Leybold Screw Vacuum Pump (SV Series) Maintenance and Repair Technical Specifications

Leybold screw vacuum pumps (represented by the SV series) are high-end vacuum equipment that employ oil-free twin-screw meshing technology. They boast advantages such as high ultimate vacuum (no-load ultimate vacuum ≤0.01mbar), wide pumping speed range (50~1200m³/h), low operating noise (≤72dB(A)), oil-free operation, and resistance to harsh working conditions. These advantages make them widely used in fields with stringent vacuum requirements, such as semiconductor manufacturing, photovoltaic industry, high-end chemicals, and aerospace. Their working principle is based on a pair of meshing male and female screws rotating at high speed within the pump chamber. Through volume changes, they achieve intake, compression, and exhaust circulation, eliminating the need for easily worn parts such as vanes and blades, resulting in a more stable structure and longer service life.To fully leverage the performance advantages of Leybold screw vacuum pumps, mitigate the risks of malfunctions caused by non-standard operations, extend equipment service life, and reduce maintenance costs, it is essential to strictly adhere to the brand's technical requirements and scientific maintenance guidelines. This article, combining Leybold's original factory maintenance standards and practical experience, details the core points of maintenance, fault diagnosis solutions, and safe operating procedures, providing professional technical guidance for equipment management personnel.

I. Daily Maintenance Guidelines (Daily/Weekly Inspections)

1.1 Static Inspection Before Start-upBefore starting the machine each day, a comprehensive static inspection must be completed to ensure the equipment is in a qualified standby state. Key inspection items are as follows:

- Appearance and Connections: Check that the bolts connecting the pump body, motor, and base are tight, without loosening or corrosion; ensure the flange sealing surfaces of the inlet and outlet pipelines are undamaged and leak-free, and that the clamps or bolts are evenly stressed; ensure the equipment grounding device is reliable (grounding resistance ≤4Ω), and that the cables are undamaged, unaged, and that the terminals are free from oxidation.

- Lubrication System: Observe the lubrication oil level gauge. The oil level must be maintained between the upper and lower marks (optimal position is 3-5mm below the upper mark). Low oil levels will lead to lubrication failure, while high levels will cause oil temperature to rise. Check the color of the lubricating oil. Leybold Gear Oil 68 is normally pale yellow and transparent. If it appears black, cloudy, emulsified, or has metal shavings deposited, it must be replaced immediately.- Cooling System: For air-cooled models, check that the cooling fan is not jammed, the fan blades are not damaged, and the heat sink is free of dust accumulation. For water-cooled models, check that the cooling water inlet and outlet pipes are unobstructed, the valves are fully open, the water pressure is maintained at 0.2~0.4MPa, the water temperature is ≤32℃, and there are no leaks.

- Auxiliary Components: Check that the intake filter element is not clogged or damaged, and the differential pressure gauge reading is ≤0.02MPa (if it exceeds this value, it needs to be cleaned or replaced); the exhaust muffler is not loose or damaged, and there is no abnormal odor.

1.2 Dynamic Monitoring During Operation

After startup, run the unit under no-load for 3~5 minutes, then connect the load. Monitor the operating parameters throughout the process, record any abnormalities, and handle them promptly:

- Operating Parameters: Monitor the motor current (must not exceed 110% of the rated current), lubricating oil temperature (normal operation ≤85℃, alarm threshold 95℃), and pump body shell temperature (≤90℃) through the control panel; the vacuum degree must meet the process requirements, and the ultimate vacuum under no-load conditions must be stable at ≤0.01mbar without significant fluctuations.- Operating Status: The equipment operates without sharp abnormal noises, impact sounds, or uneven vibrations; the effective vibration velocity is ≤4.5mm/s; the automatic start/stop function of the air-cooled fan is normal; the water-cooling system flow is stable, and there are no flow interruption alarms.

- Sealing and Venting: There are no air or water (oil) leaks at the inlet/outlet pipes and flange connections; there is no obvious oil mist or odor overflow from the exhaust port; the silencer works normally, and there is no abnormal exhaust resistance.

- Control Panel: Observe the indicator lights and display screen on the control panel; there are no fault alarms (such as low oil level, high oil temperature, abnormal vacuum, motor overload, etc.); the parameter display is clear and accurate.
1.3 Weekly Cleaning and Protection

Perform targeted cleaning of the equipment weekly to improve operational stability:

- Blow-blow the heat sink and motor cooling fan of air-cooled models with compressed air (pressure ≤ 0.4MPa) to remove dust and debris, preventing poor heat dissipation; wipe the pump body surface with a neutral detergent, do not use corrosive solvents.

- Remove the intake filter element, blow it back with compressed air (or clean it with Leybold special cleaner), let it dry, and then reinstall it; if the filter element is damaged or severely clogged, replace it directly (it is recommended to replace it every 3 months, or monthly under severe operating conditions).

- Check the cleanliness of the exhaust muffler surface; if it has excessive oil buildup, disassemble, clean, or replace it; clear debris around the equipment, maintain good ventilation, and prevent the accumulation of dust and corrosive gases.
1.3 Weekly Cleaning and Protection

Perform targeted cleaning of the equipment weekly to improve operational stability:

- Blow-blow the heat sink and motor cooling fan of air-cooled models with compressed air (pressure ≤ 0.4MPa) to remove dust and debris, preventing poor heat dissipation; wipe the pump body surface with a neutral detergent, do not use corrosive solvents.

- Remove the intake filter element, blow it back with compressed air (or clean it with Leybold special cleaner), let it dry, and then reinstall it; if the filter element is damaged or severely clogged, replace it directly (it is recommended to replace it every 3 months, or monthly under severe operating conditions).

- Check the cleanliness of the exhaust muffler surface; if it has excessive oil buildup, disassemble, clean, or replace it; clear debris around the equipment, maintain good ventilation, and prevent the accumulation of dust and corrosive gases.
II. Regular Maintenance Orders (Monthly/Quarterly/Annual)

2.1 Lubricating Oil Replacement and Lubrication System Maintenance (Core Guarantee Item)

Leybold screw vacuum pumps rely on specialized lubricating oil for lubrication, cooling, and sealing. Oil quality directly affects equipment lifespan and performance, requiring strict adherence to replacement and maintenance schedules:

- Replacement Cycle: Under normal operating conditions (ambient temperature 20~40℃, daily operation ≤8 hours, no downtime or interruption of gas flow), replace every 6 months or 40,000,000 cycles; Under unit operating conditions (high temperature, high humidity, dust-containing or oil-containing steam, or daily operation >12 hours), replace every 3 months or 2000 hours; If abnormal oil temperature rise, oil emulsification, or alarms occur, the pump is in a waiting period and should be replaced immediately.

- Oil selection: Only Leybold original screw pump oil must be used. It is strictly forbidden to mix other brands and models of lubricating oil (such as gear oil or mineral oil). The recommended models are Leybold Gear Oil 68 (normal temperature conditions) and Leybold Gear Oil 100 (high temperature conditions). It is forbidden to use over-processed or deteriorated oil. Once opened, the oil must be used within 3 months.
- Replacement Procedure: ① Shut down the machine and let it cool until the oil temperature is ≤40℃ (to avoid burns from high-temperature oil draining, and to ensure oil fluidity for easy removal of impurities); ② Close the lubricating oil inlet and outlet valves, open the drain plug at the bottom of the pump body, and completely drain the old oil. If necessary, run the machine for 1-2 minutes to drain residual oil from the pump chamber and oil passages; ③ Close the drain plug, remove and clean the oil filter (filter element needs to be replaced) and oil cooler to remove oil stains and impurities; ④ Open the lubricating oil valve, add new oil to the oil level mark, run the machine unloaded for 3-5 minutes, stop the machine and let it stand for 5 minutes, then add oil to the standard level; ⑤ Check the lubricating oil system for leaks, and record the oil type and replacement time.
2.2 Seal Inspection and Replacement

The seals of the Leybold screw vacuum pump (shaft seal, flange gasket, drain plug gasket, etc.) are responsible for preventing air ingress and oil/water leakage. A comprehensive inspection is required quarterly:

- Inspect the shaft seal (using Leybold's dedicated skeleton oil seal). If there are oil stains or water droplets leaking from the shaft seal, or if the vacuum level drops during operation or air bubbles are present at the exhaust port, the shaft seal must be replaced. When replacing, the shaft diameter must be matched (refer to the original manufacturer's manual according to the equipment model). Before installation, apply a small amount of special lubricant to the lip of the oil seal to avoid scratching the lip during installation and ensure proper assembly.

- Disassemble the inlet and outlet flanges and check if the gaskets are aged, deformed, or damaged. If any of these problems exist, replace the original gaskets. When reinstalling, tighten the flange bolts evenly to avoid uneven stress on the gaskets, which could lead to leakage.

- Check the sealing performance of the drain plug and filler cap. If leakage occurs, replace the gasket and tighten it properly (torque as required by the original manufacturer, typically 25~30 N·m).
2.3 Core Component Inspection (Semi-annually/Annually)

Every six months, core components such as the screw, pump chamber, bearings, and motor must be disassembled and inspected. A comprehensive overhaul should be performed annually to ensure component performance meets standards:

2.3.1 Screw and Pump Chamber

After disassembling the pump body, use Leybold's special cleaning agent to clean the screw surface and the inner wall of the pump chamber to remove oil, carbon deposits, and impurities. Check the meshing clearance between the male and female screws (normal clearance is 0.05~0.12mm; refer to the original manufacturer's standard according to the equipment model). If the clearance is too large (more than 0.2mm), it will lead to a decrease in vacuum and a reduction in pumping speed, requiring screw replacement. Check the screw surface for wear, scratches, and cracks, and the inner wall of the pump chamber for rust and scoring. If the wear is severe, grinding repair or pump body replacement is required.

When reinstalling the screw, ensure the screw installation direction is correct, the meshing is precise, and the bearings at both ends are reliably positioned to prevent screw misalignment and collision during operation.

2.3.2 Bearings and Shaft System
Inspect the motor and pump shaft bearings (using Leybold original deep groove ball bearings, precision grade ≥ P5). If the bearings exhibit abnormal noise, jamming, radial runout > 0.03 mm, or wear on the inner and outer rings, or damaged balls, replace them with the same model of original bearing. When replacing, apply Leybold special high-temperature grease (temperature resistance ≥ 120℃) to the inside of the bearing, filling it to 1/2 to 2/3 of the bearing's internal space.

Inspect the pump and motor shafts for bending or wear. The radial runout of the shafts should be ≤ 0.02 mm. If the shafts are bent or deformed, straightening is required. If the journals are severely worn, electroplating repair or replacement of the shaft is necessary. Inspect the couplings for aging or damage. The coaxiality deviation should be ≤ 0.05 mm to ensure smooth power transmission.

2.3.3 Cooling System Maintenance

A comprehensive maintenance of the cooling system should be performed every six months: For air-cooled models, clean the heat sinks and fan bearings, and replenish grease; for water-cooled models, disassemble and clean the oil cooler and water cooler to remove scale and grease, and check the cooling water pipes for blockages or corrosion. If the pipes are aged, replace them promptly; test the cooling system's temperature control function to ensure that oil and water temperatures are controlled within the standard range.

2.4 Electrical System Inspection (Quarterly)
Inspect the motor terminals, contactors, thermal relays, circuit breakers, and other electrical components, ensuring wiring is secure, tight, and free from oxidation. Test the thermal relay's operating performance; the set value should be 1.1 to 1.25 times the motor's rated current. Check the insulation performance of the electrical wiring; insulation resistance ≥ 1MΩ to prevent leakage accidents. Clean dust from inside the control panel and check that the sensors (oil level sensor, temperature sensor, vacuum sensor) are functioning normally and that signal transmission is accurate.

III. Common Fault Repair and Solutions (Leybold SV Series Exclusive)

Leybold screw vacuum pump faults are mostly concentrated in insufficient vacuum, excessive oil temperature, excessive operating noise, and motor overload. Accurate troubleshooting based on the brand's structural characteristics is necessary for targeted repair:

3.1 Fault 1: Insufficient ultimate vacuum, reduced pumping speed
Inspect the motor terminals, contacts, thermal relays, circuit breakers, and other electrical components, ensuring wiring is secure, tight, and free from oxidation. Test the thermal relay's operating performance; the set value should be 1.1 to 1.25 times the motor's rated current. Check the insulation performance of the electrical wiring; insulation resistance ≥ 1MΩ to prevent leakage accidents. Clean dust from inside the control panel and check that the sensors (oil level sensor, temperature sensor, vacuum sensor) are functioning normally and that signal transmission is accurate.

III. Common Fault Repair and Solutions (Leybold SV Series Exclusive)

Leybold screw vacuum pump faults are mostly concentrated in insufficient vacuum, excessive oil temperature, excessive operating noise, and motor overload. Accurate troubleshooting based on the brand's structural characteristics is necessary for targeted repair:

3.1 Fault 1: Insufficient ultimate vacuum, reduced pumping speed
Possible Causes of Failure:

- 1. Poor quality lubricating oil, low oil level, or oil emulsification/contamination leading to decreased sealing performance;

- 2. Clogged intake filter or exhaust muffler increasing airflow resistance;

- 3. Leaking seals (damaged shaft seal or flange gasket), allowing air to enter the pump chamber;

- 4. Excessive screw meshing clearance or pump chamber wear reducing volumetric efficiency;

- 5. Faulty vacuum sensor or incorrect control panel parameter settings;

- 6. Pipeline leaks, valves not fully open, or process gas containing a large amount of condensable vapor.
Repair Solution

- 1. Replace with genuine Leybold lubricating oil, top up to the standard oil level, and clean the oil filter;

- 2. Clean or replace the intake filter element and exhaust muffler;

- 3. Replace damaged seals, reinstall the flange, and tighten the bolts evenly;

- 4. Check the screw engagement clearance and replace worn screws or pump body;

- 5. Calibrate or replace the vacuum sensor and reset the control panel parameters according to the original manufacturer's requirements;

- 6. Inspect pipelines and valves, repair leaks, and ensure valves are fully open; if the process gas contains condensable vapors, install a pre-condenser.

3.2 Fault 2: Lubricating oil temperature too high (>95℃ alarm)
Possible Causes of Failure:

- 1. Low lubricating oil level or contaminated oil, resulting in reduced lubrication and cooling efficiency;

- 2. Cooling system malfunction (damaged air-cooled fan, clogged heat sink; clogged water-cooled pipes, insufficient water pressure, excessively high water temperature);

- 3. Insufficient screw meshing clearance, leading to increased friction and excessive heat generation;

- 4. Excessive equipment load, prolonged operation under high vacuum and high flow conditions;

- 5. Temperature sensor malfunction, causing abnormal signal transmission.

Repair Solution

- 1. Replenish or replace lubricating oil, clean the oil cooler;

- 2. For air-cooled models: replace the damaged fan, clean the heat sink; for water-cooled models: clear pipe blockages, adjust water pressure and temperature to the standard range;

- 3. Check the screw engagement clearance, adjust or replace the screw;

- 4. Reduce equipment load, avoid prolonged overload operation, optimize process parameters;

- 5. Calibrate or replace the temperature sensor, check signal line connections.

3.3 Fault 3: Excessive operating noise and abnormal vibration
Possible causes of failure:

- 1. Bearing wear, damage, or poor lubrication;

- 2. Screw misalignment, poor meshing, or screw wear or deformation;

- 3. Aging or damage to the coupling, or excessive misalignment between the motor and pump shafts;

- 4. Loose anchor bolts, uneven equipment installation, causing resonance during operation;

- 5. Clogged air intake filter, excessive exhaust resistance, leading to abnormal pump chamber pressure.

Repair Solution

- 1. Replace worn bearings and replenish with Leybold high-temperature grease;

- 2. Reinstall and calibrate the screw to ensure precise meshing; replace worn or deformed screws;

- 3. Replace aging couplings and recalibrate the coaxiality of the motor and pump shafts (deviation ≤ 0.05mm);

- 4. Tighten foundation bolts and adjust the equipment's level (horizontal deviation ≤ 0.2mm/m) to avoid resonance;

- 5. Clean or replace the intake filter element and clean the exhaust muffler to reduce exhaust resistance.

3.4 Fault 4: Motor Overload (Trip Alarm)
Fault Causes

- 1. Excessive equipment load, excessively high vacuum requirements, or excessive pipeline resistance;

- 2. Insufficient screw engagement clearance, jamming, or foreign objects (such as metal shavings) in the pump chamber;

- 3. Bearing wear, jamming, and increased frictional resistance;

- 4. Abnormal power supply voltage (too high or too low), aging of motor winding insulation;

- 5. Thermal relay setting too low or faulty.

Repair Solutions

- 1. Optimize process parameters, reduce equipment load, and clear pipeline blockages;

- 2. Check screw engagement clearance and clean foreign objects from the pump chamber; if the screw is jammed, disassemble, repair, or replace it;

- 3. Replace worn bearings and ensure proper lubrication;

- 4. Check power supply voltage (ensuring it is within ±5% of the rated voltage), test the motor winding insulation performance, and repair or replace the motor if necessary;

- 5. Reset the thermal relay to the motor's rated current, or replace the faulty thermal relay. IV. Long-term downtime maintenance (downtime > 1 month)
IV. Long-Term Shutdown Maintenance (Shutdown > 1 Month)

If the Leybold screw vacuum pump is to be shut down for an extended period, the following protective maintenance procedures must be followed to prevent component corrosion and oil deterioration, ensuring normal operation upon restart:

- 1. Before shutdown, run the pump under no-load for 3-5 minutes to purge residual process gases and impurities from the pump chamber;

- 2. Thoroughly drain the old oil, clean the pump chamber, oil sump, and oil passages with Leybold's dedicated cleaning agent, allow it to dry, and then add new dedicated lubricating oil (to the lower limit of the oil level gauge);

- 3. Close the inlet and outlet valves, and seal the inlet with a blind flange to prevent dust and moisture from entering the pump chamber;

- 4. Drain the cooling water from the cooling system to prevent pipe freezing and corrosion; for air-cooled models, remove the fan guard and clean the fan;

- 5. Disconnect the motor terminals and wrap them with insulating tape to prevent moisture absorption; place the equipment in a dry, well-ventilated environment free of corrosive gases, avoiding direct sunlight and rain;

- 6. Manually rotate the motor fan 2-3 times per month to drive the screw to prevent bearing corrosion and screw jamming; check the oil condition every 3 months and replace it promptly if it deteriorates.
V. Safety Operation and Leybold-Specific Precautions

- 1. Before maintenance, the main power supply and cooling water/lubricating oil supply to the equipment must be disconnected. A "Do Not Operate" warning sign must be displayed. Operation should only proceed after the pump body has completely cooled and the vacuum level has returned to zero to prevent electric shock, burns, or equipment damage due to misoperation.

- 2. When disassembling and reassembling the pump body, Leybold original tools must be used. Strictly follow the assembly procedures in the original manual to avoid violent disassembly. Handle precision components such as screws and bearings with care to avoid bumps and scratches.

- 3. When changing lubricating oil or cleaning agents, only Leybold original parts/consumables must be used. The use of aftermarket products is strictly prohibited, as it may lead to equipment malfunction and void the warranty. Waste oil and waste cleaning agents must be collected centrally and disposed of according to environmental protection requirements; indiscriminate discharge is strictly prohibited.

- 4. During start-up testing, run the equipment unloaded for 3-5 minutes to check for normal operation before gradually connecting the load. Never start the equipment without lubricating oil or with insufficient cooling.
5. When a fault alarm occurs, the machine must be stopped immediately for troubleshooting. Forced restarting is strictly prohibited. For complex fault repairs (such as screw replacement or motor overhaul), it is recommended to contact Leybold original equipment manufacturer (OEM) technicians or authorized service providers to avoid secondary damage due to improper operation.

- 6. Establish a comprehensive maintenance log, detailing the time, content, replaced parts/consumables models, fault conditions, and solutions for each maintenance session for traceability. Simultaneously, retain equipment warranty documents and conduct regular OEM inspections as required to extend the warranty period.

Conclusion

The core of Leybold screw vacuum pump maintenance lies in "OEM compatibility, precise operation and maintenance, and prevention-oriented approach." While its oil-free screw structure offers high stability, it places extremely high demands on the quality of lubricating oil, seals, and other consumables, as well as assembly precision. Through standardized daily inspections and regular maintenance, timely identification and resolution of potential faults, and the use of OEM parts/consumables, the operational stability of the equipment can be effectively improved, its service life extended, and its performance advantages as a high-end vacuum equipment can be fully realized. In practice, the maintenance cycle should be flexibly adjusted according to the equipment's operating conditions and service life, while strictly following the safety operating procedures and Leybold original technical requirements to ensure that maintenance work is carried out efficiently and safely.