Check Valves A Check Valve for High Pressures
Gas non-return valves (check valves) protect systems, outlet points and pipelines against unwanted and potentially hazardous gas mixtures. For applications in the high-pressure range, the German manufacturer Witt provides two models—one with a maximum operating overpressure of 300 bar (4350 psi)—in its current 600H and 800-ES series.
The 600H model with brass housing can be used for combustible gases, oxygen and non-flammable gases. It has a particularly sensitive mechanism and reacts from about 250 mbar (3.6 psi) opening pressure. Its maximum operating overpressure is 40 bar (580 psi). With compact dimensions and position-independent installation, a broad spectrum of applications is possible. The ambient temperature may be 70°C (158°F) in the 600 model, and several connection sizes with G threads are available, as well as a stainless steel version (600H-ES).
The 800-ES model can withstand pressures as high as 300 bar (4350 psi) when used with combustible gases. Even with oxygen, 240 bar (3480 psi) is possible. This stainless steel model is suitable for a large number of technical and corrosive gases. It can be installed independently of environmental constraints, which means the ambient temperature at the installation site can be up to 150°C (302°F) with fuel gases and 60°C (140°F) with oxygen. According to Witt, the spring-loaded valve system with elastomer seal ensures maximum leak-tightness. It opens at 2 bar (29 psi) and above.
Compact Design for Installation in Confined Spaces
Another advantage of the 800-ES is its compact design, which enables installation when space is restricted. Weighing 730 grams (1.6 lbs), the component measures less than 70 mm (2.75 inches) in length and only 18 mm (0.7 inches) in diameter. The 800-ES has a standard ¼-inch NPT thread.
Gas non-return valves made by Witt are tested individually for correct functioning before delivery. Dirt filters in the inlet ensure long service lives. Typical applications for gas non-return valves include all systems, pressure control stations and pipes conveying inflammable gases—anywhere a reverse gas flow could form unwanted and dangerous mixtures. In the worst case scenario, such a mixture could result in an explosion. Gas non-return valves prevent this by stopping a creeping or sudden gas flow in an unwanted direction.