Fluorine lined butterfly valve is a kind of lining valve commonly used in acid and alkali and other corrosive media. It has been widely used in petroleum, chemical, pharmaceutical, metallurgy, electric power and other industries. Diversity, often users do not know how to start, this article will introduce how to choose a fluorine-lined butterfly valve.
1. The fluorine-lined butterfly valve is to wrap a layer of plastic on the surface of the cast steel or stainless steel valve body and the valve group of the valve disc that is in contact with the fluid, so that the metal components of the valve are completely isolated from corrosive liquids to achieve the purpose of anti-corrosion. Since the plastic in contact with the medium has poor hardness, the medium used should not contain hard particles, crystallization, impurities, etc., so as to prevent the valve from wearing out the valve core and the fluorine lining of the valve seat or four during the opening and closing operation. Fluorine bellows. For the medium with hard particles, crystals and impurities, when selecting, the valve core and valve seat can be selected from corrosion-resistant alloys, such as INCONEL, MONEL, Hastelloy, etc.
2. The temperature of the medium used in the fluorine-lined butterfly valve: the fluoroplastic used is F46 (FEP), and the temperature of the medium used cannot exceed 150 °C (the medium temperature can reach 150 °C in a short time, and the temperature should be controlled within 120 °C for a long time) Otherwise, the F46 lining of various parts of the valve is easy to soften and deform, resulting in the valve not closing and the leakage is large. If the temperature of the medium used is below 180°C for a short time and below 150°C for a long time, another fluoroplastic—PFA can be used, but the fluoroplastic lined with PFA is more expensive than the one lined with F46. .
3. The pressure and differential pressure should be controlled within the allowable range.If the pressure and pressure difference are too large, it is very easy to cause damage to the seal during the process of opening and closing the valve, which affects the sealing performance of the valve.
4. The variety of industrial corrosive media is often not just a single variety of acid, alkali and salt. This makes it very difficult to choose a suitable lining material, which requires a comprehensive selection of parameters such as the liquid composition ratio, concentration, medium temperature, particle size and flow rate of the medium.
5. The fluorine-lined butterfly valve should correctly select the diameter of the valve according to the required flow (Cv value). The Cv value of the fluorine-lined butterfly valve is slightly smaller than that of the ordinary wafer butterfly valve and flanged butterfly valve. When selecting, the diameter of the fluorine-lined butterfly valve and the opening degree of the valve should be calculated according to the technical parameters such as the required flow rate (Cv value). It is easy to make the valve core and rod be impacted by the medium and cause the valve to vibrate, and the valve core rod will even break the valve stem under the impact of the medium for a long time. When selecting various types of fluorine-lined valves, users should understand and master the technical conditions as much as possible, so as to select and use them well and improve the service life of the valves.When encountering the range beyond the technical conditions of use, it should be put forward to the manufacturer, negotiated together, and take corresponding countermeasures to solve the problem.
6. Do not have negative pressure.Fluorine-lined valves should avoid negative pressure in the pipelines used. If there is negative pressure, it is easy to cause the fluorine-lined layer of the valve cavity to be sucked out.
(bulging) and shelling, causing the valve to open and close to fail.