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Time：2025-09-30 13:44:15 Reading volume：
Learn why vacuum pump oil spraying happens in oil purifiers, the root causes behind this issue, and proven prevention methods to protect equipment, reduce oil loss, and extend pump service life.
Vacuum oil purifiers play a critical role in transformer oil and industrial oil maintenance. However, oil spraying or misting from the vacuum pump exhaust is a common yet serious problem. It causes:
Significant oil loss
Environmental contamination
Premature vacuum pump failure
Understanding the causes and implementing prevention strategies is essential for reliable purifier operation and long equipment life.
At its core, oil spraying happens when lubricating oil enters the vacuum pump’s exhaust path and is forcibly expelled. Causes fall into three main categories:
1.1 Operational & Process Issues (Most Common)
Low Oil Temperature (<40 °C): Cold oil has higher viscosity, creating persistent foam that rises and is sucked into the pump.
Flow Imbalance / Overfilling: If the inlet flow exceeds outlet pump capacity, the liquid level rises dangerously high.
Incorrect Startup Sequence: Starting the vacuum pump before the transfer pump allows oil to surge into the vacuum pump.
1.2 Equipment & Mechanical Failures
Excessive Oil Level in Pump: Overfilling beyond the sight glass midpoint forces oil out via the exhaust.
Faulty Exhaust Valve: Worn or stuck valves fail to seal, letting oil pass into the exhaust.
Internal Pump Wear: Rotor, vane, or bearing wear increases clearances, causing oil leakage.
Clogged Spray Nozzles: Poor atomization produces large droplets, easily carried into the pump.
1.3 Oil Fluid & Contamination Issues
Severely Emulsified Oil / Hydrocarbon Contamination: Unstable oil foams violently, leading to carryover.
Wrong or Degraded Pump Oil: Incorrect viscosity or old oil loses anti-foaming properties.
Preventing vacuum pump oil spraying requires three pillars: Proactive Operation, Strict Procedures, and Preventive Maintenance.
2.1 Operational Best Practices
Maintain Correct Oil Temperature (50–60 °C): Reduces viscosity, ensures proper dehydration, and prevents stable foam.
Follow Startup/Shutdown Sequence:
Startup: Heater → Transfer Pump → Vacuum Pump
Shutdown: Vacuum Pump → Heater → Transfer Pump
Monitor Operation Continuously:
Check sight glass (fine mist = normal, rolling foam = danger).
Listen for gurgling or abnormal pump noise.
2.2 Preventive Maintenance
Maintain Pump Oil Level: Keep between ½ and ⅔ of sight glass—never overfill.
Use Correct Oil & ｒｅｐｌａｃｅ Regularly: Follow OEM grade and intervals; change more often when processing wet oil.
Inspect & Service Components:
Exhaust filter/oil mist separator → clean or ｒｅｐｌａｃｅ regularly.
Exhaust valve → inspect, clean, ｒｅｐｌａｃｅ worn parts.
Spray nozzles → clean during major service.
2.3 Emergency Response Steps
If oil spraying occurs:
Stop immediately – shut down vacuum pump.
Isolate pump – close intake valve to prevent further carryover.
Investigate cause – review operation, equipment, and oil condition before restart.
Category Checkpoint Standard
Operation Oil Temperature 50–60 °C
Startup/Shutdown Heater → Transfer → Vacuum
Level Monitoring Safe zone in sight glass
Maintenance Pump Oil Level ½–⅔ of sight glass
Pump Oil Quality: Correct grade, changed on schedule
Exhaust Filter Clean, unobstructed
Exhaust Valve / Nozzles Inspected & serviced regularly
Key Takeaway
Vacuum pump oil spraying is preventable.
The main culprits are low oil temperature, poor procedures, and lack of maintenance. By controlling temperature, following strict operating sequences, and inspecting critical components, operators can avoid oil loss, extend pump service life, and keep oil purifiers running reliably.
