Vacuum Furnace Preventive Maintenance: Daily Checklist


Extending the life of your vacuum furnace through preventive maintenance will result in decreased downtime and increased productivity. 

In an effort to help you adhere to a carefully planned schedule, we have provided a few basic checklists for daily, weekly, monthly and semiannual maintenance.

Daily Checklist

Furnace Interior

⬜ Inspect the inside of the furnace for signs of dirt and oil, which can prevent the production of high-quality work.

⬜ Check the condition of the hot zone heating elements and shielding and make sure there are no broken or missing retaining wires.

⬜ Inspect the heat shields to ensure that distortion has not shorted out an element. Shield distortion is normal due to the alternate heating and cooling of the furnace over time.


⬜ Check the O-ring or lip seal on the furnace door for grit and dirt that might cause vacuum leaks.

⬜ Clean the chamber-door or bottom-head flange and lightly grease the O-ring with a thin coating of high-quality vacuum grease. If you have a rotating door with a lip seal, use graphite powder instead. DO NOT use grease on a lip seal. For information on installing a lip seal, check out this video on our YouTube page.


⬜ Check the oil levels and condition of all pumps (e.g., roughing, booster, holding, diffusion). The roughing pump oil should be circulating. Cloudy or discolored oil may indicate the presence of moisture or other contamination.

⬜ Check that the roughing pump is operating at 140 F (60 C). Adjust pump water miser as necessary [160 F (71 C) for gas ballasting operation].

⬜ Check the temperature and cooling-water profile of the diffusion pump. Verify that the water lines are cool to the touch; it is recommended that they are at or under 85 F (29 C) at the inlet water supply fitting.

⬜ Verify the crossover setting of the diffusion pump (normal range is 60-80 microns).

⬜ Verify the vacuum level when the booster is activated. Adjust if necessary (28 to 29 inches of mercury). The adjustable vacuum component can be a vacuum switch, vacuum controller or a backset switch. This is not required if using a variable frequency drive.

Valves & Gauges

⬜ During the first vacuum pumpdown of the furnace, make sure all valves actuate in proper sequence.

⬜ Check all vacuum gauges to ensure they are properly responding to pumpdown pressures and set points.

⬜ Check the settings on the backfill valve switch. Adjust if necessary. These adjustable components are typically vacuum switches.

Water Lines

⬜ Check the water flow from each drain line. A reduction in water flow indicates restrictions that must be located and corrected.

  • Closed Loop System: Check the water lines for leaks and any hoses that appear hotter to the touch than usual; this would indicate a lack of normal flow.
  • Open System: Visually inspect all water lines for flow and temperature.

Motors, Recorders & Programmers

⬜ Inspect motors (and belts if applicable) for signs of vibration or excessive noise.

⬜ Check to be sure that all recorders are accurately responding.

⬜ Check the programmer to ensure it is operating properly.

If you need further assistance, please contact Ipsen at 1-844-GO-IPSEN.

In our next post, we will go over preventive maintenance steps to perform weekly.

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