Under the following working conditions, butterfly valves are recommended:
①Require throttling, adjustment and control flow;
②Mud medium and medium containing solid particles;
③Occasions where the valve structure length is required to be short;
④Occasions requiring fast opening and closing speed;
⑤Occasions where the pressure difference is small.
In the case of two-position adjustment, narrowed passage, low noise, cavitation and vaporization, a small amount of leakage to the atmosphere, and abrasive media, butterfly valves can be used.
When the butterfly valve is used under special conditions such as throttling adjustment or strict sealing requirements, or severe wear, low temperature (cryogenic) and other operating conditions, it is necessary to use a three-eccentric or double-eccentric special butterfly valve with a specially designed metal seal with an adjustment device .
Most of the butterfly valves that appeared in the early years used natural rubber seat seals. Although they have very excellent sealing performance, the applicable temperature and pressure are relatively low, generally around 70°C, not greater than PN10. Later, when synthetic rubber appeared and applied to butterfly valves, the applicable temperature was increased to about 120℃, and the applicable pressure was increased to PN16 accordingly. Especially the corrosion resistance and abrasion resistance have been greatly improved, and it is still widely used in the water supply and drainage industry until today. With the rapid development of the chemical industry and the emergence of fluoroplastics, the performance of the butterfly valve has been further improved. The butterfly valve seat made of PTFE material has increased the applicable temperature of the butterfly valve to 180°C, and the applicable pressure has also been greatly improved, and it is able to withstand Corrosion from strong acids, strong alkalis and chemical solvents.
The use of metal sealing materials and the three-eccentric structure design have revolutionized the butterfly valve. In the past, the problem of high pressure resistance and high temperature resistance has always been the weak link of butterfly valves. The sealing seat material of the butterfly valve is basically made of natural rubber, synthetic rubber, fluoroplastics and other materials, so the temperature and pressure it can withstand are limited.
Due to the application of metal rigid sealing ring, metal expansion sealing ring, metal elastic sealing ring, multi-layer stainless steel and graphite composite ring on the butterfly valve, plus the eccentric butterfly plate structure, its edge is spherical, conical and other forms and is similar to the metal elastic ring Cooperate to form a tight sealing pair, so that the applicable pressure of the butterfly valve is increased to above PN63, and the applicable temperature is as high as 600°C. Its excellent performance has been widely used in fields such as steam, gas, hot air and corrosive media.
