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. Due to the complexity of its structural characteristics and the complexity of lining materials Diversity, often users do not know how to start selection, this article will introduce how to choose fluorine-lined butterfly valve.
1. The fluorine-lined butterfly valve is a layer of plastic wrapped in the surface of the cast steel or stainless steel valve body and the valve group of the disc that is in contact with the fluid. The purpose of corrosion. Since the plastic is in contact with the medium, its hardness is poor, and the medium used should not contain hard particles, crystals, impurities, etc., so as to prevent the valve from wearing out the valve core, the fluorine-lined layer of the valve seat or the fluorine layer during the opening and closing of the valve. 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 by the fluorine-lined butterfly valve: the fluorine plastic used is F46 (FEP), and the temperature of the medium used cannot exceed 150°C (the temperature of the medium 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 the valve parts is easy to soften and deform, causing the valve to close undeadly and large leakage. If the temperature of the medium used is below 180℃ for a short time and below 150℃ for a long time, another fluoroplastic can be used.
-PFA, but PFA lined with fluoroplastics is more expensive than F46 lined.
3. The pressure and pressure difference should be controlled within the allowable range. If the pressure and pressure difference are too large, it is easy to cause damage to the seal during the opening and closing of the valve, which will affect the sealing performance of the valve.
4. The multiple styles of industrial corrosive media are often not just a single species of acid, alkali, and salt. This makes it difficult to select the appropriate 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 be correctly selected according to the required flow rate (Cv value). The CV value of the fluorine-lined butterfly valve is slightly smaller than that of the ordinary wafer butterfly valve and flange butterfly valve. When selecting, the diameter and opening degree of the fluorine-lined butterfly valve should be calculated according to the required flow rate (Cv value) and other technical parameters. If the diameter of the valve is selected too large, it will inevitably make the valve open for a long time. Operation under small conditions, coupled with the pressure of the medium, will easily cause the valve core and rod to be impacted by the medium to cause the valve to vibrate. The valve core rod will even be broken under the impact of the medium for a long time. When selecting various types of fluorine-lined valves, users should understand and grasp the technical conditions of use as much as possible, so that they can be selected and used well, and the service life of the valve can be improved. In the event of exceeding the scope of the technical conditions for use, it should be proposed to the manufacturer, negotiated together, and adopted corresponding countermeasures to solve it. 6. Avoid negative pressure. The fluorine-lined valve should avoid the use of negative pressure in the pipeline. If there is negative pressure, the fluorine-lined layer in the inner cavity of the valve will be sucked out (bulged) and shelled, which will cause the valve to open and close to malfunction.