Ask the Expert: Protecting Your Vacuum Furnace from Humidity (Part 2)

By Janusz Kowalewski, Southeast Asia Sales Director
Q: Operating a furnace in an environment that has been dealing with high heat and humidity has posed more challenges than we’ve experienced in the past. What are some things that we should be watching out for when operating our furnaces to make sure they’re running efficiently despite the temperature and humidity?

While serving clients across many Asian countries in tropical climates, I have noticed the challenges of operating vacuum furnaces in high temperatures and humidity above 90 percent. The recent record-breaking temperatures highlight the difficulties of running a vacuum furnace in these conditions.

Electrical components cannot function effectively in humidity levels above 90 percent, which leads to a rapid decrease in efficiency. For instance, at temperatures above 104 degrees Fahrenheit (40 Celsius), efficiency of the variable frequency drive (VFD) drops by two percent with each additional degree Celsius.

High temperatures cause changes in electricity flows, which increase resistance. Additionally, excessive humidity reduces transformer insulation and resistance, while oxidizing electrical conductors. And the difference between cooling water temperature and ambient temperature with high humidity can cause the vacuum vessel to “sweat,” affecting the entire furnace’s electrical system and transformers’ performance.

Here are nine key things you can do to maintain vacuum furnaces during hot, muggy weather:

  1. Check, secure, and mark all electrical connections. Apply conductive copper grease to improve electrical contact between surfaces.
  2. Clean all vents in the control cabinet without the air-conditioning. Use silica gel to reduce moisture. 
  3. Clean the hot zone, check insulation and ceramics, and repair if necessary. Run periodic burnout cycles.
  4. Clean the main O-ring periodically and reapply a thin silicon vacuum grease or graphite layer.
  5. Check the vacuum oil pump condition and change it if contaminated to avoid solidification during prolonged shutdowns.
  6. At high temperatures, vacuum oil loses its viscosity and lubrication properties. Replace pump oils on a timely basis. 
  7. Check all water and gas connections for leaks, then clean them to prevent impurities from forming a hard layer and blocking power feedthrough and flowmeters.
  8. Periodically flush the pressure vessel and heat exchanger with Rydlyme solvent. 
  9. Apply grease to all points per your furnace’s specification, particularly the cooling motor bearings. Be sure to use grease with the proper viscosity. 

These steps will help ensure the proper functioning of your vacuum furnace and reduce energy consumption.

If you’re struggling with heat or humidity affecting the efficiency of your furnace, or if you have another issue that we can help you resolve, call us for technical support. Our support hotline is 844-Go-Ipsen, or fill our our online form.