Revision 9/20


Vacuum pumps are used in a wide variety of experimental set ups.  If vacuum pumps are not properly installed, trapped and exhausted they may expose you to hazardous chemicals and vapors.   

Operation Checklist

  • Belt guards must be in place.
  • Service cords and plugs must be free of defects.
  • Plug the pump directly into an outlet.  Do not connect to an extension cord or power strip.  See the Electrical Safety Fact Sheet for more information.
  • Locate in a vacuum pump cabinet (if one is available) or other ventilated cabinet.
  • Place the pump on a tray so that spilled oil is contained.
  • Shield any glassware under vacuum.
  • Pump oil may be contaminated and should be disposed as chemical waste.
  • Pump oil must be compatible (i.e. do not use hydrocarbon pump oil with oxidizing gases or vapors) with the vapors that will pass through the pump.
  • Use a cold trap to prevent the degradation and contamination of pump oil.
  • Keep combustibles away from pumps.  Diffusion pumps contain oil at very high temperatures.
  • Connect the pump inlet and outlet properly.  Pump connections can look the same.  Reversing the flow direction can pressurize apparatus leading to rupture, failure of vessel, or oil contamination.

Cold Trap

A cold trap must be placed between the pump and the experiment to minimize the amount of volatile chemicals from reaching the pump oil.  Pump oil will break down if exposed to high concentrations of solvents from the vacuum line.  This can result in pump damage.  EHRS recommends using a second cold trap between the pump and the experiment for added protection.  See Safety Alert: Vacuum Pump Explosion in Chemistry Building for more information. 

The trap must be adequately sized and cold enough to condense vapors in the experiment.  Extreme care must be exercised to prevent the introduction of room air into a trap containing liquid nitrogen.  Liquid Nitrogen condenses oxygen and this may cause an explosion.  See SOP: Cryogens and Dry Ice for more information about preventing the formation of liquid oxygen and what steps to take if you observe that oxygen has condensed.

Maintain trap during the experiment.  Check frequently for blockage.  Empty the condenser trap immediately after evaporation is complete to eliminate the possibility that solvent will evaporate as the condenser warms to room temperature.

Use with Hazardous Chemicals

Vacuum pumps which are used to evacuate systems containing toxic, corrosive or volatile substances must be vented into the building’s exhaust system.  Failure to properly vent the pump can result in contamination of the lab with hazardous chemical vapors.  See Safety Alert: Vacuum Pump Explosion in Chemistry Building for more information. 

Vacuum pump in vacuum cabinet with exhaust vented through cabinet wall into fume hood
Vented vacuum pump

Use an oil mist separator (purchased from the pump vendor) to prevent oil loss.

Vacuum pump fitted with an oil-mist separator
Oil-Mist Separator

Connect the exhaust line to the exhaust port in the vacuum cabinet (if one is present) using a thimble connection or run the hose into the fume hood.

Note that some oil mist separators may not fit into your vacuum pump cabinet.  Measure before you order.

Pumps for rotary evaporators must be located in a fume hood, vent to dedicated lab exhaust, or be equipped with adequate condensers and traps to prevent emission of solvent vapors into the lab.

Pump Maintenance

  • Vacuum pumps must be serviced by an authorized vendor on the schedule recommended by the pump manufacturer.
  • Keep detailed records of all pump maintenance including routine maintenance and vendor-provided services.
  • Routine maintenance such as pump-oil changes may be performed by lab workers.  Follow all manufacturer recommendations for oil changes and routine maintenance.
  • Never service a pump that is connected to power. Allow the pump to cool completely before venting or servicing, and disconnect it from power completely.  Pumps may start automatically if connected to a power source.  If the pump cannot be unplugged directly, contact EHRS for information about lock-out/tag-out before attempting to service the equipment.