This section is from the book "A Treatise On Beverages or The Complete Practical Bottler", by Charles Herman Sulz. Also available from Amazon: A Treatise On Beverages.
" While the charge in the first generator is being used, the second should be charged and prepared for use. Close the cock between the equalizing valve of the second generator and the cylinders to prevent the pressure from passing over before it is needed. Take out the top screw of the equalizing valve, thus closing it. When the charge in the first generator is exhausted, and the pressure reduced to the lowest possible point by agitating the water and gas in the cylinders, close the cock between the equalizing valve of the first generator and the cylinders, and open the cock between the equalizing valve of the second generator and the cylinders. Set the equalizing valve of the second generator, as directed for the equalizing valve of the first generator, and allow the gas from the second generator to pass over and supply the cylinders. When the second equalizing valve has been adjusted, and the second generator is supplying the cylinders with gas, the first generator should be cleaned out and recharged. If any portable fountains are to be charged, the gas remaining in the first generator may be utilized by partially charging them. 'Start the clamp on the generator-filling bung, allowing the gas to escape slowly until the pressure is reduced to ten or fifteen pounds. Open the blow-off cock gradually and allow the spent charge to escape, turning the agitator constantly meanwhile. Never blow off the generator suddenly, as there is danger of collapsing the lining. When the pressure gauge indicates that the pressure has all escaped, and while the exhausted charge is escaping, remove the cap from the filling bung; attach a hose, provided with a curved nozzle of proper size to the cock at end of water-supply pipe, start the pump and throw the stream of water into every part of the generator body, turning the agitator constantly to facilitate cleaning the generator. Unless the generator is to be immediately re-charged, the acid chamber should be thoroughly cleaned by filling it with water through the filling bung, and discharging into the generator body by opening the vitriol valve. The generator should be thoroughly cleansed after each charge, as material allowed to remain will become hard and exceedingly difficult to remove, and if allowed to accumulate will eventually interfere with working the generator. When the charge is blown off, the contents of the purifiers will be discharged into the generator body, being forced out by the pressure remaining in the purifier. But the purifier blow-off cocks should always be opened, and whatever remains discharged. The purifiers should be washed out with the hose, and refilled (two-thirds full) before recharging. As the use of the equalizing valves allows the geuerators to be run at much higher pressure than is required in the cylinders, portable fountains may be charged at any time without interfering with bottling operations. The regulating valves are not intended to be absolutely tight, and if the cocks between them and the cylinders are allowed to remain open when there is a charge in the generator, and bottling has ceased, the pressure will leak into the cylinders until equalized. When bottling is resumed, the regulating valves will act as before. As now arranged, either end cylinder may be separated from the others by closing the cocks on the bows, and the separated cylinder may be charged at high pressure for filling syphon by connecting it with the generator by means of nipples on cylinder inlet bow and generator tee, and a rubber charging pipe provided for the purpose. The syphon filler can be connected with a nipple on the outlet bow. Since the above was written, the equalizing or regulating valve has been improved, so that it may be set at high pressure for syphons as readily as for low pressure for ordinary bottling. This improvement allows the charging pipe above mentioned to be dispensed with.
"The vitriol-valve attachment is operated by grasping the hand wheel with both hands. To open, turn the wheel, bringing the right hand towards you. To close, turn the wheel, carrying the right hand from you.
"If the valve blows off it will sometimes cause it to leak off the gas below the required point of safety To obviate this and stop the escape, it is simply necessary to cause the valve to snap down upon its seat. This is done by pressing firmly on top of the valve, and at the same time brushing the finger sharply down the projecting lever, causing the lever handle to fly back instantly. As 180 pounds pressure is sufficient for the best soda water, the valve when sent to the customer is set at 210 pounds, and the operator will observe that it is set about right, when the part that is filed off the screw is even with the top of the lock nut. It can, however, be regulated to blow off at a greater or less pressure. To do this, first loosen the lock nut to which the lever handle is attached, and then with a wrench turn the nut underneath the lock, nut down for higher pressure, and up for a lower pressure. Be sure to secure with lock nut after adjusting. It should be remembered, however, that a very slight alteration of this screw effects a great increase or decrease of pressure, and also that the valve should always be set to operate inside of 225 pounds".
Fig. 169. - Safety Valve.
The gas pipe P is liable to become choked by too rapid reduction of pressure in generator, which allows the gas to expand and swell the mass, so as to fill up the generator. Opening the cock, which allows the gas to pass into the cylinder or fountains too quickly, is the cause of this " foaming," and the rapid rush of gas through the gas pipe P often carries enough marble, acid and water with it to choke the gas pipe.
Fig. 170. - Sectional View of Tuft's Iron Generator.