At this stage, the electronically controlled triple eccentric butterfly valve is mainly aimed at a regulating machine for flow. At present, because the pressure loss of the butterfly valve in the pipeline is relatively large, of course, in addition to the above, it should also be considered that the butterfly plate needs to bear a medium pressure of the pipeline when it is closed. In addition, the operating temperature of the elastic valve seat material also needs to be considered in the case of high temperature.
On the leakage problem of the valve, traditionally, the leakage of the valve seat is often concentrated, that is, the internal leakage, and the leakage of the packing part, that is, the external leakage, is ignored. In fact, in the contemporary society where environmental issues are increasingly valued, it has become an indisputable fact that external leakage is far more harmful than internal leakage. The triple offset butterfly valve is a rotary type valve, and its stem action is only 90 ° rotation. Compared with gate valve, globe valve and other valve stem action with spiral multi-turn reciprocating motion, the wear degree of the packing part is very low. The service life is very long, and the highest standard design is adopted in the external leakage prevention structure such as packing seal, so that the standard sealing performance can be guaranteed to be less than 100ppm when the external leakage test is carried out according to the specifications.
Many valves claim to have a fire-resistant construction, but the vast majority of them use a soft-hard dual-seat construction to reduce leakage, which can be dangerous. Because the incomplete combustion of the soft-sealed valve seat during a fire will cause stress on the metal support valve seat and deformation due to temperature difference, resulting in failure of the refractory function. Therefore, currently Europe and the United States are gradually eliminating this kind of refractory valve that does not live up to its name. This ensures that it can be used in various hazardous areas such as petroleum, petrochemical and so on. In the conservative United Kingdom, the valves used in all key parts of its oil fields are almost all covered by butterfly valves, which is the best example.
At present, the structural length and overall height of the valve body are relatively small, the opening and closing speed is relatively fast, and it also has some characteristics of fluid control. The structure principle of the butterfly valve is mainly suitable for the manufacture of large-diameter valves. And when the butterfly valve is required for flow control, the size and model of the butterfly valve should be correctly selected to ensure that the butterfly valve can work correctly and efficiently.
In the process of throttling, regulating and mixing the medium with mud, the main requirements are that the length of the structure is short and the speed of opening and closing is fast. At present, the pressure difference of low pressure cut-off is relatively small. At this stage, it is recommended to choose a triple eccentric butterfly valve for adjustment and maintenance. And in two-position adjustment, narrowing channel, low noise, cavitation, gasification, a small amount of atmospheric leakage, and abrasive media can choose butterfly valve. At present, for the main throttling adjustment under special working conditions, tight sealing is required. Maybe when the butterfly valve is used under severe wear and low temperature (cryogenic) conditions, a specially designed metal sealing belt adjustment device is required, using triple eccentric or double eccentricity. Eccentric special butterfly valve.