One of the common questions received in the Foundation for Cross-Connection Control and Hydronic Research office has to do with the level of backflow protection needed on post-mix soft drink carbonators. The post-mix soft drink carbonator takes water and carbonates it using carbon dioxide (CO2) from a refillable tank.This carbonated water is then mixed with syrup to produce the soft drinks served at restaurants, movie theaters and other establishments.
Initially, one wonders whether any backflow protection is needed. After all, we drink the sodas, don't we? What would be the problem if some soda got into the drinking water? Further investigation shows that the CO2 is under pressure and could, thus, create backpressure into the drinking water system. In such a case, when backpressure is present, a minimum of a double check valve assembly is typically required. There would, however, seem to be no contaminants (i.e., health hazards) which would warrant a reduced pressure principle assembly.