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.
9. In case the generator should be overcharged by accident, the safety valve should blow off the superfluous gas. If necessary the cap of generator may get a turn or two to allow some gas to escape, but decidedly do not open it, otherwise the whole contents would be discharged violently. Do not open discharge valve, as it would cause the collapsing of the lining. When the fountains are properly charged, shut valve in acid-chamber tightly, close valves on fountains; be sure of this, otherwise the contents will syphon over when the pressure of either one is relieved.
10. The more thoroughly the water in fountains is agitated and the cooler the temperature of the liquid is, the more gas it will absorb and the more pungency the beverage will acquire. In summer time in some establishments the fountains are surrounded by a wooden box filled with ice or by cloths, perpetually kept wet, to keep them cool, or the purified water for charging the fountain is run through a tin coil covered with ice, to cool it.
Flatness in carbonated beverages is due to lack of gas. Carbonators, as a rule, make no provision for the temperature of the water to be charged. If the water is kept at a temperature of about 50° F. it will be in proper condition for carbonating, and will the more readily absorb gas. Manufacturers apparently neglect this requisite of their goods. The flavor of a beverage is materially developed by the pungent effervescence of the liquid.
11. A charged fountain ought to be discharged as soon as possible. The pressure is diminished by standing, the water absorbing the gas if the temperature does not rise. After standing it is well to turn a little more gas into the fountains before commencing to bottle the beverage. If the temperature is rising, the water in fountains will separate from some of the absorbed gas, and this will collect above the surface of the water and escape first when discharging. Maintain a uniform pressure in the fountains while the beverage is being bottled, by evolving more gas in the generator, allowing it to enter into the fountain. Do not keep the pressure in generator and fountains longer than absolutely necessary, not only to save the apparatus from a long strain, but especially for the benefit of the beverage, which will profit by being bottled immediately.
12. Never charge several fountains at the same time. Charge one after the other. When a fountain is exhausted, distribute the remaining gas as already directed. When a pump is available, pump in water against the pressure of this gas, agitate, and impregnate the water, thus saving the remaining gas.
13. Emptying the apparatus and recharging: After fountains have been discharged and the contents in generator is exhausted, empty and recharge. Close the valve between generator and purifiers and then open the discharge valves of purifiers and let the water run out. On some apparatus there is no valve between, and the contents of the latter will discharge with the generator - syphon over when the latter is discharged. In this case discharge first the generator, otherwise its contents would obstruct the purifiers. After opening the discharge valve of generator to let out the refuse, turn the agitator quickly. A pressure of 5 to 10 pounds may be left to blow out the residue. Allow no residue to remain; it must be blown out immediately, otherwise it gets hard, is difficult to remove and would injure the lining. If too high a pressure is used for blowing off the residue, the lining will collapse. Wash out the generator thoroughly; also the acid-chamber.
14. Rinse the fountains after every operation, as an impure water may have left a sediment; if flavored syrups have been introduced, rinsing is especially necessary. Once in a while unscrew all piping and rinse them; it will do good. Screw them tightly to their joints again. Renew the washers in the couplings, and use lead washers on generator and leather washers on fountains.
15. After the liquid contents of a fountain is exhausted, the remaining gas may be entirely or partly saved. If a pump is attached to the apparatus, inject water into the fountain and agitate. Operate as formerly directed. If no pump is available, pass the remaining gas of an exhausted fountain into the next or second fountain, which is either yet uncharged or charged with a lower pressure than the remaining gas exerts; simply divide the remainder among the different fountains and thus save some gas. The balance blow off by loosening the cap. But if a fountain was charged with any favored liquid, such as root beer, tonic beer, etc., we strongly advise not to utilize the remaining gas of such an exhausted fountain for carbonating the liquid of another, as the gas is loaded with flavor which would impair the next liquid, which possibly is destined to get quite a distinct other and delicate flavor, for instance lemon, etc.
16. Hard residue. If the residue is hard and clings to the side and bottom of generator, fill in hot water and turn the agitator quickly for some time, then open discharge valve, agitating briskly.
Another remedy is to mix equal parts of sulphuric acid and water, pour into the generator and turn the agitator slowly, in one direction only, until the obstruction is removed. To prevent the residue from getting hard, discharge immediately with five or ten pounds of pressure, after the generator is exhausted. In no case should extreme force be used to turn the agitator. Never use sticks or sharp instruments to turn the residue loose, as the lead lining is liable to get injured to the great disadvantage of the apparatus.
17. Recharge and operate again as directed.
18. Grease of any kind will " kill" carbonic acid very quickly Parts of machinery coming in contact with the carbonated liquid, such as the inner surface of a pump cylinder, should therefore be kept well protected against the presence of lubricating oil or grease. The same holds good for all portions of the apparatus, from the generator to the final exit of the beverage at the bottling bench.
19. Gasometer. The water in gasometer should be renewed every one or two weeks when impure carbonic acid has passed through; under ordinary circumstances it should be changed every month. Use only pure water, either boiled or filtered; impure water is decidedly to be avoided. Whenever the water is changed, the gasometer vat ought to be thoroughly and carefully cleansed from foul sediments or separations which are at the bottom or cling to the sides.
The use of water is sometimes connected with inconveniences and trouble. In summer time it must be more frequently renewed to prevent its becoming foul. In winter time it is liable to freeze. Apart from this, the water absorbs part of the carbonic acid gas and separates instead a corresponding amount of atmospheric air. A proper substitute for water are the aqueous solutions of neutral salts.
Dr. Hirsh recommends the addition of 5 to 10 per cent, either of sulphate of magnesia or of chloride of calcium, that is, to 12 1/2 gallons of water 5 to 10 lbs. of either salt. This solution keeps for years without requiring renewal or purification. It freezes but at very low temperature, and has a very limited solubility for carbonic acid or atmospheric air. The addition of 1/10 per cent of alum to water in gasometer-vat, or vegetable or animal charcoal, occasionally renewed, will preserve it for a few months, but alum reacts on the metal of the gasometer-bell and should therefore be left out. Oils, alcohol, glycerine are too expensive, alkaline or aciduous liquids unfit for use. The' gasometer-bell keep always properly balanced, so it can easily rise and the carbonic acid gas get space for expansion.