In the previous article introduction, we learned that the sealing performance of the soft seal butterfly valve is superior, and it can achieve two-way sealing and zero leakage. Soft seal applicable media include air, water, steam, various corrosive media, mud, oil products.
The butterfly valve can be divided into soft sealing butterfly valve and hard sealing butterfly valve according to the different materials of the sealing surface. Sealing surface refers to the valve seat of this component. Soft sealing butterfly valve sealing surface material we often see are EPDM, nitrile and PTFE. These three kinds of different materials of soft seal butterfly valve, the applicable medium in the pipeline is also different.
Also called EPDM, code EPDM. EPDM rubber is the most commonly used valve seat material for soft seal butterfly valves. Its use is also very extensive. In the ambient temperature and pressure working environment, EPDM material seats are used and have very good sealing performance. EPDM rubber has ozone resistance, aging resistance, and long service life. The soft sealing butterfly valve for the seat material is available in the medium with fresh water, sewage, sea water and similar slurry containing impurities.
Nitrile rubber, code-named NBR, has one of the biggest characteristics of this material is its excellent oil resistance, in addition to a certain degree of wear and heat resistance. Soft seal butterfly valve uses nitrile rubber as sealing surface material, which can be applied to petroleum pipelines and over oiled media. In addition, nitrile rubber is not suitable for fresh water and other media, because it itself contains a certain degree of toxicity, will cause harm to human health.
PTFE is a fluoroplastic codenamed PTFE. PTFE is characterized by resistance to a variety of acids and alkalis and various organic solvents; PTFE is used as the soft seal of the valve seat material, mainly used in chemical, oil refining, chemical fiber, phosphate fertilizer, non-ferrous metallurgy, acid production, dyeing and other industries. In the field, the applicable medium is a corrosive strong acid and alkali medium.
From the above introduction, it can be seen that the soft seal butterfly valve has a very wide range of media and can be used in many fields. However, the soft seal butterfly valve also has some defects. Because of its own sealing material, it is not suitable for high temperature and high pressure, severe erosion conditions. In addition, to ensure the sealing performance of the soft seal butterfly valve, we must pay attention to the regular maintenance of its sealing surface.