Second, the conventional wisdom has always been that improvements in process optimization always come from upgrades in control room control instrumentation. However, the test data shows that the dynamic characteristics of the valve can have a significant impact on circuit performance with the same control instrumentation. If the accuracy of the control valve can only be as low as 5%, it can not do much to spend a lot of money configuring an advanced control instrumentation system with a control accuracy of up to 0.5%. 2, the valve model options: Looking for a match with the use of the occasion of the valve, we should first look at the four basic types of throttle control valve, namely the cage ball valve, rotary ball valve, eccentric valve and butterfly valve. Cage ball valves are available in a wide variety of trim forms to meet the needs of most applications, making them the first choice of any valve. There are many kinds of cage ball adjusting pieces, including balance adjusting piece, unbalance adjusting piece, elastic seat adjusting piece, constrained adjusting piece and full size adjusting piece. In many cases, the various trim configurations of a valve body are interchangeable. Cage ball valves also have several disadvantages. First, the size of the valve is limited (usually 16 inches); second sight valve with the same specifications (such as float valve or butterfly valve) compared to its capacity is relatively low; third is the higher price, especially large Cage ball valve. However, cage ball valves have excellent performance, often enough to compensate for these drawbacks, in reducing process variability. Rotating float valve flow than the same diameter cage valve larger. Although the control range of the rotary float valve is larger than the cage ball valve, it is still superior to most other types of valves. Rotary float valve allows the pressure drop and allowable temperature range smaller than the cage valve. Normally their pressure drop is limited to 7.0x105kg / m2, suitable for use at temperatures below 398 ° C. Float valves are not suitable for liquid that is easy to empty and often emit more noise when used in gases with higher pressure drops. Eccentric valve friction than the smaller ball valve, the price is lower. Unique structural design makes it more precise for the control of process variability. This is evident from the new BV500 product from Fisher, a well-known American valve manufacturer. In addition, the advantages and disadvantages of eccentric valve float valve is not much difference. By valve performance to measure, the valve belongs to the low valve. Butterfly valve flow, the cheapest price, but there are many different caliber. However, the butterfly valve characteristic curve is only a proportional curve, which greatly limits the butterfly valve to reduce flow variability performance. For this reason, the butterfly valve can only be used in fixed load situations. Although butterfly valves are available in a variety of different caliber and can be made from most cast alloys, butterfly valves do not meet the ANSI requirements for face-to-face dimensions and are not suitable for fluids or noises that are subject to cavitation . 3, the choice of valve material With the development of science and technology, all parts of the valve material has begun a new revolution. From the body, disc, seal, packing, hand wheel, stem has a lot of different material options. Some new materials greatly enhance the valve durability, corrosion resistance, ease of operation, while reducing costs. For example, some new materials, such as PP and PVDF, have begun to replace the use of stainless steel in corrosive fluids. The new plastic is lighter than stainless steel and has a longer service life. With the development of new polyethylene and polypropylene materials, The cost of these materials is many times lower than stainless steel. The above is Yongjia Liangbang Valve Co., Ltd. for your conclusion.