一、 Use of vacuum pump

1. Over 70 degrees. The measurement of pumping speed from dry to dry is complicated and generally not checked.

2. The mechanical vacuum pump which needs cooling water should be supplied with cooling water before starting up. The outlet temperature of cooling water should not exceed 30 ℃.

3. The pipeline of continuous vacuum pump and the system to be pumped should be as short and thick as possible, and the inner diameter of the pipe should not be smaller than the diameter of the air inlet of the dry vacuum pump, so as to avoid the influence of the resistance of the dry pipe on the pumping rate.

4. In order to keep the working room clean and healthy and benefit the health of the staff, the exhaust gas is directly led to the outdoor by leather tube.

5. When the vacuum pump is not working for a long time or the ambient temperature is low, it may cause difficulty in starting. At this time, the air outlet of the vacuum pump should be connected with the atmosphere, and the belt pulley should be rotated with plenty of power (the vacuum pump can be started after several cycles without power supply). If the vacuum pump is directly connected, the motor can be continued to move for several times, and the oil in the vacuum pump cavity can be discharged into the oil tank to start. If not, radiation heating or infrared lamp can be used to directly heat the vacuum pump until it can be active.

6. Before use, check whether the mechanical vacuum pump oil reaches the oil mark position of the window. At the same time, the rotation direction of the motor pulley must be checked. The observer is facing the pulley, and the pulley should rotate clockwise. If it rotates in the opposite direction, any two-phase connector in the phase power supply can be replaced. Otherwise, the rotary vane vacuum pump will not be able to pump air, instead, the vacuum pump oil and atmosphere will be pumped into the system, causing serious pollution.

7. At the end of the work, the high vacuum valve should be closed first, then the low vacuum valve should be closed, and then the rotary vane vacuum pump should be stopped, and then the air should be vented (if the electromagnetic vacuum belt vent valve is used, it can be automatically vented) to prevent the oil from returning to the vacuum system, and finally cut off the main power supply and cut off the water supply.

8. Pay attention to prevent hard materials (metal chips, glass fragments, etc.) from falling into the vacuum pump and scratching the moving parts of the vacuum pump. When the vacuum pump is out of use for a long time, it should be stored in a dry and clean environment, and the air outlet and exhaust port should be blocked to prevent dirt from falling in.

9. When disassembling, cleaning and assembling mechanical vacuum pump, attention must be paid not to damage the sealing surface, do not lose screws, and the parts cleaned and dried should be blown or dried (the temperature should not be too high and the time should not be too long). When assembling, apply a small amount of grease on the wall of the vacuum pump to remove the dead space as far as possible. The amount of oil is based on the oil line, and excessive oil will be injected.

二、 Maintenance of vacuum pump

After a long-term use of the rotary vane vacuum pump, there will be some abnormal phenomena, such as the vacuum drop, oil leakage at the seal, stagnation of the vacuum pump rotation, even "stuck", serious oil pollution, rust in the vacuum pump cavity, large impact sound of the rotary vane, hard objects falling into the vacuum pump cavity, causing the vacuum pump overheating and other abnormal phenomena. At this time, the vacuum pump must be disassembled and cleaned. The steps are as follows,

1. Remove the vacuum pump and cut off the power supply,

2. Use gravity method or pressure method to discharge and collect dirty oil to avoid environmental pollution;

3. Remove the belt and pulley key (the double-stage rotary vane vacuum pump includes the belt);

4. First remove the low vacuum end, remove the rear end cover, and then take out the low vacuum rotor, rotor and spring;

5. Remove the front cover and take out the high vacuum rotor, rotor and spring;

6. Remove the mirror, exhaust valve, exhaust cover, etc;

7. Clean the removed metal parts thoroughly with gasoline and dehydrate them with alcohol. Rubber parts can be dissolved in 15% sodium hydrofluoride and boiled to remove oil. For parts with burr or rust, it can be gently ground with oilstone or metallographic sandpaper to remove rust spots and burrs. The cleaned parts must be dried;

8. During assembly, first install the second stage, hold up the spring and rotating blade into the rotor, then put it into the vacuum pump chamber, install the front end cover, and then install the positioning pin. Tighten the screws evenly and symmetrically. After assembly, the rotation should be flexible and even. After installing the front stage rotor and rear end cover, install the exhaust valve (the exhaust valve piece should be close to the valve seat) and other parts, such as air ballast device.

Precautions for maintenance of vacuum pump:

1. Check whether the oil level is low and the dry oil mark is regular. If the low dry oil mark, should be timely refueling, apricot. Will affect the vacuum degree of the vacuum pump. The amount of fuel should not be too much, otherwise it will cause difficulties in starting and fuel injection.

2. Should always pay attention to whether the vacuum pump operates normally, whether there is any special sound, whether the machine is overloaded, and whether the temperature of the motor vacuum pump is too high.

3. Water cooling vacuum pump, should prevent cooling water interruption, vacuum pump temperature should not exceed 70 degrees. If the ambient temperature is lower than 5 degrees, the cooling water in the vacuum pump should be drained after shutdown to prevent the vacuum pump body from freezing and cracking.

4. The vacuum pump should be kept clean by belt, and no other objects should be placed on the vacuum pump.

5. Pay attention to the belt tightness is appropriate. Adjust or replace if necessary.

6. The vacuum pump oil should be replaced 1-3 times a year. The mechanical vacuum pump used in vacuum melting may change oil frequently every month. This is due to the dry vacuum pump in the use process, vacuum pump oil will be ash, moisture or other dirt pollution or soap, carbonization, affect the performance of the vacuum pump, therefore, the need for regular oil change according to the specific situation.

三、 Method of changing vacuum pump oil

1. By gravity method, the container is placed under the oil drain port, and the screw at the oil drain port is screwed to let the old oil in the vacuum pump flow into the container automatically. After the old oil is drained out, a small amount of clean vacuum pump oil (100 ~ 500ml) is injected into the air suction port to flush the inside of the vacuum pump cavity. Then, start the vacuum pump and run for about 1min, and then turn off the vacuum pump to discharge the injected new oil. If the discharged oil is still not dry, continue to inject new miscellaneous oil for flushing until it is clean. Then, screw on the oil drain screw. Screw off the screw on the oil filling hole, add the vacuum pump oil to the vacuum pump to make the oil level reach the oil mark, and then screw on the oil filling screw.

2. Place the container under the oil drain port by pressure method, and screw the drain hole screw. Close the suction port, open the vacuum pump at the same time, open the air ballast valve and cover part of the exhaust port of the vacuum pump to generate a sufficient internal pressure to discharge the dirty oil quickly. Then, according to method (1), flush the inside of the vacuum pump chamber and replace with new oil

Precautions for changing vacuum pump oil:

1. Attention should be paid to cleaning, strictly prevent dirt mixed into the vacuum pump.

2. Start the vacuum pump should not be too long, so as to avoid excessive dry exhaust valve plate and fatigue.

3. It is strictly forbidden to wash the vacuum pump without disassembly with medium oil, gasoline and alcohol.

4. It is better to change the oil after the oil temperature rises, so as to drain the visceral oil of the vacuum pump.

四、 Precautions for dismantling and washing mechanical vacuum pump

1. Disassembly and cleaning of mechanical vacuum pump should be carried out in the clean room. During disassembly and cleaning, attention should be paid to the original location, direction and combination tightness of each component and part, and records or marks should be made to avoid wrong assembly;

2. When taking out the rotating blade and rotor, it is necessary to hold the rotating blade tightly by hand. Due to the large spring force on the rotating blade, it is easy to get out of hand and fly out if it is not careful, and the edge angle and center surface of the rotating blade can not be used.

3. The removed parts should be separated and properly handled. Do not put them in a disorderly way. Otherwise, they will be easily damaged or lost.

4. During assembly, a small amount of vacuum pump oil should be coated on the surface of rotating parts for lubrication. Pay attention to cleanliness. It is strictly prohibited that iron chips, mud, sand and dust fall into the vacuum pump. The positioning pin should be in good contact. The installed vacuum pump should rotate easily without uneven weight and blocking.

5. After the final assembly, add vacuum pump oil from the oil filling hole to the oil mark.

6. Before start-up, a small amount of vacuum pump oil should be injected into the suction port to make the vacuum pump fully lubricated.

The reassembled vacuum pump should be tested for several hours to see if it meets the requirements.

五、 Causes and troubleshooting of vacuum pump

1. The vacuum is not high

(1) The temperature of vacuum pump is too high. The gas should be allowed to cool before entering the vacuum pump. 2. Inhale hard materials to wear the vacuum pump body. The vacuum pump should be disassembled to remove hard objects and repair or replace the scratched parts. 3. The cooling water flow of vacuum pump is the most insufficient. If the rotor is not properly assembled, the water flow should be increased. It should be disassembled for inspection and reassembled.

(2) There is a problem with the vacuum pump oil. 1. The oil level is too low. Add enough oil to the center line of the oil gauge. 2. The oil should be replaced with new oil. 3. The brand of oil does not match. The specified brand of vacuum pump oil should be replaced. 4. The oil circuit is blocked, and the vacuum pump cavity does not maintain appropriate oil quantity. Check the oil inlet quantity of oil circuit and oil valve to keep the oil way smooth.

(3) Air leakage of vacuum pump: 1. Air leakage of sealing ring. The sealing condition of all sealing parts should be checked and the damaged sealing ring should be replaced. 2. The gasket of gas ballast valve is damaged or not tightened. The gasket should be replaced and the air ballast valve should be tightened; 3. The exhaust valve plate is damaged and the sealing is not good. 4. When the diaphragm is pressed into the vacuum pump, the interference is too large, resulting in the vacuum pump cavity deformation and air leakage. The vacuum pump cavity should be repaired or replaced. 5. The end cover should be removed to check whether there are impurities or unevenness, and clean or repair.

(4) The rotor spring is deformed or broken, and the rotating blade does not work properly. The spring deformation should be repaired or replaced to make the rotor rotary blade fit well,

(5) The filter screen at the air inlet is blocked. The filter screen should be removed, cleaned and then installed,

(6) The fit clearance is too large due to poor machining or wear. Check the fit clearance between the vacuum pump cavity, rotor, rotor and end cover plate, and repair or replace it according to the specified accuracy requirements.

(7) The vacuum pump is too thin and too high to make the vacuum pump heat up. Cooling water or electric fan should be used to cool down the temperature. At the same time, the clearance of relevant parts should be checked and repaired or replaced according to the specified accuracy requirements.

Abnormal operation of motor and vacuum pump, overload operation of motor and vacuum pump, abnormal noise, noise, difficult rotation or "stuck" phenomenon during operation of vacuum pump.

(1) If the temperature of vacuum pump is too high, please refer to Item 1 (1),

(2) The spring is deformed or broken, which makes the rotary blade bear uneven force and produce impact sound;

(3) One side wear caused by improper assembly shall be reassembled;

(4) Filter screen damage, metal chips, glass chips, etc. fall into the vacuum pump, so that the operation of obstacles. The vacuum pump should be removed to check, remove debris, repair or replace worn parts, and install the filter screen,

(5) The pollution in the vacuum pump cavity is serious, which leads to the corrosion of parts. The vacuum pump should be removed for washing, rust removal and oil change,

(6) The vacuum pump oil becomes turbid and its viscosity increases. Replace the vacuum pump oil with a new one,

(7) The vacuum pump cavity, shaft and sleeve fit too tightly, resulting in poor lubrication. It is necessary to reassemble, dredge and adjust the oil circuit to strengthen lubrication,

(8) The motor is faulty and produces noise. Repair the motor or grease the bearing.

Oil leakage and fuel injection of vacuum pump

(1) The sealing rings of rotating shaft, oil window, oil drain hole and oil tank are damaged or assembled incorrectly. Check and replace the sealing ring of glass damage carefully. When assembling the screw, the force should be even,

(2) The front and rear end faces are not flat or the end plates are not compressed, resulting in oil leakage at the end face. The end face should be flattened and the front and rear end plates should be pressed;

(3) The inlet pressure is too high. Try to reduce the air intake,

(4) There is a leak in the box. Check and block the orifice,

(5) If the fuel quantity is too much, it is necessary to drain the excess oil,

(5) If the oil screen under the exhaust cover is installed reversely to cause fuel injection, it should be re installed;

(7) Sudden exposure to the atmosphere causes fuel injection. Close the low vacuum valve immediately.

It is difficult to start the vacuum pump

(1) The vacuum pump has returned oil. Pull the belt pulley by hand and rotate it for several times to start,

(2) The vacuum pump cavity is filled with vacuum pump oil due to long-term non operation or not put into the atmosphere after shutdown. Pull the pulley by hand and rotate it several times to start,

(3) If the oil temperature is too low, the oil should be heated or the indoor temperature should be kept above 15 degrees. You can also pull the belt pulley by hand to rotate it for several weeks, and then continue to power on for several minutes, and then it can work normally

(4) The oil has deteriorated and should be replaced with a new vacuum pump oil,

(5) The power supply should be overhauled for lack of phase.