compressed, it opens the secondary valve upon which it rests. Pressure being let on, raises the piston, and therewith the main valve to its full capacity. The main valve remains open until the back pressure communicated from the outlet through out the side passage is sufficient to raise the follower under spring, and thus close the secondary valve, when the steam or water escaping around or through the loose-fitting piston fills in the space on top of said piston, and forces it toward its seat, thus uniformly main taining the pressure at which it is set.
Repeating Rifle : see Fire-arms.
Re-sawing Machines : see Saws, Wood.
Revolvers : see Fire Arms.
Rifle: see Fire Arms.
Rim Planer : see Wheel-making Machines.
Riveting, Electric : see Welding, Electric.