This very handy fitting could save you your regulator and is a good investment. This particular type of check valve has low opening pressure of only 1 psi. This check valve is suitable for clean liquids such as water or for gas. The spring and internal components are made with stainless steel and quality EPDM seals.
This fitting is ideally used with EVABarrier 5mm x 8mm or EVABarrier 4mm x 8mm