Electric valve selection skills Water vapor erosion affects service life

At present, the control valves commonly used in engineering are mainly solenoid valves and electric valves. However, they all have defects in use, such as solenoid valves are easy to be blocked by foreign objects, water resistance is large, and long-term dedicated maintenance is required. Although electric valves have no water resistance, they need necessary control circuits, so they are affected by water vapor corrosion. Service life is also the main problem that plagues promotion.

The design problem of the locator

From the initial thinking of the design, the design of the actuator and the positioner must be considered together. How to design a good positioner? Know from its important characteristics, it must be a high gain device. The gain is composed of two parts: static gain and dynamic gain. The way to increase the static gain is to design a preamplifier. For example, nozzle-baffle device. So some friends would like to ask how to obtain the dynamic gain? It is obtained through a power amplifier, which is a spool valve (general). Now someone has used a microprocessor to set the positioner. It seems that the control valve will talk to us in the future and tell us where it is broken. At that time, the maintenance was easy. Closer to home. A high-performance positioner with both high static and high dynamic gains can provide the best overall performance in terms of reducing process deviations for any given regulating valve assembly.

How to overcome the influence of scale on the use of regulating valve to the greatest extent

Whether it is a solenoid valve or an electric valve, scale will not only cause leakage of the regulating valve, but even affect the normal operation of the regulating valve in severe cases. Therefore, how to eliminate the influence of scale has become a common concern in the industry.

The scope of the control valve process is too wide to explain to you one by one here. I hope that the content of this aspect can be checked by myself. However, the poor performance of the control valve due to the design of the actuator and the use of filling materials can still be summarized as follows: 1. The existence of a dead zone in the process will cause the process variable to deviate from the original set point. Therefore, the output of the controller must be increased enough to overcome the dead zone, and only this corrective action will occur. 2. ① The main factors affecting the dead zone. Friction, wandering, torsion of valve shaft, dead zone of amplifier. Various control valves are not the same as sensitive to friction. For example, rotary valves are very sensitive to friction caused by high seat load, so pay attention to this when using. But for some seal types, high seat load is necessary in order to obtain the closing level. Haha, in this way, this kind of valve is very poorly designed, and it is easy to cause a large dead zone. The effect of this on the process deviation is obvious and it is simply decisive. ②Abrasion. It is unavoidable that the control valve wears during normal use, but the wear of the lubricating layer is the most severe.According to our experiments, the lubricating rotary valve only goes through hundreds of cycles, and the lubricating layer can almost be used as a brush (exaggerated Point, otherwise writing an article is very depressing). In addition, the load caused by pressure will also cause the wear of the sealing layer, which are the main factors leading to the increase of friction. The result? The performance of the control valve is devastating! ③, the friction of the filler is the main source of friction of the control valve, and the friction caused by different fillers is very different. ④ Different types of actuators also have a fundamental impact on friction. Generally speaking, spring-film actuators are better than piston actuators.