Bulk cryogenic storage of carbon dioxide (CO2) gas is a recent historical development in the beverage industry. Vacuum jacketed storage containers delivering 300 pounds to 750 pounds or more of liquified CO2 gas are widely used. These containers safely deliver gaseous CO2 at pressures above 90 pounds per square inch by converting the liquid CO2 to gas using a natural conversion process through a simple temperature increase effected by ambient temperatures at the location of use.
The gas delivered from such tanks is widely used in conjunction with beverage dispensing machines of the type commonly found in restaurants, convenience stores, theaters, amusement parks and the like. The carbon dioxide (CO2) is mixed with water to produce carbonated water under pressure. The carbonated water then is mixed with a syrup at the dispensing machine to produce the finished carbonated beverage.
CO2 in its gaseous state is a tasteless, colorless, odorless gas which naturally displaces oxygen. If this gas is accumulated in sufficient density in a closed space, such as a storage room, it is hazardous, if not lethal. In facilities which initially produce CO2 gas for ultimate delivery and consumption, multiple safety procedures are employed. Among these are detectors which sense when the CO2 gas level in a particular area exceeds a safe level, to produce a warning alarm.
Bulk storage tanks, however, frequently are located in a confined area adjacent a beverage dispensing machine, frequently, in a small room one wall of which backs onto the location of the machine, or in some other area which is frequented by employees of the establishment using the beverage dispensing machine. CO2 sensors or safety devices typically are not employed where bulk storage tanks are used to supply CO2 to a beverage dispensing machine. In such situations, both employees of the establishment and customers may be exposed to unsafe levels of CO2 gas without their knowledge.
If the syrup box or container used to deliver the flavored syrup to the beverage dispensing machine is empty while the CO2 dispensing line is connected to it, the drop in pressure will allow CO2 gas to pass outwardly into the surrounding area. Also, if a leak should occur in the gas line for delivering the gaseous CO2 to the carbonator or beverage box of a beverage dispensing machine, or if for any reason there is a failure to turn off the delivery of CO2 gas, a drop in pressure, sometimes sudden, takes place at the bulk storage tank.
A sudden drop in pressure of CO2 delivered from the tank causes the liquid CO2 in the bulk container to turn into “dry ice”. When this occurs, further delivery of gaseous CO2 from the tank is precluded. This necessitates some type of a service call, since when this occurs, further operation of the beverage dispensing machine ceases. Service calls of this type are unscheduled and are expensive, driving up the operating costs of the entire system.
It is desirable to provide a safety system for bulk cryogenic storage tanks which overcomes the disadvantages of the prior art.