Supplying zinc free products and stainless steel solutions.  We are leaders in back flow prevention both in brass and stainless steel.  ABF ASSE 1022 vented dual check back flow preventor protects the connected plumbing and drinking water from the corrosive effects of CO2 gas. The CO2 gas mixed with water in a carbonator tank downstream from the back flow preventor exerts back pressure on the discharge primary check valve on every pumping cycle.If this check valve becomes fouled and leaks, the CO2 gas and water mixture will exhaust through the vent fitting. The secondary check insures that it cannot pass to the inlet or contact any brass or copper from the connected plumbing. The simple internal construction is easy to clean. It utilizes a lead free brass body and stainless steel discharge retainer. Under no circumstance is the CO2 gas and water mixture exposed to the lead-free brass inlet or the connected plumbing.