The seal use of the ball valve is different, mainly in the structure, and the standard of the manufacture of the valve is different.
The hard seal of the ball valve is the seal between the metal and the metal, and the sealed sphere and the seat are all metal. It is difficult to process the processing precision and process. It is usually used in high pressure, usually above 35MPa. Soft seal is the seal between metal and non-metallic, such as nylon, Teflon, manufacturing standards are the same.
The hard and soft seal is for the sealing material of the valve seat. The hard seal is precisely machined with the seat material, ensuring the accuracy of the matching with the spool (sphere), usually with stainless steel and copper. The soft seal is the sealing material embedded on the valve seat as non-metallic material, because the soft sealing material has certain elasticity, so the requirement of machining accuracy is relatively hard and sealed will be low.
As many of the chemical machinery industry, the working environment is more complex, many of which are high temperature and high pressure, friction medium, strong corrosive, technological advances now, various materials with better, processing and other aspects can keep up with the valve seal is widely spread.
In fact, the principle of hard seal ball valve is the same as that of soft seal. Only because of the seal between metals, we must take account of the hardness relationship between metals, and what kind of media they are going to operate. It is generally required to do hardened treatment, and the ball and seat must be continuously lapping to seal it. Hard seal ball valve production cycle is long, processing is more complex, hard sealing ball valve is not easy to do.
Conditions of use
Soft seal seals are generally able to reach very high, and according to the requirements of the seal can be high or low; soft sealing need to fire, because under high temperature, the soft sealing material will leak, and the seal is not the problem; the seal can generally do a very high pressure, soft seal is not soft; because the sealing problem of medium flow, can not be used in some occasions (such as some corrosive medium); finally seal valves are generally higher than the soft seal your. As for manufacturing, there is little difference between the two, mainly the difference in the seat, the soft seal is non metal, the hard seal is metal.
On the equipment selection
Soft and hard seal ball valve selection process based primarily on media, temperature and pressure, the general medium containing solid particles or wear or temperature higher than 200 degrees the best use of the hard seal, pressure valves larger than 50 caliber also consider opening the valve torque, fixed seal valve with large torque should be selected, both soft and hard seal the seal level can reach 6.
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