Beijing Super Q Technology Co., Ltd. has EV series oil-lubricated 600L, 1200L, 1600L compound molecular pumps and 3600L turbine type molecular pumps; grease-lubricated 300L, 650L, 1300L, 2000L compound molecular pumps. This article focuses on explaining the characteristics, installation, use and maintenance of EV-Z series grease lubrication compound molecular pumps.
Structure characteristics
EV series grease molecular pump adopts imported precision ceramic bearings, the pump rotor through the dynamic balance, stable and reliable operation, the motor squirrel cage three-phase motor, bearing lubrication by grease lubrication, can be mounted in any orientation.
nstallation and use
I. About Ultimate Pressure
The “Ultimate Pressure” of the molecular pump is based on the ISO international standard “Test method for performance of turbomolecular pumps”, After fully baking the pump body and the test cover (48 hours of drying and degassing), the lowest pressure measured at the specified position of the test cover. pressure value. In actual use, the value of ‘limit pressure’ is related to the working pressure and effective pumping speed of the configured backing pump. Choosing a higher performance backing pump is very beneficial to obtain higher vacuum and reduce exhaust time.
In addition, due to the particularity of the exhaust principle of the molecular pump, the air inlet of the pump is required to be as wide as possible, and the gas path from the vacuum chamber to the molecular pump port should avoid turning as much as possible, so as to exert the best efficiency of the molecular pump, and Guaranteed higher ultimate vacuum.
II.Installation
2.1 Open the Package
Before installation, check whether the molecular pump has been damaged in transit.
The method is as follows: refer to the power supply instructions of the molecular pump, connect it correctly with the molecular pump, do not need to pass water or vacuum, start the molecular pump, and check whether it is running and whether there is any abnormal sound. If there is any abnormality, press the stop switch in time to stop the pump. Note: The power frequency should not be higher than 25Hz during trial operation
2.2 Connecting the High Vacuum Flange
The connection of the molecular pump can be hoisted by the high vacuum flange or fixed on the base. The molecular pump must be fixed when the high vacuum flange of the molecular pump is connected to the system through a metal bellows.
(The flange sealing surface have No scratches, and there shall be nothing on the sealing ring)
2.3 Foreline vacuum connection
An isolation and vent valve should be installed between the foreline pump and the molecular pump to prevent the mechanical pump from returning oil after shutdown.
2.4 Connecting the gas charging device
In order to have a clean vacuum environment, after the molecular pump is stopped, the vacuum system can be filled with nitrogen or dry air. Generally, a vent valve can be connected to the front-stage pipeline, or a high vacuum valve can be used to vent the gas at the high vacuum end.
III．Connecting the cooling
Due to the high-speed rotating friction of the bearing, the heating of the pump body, and the temperature rise of the motor, the bearing and the motor must be cooled when the molecular pump is working. Air cooling is generally used, and water cooling is used when the ambient temperature is higher than 38°C. The soft water pipe with an outer diameter of 10mm can be directly connected to the water inlet and outlet of the molecular pump. A circulating water system with pure water is used, and tap water with low precipitation can also be used (the water temperature must be ≤28°C).
Accidental water stoppage or high water temperature will make the temperature sensor of the molecular pump body act, and the power supply will immediately alarm and stop the output.
There is an interval of about 15 minutes (the specific time depends on the temperature rise rate) after the unexpected water stop or the water temperature is too high until the molecular pump alarms due to overheating.
IV．Baking
The ultimate pressure depends on the cleanliness of the inside of the pump and the vacuum path including the vacuum chamber. In order to obtain the ultimate pressure in the shortest time, the vacuum system and the molecular pump must be baked. Baking should be carried out with the molecular pump running normally.
The baking temperature of the molecular pump should be lower than 80°C, the high vacuum flange connected to the pump port should not be higher than 120°C, and the baking temperature of the vacuum system is generally less than 300°C. of damage.
The baking time depends on the pollution degree of the system and molecular pump and the expected limit working pressure, but the minimum time should not be less than 4 hours.
For obtaining a vacuum of 10-4Pa, in principle, no baking is required; for obtaining a vacuum of 10-5Pa, only baking the vacuum system itself is sufficient; for obtaining ultra-high vacuum, the vacuum system and the molecular pump usually need to be baked at the same time. The measurement system should be fully baked, otherwise it will affect the accuracy of the measurement data due to its outgassing.
V．Operation
Confirm that the pre-vacuum is better than 15Pa, press the RON key to start the molecular pump, and press the STOP key to stop after use. Attention! The soft start key must be used for the first use or re-use after long-term idle use. The soft start operation is as follows: the current stage vacuum is better than 15Pa and the soft start key is pressed. After 110 minutes, the molecular pump reaches the working frequency of 550Hz (550Hz corresponds to EV300Z molecular pump, 400Hz Corresponding to EV650Z, 1300Z, 2000 molecular pump,), then press the soft start key (the key is up) to stop the soft start.
（During the normal operation of the molecular pump, it is forbidden to carry, move or fill with air.）
VI．Maintenance and Repair
6.1 Cleaning the pump
When the air leakage and desorption rate of the vacuum system do not change, and the vacuum performance cannot be restored even after a long time of baking, or when the backing pump is seriously returning oil, the pump should be cleaned.
（If the pump needs to be repaired and cleaned, it must be disassembled by professional technicians. If it is disassembled without training, the consequences will be at your own risk.）
6.2 Replacing the bearings
Since the pump needs to be balanced, the bearing cannot be replaced by the user.
6.3 Impact Protection
Molecular pump is a high-speed rotating machine. The gap between the moving plate and the static plate is very small, and it cannot withstand excessive impact. The speed and acceleration of the moving carrier in contact with it should be limited. In addition, the sudden impact of atmospheric volume and the drop of external hard objects during the normal operation of the molecular pump will also cause serious damage to the molecular pump.
6.4 Vibration isolation
Usually, the molecular pump has been strictly tested, and the vibration is very small, and it can be directly connected to the pumped system. For high-precision instrument applications (such as electron microscopes, etc.), it is recommended to use vibration isolators to minimize the impact of vibration on the instrument.
6.5 Strong magnetic field shielding
The rotating rotor generates eddy current in the magnetic field, which will cause the rotor to heat up. Since the heat will weaken the strength of the aluminum material, the application of the molecular pump in the magnetic field is limited to a certain extent.
6.6 electromagnetic interference
Certain high-frequency instruments, such as molecular pumps and frequency converters, may cause electromagnetic interference to the surrounding environment. But in the case of meeting international standards, the application of molecular pumps will not be limited. If the requirements are met, corresponding certificates should be issued at the same time.
6.7 Strong radioactivity restriction
Most materials will change their properties in a strong radioactive environment, especially organic materials (such as molecular pump oil, sealing rings) and semiconductor components. Molecular pump can resist radiation intensity of 105rad. By selecting anti-radioactive materials and using a motor-driven power supply, the anti-radiation strength can be improved. When pumping tritium, in order to prevent the radioactive element tritium from escaping into the atmosphere, all sealing rings in the molecular pump must be made of metal materials
6.8 Foreline pump
At the high-pressure end of the molecular pump performance curve, the inlet pressure ranges from around 200 Pa to 10-1 Pa, spanning three orders of magnitude. The mean free path of gas molecules becomes smaller, and the pumping effect begins to deteriorate. Therefore, in the transition zone, the greater the use of the backing pump, the greater the pumping speed of the molecular pump. The foreline pump should be no less than 3 L/S minimum.
Common faults and trouble shooting
EV-Z series grease-lubricated compound molecular pump is a mechanical vacuum pump that realizes air extraction through relatively high-speed rotation of multi-stage dynamic and static turbine blades. The turbomolecular pump has the characteristics of high pumping speed and high compression ratio in the molecular flow region, and is more energy-saving than the diffusion pump and has no oil and steam pollution. EV series grease-lubricated compound molecular pump is the molecular pump with the largest pumping speed of 100 calibers in China.
This molecular pump has no selectivity and no memory effect on the gas to be pumped. Due to the high compression ratio of the gas with large molecular weight, the pump can obtain clean high vacuum and ultra-high vacuum without cold traps and oil baffles. . It is widely used in various fields of electronics, metallurgy, chemical industry, scientific research and vacuum technology.
Post time: Jul-01-2022