High temperature regulation and control is a difficult problem in automatic control. It is more difficult to cut off high temperature and ultra-high temperature. This problem is mainly manifested in blocking and cutting off caused by high temperature expansion. Therefore, high temperature and ultra-high temperature control has always been the focus of attention of domestic and foreign manufacturers and design institutes.
(1) The selection of valve body and valve trim materials is used for regulating valves in environments above 450 ℃. The maximum temperature that can be used for general materials is about 500 ℃. For occasions higher than 538 ℃, the valve body is usually made of chromium molybdenum steel. For the occasions with the highest temperature of about 1035 ℃, SUS310S stainless steel is usually selected, and the carbon content of the material must be controlled between 0.04% and 0.08%. For higher temperatures, it is recommended to use lining non-metallic heat-resistant materials (which can be used in high temperature situations at 1200 ℃) or special high-temperature high-strength alloys (such as high-temperature high-strength alloys for engine combustion chambers, which can be directly used in high temperature situations at 1000 ℃).
(2) The polytetrafluoroethylene packing with the standard temperature resistance performance of the packing can only be used in the occasions below 200 ℃. If it is required to be used in the occasions with medium and high temperature, the extended valve cover must be used to prevent the packing from being affected by extremely high temperature. However, the longer and thinner valve stem has poor strength under high temperature conditions and is prone to bending. Therefore, flexible graphite packing with excellent temperature resistance (up to 600 ℃) should be used under high temperature conditions, which can also greatly reduce the height of the extended bonnet. At the same time, the method of "rotary valve+coarse stem" is used to improve the overall strength of the valve, so as to better solve this problem.
(3) It is difficult to select a sealing method to achieve high cutting performance at high temperature. Many conventional high-performance sealing methods are not desirable (such as O-ring, tetrafluoro material, elastic metal material, etc.). Within 500 ℃, special composite graphite valve seat soft sealing mode can be adopted. When the temperature is above 500 ℃, metal to metal hard sealing can only be used (butterfly valve structure is generally used).

The second way to choose correctly is to look at the model. If the models of the electric butterfly valves we purchase are different, the working effects and adaptive conditions it brings are also different. Now many manufacturers produce products with different materials. If our factory produces a large number of products, it has high requirements for materials, otherwise such equipment will have a certain adverse impact on the production progress. It will have a serious negative impact on both manufacturers and purchasers.