Model 955 6,000 PSI In Line Check Valve

*The default selection shown above is generally good in stock, and can ship immediately. Choosing non-standard options may increase lead time 3-5 days.

GENERAL INFORMATION Check valves permit flow only in one direction in a gas or liquid line thus eliminating the possibility of back flow. Two sizes are offered. The model 955 is 1/4" pipe thread size. The model 634 is 1/2" pipe thread and handles higher flow rates. The 955 valve offers the unique feature of permitting flow from either the male or female thread end by reversing the internal spring and poppet. The internal design of both valves are similar. The larger 864 model was introduced in 1978. It has proven so reliable over the years the design was used in the smaller 955 valve a few years later. They use a standard 0-ring seal. This insures bubble tight sealing even with slight differential pressures in the reverse direction. In the event the seal is damaged, it can be easily changed. With flow in the forward direction the valves open easily since a light spring can be used with an 0 ring seal. They handle the full range of rated flows without chatter or noise common to some check valves. SPECIFICATIONS • Maximum pressure ---- 6000 PSI (140 MPa) • Maximum differential pressure across valve - 6000 PSI • Opening pressure ---- 5 to 10 PSI • Flow coefficient model Cv 0.22 (3/16" orifice) model 684 ----- Cv -0.50 (9/32" orifice) • Fluids ----------- gases or liquids • Ports   Model 955 inlet 1/4" M NPT: outlet, 1/4" FNPT   Model 955R ------ inlet 1/4" FNPT, outlet, 1/4" MNPT   Model 684 inlet 1/2" MNPT: outlet, 1/2' FNPT • Size   Model 955 ------ 1" hex by 2.4" long   Model 684 --- 13/0" hex by 2.5" long • Materials - body - anodized aluminum internals - brass, seal: Viton, spring: stainless steel TYPICAL APPLICATIONS • Used between compressors and separators to prevent leak down via compressor valves and rings and to permit easy unloading of the compressor • Filling station control and logic • Numerous other control and logic functions in gas and liquid fines • Control in cascade filling systems

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