A, Alkali chamber; B, Acid chamber; C, Purifier; Z), Agitator; E, Acid valve; F, Pressure gauge; G, Safety valve: H, Low Pressure blow-off cock; J, Clamp and cap; J, Frame; K, Equalizing pipe; L, Acid valve seat; M, Purifier blow-off cock; N, Purifier gas cock; O, Agitator wheel; P, Gas pipe; Q, Q, Rubber gaskets; R, Acid valve handle; S, Agitator shaft; T, Filling bung; U,U, Trunions or Ears; V,V, Filling bungs; W,W, Brass tubes; X, Box and nut at agitator end; Y, Acid chamber hood; Z, Purifier hood; a, Screw socket for raising acid valve; 6, Brass rod of acid valve stem; c, Cap; d, Acid valve nipple; e, Square socket which prevents acid valve from turning; /, Spindle; g, Fitting which supports acid valve seat; h, Clamp cap for filling bung; i, Screw for filling bung; j, Yoke for filling bung clamp; k, Rubber washer; I, Plug of blow-off cock, which fills nipple; m, Wheel of blow-off cock - this wheel does not descend when valve is opened; n, Ports for keeping valve clear; o, Spindle which opens and closes cock; p, Discharge port; q, Lead washer which makes joint tight when blow-off is closed; r, Cap; s, Lead washer. The black line indicates lead lining.

"It has been found in blowing off the spent charge from a generator, having the ordinary blow-off cock, that a solid plug of marble dust forms in the bung and the blow-off cock above, and partly supported by the valve seat.

"To blow off the generator this plug must be dislodged, and from 40 to 90 lbs. pressure has been found necessary to dislodge it. A generator full of gas at 40 to 90 lbs. represents a considerable quantity of acid and marble dust, and if the generator can be blown off at 5 lbs. pressure, this can be saved. The low pressure blow-off cock illustrated before, has a metal plug which fills the bung completely, thus preventing entirely the formation of a plug of marble dust; consequently the spent charge can be blown off with a very slight pressure. In opening the low pressure blow-off cock, the wheel does not descend, the spindle moving through it, and being prevented from revolving by its square shape.

Fig. 171. - Tuft's Low-Pressure Blow-off Cock.

"The operation of the wheel is the reverse of that of an ordinary cock. Turn to the right to open and to the left to close. To blow off, open the valve wide. It is necessary after washing out the generator to partly close the cock to black mark on spindle, and pour water through filling nipple to wash out the cock. To take out the swindle and valve, apply a monkey-wrench to the square spindle, and thus unscrew the cap".

This valve is to keep a uniform pressure in the cylinders or fountains. It automatically closes when the pressure in the cylinders reaches the point at which it is set, and opens when the pressure falls below the point at which it is set. It may be set at any pressure from five to two hundred pounds, by simply turning the handle. It will let gas pass at lower pressure than that at which it is set. It assures a uniform pressure and is a useful appendage of an apparatus.

Fig. 172. - Tuft's Automatic Equalizing or Regulating Valve.

Fig. 173. - Sectional View of Fig. 172.

The patentee gives the following directions for its use: "Be sure that the gas flows in the direction of the arrow on the side. Before charging the generator, turn back the handle on top of the equalizing valve, and take it entirely out, thus insuring that all pressure is removed from the spring; this closes the valve; then charge the generator to 150 pounds pressure. Open the cock between the valve and the cylinders, and the inlet cock of the cylinder to be charged, wide open. If in order, the valve will open for a few seconds (until the chamber over piston fills), and then close, shutting off all gas from the cylinders. To open the valve, return the handle to its place and turn down until it opens; continue turning down slowly, meanwhile agitating water and gas in the cylinder, until the desired pressure is indicated by the gauge on the cylinders. A slight turn of the handle either way will alter the pressure, and, when once set, it will maintain a uniform pressure at that point. If it should fail to close when the handle is turned back, it will be on account of dirt.

"To open the valve for examination: First turn the handle on the top and take out the spring under it; then remove the cap, taking care to slide it off sidewise with the hand under the diaphragm to keep it in place. Remember, the diaphragm always goes in with the convex side down. Unscrew the cap inside by means of the square top, then remove the spring and piston under it. If the piston sticks it can be pushed up by the stem projecting through the bottom.

"See that the seat, valve, piston and stem are entirely clean and free from all dirt, and that the hole in the piston (about the size of a pin) is clear. If the piston valve does not drop freely into its seat (when perfectly clean), take it out and reverse it and try the piston in bottom side up; also try the stem by reversing the piston and pushing the stem up from the bottom. Wipe it perfectly clean, and if it is cut, polish it with fine emery paper; be sure to wash all the emery out. If in order, the piston should drop freely into its place on the seat like a check valve, and be perfectly free.

"Before replacing the inside cap, see that the secondary valve (in it) is free from dirt and perfectly tight. Screw the inside cap lightly into its place, and close up the regulator by putting the outside cap (containing the diaphragm, follower and spring) on, and screwing it firmly to its seat, thus making a gas-tight joint. Be sure there is no dirt on top of regulator where the diaphragm makes its seat, also that the diaphragm is clean; then you will have a joint that will not leak.

"When the valve is set at a given pressure, it will allow any lower pressure to pass, but will not allow a higher. In brief, place it so that gas passes through it in the direction of the arrow on the side. Before charging generator take out the top screw of valve, so as to take off all pressure from the spring. Charge the generator to 150 pounds. Open the cock between the valve and the cylinders, and the inlet cock to cylinder which is to be charged wide open, put in and turn the top handle so as to put pressure on the top springs, and keep on turning very slowly, agitating water and gas in the cylinder at the same time, until the desired pressure is reached. When the valve is set let it alone.

Shut off and let on gas with valve cock and cylinder inlet cocks. A lower pressure than that at which the valve is set can always pass, but a higher pressure cannot. This valve is not intended to be tight. To cut off generator from cylinders, use cock attached to valve".

Fig. 174. - Lippincott's Continuous Apparatus.