Series SD-2 Dual Check Valve Backflow Preventer for Carbonated Beverage Machines are designed to prevent the reverse flow of contaminated water, such as carbon dioxide gas and carbonated water, from entering into the potable water supply due to backpressure backflow. It consists of a stainless steel body construction with internal rubber components and is designed for continuous or intermittent pressure applications. Series SD-2 is ideal for use on post-mix carbonated beverage equipment and dispensing equipment for tea and coffee and comes in a variety of models. Maximum Working Pressure: 200psi (13.8 bar).