Tag: check valve

The tilting-disc swing check valve is another variant of the basic type of check valve. In these valves, the disc swings partly through the seat. The geometry for sealing and avoiding jamming is more complicated than for other swing checks. One variety pivots the disc in the seat area – but somewhat off-center. This means that the zones around the pivot are more difficult to seal, analogous to the problem of the symmetrical butterfly valve. The disc is nearly balanced, reducing slamming. Seal material is basically Buna-N, but Viton, Teflon, and even monel are possible. The valve is a very short wafter type, so the open disc protrudes beyond the body.
Tilting-disc valves with the pivot outside the seating area are available in many forms. The geometry of the pivot location and angle of the seating surfaces allows the disc to lift away from the seat at all points and prevents the disc from becoming wedged so tightly in the seat that it cannot move. Extreme and sudden temperature changes and differentials get close consideration in this. The disc and seat may be likened to a slice from a bottle stopper, made at an oblique angle to the cone axis to allow the “stopper” to be removed by a twist about the pivot downstream. The machining of the oval seat ring and disc in this valve requires skill. In some instances, the cone is cut at right angles, but location of the pivot downstream and above the valve axis permits the top of the disc to swing through the seat.
In some tilting-disc check valves, the disc has a slight clearance on the pivot, to help assure a tight seat. In other tilting-disc vales, the heavy pivot shaft is rigidly attached to the disc and supported in close-clearance bearings. The pivot shaft is generally large-diameter in tilting-disc valves, so attachment of dashpots, indicators, and limit switches is easy.
Because of the partial balance of the disc, the fluid-dynamic characteristics of the disc are important. The forward-flowing fluid must open the disc easily, and then hold it open with little flutter. When flow slows and stops, the disc must close quickly and silently. Several tilting discs have curved undersurfaces to develop fluid-dynamic forces. One variety has a flap above the main disc, which also serves to limit disc opening, removing a load from the main disc.
Access to the internals of some tilting-disc check valves, when they are mounted in the line, is through conventional bonnets or removable plates. The internals of other models are inaccessible, because the valve body is of the wafer or short-spool type. In general, valves that must be welded into the line tend to resemble the standard types of checks, with welds at a safe distance from the seat. One line of tilting-disc checks has obliquely split bodies for pressure classes to 1500 ANSI, but is a wafer body between weld-end flanges in higher-pressure classes.
SGV Tilting Disc Check Valves consist of a cylindrical housing, with a pivoted circular disc. The pivots are located just above the center of the disc, and offset from the plane of the body seat. This design gives a bell-crank action to the disc. The seat is of circular bevel type and the disc drops in or out of contact without rubbing or sliding.It is mounted at the outlet pipeline of the pressurized output water pump in industrial (and urban) water supply and drainage system,high-rises, sewage discharge, hotel and restaurants, functioned to cut off the backflow of medium and eliminate destructive water hammer.
Featured by small volume, lightweight, Low head loss ,easy installation, Energy efficient, little occupation of space, saver if time and labor for servicing and maintenance, and etc., this valve is an optimal solution for water supply and drainage products

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