TURBOVAC Molecular Pump Maintenance Guide

TURBOVAC Turbomolecular Pump: Complete Guide to Installation, Debugging, Troubleshooting, and Maintenance

Introduction: When your turbo molecular pump needs to be replaced or repaired

Turbomolecular pumps are the core equipment for generating high and ultra-high vacuum in semiconductors, analytical instruments, vacuum coating, and research laboratories. The TURBOVAC series (35 LS, 50, 151, 361, 600 C, 1000 C, etc.) of Oerlikon Leybold Vacuum (now part of the Leybold brand) uses grease lubricated bearings and is widely used in leak detection, surface analysis, electron microscopy, and industrial coating due to its high compression ratio, clean oil-free operation, and reliable performance. However, as the running time increases (usually bearing replacement is recommended after 15000 hours), engineers often face faults such as pump failure to start, increased noise, failure to meet maximum pressure standards, overheating shutdown, etc. It is crucial to master fast diagnosis and correct maintenance methods when the original factory maintenance cycle is long or spare parts are discontinued.

This article is based on the official operating manual of the TURBOVAC series, providing a detailed technical guide from safety regulations, installation points, cooling configuration, use of purge gas, start-up and baking, troubleshooting to preventive maintenance to help on-site engineers quickly restore equipment performance.

Safety first: Protection against mechanical, electrical, and thermal hazards

The rotor of the TURBOVAC turbomolecular pump operates at a speed of up to 36000 rpm, storing a large amount of kinetic energy. Once the rotor gets stuck or collides, it will release enormous energy. The manual emphasizes: "If the system malfunctions (such as rotor/stator contact or even rotor collision), rotational energy will be released. To avoid equipment damage and personnel injury, it is necessary to strictly follow the installation instructions in this manual

1.1 Mechanical hazards

It is strictly prohibited to operate the pump without flange connection to the vacuum chamber (such as bench testing). The small diameter connection of the high vacuum flange (such as the DN 40 KF flange of TURBOVAC 50) is not strong enough to prevent the pump from rotating when it suddenly gets stuck. The rotation of the pump can cause leakage in the front stage pipeline. The pump must be additionally fixed to prevent rotation.

The high vacuum flange must be securely connected. The manual provides different brake torque values for different models: TURBOVAC 35 LS/35 LS2 is 150 Nm, 50 is 450 Nm, 151 is 283 Nm, 361 is 580 Nm, 600 C is 1486 Nm, 1000 C is 1500 Nm. The clamping bolts (steel) need to be tightened to 35 Nm, and 12.9 grade bolts are 50 Nm. CF flanges are tightened according to DN 40 CF (15 Nm), DN 63 and above (30 Nm).

The splash guard must always be installed to prevent foreign objects from entering the pump and damaging the rotor.

1.2 Electrical hazards

There is a voltage of up to 400 V on the connecting cable between the frequency converter (TURBOTRONIK) and the pump; The power supply lines for fans, flange heaters, and valves are equipped with main power voltage.

Before carrying out any maintenance, all power sources must be disconnected. Even if the connecting cable is plugged in, the output terminal of TURBOTRONIK may still be live.

1.3 Thermal hazards

The temperature of the pump during operation can exceed 70 ° C (up to 120 ° C), and contact may cause burns. Hot components must be shielded from contact and protective clothing must be worn.

1.4 Material and Substance Hazards

The front-end pipeline must be sealed. Dangerous gas leaks or reactions with air/moisture can pose risks. Pumps that have handled hazardous gases must take appropriate protective measures (gloves, respirators, fume hoods) before opening the interface.

The standard version pump is not suitable for explosive environments. If you need to use it, you must consult the manufacturer.

Installation points: from flange fastening to anti vibration measures

2.1 Installation of high vacuum flange

When using ISO-K flanges, place the O-ring into the centering ring to ensure that the O-ring is flat and free of distortion, and then add the outer ring. For ultra-high vacuum applications, a collar flange with a retainer and a metal sealing gasket are required.

Key torque value (braking torque): This is the torque that the flange connection must withstand when the pump suddenly gets stuck. The manual clearly lists the braking torque for each model, and it is necessary to use a sufficient number and strength of bolts during installation.

Model: Braking torque (Nm), number of clamping bolts

35 LS / 35 LS2 150 4

50 450 6

151 / 151 C 283 8

361 / 361 C 580 8

600 C 1486 10

1000 C (DN 160) 1500 16

1000 C (DN 250) 1500 10

2.2 Anti rotation additional fixation

For the TURBOVAC 50, the KF connection strength of its high vacuum flange is insufficient to resist the rotational torque when stuck. The manual specifically states that "the pump must be additionally fixed to prevent sudden stuck rotation

2.3 Dust and Vibration Prevention

If particles may be generated in the chamber, a fine mesh filter should be installed between the high vacuum flange and the pump.

For vibration sensitive equipment, a dedicated vibration damper can be installed at the high vacuum flange of the pump. If the TURBOVAC 1000 C is connected through a shock absorber, it must be additionally fixed at the base flange.

2.4 Installation posture

Due to the use of grease lubricated bearings, TURBOVAC can be installed and operated in any posture (horizontal, vertical, inverted, etc.) without the need for additional support.

Cooling method selection: When do you need water cooling?

The operating temperature of TURBOVAC directly affects the bearing life and pumping performance. The manual provides a clear cooling demand decision table based on ambient temperature, pre stage pressure, and high vacuum pressure.

3.1 Air cooling vs. water cooling

No additional cooling required: When the ambient temperature is less than 30 ° C, there is no baking, the high vacuum pressure is less than 10 ⁻ mbar, and the pre stage pressure is less than 5 × 10 ⁻¹ mbar, the TURBOVAC 35 LS can be naturally cooled.

Air cooling: When the ambient temperature is 30-40 ° C or there is baking or high pressure, an air cooling unit (fan) needs to be installed. During installation, keep the fan at least 20 cm away from surrounding objects to avoid inhaling hot air from nearby equipment.

Water cooling: Water cooling must be used when the ambient temperature is>40 ° C (or>45 ° C depending on the model), or when operating continuously under high vacuum pressure>10 ⁻⁴ mbar, fast cycle operation, baking temperature>35 ° C.

3.2 Cooling water specifications

The manual specifies strict water quality requirements:

Inlet pressure: 3-7 bar (absolute pressure)

Appearance: Colorless and transparent, oil-free and fat free

Sediment:<250 mg/L

Particle size:<150 μ m

PH value: 7-8.5

Total hardness: ≤ 20 ° German hardness (approximately 3.57 mmol/L)

Water quality that does not meet the requirements can cause scaling or corrosion in the cooling channel, affecting heat dissipation.

3.3 Cooling water flow rate

Figure 7 in the manual shows the cooling water consumption curves for different models. For example, TURBOVAC 151/361 has a flow rate of approximately 60-100 L/h at an inlet water temperature of 20 ° C. It is necessary to ensure sufficient flow, otherwise an overheating alarm will be triggered.

Purge Gas and Treatment of Corrosive Media

Meaning of Version 4.1 C

Pumps with "C" in the model (such as TURBOVAC 151 C, 361 C, 600 C, 1000 C) are equipped with a purge gas interface to protect the bearing and motor areas from corrosive gases.

Manual warning: "TURBOVAC is not suitable for corrosive or dusty media unless appropriate attachments are used. When dealing with corrosive media, the C-version pump must use purge gas; When dealing with dusty media, a fine mesh filter must be installed. ”

4.2 Applicable gases

Recommended gases: Inert gases such as nitrogen (N ₂) or argon (Ar), temperature 5-80 ° C, relative humidity ≤ 10 ppm.

In special circumstances: After consultation, dry, filtered, oil-free air (filtration accuracy<1 μ m) can be used. The filter needs to be replaced regularly (at least once a year).

4.3 Blowing gas flow rate and function

The blowing gas forms positive pressure in the bearing and motor areas to prevent corrosive process gases from flowing back into sensitive components. When the pump is stopped, it is also necessary to ventilate by blowing the gas valve to ensure that the pressure in the bearing area is higher than that in the other vacuum areas, in order to prevent particles or corrosive gases from being pressed into the bearing.

Precautions for startup, baking, and operation

5.1 Starting pressure

TURBOVAC must be started under a certain pre stage pressure, otherwise it will cause motor overload and heating. Manual Figure 8 shows the starting pressure curve: for most models, the starting pressure should be less than 10 ⁻¹ mbar (such as TURBOVAC 50/151/361 starting pressure of 1 × 10 ⁻¹ mbar). If the ratio of the pumping speed of the front stage pump to the chamber volume Sf/V is greater than 100 h ⁻¹, both the front stage pump and the turbo pump can be started simultaneously.

5.2 Baking

To achieve a maximum pressure below 10 ⁻⁸ mbar, the vacuum chamber and TURBOVAC need to be baked. Pumps using CF flanges can be equipped with flange heaters, with a maximum baking temperature of 100 ° C. Precautions:

Protect the rotor from strong thermal radiation.

The heating temperature of the front stage side (such as adsorption trap) shall not exceed 80 ° C.

During the baking period, the front-end pump must continue to operate to extract the released steam.

5.3 Hazards during operation

High temperature burns: If the pump body temperature is greater than 70 ° C, warning signs are required.

Vibration: Avoid excitation of rotor resonance by acceleration force during pump operation. If the natural frequency of the system causes resonance, it can be solved by changing the mass or installing shock absorbers.

Common troubleshooting: from "not starting" to "maximum pressure not meeting standards"

Chapter 6 of the manual provides a detailed fault diagnosis table. The following is an interpretation of common faults and countermeasures.

6.1 Pump does not start

Possible causes and corrective measures

Check if the motor connection cable is not connected, loose or damaged, and connect it correctly. Replace it if necessary

Pump stuck and replaced (requiring factory repair)

On site inspection: Firstly, confirm whether TURBOTRONIK has output and measure whether the motor winding resistance is normal. If there is significant resistance or abnormal noise when turning the pump port, it may indicate that the rotor is stuck.

6.2 High operating noise and obvious vibration

Possible causes and corrective measures

Unbalanced rotor needs to be returned to the factory for balancing (OLV service department only)

Bearing damage requires replacement (OLV service department only)

The pump operates at the natural frequency of the system, causing resonance and changing the system mass or installing shock absorbers

Experience tip: Sudden sharp noise usually indicates bearing failure and should be stopped immediately to avoid secondary damage.

6.3 Unable to reach maximum pressure

Possible causes and corrective measures

Measurement equipment malfunction or regulatory contamination inspection or replacement of regulations

System, pipeline or pump body leakage detection and repair

Slight contamination inside the baking pump (see section 5.3)

Oil pollution in the pump is returned to the factory for cleaning

Replace the front-end pump with a higher pumping speed if the pumping speed is insufficient or the maximum pressure is too high

Leakage at the power cord inlet and return to the factory for repair

Check the connection line for incorrect pump rotation direction and exchange phase sequence

Special note: For TURBOVAC 50, if CF flange is used, the sealing requirements are extremely high. Any slight leakage will lead to an increase in the ultimate pressure.

6.4 Pump Overheating (TURBOTRONIK Alarm)

Possible causes and corrective measures

If the pressure in the front stage is too high, check the front stage pump and replace it with a higher pumping speed if necessary

Excessive air load or system leakage, sealing off leakage points, or increasing the size of the front stage pump

Cooling fan blockage cleaning vent

If the ambient temperature is too high, use air cooling or water cooling instead

Check the water circuit for insufficient or interrupted cooling water to ensure flow rate

Bearing damage, return to factory for repair

Preventive measures: Regularly check the cooling fan filter, cooling water flow switch, and temperature sensor.

6.5 Pump or vacuum chamber contaminated with oil

Possible causes and corrective measures

Repair or replace the anti backflow valve of the front stage pump if it fails

Failure to properly release air during shutdown. Check the release valve and release air according to regulations

System configuration error: Installation of pre extraction pipeline or adsorption trap for oil vapor backflow during the operation of the front-end pump

Saturation regeneration or replacement of adsorption trap

Maintenance and Bearing Replacement: The Key to Extending Pump Life

7.1 Standard Maintenance Interval

TURBOVAC 35 to 361 C: It is recommended to replace the bearings after 15000 operating hours at the latest.

TURBOVAC 600 C and 1000 C: Bearings must be replaced after 10000 operating hours at the latest.

Rotor replacement: Based on the degree of thermal stress, it is recommended to replace the rotor components after 45000 to 100000 hours (only completed by Oerlikon Leybold Vacuum service).

7.2 Maintenance of Blowing Gas Filters

If blowing gas is used, the filter will gradually clog. Experience has shown that filters need to be replaced every 1-6 months.

7.3 Maintenance of adsorption trap

Regularly regenerate or replace the adsorbent, refer to the operating instructions of the adsorption trap.

7.4 Precautions for returning to the manufacturer for repair

The Declaration of Pollution must be filled out, detailing whether the pump has been in contact with harmful substances. Devices without this form will be returned.

When packaging, it is necessary to ensure that the pump is not damaged during transportation and that pollutants do not leak. Use the original packaging set to seal the flange, cooling water interface, and cable entry.

Shutdown and deflation: key steps to prevent bearing damage

8.1 Correct shutdown sequence

Turn off TURBOVAC on TURBOTRONIK.

Close the front stage pump (if there is no anti backflow valve, close the front stage pipeline valve).

Immediately turn off the cooling water or fan to prevent condensation from forming inside the pump.

If the pump has been used to handle corrosive gases, it needs to be purged with dry nitrogen for 1 hour before shutdown.

8.2 Bleeding method

The turbo molecular pump must be vented before completely stopping, otherwise the atmospheric pressure will reverse and impact the rotor, causing bearing damage or rotor deformation. The manual provides three ways to release air:

Through high vacuum side venting: the smoothest and least bearing force on the shaft. But it is necessary to avoid direct impact of gas jets on the rotor.

Bleeding through the front-end pipeline: It is necessary to ensure that no oil or particles are carried into the pump by the airflow.

Blowing gas/venting valve for venting: For C-version pumps, this method is recommended. When releasing air, first open the purge gas valve to make the pressure in the bearing area higher than the rest of the vacuum area, to prevent particles or corrosive gases from being pressed into the bearing.

8.3 Pressure rise speed limit

All TURBOVAC can release air at full speed, but the pressure rise rate cannot exceed the pressure rise curve given in the manual. Usually, the deflation time should be long enough (several seconds to tens of seconds) to allow the pressure to slowly rise. When there is a risk of particles, the venting must be slower and maintain laminar flow. The slower the pressure rise, the longer the bearing life.