Stainless Steel Poppet Check Valve, Fixed Pressure, 1/4 in. Swagelok Tube Fitting, 50 psig (3.5 bar). Swagelok tube fitting. Spring-assisted poppet check valve providing unidirectional flow on instrument, sample and small-bore tubing lines; the fixed cracking pressure is set by the internal spring. Maximum working pressure and temperature ratings are governed by the series, seat/seal material and end connections per Swagelok catalog MS-01-176; select and install against the applicable Swagelok data sheet.