Mechanical vacuum pumps

For you to introduce a mechanical vacuum pump, here also known as piston vacuum pump.

Piston pump of structure and principle

1. Piston pump is composed of pump body, piston, eccentric wheel, etc.
2. Working principle: a piston is installed in the pump body, and an eccentric wheel is installed in the piston. The eccentric wheel is driven to rotate by the shaft leading to the outside of the pump cylinder. The center of the shaft coincides with the center of the pump cylinder. The outer circle of the piston slides on the inner surface of the pump cylinder. The upper part of the piston slides up and down and swings left and right freely in the semicircle piston guide rail. Therefore, the pump cylinder is divided into two chambers a and B by the piston. If the axis rotates counterclockwise, chamber a will gradually expand and chamber B will gradually shrink. With the operation of the piston, finally until chamber a becomes maximum and chamber B becomes minimum.

Piston pump installation and use:

1. The base of the pump shall be installed on the concrete foundation, and 5-10cm groove shall be reserved around the foundation to prevent contamination of the site during oil discharge or water discharge.
2. During installation, it is not necessary to calibrate the level first, and then tighten the foundation screw.
3. Before use, all dust and dirt on the pump must be removed. The pump room must always be kept clean and the ambient temperature should be within the range of 5-40 ℃.
4. The suction port of the pump shall be equipped with dust-proof device according to the use. It is absolutely forbidden to pump in hard substances such as glass fragments, sands, metal sheets or oxides (these impurities should also be noted when assembling the vacuum system). As the clearance between the slide valve and the inner wall of the pump cavity is very small, no impurities are allowed to enter. Once impurities enter, serious accidents will occur, so measures should be taken in advance.
5. When the pump is working under the rough vacuum (the inlet pressure is more than 133pa), the oil mist shall be discharged from the exhaust port. The cause of the oil fog is that the pressure in the compression chamber is significantly increased when working in a rough vacuum, and the exhaust gas rushing violently from the small exhaust port. The oil near the small hole and the exhaust valve is atomized according to the same principle as the sprayer, and is discharged from the pump with the gas. This oil mist is basically there regardless of the size of the phenomenon. In addition, this kind of oil mist has no adverse effect on the pump, but it can not only pollute the air, but also damage the indoor floor and appliances. In order to prevent this kind of pollution, the exhaust pipe shall be connected to the outdoor during installation. The outlet of the outdoor exhaust pipe shall face down to avoid rainwater dripping.
6. The air inlet pipe should be very tight, even if there is a small leakage, it will affect the vacuum degree. In principle, the air inlet pipeline shall be as short as possible, with less joints and elbows, and the pipeline connected with the pump body shall not be smaller than the diameter of the pump.
7. The cooling water inlet pipe shall be equipped with valves to adjust the water volume. During operation, the temperature of cooling water in the pump water jacket shall be controlled between 20-40 ℃, and the water temperature shall not exceed 40 ℃, so as to avoid scaling in the water jacket.
8. If the extracted gas is higher than 40 ℃, it shall be cooled to normal temperature.
9. When the pump is working, the maximum temperature shall not exceed 85 ℃
10. When the pump is running under normal working conditions, the oil level shall be within half of the oil level on the oil tank, and when it is insufficient, it shall be supplemented with oil.
11. When the pump changes oil, add about 1kg of oil to the air inlet of the pump, and the rest of the oil will be added through the oil filling hole on the oil tank.
12. A clearance height of 300 mm shall be applied above the pump, i.e. the pipe with a height of 300 mm shall be connected at the pump exhaust port first, and then the exhaust channel. In this way, when removing the pump, the oil tank can be disassembled as long as the pipe is removed without moving the exhaust channel.

Piston pump start and stop

1. Preparation before starting:
A. check the tightness of the belt and relax before starting. After starting, adjust the bolt on the base and tighten it slowly to reduce the starting torque.
b. Check whether all parts are loose and whether the motor steering meets the requirements of the pump.
c. Check whether the oil level in the oil tank is about half of the oil level in the oil tank.
d. For the pump that has not worked for a long time, the method of starting the motor intermittently shall be applied before starting to check whether the rotation is flexible.
e. Open the cooling water valve.
f. If the room temperature is too low in winter, the pump should be heated before starting. Because of the high viscosity of oil at low temperature, such as sudden start-up, it will overload the motor and damage the pump parts.
g. If there is a significant difference between the oil level of the oil mirror on the oil tank and the oil level when parking, the pump belt pulley must be turned to drain the oil in the pump cavity into the oil tank before starting. In the vacuum state, when more oil is left in the pump cavity at the same time, it is not allowed to start.

2. start:
a. Turn on the power switch and start the motor.
b. Check whether the cooling water and lubricating oil are normal.
c. After running for about five minutes and all aspects are normal, slowly open the air inlet valve to avoid the increase of pump load.
3. Shutdown: the shutdown of pump is particularly important, otherwise it will be difficult to start next time. In principle, the shutdown shall be carried out according to a series of procedures:
a. Close the intake valve on the intake pipe.
b. Open the charging valve to break the vacuum in the pump.
c. Wait about half a minute, turn off the power. The above procedures should not be sloppy, or the oil in the oil tank will continuously flow into the pump cavity due to the vacuum in the pump cavity after parking, so that the pump cavity is full of oil. From the point of view of parking, this is not a great harm, but there will be problems when driving again. That is to say, when the pump cylinder is full of oil, almost all the oil will be discharged from the exhaust port when the rotor turns the first circle; on the other hand, because the oil can hardly be compressed, and the viscosity is large, it will be squeezed out from the small exhaust port of the pump at once, and the resistance is very large, so not only the motor requires a very large starting torque, but also the shaft and eccentric wheel increase a lot in an instant Large impact force is very dangerous for pumps and motors, especially when the ambient temperature is low. If the above procedures are followed, the above risks can be avoided.

Piston pump maintenance and precautions

1. maintenance:
a. Pay attention to the cleaning of oil level and oil. Change the oil after the new pump works for 150 hours, and then change the oil every 2 to 3 months. If the service conditions are not good and the vacuum degree drops, the oil change time can be shortened.
b. Keep the pump and pump room dry and clean.
c. Always pay attention to pump temperature and cooling water and oil temperature.

2. Precautions:
a. In the cold zone, the water in the cooling water jacket must be drained completely after parking, otherwise the water in the jacket will freeze and damage the pump shell.
b. Lubricating oil shall be mechanical vacuum oil (i.e. sy1634-76, No.1 vacuum pump oil specified by the Ministry of petroleum, code: kk-1), otherwise, the required vacuum degree cannot be reached.
c. Pay attention to the oil cleaning, and clean the copper wire valve in the oil filter frequently.
d. If it is not used for a long time, the pump shall be started every 7-10 days for about one hour to avoid corrosion in the pump.

Piston pump disassembly and assembly

1. Disassembly procedure: (drain water and oil first)
A. Protective cover.
B. Pump V-belt pulley, balance pulley.
C. Oil pipe and oil pump.
D. Bearing cover and sealing device.
E. A and B pump covers (remove together with bearings).
F. Slide valve and slide guide assembly.
G. Eccentric, flat key and shaft.

2. Removal procedure of exhaust valve:
A. bolt
B. bonnet
C. valve body
The rest of the parts separate themselves. When assembling, the order is reversed.

3. Attention shall be paid to disassembly and assembly:
A. It is not allowed to hit the machined surface directly with a hammer.
B. Prevent bruising and knocking.
C. During installation, the parts shall be cleaned carefully until there is no stain on the brush with white cloth.
D. Note that the sealing surface shall be free of air leakage and oil leakage

Mechanical vacuum pumps