Author:Site Editor Publish Time: 2019-03-13 Origin:Site
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.
The valve flap of the lift check valve is automatically operated. Generally, a conical disc is pressed between the inlet and the outlet of the valve on the metal valve seat. A spring can be added to the valve flap to preload. When the fluid is flowing forward, the cone valve is disengaged from the wide seat and the valve is opened under the action of fluid pressure. When back flowing, the valve flap falls back to the valve seat under the combined action of its own weight, spring force (if spring preload is provided) and fluid return pressure, and the valve closes.
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.