There are many types of pneumatic valves, but the functions are different. In order to facilitate the use, we should pay attention to the selection method, and comprehensively consider from many aspects, so as to select the appropriate products for use. Below is a detailed introduction for you, which are the specific purchasing skills and methods for your reference.
1、 Installation space size. Pneumatic valve products are generally small valve products, but there are also a certain number of customers require larger valve diameter, there is the problem of selecting the driver. Generally, the larger valve caliber is pneumatic actuator, and the smaller caliber ball valve and butterfly valve.
2、 It is pressure and temperature resistant. This involves the selection of the nominal pressure and working temperature of the pneumatic valve. In terms of pressure resistance, it is difficult not only to have high pressure, but also to solve the problem of temperature resistance of cavitation in differential pressure. It is usually easy to solve the problem below 450 ℃, and it is not difficult to solve the problem between 450 ℃ and 600 ℃. However, when the temperature above 600 ℃ is 80 ℃, it is not advisable to cut off the system regulating valve.
3、 Under the regulation function, the regulation performance of small opening with smooth valve action is required to be good, and the resistance of regulation ratio to meet the flow characteristics required by the selection of regulation speed is small, with flow ratio (called the ratio of rated flow parameter and diameter of valve).
4、explosion-proof type, it is more appropriate to choose pneumatic actuator in inflammable environment, and the explosion-proof triple parts must be nearby. What is a flammable environment, such as dust, coal ash, oil and gas, flammable liquid, etc., these environments must be installed with gas valves.
5、 It is the leakage and cut-off pressure difference. These are two inseparable and interrelated factors. The leakage amount meets the process requirements, and the cut-off pressure difference (the pressure difference when the valve is closed) with the reliability protection measures for the sealing surface must be proposed (unfortunately, this parameter is not included in the calculation specifications of regulating valves of many design institutes). If the selected valve has enough output, the driver will be larger or smaller.
6、 It’s anti blocking. Even if it is a clean medium, there is a blockage problem. This is whether the pipeline is clean or not entering the valve through the medium, resulting in blockage. This is a common fault, so the anti blocking performance of the valve should be considered. Generally, the anti blocking performance of angle stroke type pneumatic valve is much better than that of straight stroke type, so the use of angle stroke type pneumatic valve will be more and more in the future.
7、is corrosion resistance, it includes erosion resistance, cavitation, corrosion. It mainly involves the selection of materials and the service life of the valve, at the same time, it involves the economy. The essence of this problem is that the selected valve has better wear resistance and reasonable price. If the PF4 valve can be selected, it is not suitable to choose the square high-pressure valve with high anti-corrosion effect and simple structure (meeting the service life of about 2 years), so it is not suitable to choose other high-pressure valves with complex structure and high price.
If you don’t know how to choose, you can refer to the method described above for purchase. After all, different pneumatic valve features and functions are different. If you don’t choose properly, it is often not conducive to use. I hope that the above-mentioned purchasing methods introduced for you can help you.