DC Motor Yibin Tianruida Auto Parts Co.,Ltd , https://www.trdautoparts.com
1, observation method This method is observed after the event, according to the destruction of the surface shape to judge. Due to cavitation, casting porosity, erosion, erosion, etc. will cause the metal surface shape and the ideal shape of the different. Cavitation damage to the metal surface is usually honeycomb, which is caused by local high-speed water hit the metal surface fatigue damage, so the honeycomb holes are generally connected with the outside, most of the pit and the metal surface perpendicular to. Loose casting defects often lie deep inside the metal, sometimes due to the erosion of water will loose the metal inside, stomatal surface was mistaken for foot cavitation, but the mechanical method to continue to remove the surface will find that there are still pores inside. Scour wear traces often appear with the same direction of the water groove, but pay attention to whether there is a flow of vortex. 2, the noise method This method is relatively simple, you can not contact with the pump. However, as the noise method is more affected by ambient noise, it shows the highest intensity. In general, pump cavitation has reached a very strong stage, when the ear has been able to judge the cavitation condition by a strong cavitation crack. Therefore, the pump body noise method is not suitable for on-site monitoring of cavitation.
3, Vibration method A method of measuring pump vibration frequency through accelerometer probe, the method is simple, but the sensitivity is low. Special e for large pumps, pump body stiffness. The partial cavitation caused by the bubble burst bubble generated by the vibration of the reaction slow, at the same time, pumps on the vibration source more. Vibrations due to cavitation are often masked by other vibrations. Therefore, the vibration method is only suitable as an aid to on-site monitoring of cavitation.
4, ultrasonic method ultrasonic measurement of cavitation method is simple, easy debugging, and free from interference from other environmental noise, the occurrence of cavitation and the development of strong sensitivity. Therefore, as the pumping station on-site monitoring of cavitation at a more ideal way.
Second, to reduce the pump cavitation damage in service methods 1, into the pool in the use of the site, the pump cavitation (including other failures) on the silk lips æ° animal husbandry 纯 pure éª sheath ç›´ straight plaque embarrassment Award 阋 Aberdeen Aberdeen Aberdeen charms G 9 cheat owe cheatboard 邪 æ¾¹ gluttonous Ω Ω fans know how to cultivate [æ¦ lips æ° æ° animal husbandry éž« ç»» ç»» 乇 乇 ç » Wu å¹ blowing horn harsh Φ male æ ¡ school Tuo Tuo every throbæ‚ é‚ª 濉 ç¡— A ç¡— 猓 mo 虢 æ° æ° æ° Raiders è´Ÿ negative 纬 grumble â’ æ±— H 纾 harsh 诶 诶 æ°¤ 乇 Torr 诘 wood å—¬ harsh 窈 fresh left æ¬ è£¼ provocation è 梦 dream ç‰ å ‹ 2 In addition to the pipeline inlet pipeline should be set to minimize the pipeline loss (such as the use of elbows and unnecessary valves), let the inlet pipe may not have higher than the pump inlet parts to prevent the tube of gas. It can also be said to reduce the resistance of the suction pipe, such as increasing the diameter, reducing the pipeline attachment, the end of the valve, elbow, valve and so on. This method by improving the inhalation conditions to achieve the purpose of improving the NPSHa value, but also more convenient and practical.
3, using the injection structure jet device in principle equivalent to liquid jet pump. A high-pressure water is drawn at the pump outlet leading to the high-pressure water chamber and the high-pressure water enters the suction pipe of the pump through the annular nozzle. The high-pressure water is mixed with the water in the suction pipe to exchange energy, and the energy of the mixed water after mixing is increased relative to the water energy of the original suction pipe so as to meet the cavitation margin necessary for the pump inlet. In addition, it can be achieved by increasing the pressure booster pump, increasing the gas pressure in the sump, lowering the temperature of the conveying medium, and adopting a double-suction pump to achieve the purpose. However, the actual operation is rather difficult and the cost is increased.
4, imported qi qi gas method does not prevent the cavitation cavitation, but the appropriate qi will reduce the hole crack damage to the flow channel wall, fill the gas like a layer to protect the sponge of the side wall. This method is commonly used in water turbines and the like, but very little is used to supplement the gas in the pump because it is difficult to grasp the amount of gas supplied. Some people have made some researches on the gas cavitation of the gas-filled waterproof pump and achieved some results, but at the same time pointed out: gas-controlled pump cavitation is very technical and can only achieve good results if the gas-supplementing flow, effect. Otherwise, the flow, lift and efficiency of the pump will drop a lot, causing adverse consequences.
5, the use of anti-cavitation material with different materials cavitation resistance is very obvious area? E. There are many factors that affect the anti-erosion ability of materials. Generally, materials with high hardness and high elasticity are more resistant to erosion. Foreign recommended low-carbon chromium-nickel alloy steel, as cavitation in the state of hydraulic machinery, has good anti-corrosion properties. It is also effective to use cavitation-resistant materials when cavitation can not be avoided. Impeller room will be replaced by the original cast steel stainless steel, cast iron and copper than the obvious contrast. Cavitation erosion will be doubled. Facts have proved that the pump running in the low-temperature heating system of our company has very prominent cavitation phenomenon. It is the easiest way to solve or reduce cavitation to replace the over-flow part which is resistant to cavitation.
6, the impeller protective layer on the impeller coating method is more commonly used, non-metallic coating epoxy resin, nylon powder, polyurethane and so on. In addition, the method of surfacing the alloy or sprayed alloy on the surface of the flow channel also achieved certain effects on cavitation damage, such as stainless steel electrode surfacing method, stainless steel inlaid repairing method and alloy powder spray welding. Non-metallic and alloy (including stainless steel) compared to several methods, the non-metallic coating method is economical, but often the phenomenon of coating loss, the actual Nguyen construction should continue to sum up experience. The use of alloy surfacing is generally implemented by the user, the use of alloy powder spray welding effect is good but the cost is high, and some places may not be able to proceed. There are many examples of ways to protect layers. Such as: a pump station using metal alloy powder spray welding blade, made better anti-cavitation effect, the service life can be extended.
7, trimming blade head trimming blade head to reduce cavitation damage have a significant effect. The principle is to reduce the import of leaves squeezed, reducing the flow rate of the leaves imported. The method is thinning the back of the blade head, near the impeller repair more front cover.
Third, the conclusions of the pump to reduce cavitation damage have examples of applications, sometimes need several ways to use at the same time. In summary, the centrifugal pump installation process, in order to try to avoid cavitation phenomenon, should follow several principles: The pump installation height must be lower than the pump suction height; suction pipe should be short and straight pipe fittings as much as possible Less, the diameter of the suction tube should not be less than the diameter of the suction port; diameter can not have gas accumulation. In short, the operation of the centrifugal pump, pay attention to whether there is no abnormal noise, pressure gauges and other observations are normal, but should also regularly check the bearing, shaft seal fever, and pay attention to lubrication and shaft seal at the abnormal Exudate situation.
Method to reduce cavitation damage of centrifugal pump
First, the diagnosis of cavitation pumps in service Pump users generally or can not use the method used by the manufacturer to determine whether the pump cavitation occurs, that is, when the flow rate decreases at a certain time to determine whether the cavitation occurs. In-service pump cavitation, in addition to observing cavitation damage, you can also use ultrasonic method, pump noise method, vibration method to determine.