This Duotight check valve is a great idea for protecting your regulator. It has a low opening pressure of 1 psi, and since it cannot be opened or taken apart, it is recommended for gas applications only. The internal components are made from stainless steel. Compatible with EVABarrier 9.5 mm OD tubing).
Please note: exposure to chlorine will degrade the acetal plastic and stainless steel these fittings are made from. Do not use in contact with bleach or other chlorinated cleaning chemicals.