What aspects should be paid attention to when selecting viton-lined valves?

Viton-lined valves have been widely used in petroleum, chemical, pharmaceutical, metallurgical, electric power and other industries that are exposed to acid and alkali and other strong corrosive media. However, how to choose and use viton-lined valves is based on our customers for many years. Field application experience, when selecting viton-lined valves, the following precautions are put forward for several operating conditions such as medium temperature, pressure, and pressure difference:

  1. The medium conditions used in viton-lined valves should not contain hard particles, crystals, impurities, etc., so as to prevent the valve core, the viton-lined layer of the valve seat or the PTFE bellows from being worn out during the opening and closing of the valve. For the medium with hard particles, crystals and impurities, when selecting, the valve core and valve seat can be changed to Hastelloy.
  2. The temperature of the medium used in viton-lined valves: the viton used in various viton-lined valves is F46 (FEP), then 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 can be used for a long time. It should be controlled within 120°C), otherwise, the F46 lining of each part of the valve is easy to soften and deform, which will cause the valve to close undeadly and cause large leakage. If the temperature of the medium used is below 180℃ for a short time, and below 150℃ for a long time, another viton—PFA can be used, but the price of PFA lining is more expensive than that of F46.
  3. The Viton-lined valve should correctly select the valve diameter according to the required flow rate (Cv value). When selecting, the fluorine-lined valve should be selected according to the required flow rate (Cv value) and other technical parameters to calculate the diameter of the valve and the opening degree of the valve. 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 viton-lined valves, users should understand and master 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.

4. Don’t have negative pressure. The viton-lined valve should avoid the use of negative pressure in the pipeline. If there is negative pressure, it is easy to cause the viton-lined layer in the valve cavity to be sucked out (bulged) and shelled, resulting in failure of the valve opening and closing.

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