Maintenance knowledge of Centrifugal pump
First, before installation
1.We’d better coated with a suitable rust inhibitor on the centrifugal pump surface which has not been installed and used to prevent the pump is oxidized ;
2. Bearing maintenance of its oil lubrication, we’d better be filled with a suitable fluid. However, these oil selection also has a lot of skill. For example: During use, preferably filled with a grease, rather than going to use those mixed grease. Because the life of the mechanical mixing grease has a great harm.
Second, hold down
During the centrifugal pump use, such as for special reasons (annual leave) to suspend production, resulting in long-term hold pump, then we should note in the storage process:
1. The media in the pump should be rinse with water to ensure that no residue cavity, prevent deterioration and other causes liquid mixed fluid medium;
2. The centrifugal pump must be stored in those clean environments, and extremely dry place, otherwise, it is prone to rust liquid, liquid injection and corrosion inside the pump casing structure.
Special note: If not stored properly, may cause permanent and irreparable harm, so that will has a great impact on our future use.
In actual use, there may be more questions, if you want to learn more about the centrifugal knowledge, welcome to call for free advice, with your support we can do better.
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Effectively improve the performance of sewage pumps
1.Installed valve at the end of suction pipe of Self-suction sewage pump .
Suction bottom valve is actually a kind of check valve, which ensures that water can only enter the suction pipe from the pool and can not be back, so if the suction pipe filled with water, although the water pump axis elevation above the pool water level, but due to suction bottom The role of the valve, the suction pipe will not flow into the pool of water, so that the suction pipe has been filled with water to ensure that the pump can automatically and quickly start. The reliability of this method of water absorption by the impact of the quality of the end of the valve, for example, closed lax, water leakage, the water will slowly sink into the pool, a long time, there is no water suction pipe, causing the pump starts still Need artificial irrigation.
2.Self-suction sewage pump to reduce the inlet pipe bend, drop height and horizontal distance.
3.Self-priming pump set suction pump before the pump.
This approach requires a suction pipe on the pump suction pipe, the first run before the tank, the tank should be filled with artificial water, the first stop, because the intake pipe suction tube height above the surface height of
the pipe, despite the The water level inside the tank is lower than the height of the water surface of the tank, the water inside the tank will not turn back into the pool, so the water canister can store a certain water, and because of the height of the water pipe Below the tube surface height, it can ensure that the pump suction tube filled with water, after the pump and then run, the water tank was pumped away, negative pressure tank, the pool of water under the effect of atmospheric pressure added to the Suction tank inside, through the sink tank inside.
4.Self-suction sewage pump in the pump suction pipe set vacuum pump, pump start, the vacuum pump first start, so that the pump suction tube filled with water first, to ensure that the pump automatically and quickly start. This method of water needs to have a sound automatic control system to ensure the normal work.
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Maintenance of submersible pump motors and maintenance of related valves, pipes and accessories
The visual inspection should be neat and tidy, the nameplate is intact, and the grounding wire is well connected.
Disassemble the wire connecting piece in the motor terminal box, and test the insulation resistance value of the phase and phase of the motor winding and the ground between the ground and the ground with a 500V megohmmeter to be not less than 0.5 megohm.
The three-phase wires and connecting pieces in the motor terminal box should be tight and tight.
Maintenance of valves, pipes and accessories related to Forever submersible pumps:
The switches of each valve should be flexible and reliable, with no leakage inside or outside.
The check valve should be flexible and there is no water leakage inside and outside the valve.
The pressure gauge is accurate and the dial is clear.
The appearance of the pipes and accessories is neat and beautiful, without cracks, and the paint should be intact without falling off.
Jog to determine if the pump steering is correct, if it is wrong, it should be corrected.
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What are the application conditions of large flow submersible pumps?
Pumping medium: similar to clean water, liquid with a solid content of not more than 0.02%
Medium temperature: 40°C for ordinary pump and 120°C for hot water pump
Media PH value: 3 to 10
Power requirements: frequency is 50Hz, 60Hz (can be customized), rated voltage 380V [660V, 1140V, 3000V, 10KV] ± 5%
Technical parameters
Flow range: 5 to 650 cubic meters / hour
Lift range: 2 to 1500 meters
Power range: 3 to 410kW (secondary speed motor, customizable four or six motor)
Speed: 2900 rpm (secondary speed motor)
Optional material: HT200, 304, 316, 316L, tin bronze large flow submersible pump
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Several methods for controlling the flow of submersible pumps
For the use of submersible pumps, we are mainly drainage, then I believe that many of the control of the water output and water flow are not understood, and then explain the various adjustment methods of the water flow control of the submersible pump.
1. Variable speed adjustment. Changing the speed of the submersible pump can change the performance of the pump, thus changing the operating point of the pump. This method is called variable speed mediation.
2. Reducer adjustment. After the impeller is turned, the performance of the pump will change according to a certain law, so that the operating point of the pump changes. The method by which the turning impeller changes the operating point of the pump is called the variable diameter adjustment.
3. Variable angle adjustment. Changing the installation angle of the blade can change the performance of the pump to achieve the purpose of changing the operating point of the submersible pump. This way of changing the operating point is called the variable angle adjustment of the pump.
4. Throttling adjustment. For the water pump device in which the gate valve is installed in the outlet pipe, when the gate valve is closed for a small time and the local resistance is increased in the pipeline, the pipeline characteristic curve becomes steep, and the operating point moves to the upper left along the Q-H curve of the water pump. The smaller the gate valve is closed, the greater the increased resistance and the smaller the flow. This method of changing the operating point of the pump by closing the small gate valve is called throttle regulation or variable valve regulation.
When the small gate valve is closed, the local head loss of the pipeline increases, the pipeline system characteristic curve moves to the upper left, and the pump operating point also moves to the upper left. The smaller the gate valve is closed, the greater the local head loss and the smaller the flow rate. It can be seen that the throttling adjustment not only increases the local head loss, but also reduces the amount of water, which is uneconomical. However, due to its simplicity and ease of use, it is widely used in small water pump devices and pump performance tests.
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Supply and demand of pump market
Pumps are general-purpose mechanical products. China’s pump products have approximately 450 series and more than 5,000 specifications. They are widely used in agriculture and water conservancy, construction industry, petroleum industry, power industry, shipbuilding industry, mining, metallurgical industry and environmental protection industries. . In recent years, with the rapid growth of the domestic economy, the market’s demand for pump products has also grown rapidly. According to statistics from the Industrial Pump Research Institute of Zhejiang University of Technology, the sales revenue of the pump industry in China exceeded RMB 100 billion in 2009, and the industrial output value of the industry was around RMB 108 billion, with a balance between production and sales. The regional industrial output value of the industry is: 26 billion yuan in Wenling, Taizhou, 10 billion yuan in Wenzhou Yongjia, 5 billion in Hangzhou, 15 billion in Shanghai, 6 billion in Shandong, 8 billion in Shenyang, and Dalian 6 billion yuan, 5 billion yuan in Guangzhou, 3 billion yuan in Beijing Tianjin, 2.5 billion yuan in Shijiazhuang, and Changsha 25 In recent years, the pump industry has maintained a momentum of rapid growth. In 2007, the growth rate was 23.20%, but due to global finance Affected by the economic crisis, the growth rate of the industry in 2008 has dropped slightly, to 13.5%. With the rapid development of the pump industry and the fierce market competition, the growth rate of the pump industry will tend to be stable, and it is expected that the future.
The five-year industry development rate is between 13% and 17%. The industry’s development focus will shift from quantitative growth to quality improvement.
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How to improve the anti – cavitation performance of centrifugal pump
(1)Improve the centrifugal pump suction port to the impeller near the structural design. Increase the flow area; increase the radius of curvature of the inlet section of the impeller cover, reduce the rapid acceleration and decrease of the liquid flow; reduce the thickness of the inlet of the blade, and make the leaf inlet rounded so that it is close to the streamline, Reduce the speed of the blade around the blade and increase the surface of the impeller and the blade surface to reduce the loss of resistance;
(2)Use pre-induction wheel, so that the flow in the pre-induction wheel in advance to work to improve the flow pressure.
(3)Use double suction impeller, so that the flow from the impeller on both sides of the same time into the impeller, the import cross-section doubled, the import flow rate can be reduced by double.
(4)The design of the use of slightly larger positive angle to increase the blade inlet angle, reduce the blade at the entrance of the bend, reduce the blade blockage to increase the import area; improve the working conditions under high flow to reduce Flow loss. But the angle should not be too large, otherwise the impact of efficiency.
(5)Use anti-cavitation materials. Practice shows that the higher the strength, hardness and toughness of the material, the better the chemical stability and the stronger the resistance to cavitation.
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Fast and easy assembly of multi-stage centrifugal pump
Multistage centrifugal pumps should be placed as far as possible in a well ventilated place to facilitate rapid cooling and reduce motor temperature. Otherwise, run for a long time, easy to burn the motor.
If the use of multi-stage centrifugal pump, because did not remove the plastic film covered in the motor, causing the motor overheating, burn the coil. In addition, before starting, be sure to check the water inside the pump, otherwise, not only affect the self-priming performance, and easy to burn the shaft seal parts. Under normal circumstances, multi-stage centrifugal pump starts after 3 to 5 minutes that should be out of water, or should immediately stop inspection.
When the multi-stage centrifugal pump once a failure, avoid their own hands. Because of their own demolition, I do not know where the fault caused by blindly split a pass; Second, no special tools and often damage the original good parts. The best way is to have experienced, large-scale maintenance point repair, and timely replacement of “overage” parts and some wearing parts. Under normal circumstances, multi-stage centrifugal pump should be repaired once every six months, put an end to “sick” work.
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The reasons of no flow of multi-stage centrifugal pump
First,multi-stage centrifugal pump outlet pipe resistance is too large; pump direction of rotation; multi-stage pump impeller flow blockage or damage, pump speed is insufficient.
Second, check or shorten the horizontal multi-stage pump outlet pipe to eliminate dirt or replace the impeller impeller; check the pump motor, increase the pump speed.
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The main purpose of low temperature submersible pumps
The use of low-temperature submersible pumps is mainly used in oil and chemical plants to transport liquid hydrocarbons, liquefied natural gas and liquid nitrogen and liquid liquefied gas in refrigeration systems. Therefore, it is also called cryogenic pump.
The installation of the cryogenic pump and the operation of the cryogenic pump are:
1) cryogenic pump assembly parts are strictly prohibited with water and grease, parts must be washed with a solvent clean, dry and then assembled.
2) not only the cryogenic pump itself to be cold, low temperature pump suction line must also have cold measures to prevent the heat in the operation from the outside, so that the liquid vaporization, affecting the performance of the pump.
3) If there is oil, moisture and air in the cryogenic pump and piping, it will freeze when it enters the cryogenic liquid, so it needs to be cleaned before the cryogenic pump is put into operation and then scavenged with dry nitrogen. Pump the water and air, and pre-cooling.
4) The suction port and the suction pipe of the cryogenic pump should have the exhaust device so that the pump can remove the gradually accumulated gas before and during the operation to ensure the reliable operation of the cryogenic pump.
5) In the case of explosive gas, the motor should use vertical explosion-proof motor.
6) low temperature transmission can also use low temperature shielding pump or stainless steel magnetic pump.
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