Type: Rising Disc Check Valve Design & Manufactured to API 6D, ASME B16.34 or Equivalent P.T Ratings to ASME B16.34 Face to Face dimensions to ASME B16.10 Flanged Ends to ASME B16.5 Butt-weld Ends to ASME B16.25 Threaded Ends to ASME B1.20.1 Socket-weld Ends to ASME B16.11 Valves Marking to MSS SP-25 Inspect & Tested to API 598 Size Ranges from 1 1/2” thru 24” Pressure Ratings from Class 600 to Class 2500, PN110 to PN420 Structures in Bolted or Pressure Sealed Union Cover Ends Connections in Flanged R.F or RTJ, Threaded NPT, BSPT, Welded S.W, B.W and Grooved Body Materials available in Cast Carbon Steel, Low Temp. Carbon Steel, Alloy Steel, Stainless Steel, Monel, Alu. Bronze etc. Trim Materials available in 13%Cr, F11, F22, SS304, SS304L, SS316, SS316L and other specials.
What are Rising Disc Check Valves
As shown in Figure 1, the rising disc check valve is a check valve with a valve flap that moves up and down along the axis of the sealing surface of the valve flap. The structure of the rising disc check valve has many similarities with the globe valve, in which the valve body is exactly the same as the globe valve body and can be used. The form of the valve flap is also similar to the valve flap, the upper part of the valve flap and the lower part of the valve cover is set up with a set of guide shaft, sleeve, valve guide shaft can be in the valve cover guide sleeve free lift. The purpose of using the guide sleeve is to ensure that the valve flap accurately back down on the valve seat. A pressure relief hole is machined in the upper part of the valve cover guiding sleeve to discharge the medium in the sleeve when the valve flap rises, so as to reduce the resistance when the valve flap opens. Lifting check valve action is reliable, but the flow resistance is large, suitable for smaller diameter occasions.
Figure 1 rising disc check valve Lift check valve flap is automatic work, generally between the import and export of the valve is a conical flap pressed on the metal seat. A spring can be added to the valve flap to preload it. When the fluid is flowing forward, the conical flap is released from the seat under fluid pressure and the valve opens. Backward flow, the valve flap in the self-weight, spring force (if there is a spring preload), the combined effect of fluid back pressure, back down to the seat, the valve closed. Lift check valves with metal-to-metal sealing subsets allow a small amount of leakage, and are only suitable for applications where the requirements for fluid backflow sealing are not very strict, and are generally used only in water systems, so they are usually used to stop the backflow of condensate from steam traps, and also for the outlet of condensate circulation pumps.
Fig. 2 disc silent check valve The main advantages of rising disc check valves are their simple construction, the fact that the conical flap is the only moving part, the durability of the valve and the fact that it requires little maintenance, and the fact that it has a metal seat, so there is very little wear. The limitation of rising disc check valves is that they must be installed on horizontal piping. The piston rising disc check valve is a modification of the standard rising disc check valve and includes a piston-shaped valve flap and a vibration dampening device that dampens the valve during operation, eliminating damage caused by frequent valve movement, for example, in piping systems subject to water shock pressure or where fluid direction changes frequently (such as boiler outlets). Lift check valves, because their flap stroke is about 1/3 of the flap diameter, greatly reducing the time required to close the flap, thus effectively reducing the water hammer pressure of the check valve. In addition, in some rising disc check valve, there are some new structural design, in the valve flap with a cylindrical spiral spring, due to the role of spring load and its minimum flap stroke, closing more quickly, more favorable to reduce the pressure of water hammer.
Fig. 3 spherical disc rising disc check valve
1 – valve body; 2 – sphere; 3 – valve cover The flap of the rising disc check valve can move freely up and down, the fluid should push the flap from bottom to top, when the lower inlet pressure of the flap is less than the upper outlet pressure, the flap will close by its own weight and the double action of the upper fluid pressure. Compared with other types of check valves, the rising disc check valve has the shortest stroke, so only a relatively short stroke is needed to make the valve fully open. For example, the rising disc check valve shown in Figure 6-2 has a ring-shaped passage at the valve seat, and this valve has the smallest opening stroke, so the rising disc check valve has the ability to close quickly. The check valve shown in Figure 2 is specifically designed for gas systems. Depending on the gas flow conditions, the valve can be used either as a constant flow check valve, where the valve always remains fully open regardless of small flow fluctuations in the system, or as a pulsating flow check valve, where the valve opens and closes with gas flow pulses. With the action of the spring, the valve blade responds to the change in gas pressure on both sides of the valve at the moment before the gas reaches the backflow condition, and is closed to the valve seat after a very small movement distance to prevent gas backflow. When the flow pulsation is not enough to cause chattering, constant flow check valves can be used in centrifugal pumps, Roots compressors, screw-type compressors or reciprocating compressors. Anti-pulsation check valves are used in reciprocating compressor systems if the flow pulsation can cause the valve to open and close with it. These valves are designed on the same principle as compressor valves, so that they can withstand repeated shocks between sealing surfaces. Manufacturers will recommend that constant flow check valves or anti-pulsation check valves should be used for specific operating conditions.
Figure 4,5,6 The operating characteristics of a check valve depend on its design principle. It is mainly based on the following aspects: minimum valve travel with multi-stage annular seat throttle orifice, low inertia of the disc closing member, frictionless guiding of the closing member, and selection of a spring matched to the operating conditions. In most rising disc check valves, the flap has a guide structure to ensure that the flap is coaxial with the seat and remains sealed. However, if contaminants enter the valve guide, the valve may seize or close slowly, so this type of valve is only suitable for low-viscosity media that are free of solid particles. The check valve shown in Figure 3 has a spherical flap with a large gap between it and the guiding mechanism, making it suitable for use in applications where dirt is present. When the valve is closed, the spherical flap rolls into the seat to automatically center and obtain an accurate seal. The check valve shown in Figure 4 is an angular rising disc check valve with a slow-closing device, with a piston cylinder designed as upper and lower sections, the two sections having different diameters. This structure check valve can be closed quickly in the first stage, and in the second stage, the valve can be closed slowly due to the reduction of the piston cylinder diameter. The head of the valve flap is designed in a specific shape so that when the fast closing phase of the valve ends, only a small flow path area is left between the valve flap and the valve seat, which effectively limits the backflow rate of the valve. This check valve is specially designed for important low impact pressures. Low impact pressure is achieved in two ways: first, by giving the closing member a conical projection so that the medium can be slowly throttled when the valve is closed; second, by installing a damper on the closing member that acts at the last moment of closure. The spring used to provide auxiliary closing force was eliminated because the breakage of the spring is a danger when the valve works under such conditions. The rising disc check valve must be installed in a suitable orientation to ensure that the gravity of the closing member acts in the direction of the valve closing. Since the closing force of the spring-loaded small rising disc check valve comes mainly from the spring, this valve can be installed without much consideration of the installation orientation. For these reasons, the valves shown in Figure 3 and Figure 5 can only be installed in the horizontal flow orientation. The valve shown in Figure 4 can only be installed in the vertical upward flow direction. The valves shown in Figure 6 can be installed in either horizontal or vertical upward flow orientation. The valve shown in Figure 2 can be installed in any orientation of flow, including vertical downward flow. As shown in Figure 7, the lifting vertical check valve is a check valve with a lifting motion of the valve flap along the axis of the valve body path. Lifting vertical check valve also belongs to the lifting check valve. Its principle of action and rising disc check valve is exactly the same, the difference is that its inlet and outlet in a straight line, can be installed directly on the vertical pipeline, does not affect its action performance, vertical pipeline selection of this kind of check valve is very suitable.
Figure 7,8 Spring rising disc check valve (Figure 8) the spring is placed on the valve part, when the inlet fluid pressure generated by the thrust on the valve is greater than the spring load, the spring is compressed, the valve flap open. The greater the fluid pressure, the greater the valve opening. Conversely, when the fluid pressure drops, the spring stretches and pushes the valve flap to close the valve. Due to the role of the spring, it is conducive to reducing the water hammer pressure generated when the valves open and close, and the fluid flow path is smooth and the resistance is small. In addition, the small diameter spring check valve valve flap is often made of round ball, the structure is more simple.
We focus on valves in standard and special materials as customer request. Our main materials show as the follows: Any request for other materials, please contact our machinery sales or engineering team on email.