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(2) In the horizontal section of the inlet pipe in contact with the water pump, a downward slope of 0.5% or more is applied in the direction opposite to the flow direction of the water inlet pipe, and the end of the inlet pump connected to the pump is the highest, not completely horizontal. If it is lifted upwards, air will remain in the inlet pipe, which will reduce the degree of vacuum in the pipes and the water pump, affecting water absorption.
(3) The filler of the pump has been worn out for a long time or the packing is too loose, causing a large amount of water to be ejected from the clearance between the packing and the shaft sleeve of the pump shaft. As a result, external air enters the interior of the pump from these clearances. Affected the lifting of water.
(4) The water inlet pipe has holes due to long-term potential underwater and corrosion of the pipe wall. After the water pump works, the water surface continues to drop. When these holes are exposed to the water surface, air enters the water inlet pipe from the hole.
(5) There is a crack at the elbow of the inlet pipe, and there is a slight gap between the inlet pipe and the pump, which may cause air to enter the inlet pipe.
Second, the pump speed is low (1) human factors. Some users were arbitrarily coupled with another motor due to the damage of the original motor, resulting in the consequences of small flow, low head, and no watering.
(2) The mechanical failure of the pump itself. The loosening of the impeller or the pump shaft fastening nut or the deformation and bending of the pump shaft causes the impeller to move more, directly rubbing against the pump body, or bearing damage, which may reduce the pump speed.
(3) The maintenance of the power machine is not working. The motor is lost due to the windings burned out, and the number of windings, wire diameters, and wiring methods in the maintenance, or failures in the maintenance that are not completely eliminated will also cause the pump speed to change.
Third, the pump suction process is too large Some water sources are deeper, and some water sources have a more flat outer periphery, and the pump's allowable suction range is ignored, resulting in the result that there is little or no suction. To know that the degree of vacuum that can be established at the suction port of the pump is limited, the absolute vacuum suction is approximately 10 meters of water column height, and the pump cannot establish an absolute vacuum. Moreover, if the vacuum degree is too large, the water in the pump is easily vaporized, which is unfavorable to the work of the water pump. Therefore, each centrifugal pump has its maximum allowable suction range, generally between 3-8.5 meters. The installation of the pump must not be simple and convenient.
Fourth, the flow of water in and out of the water pipe resistance loss is too large Some users have measured, although the vertical distance from the reservoir or water tower to the source of the water is also slightly less than the pump lift, but the amount of water is not lifting or mention water. The reason is often that the pipeline is too long, the water pipe bends more, and the resistance loss of the water flow in the pipeline is too large. The reason is often that the pipeline is too long, the water pipe bends more, and the resistance loss of the water flow in the pipeline is too large. In general, the 90-degree elbow is more resistant than the 120-degree elbow, and each 90-degree elbow head loss is about 0.5-1 m. The resistance of each 20-m pipe can make the head loss about 1 m. In addition, some users are also free to enter and exit the pipe diameter of the pump, which also has a certain impact on the lift.
Fifth, the influence of other factors (1) bottom valve will not open. It is usually due to the long time for the pump to stand, the bottom valve gasket is stuck, and the bottom valve without the gasket may rust.
(2) The bottom valve filter net is blocked; or the bottom valve is potentially blocked in the sludge layer in the water.
(3) The impeller wears badly. Impeller blades wear over a long period of use, affecting the performance of the pump.
(4) Gate valve failure or blockage of the check valve will result in reduced flow or even failure to catch water.
(5) The leakage of the outlet pipe will also affect the amount of water pumped.
Six, common and simple equipment fault diagnosis methods commonly used simple state monitoring methods are auscultation, touch measurement and observation methods.
1. When auscultation equipment is in normal operation, the accompanying sound always has a certain rhythm and rhythm. As long as you are familiar with and master these normal rhythms and rhythms, you can use the human auditory function to compare whether the device has abnormal noises that are heavy, miscellaneous, strange, and chaotic, and determine hidden troubles such as looseness, impact, and imbalance within the device. Use a hammer to hit a part and listen for cracks. You can determine whether or not there is a crack. The electronic stethoscope is a vibration acceleration sensor. It converts the vibration condition of the device into an electrical signal and amplifies it. The worker uses the earphone to monitor the vibration sound of the operating device to achieve a qualitative measurement of the sound. By measuring the signals at the same measuring point, at different times, at the same speed, under the same conditions, and comparing them, it is judged whether the device is faulty. When the earphones appear crisp and sharp noise, the vibration frequency is relatively high. Generally, parts with relatively small sizes and relatively high strength have local defects or micro cracks. When the headset emits turbid and low-level noise, it indicates that the vibration frequency is relatively low. Generally, parts with relatively large sizes and relatively low strength have large cracks or defects. When the noise from the headset is stronger than usual, it means that the fault is developing. The louder the sound, the more serious the fault. When the noise from the headphones is intermittently and randomly occurring, it indicates that parts or components have loosened.
2. The touch-sensing method uses the tactile sense of the human hand to monitor the temperature, vibration, and clearance of the device.
The nerve fibers on the person's hand are sensitive to temperature and can more accurately distinguish temperatures within 80°C. When the temperature of the parts is around 0°C, the hand feels cold, and if it touches for a long time, it will have a tingling pain. At around 10°C, it feels cooler but generally bearable. At about 20°C, the hand feels cool, and the touch becomes warmer with longer contact time. At around 30°C, it feels warm and comfortable. At around 40°C, it feels hotter and has a slightly hotter feel. When the temperature is around 50°C, the hand feels hot. If you use the palm for a long time, you may feel sweat. At about 60°C, the hand feels hot, but it can generally endure for 10s. When the temperature is about 70°C, the hand feels hot and burns, and generally can only stand for 3s, and the touch of the hand will turn red quickly. Touch, touch and touch again to estimate the temperature rise of the parts. You can feel the gap size of 0.1mm-0.3mm by shaking the motive element by hand. Touch the parts by hand to feel the strength of the vibration and the impact, as well as the crawler's crawling conditions. Using a thermometer equipped with a surface thermocouple probe to measure the surface temperature of rolling bearings, plain bearings, headstocks, motors and other mechanical parts, it is possible to determine the location of thermal anomalies, data accuracy, and the convenience of touch detection.
3, observe the corporate vision can be observed on the device for loose parts, cracks and other damage; can check the lubrication is normal, whether there is no dry friction and run, run, drip, leakage; can see the metal deposits in the fuel tank deposits The number of particles, size and characteristics to determine the wear of the relevant parts; can monitor the movement of equipment is normal, with or without abnormal phenomena; can watch the equipment installed on the equipment to reflect the working status of various instruments, understand the data changes, By measuring tools and directly observing the surface condition, the product quality can be detected and the working condition of the equipment can be judged. By comprehensively analyzing the observed information, you can judge whether the equipment is faulty, fault location, fault level, or the cause of the fault. Through the instrument, observe the wear particles collected from the equipment lubricating oil, and the easy way to realize the wear condition monitoring is the magnetic plug method. Its principle is to insert a magnetic plug into the lubricating oil, collect the worn out ferrous abrasive grains, and use the reading microscope or directly observe the size, quantity and shape characteristics of the abrasive particles to judge the wear of the mechanical parts surface. degree. The magnetic plug method can be used to observe the larger size of the abrasive particles that appear later in the wear of mechanical parts. During observation, if a small number of abrasive particles are found and the number is small, it indicates that the equipment is operating normally. If a large number of abrasive particles are found, attention must be paid to it and the equipment operation status must be strictly observed. If a large number of consecutive particles are found, it is an impending failure. The precursors should be checked immediately for failure to locate and troubleshoot. Speaking in great detail, these diagnostic methods require a long period of experience to accu- rate accuracy.
First, the pump does not cause water analysis of the water inlet pipe and the pump body air (1) the pump is not filled with enough water before starting, sometimes the water seems to have overflowed from the bleed hole, but did not turn the pump shaft to completely discharge the air, resulting in A little air remains in the inlet pipe or pump body.