Lifting check valve: The check valve sliding along the vertical center line of the valve body. The internal thread check valve can only be installed on the horizontal pipe. The upper part of the valve flap and the lower part of the valve cover are machined with a guide sleeve, and the valve guide can be easily lifted and lowered in the valve guide.
When the medium is downstream, the valve flap is opened by the medium thrust. When the medium stops flowing, the valve flap is self-retained. The drooping falls on the valve seat to prevent the medium from flowing back.
The valve flap of the lift check valve is located on the valve seat sealing surface of the valve body. In addition to the valve flap being free to lift and lower, the valve is like a shut-off valve. The fluid pressure causes the valve flap to lift from the seat sealing surface. The return of the medium causes the flap to fall back onto the valve seat and shut off the flow. Depending on the conditions of use, the flap may be of an all-metal construction or may be in the form of a rubber or rubber ring on the valve disc holder. Like the shut-off valve, the passage of fluid through the lift check valve is also narrow, so the pressure drop through the lift check valve is larger than that of the swing check valve, and the flow rate of the swing check valve is very few limited.
The main advantage of the lift check valve is its simple construction. Since the conical disc is the only moving part, the valve is durable and requires little maintenance, and because it is a metal seat, there is little wear. The limitation of the lift check valve is that it must be installed on a horizontal pipe.
The lift-type check valve with metal-to-metal seal pair allows a small amount of leakage. It is only suitable for applications where the fluid back flow sealing requirements are not very strict. It is generally only used in water systems, so it is usually used to prevent condensation of steam traps. Back flow, also used for the outlet of the condensate water pipe centrifugal pump.
The structure of the lift check valve has many similarities with the shut-off valve, wherein the valve body is exactly the same as the valve body of the shut-off valve and can be used universally. The form of the valve flap is similar to the valve flap of the shut-off valve. The upper part of the valve flap and the lower part of the valve cover are provided with a set of guide shafts and sleeves, and the valve guide shaft can be freely raised and lowered in the valve cover guide sleeve. The purpose of the guide sleeve is to ensure that the valve flap is accurately returned to the valve seat. A pressure relief hole is formed in the upper part of the bonnet guide sleeve. When the valve flap is raised, the medium in the sleeve is discharged to reduce the resistance when the valve flap is opened. The lift check valve is reliable, but the flow resistance is large, which is suitable for small caliber applications.