Looking for professional high-quality high vacuum pump manufacturer, provide inquiry quotation, picture, specification and price. The professional design scheme serves you. Here are some high vacuum pumps:
Turbine molecular pump exhaust
If the vane pump is used as a front-end pump, when the pressure between the current vacuum and the high vacuum has been balanced, the turbine molecular pump without exhaust will be polluted by hydrocarbons after it stops rotating. If the valve is not installed on the high vacuum side, the contamination will spread to the receiver or equipment. For large chambers, gas is drawn in very quickly, which can cause rotor damage as mentioned in Section 1.1. Using dry gas, such as nitrogen or oil-free air, to exhaust the pump can not only prevent pollution, but also properly inflate the front pump.
Using exhaust valve and turbine molecular pump controller at a certain speed can exhaust the pump safely. Since the compression ratio of the turbomolecular pump is also dependent on the speed, the optimal initial exhaust speed should be 50% of the rated speed and should start at 20% of the latest speed. In addition to the factory settings, modern electronic technology allows some flexibility in the exhaust speed. The use of a ball bearing turbomolecular pump also protects the receiver from contamination after proper venting.
There are processes in which pump independent exhaust takes precedence over the control system. This will result in damage to important connections related to pump speed. When venting the pump controller, there is no need for additional monitoring of pump speed. When exhausting, the inner surface of the pump is covered with dry nitrogen, which will significantly shorten the discharge time, because there is no gas or water that is difficult to remove gathering on the surface.
Exhaust gas shall not enter from the front stage side, because condensate, particles and even oil may be brought into the high vacuum side.
In the unstable power grid with frequent blackouts, especially in summer when overload occurs due to the use of air conditioning, it is better to use the so-called cut-off exhaust valve, which can automatically exhaust the pump when power is cut off and properly close it. Frequent exhaust, especially in the high vacuum side, will lead to pump overheating, resulting in mechanical pressure, and because of a large number of gas friction will shorten the service life of the bearing.
High vacuum pump process adaptability
It is important to ensure that the turbomolecular pump is suitable for the process. The pump manufacturer’s detailed recommendations and accurate information about the process and its characteristics are necessary for the operator. At present, these two aspects need to be improved. For corrosion processes, especially in the semiconductor industry, it is necessary to use sealed gas operated pumps, synthetic PFPE oil for ball bearing molecular pumps, and rotor made of corrosion-resistant materials (such as nickel or ceramic coating).
Sealing gas, such as dry nitrogen, can form a very good anti-corrosion and dust-proof protective film on the outside of these ball bearings connected with labyrinth seal. This additional gas load must be taken into account when estimating the size of the front stage pump. The sealing air valve provided can regulate the optimal sealing air flow. The seal gas pressure specified in the operating instructions must be observed.
When the oxygen concentration in the pump is higher than that in the atmosphere, it is necessary to ensure that the mineral oil will not be oxidized by oxygen, thus losing its lubrication performance. This can be avoided by using nitrogen as the seal gas and / or PFPE oil.
For processes that tend to form deposits, such as CVD (chemical vapor deposition), the coating process will continue on the rotor and the shell parts facing the treatment chamber. This will cause imbalance and vibration, resulting in rotor breakage. In such processes, it is important to take these precautions and additional monitoring options into account even when designing treatment rooms.
If possible, the turbine molecular pump should be installed upside down. Due to the influence of gravity, these dust will fall naturally and is not easy to deposit in the pump. It is recommended to install a baffle to prevent dust from falling directly on the running pump.
If the overhead installation cannot be realized, it can be installed on the side of the T-frame at a 90 degree angle. The front port should be facing down.
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