In the process of using the vacuum pump, whether it is a domestic vacuum pump or an imported vacuum pump, regardless of the quality, after a long time of work, if the maintenance is not performed in time and correctly, more or less failures will always occur. If the vacuum pump cannot be started normally due to long-term non-use or failure, a detailed analysis of the specific problem is required. The article mainly explains the reasons and troubleshooting methods of the vacuum pump cannot be started or cannot be started due to a fault.
1. The reasons for this failure due to the vacuum pump being unable to start are as follows:
(1) The drive motor voltage is incorrect or overloaded.
(2) Motor starter overload protection is too small or the set value is too low
(3) The fuse is blown.
(4) If the vacuum pump is equipped with an AC motor: the capacitor of the motor is damaged.
(5) Check the use of vacuum pump oil. The vacuum pump returns oil, the oil temperature is too low, and the oil has deteriorated. Fill the vacuum pump cavity with vacuum pump oil. Observe whether the oil has emulsified (white foam) or carbonized (blackened). The deterioration of the vacuum pump oil will affect the friction between the rotating blades and the rotor, and cause the blades to get stuck in the pump cavity.
(6) The vacuum pump or motor is stuck.
(7) The oil pump is worn out or foreign matter accumulates.
(8) The suction pipe is blocked.
2. The vacuum pump cannot be started and the maintenance solutions are as follows:
(1) Provide the correct voltage for the motor.
(2) Compare the setting data of the motor starter overload protection with the data on the motor nameplate, and correct it if necessary. If the ambient temperature is high: the set value can be increased by 5% based on the normal motor current.
(3) Check the fuse.
(4) Repair or replace the motor. (Professional technicians are required to operate)
(5) Replace the vacuum pump oil, disassemble the vacuum pump, and repair the cylinder block and other parts. If the blades are severely damaged, the vacuum pump blades need to be replaced.
(6) Make sure that the motor is turned off, and then disconnect the fan cover. Rotate the motor and vacuum pump by hand. If the hand plate does not move, please remove the motor from the pump and check the vacuum pump and motor separately. If the vacuum pump is stuck, it needs to be repaired (repair and inspection by professional technicians).
(7) Replace the worn parts of the oil pump, clean the foreign matter inside and outside the vacuum pump, and repair the pump (maintenance and inspection by professional technicians are required).
(8) Remove the suction pipe, operate the pump alone, touch the air inlet and outlet with your hands to see if the pump can work normally. If the pump cannot pump air at this time, it means there is a problem with the pump itself.
If the vacuum pump fails to start normally, find the cause or location of the fault. The inner cavity of the pump should also be disassembled in time for cleaning and inspection to prevent secondary damage to the pump outlet. If you don't know much about the inside of the vacuum pump, you need to find a professional vacuum pump maintenance manufacturer to perform professional vacuum pump maintenance.
Rotary vane vacuum pump fault judgment and vacuum pump maintenance: There are many common failure types of rotary vane vacuum pumps, and the failures can be divided into operation failures and performance failures. Once a failure occurs, it is necessary to analyze the cause of the failure, and perform proper vacuum pump maintenance according to the problem and cause of the failure.
The common faults of the rotary vane vacuum pump are as follows:
1. The pump does not rotate. If the situation is unknown, do not start the pump first to avoid aggravating the fault.
2. The pump temperature is too high. Indicates that the oil temperature measured near the low exhaust valve exceeds the value in the user manual. As the temperature of the pump rises, the viscosity of the pump oil will decrease significantly, and the saturated vapor pressure of the pump oil will increase, which will increase the pressure of the pump and reduce the pumping efficiency; make rubber parts prone to aging; thermal expansion will decrease The working clearance, especially the thickness direction of some non-metallic rotating blades and the clearance of the inner hole of the copper sleeve will affect the reliability of the pump. The reason for the high pump temperature may be that the pump temperature is too high, the intake air temperature is too high, the intake air cooling device is faulty, the inlet pressure of the pump is too high and it cannot be operated continuously for a long time; the cooling water volume of the water-cooled pump is insufficient, and the circulating water design effect is not good; Temperature control water volume control valve failure, etc.
3. Oil leakage. It may occur in shaft seals, sealing surfaces of fuel tanks and pump parts, drain plugs, oil traces, oil hole partitions, through-hole connections between stator parts and supports, and gas ballast valves. It may be caused by seal aging, improper installation, damage and malfunction, uneven surface, impurities, roughness and loose casting. If the oil returns after the pump is stopped, the oil will enter the gas ballast valve, and if the gas ballast valve is not closed, the oil may leak. When making homemade rubber gaskets, use oil-resistant rubber. It should follow the original design shape. If the sealing surface is too large, if it is not pressed tightly, the sealing surface will leak.
4. The high power exceeds the standard. This may be caused by long-term continuous operation, such as excessive intake pressure, excessive exhaust pressure, sticking caused by debris, excessive pump temperature, too small matching gap (such as rotating blades), excessive voltage, and pump Excessive liquid returns to the pump. Otherwise it will damage the motor, try to avoid long-term continuous operation when the power is too high. If there are deposits on the surface, they need to be removed regularly.
Rotary vane vacuum pump repair method:
1. Before performing vacuum pump maintenance, prepare inspection methods.
2, judge the fault and diagnose the fault. Judgment is accurate and saves trouble. The diagnosis needs to be verified.
3. To troubleshoot, first simplify and then complicated, and first easy and then difficult. Do not dismantle those that do not need to be dismantled. Vacuum pump unit to reduce new damage caused by lack of special tools and improper operation. Generally speaking, the spliced rotor is not removable, otherwise the shape and position tolerance will not be guaranteed and the rotor will be scrapped.
4. For toxic, harmful and corrosive pumps, users should be asked to clean them first and inform the necessary protective measures to protect the health of maintenance personnel.
1. Analysis of the cause of corrosion on the surface of the screw pump rotor
The feed medium of the vacuum pump contains sulfur dioxide and water. The sulfur dioxide combines with water to produce sulfurous acid. Sulfurous acid has a corrosive effect on metals. To prevent corrosion of the rotor and pump cavity, a Teflon layer is applied to the surface of the rotor and pump cavity. The corrosion of the rotor and pump cavity indicates that the layer is damaged, and the sulfurous acid has corroded the pump cavity.
2. Analysis of the causes of damage to the Teflon layer of the rotor and pump cavity
There may be three reasons for damage to the surface layer of the rotor and pump cavity:
One is that solid particles enter the pump cavity, and the solid particles cause damage to the coating.
The second is that chemical substances form colloids on the pump cavity and rotor, and the colloid is carbonized and hardened, destroying the coating of the rotor and pump cavity.
Three are other reasons.
1. Analysis of the destruction of solid particles
Inspect the pump inlet equipment and pipelines, no freely moving solid particles such as metal fragments, iron chips, etc. were found.
2. Analysis of the destruction of colloidal carbon deposits
Figure 1 is a photo of the attachment on the inner wall of the pump inlet pipe. The substance is dark brown. After analysis, it contains iron, carbon, oxygen, etc. It is a polymer substance such as butadiene and sulfolane. The substance is glued to the inner wall of the pipe. . If the substance adheres to the pump cavity and the surface of the rotor, it is easy to be carbonized and hardened, thereby destroying the surface layer of the rotor.
3. Analysis of process factors
The gas phase outlet pressure of the vacuum pump is 80kpa(A), which is negative pressure, while the liquid phase outlet of the pump is normal pressure. Under normal conditions, the liquid at the outlet of the pump cannot enter the underground liquid tank normally, and a backflow is formed, which causes the accumulation of liquid substances at the outlet of the pump. , These liquid substances contain sulfurous acid, and the concentrated sulfurous acid liquid at the outlet of the pump will cause impact corrosion on the vacuum pump. It should be said that the backflow of the liquid at the outlet of the pump is the main cause of corrosion of the pump rotor and pump cavity.
How much do you know about the maintenance of vacuum pumps? Now I will reveal some maintenance tips for vacuum pumps:
1. Check the oil level frequently, and adjust it to meet the requirements if it does not meet the requirements. When the vacuum pump is running, the oil level is at the center of the oil standard.
2. The oil change period is determined by the user's discretion in consideration of actual conditions of use and whether it can meet performance requirements. Generally, when a new vacuum pump is pumping clean and dry gas, it is recommended to change the oil once every 100 hours of work. After no ferrous metal powder can be seen in the oil, the oil change period can be extended appropriately in the future.
3. Frequently check the oil quality. If the oil is found to be deteriorated, it should be replaced with new oil in time to ensure that the vacuum pump is working properly.
4. The lubricating oil of the vacuum pump shall be changed after 100 hours during the working month, and the oil shall be changed once every 500 hours thereafter.
5. Under normal circumstances, the vacuum pump should be overhauled after 2000 hours of operation. Check the aging degree of the rubber seals, check whether the exhaust valve plate is cracked, and clean up the dirt deposited on the valve plate and exhaust valve seat. Clean the parts in the entire vacuum pump cavity, such as rotors, rotary vanes, springs, etc. It is generally cleaned with gasoline and dried. After cleaning the rubber parts, wipe them with a dry cloth. When cleaning and assembling, handle with care and be careful of injury.
6. Add bearing lubricating oil to the bearing body, observe that the oil level should be at the center line of the oil mark, and the lubricating oil should be replaced or replenished in time.
7. Check whether there is any looseness in the vacuum pump pipeline and joints. Turn the vacuum pump by hand to see if the vacuum pump is flexible.
8. After reassembly, a test run should be carried out. Generally, it should be run dry for 2 hours and the oil should be changed twice. Because a certain amount of volatile matter will be left in the vacuum pump during cleaning, it should be put into normal work after it runs normally.
9. Turn on the motor. When the vacuum pump is running normally, open the outlet pressure gauge and the inlet vacuum pump. After seeing the proper pressure, open the gate valve gradually, and check the motor load at the same time.
10. Try to control the flow and head of the vacuum pump within the range indicated on the label to ensure that the vacuum pump runs at a high efficiency point to achieve the energy-saving effect.
11. To stop using the vacuum pump, first close the gate valve and pressure gauge, and then stop the motor.
12. During the operation of the vacuum pump, the bearing temperature should not exceed the ambient temperature of 35C, and the high temperature should not exceed 80C.
13. During the working month of the vacuum pump, the lubricating oil shall be changed after 100 hours, and the oil shall be changed once every 500 hours thereafter.
14. Regularly adjust the packing gland to ensure that the leakage in the packing chamber is normal (it is better to leak out as a drip). Regularly check the wear of the shaft sleeve, and replace it in time when the wear is large.
15. If the vacuum pump is out of service for a long time, it is necessary to disassemble the pump completely, wipe off the water, coat the rotating parts and joints with grease and install them, and keep them properly. When the vacuum pump is used in the cold winter season, after stopping, unscrew the water drain plug at the bottom of the pump body to drain the medium. Prevent freezing and cracking.
Company Address: 9th Floor, Chuangxin Building, East Section of Furong Road, Changqing District, Jinan City, Shandong Province
Production base: No. 11111, South Second Ring Road, Shizhong District, Jinan City