Analysis and Selection of Fluorine Lined Check Valve
The check valve is a type of automatic valve that uses the force of the medium to open and close disc, preventing backflow of the medium. When a fluorine lining is applied to the flow surface of the check valve, it isolates the medium from direct contact with the metal body. This type of valve is known as a fluorine-lined check valve. It automatically opens when corrosive media flow in the forward direction and closes against the flow , effectively preventing backflow. T
FREE-VALVE The check valve is a type of automatic valve that uses the force of the medium to open and close disc, preventing backflow of the medium. When a fluorine lining is applied to the flow surface of the check valve, it isolates the medium from direct contact with the metal body. This type of valve is known as a fluorine-lined check valve. It automatically opens when corrosive media flow in the forward direction and closes against the flow , effectively preventing backflow. This flow control method helps maintain system pressure after pump shutdown, ensures proper operation of reciprocating pumps and compressors, and prevents reverse rotation of standby rotary pumps and compressor units.
2. Fluorine-lined check valves must be installed in all locations where corrosive media flow against the intended direction in pipelines.The parameter range for fluorine-lined check valves is as follows:
Nominal size: DN10-DN600
Nominal pressure: PN2.5-PN25
Operating temperature: t≤150°C
Applicable media: strong acids, strong alkalis, etc.
3. Structural Forms of Fluoroplastic-lined Check Valves
Fluorine lined check valves are available in various structural designs. Nearly all general check valve designs can be adapted with a fluorine lining. Common structural forms of fluorine lined check valves include: lift type H41F46, swing type H44F46/H44J, vertical type H41F46, and butterfly type H76F4. Each structural type of fluorine lined check valve functions in the same way as general check valves.
3.1 The disc of the fluorine lined lift check valve(Model:H41F46) moves vertically along the valve seat centerline. Its valve body is identical to that of a globe valve and can be used interchangeably. A pressure relief hole is machined either in the lower part of the disc guide sleeve or the upper part of the bonnet guide sleeve. When the disc rises, the medium inside the sleeve is discharged through the pressure relief hole. This valve can only be installed in horizontal pipelines.Compared with other types of check valves, the lift check valve has the shortest lift stroke, so it may be a fast-closing valve. However, if dirt enters the movement guide rail of the closing element, the closing element may become stuck in its guide rail or its movement may slow down.
3.2 The disc of a fluorine-lined swing check valve(Model:H44F46/H44J) is disc-shaped and rotates around a fixed shaft outside the seat passage. A swing check valve consists of a valve body, valve cover and disc; its passage is streamlined with low fluid resistance.To prevent the disc from stalling, the swing check valve should be installed vertically. However, in the fully open position, the closing torque determined by the disc weight is extremely small, causing such valves to tend to close slowly. To overcome this slow response to backflow for wafer type swing check valve, the disc can be fitted with a spring-loaded lever.All components of the fluorine-lined swing check valve are housed within the valve body without penetrating it. Except for the middle flange section which uses sealing gaskets and rings, there are no external leakage points throughout the valve, thus completely eliminating the possibility of external leakage.The disc of the fluorine-lined swing check valve are installed inside the valve body without penetrating it. Except for the use of sealing gaskets and rings at the middle flange, there are no external leakage points in the whole valve, which completely prevents the possibility of valve leakage.
3.3 The discs of fluorine-lined butterfly check valves(H76F46/H76F4) are available in a butterfly-shaped disc. The rotating shaft of the disc is located at the center of the internal valve passage. This type of check valve features a simple structure but poor sealing performance. Fluorine-lined butterfly check valves are usually limited to applications where swing check valves cannot meet the requirements.This type of valve is less commonly used compared to other type of check valves.
3.4 Fluorine-lined vertical check valves(Model:H41F46) adopt a ball core disc and a straight-through structure, with smooth and unobstructed flow passages and low fluid resistance. They are installed vertically in anti-corrosive industrial pipelines, with the arrow indicating the direction of fluid flow.
