Reverse flow check valves are an important part of any oxy/fuel system.  Without check valves, reverse flow of oxygen and fuel gases can occur when a tip becomes clogged, or when one cylinder empties during use allowing the higher pressure gas to back up into the other hose and into the regulator, thereby creating conditions which could lead to a regulator explosion.  Smith's reverse flow check valves close automatically when outlet pressures drop below 1/2 PSIG, preventing reverse flow of gases.
Smith Reverse Flow Check Valves Available In 3 Styles.

• H693A and H694A are installed in the regulator body after first removing the regulator outlet fitting.
• H691B, H692B and H698 are attached directly to the existing regulator outlet fitting.
• H695, H696 and H697 check valves are attached directly to torch handle.