The Case of the Oil-Based Van De Graff Generator

By Jay Gamerman
One of our technicians was doing a final filtering of several gallons of a new synthetic hydraulic oil out in the shop when she noticed that the diapers around the plastic bucket were starting to levitate a bit. Her interest was further peaked when she put her finger near the oil in the bucket and noticed that the oil moved away from her finger. One of the other technicians called me over to see the interesting phenomenon. Upon looking at the set up, I also noticed a static electricity crack every so often and suggested that the filtering setup be shut down and tagged out until we could determine the source of the static charge. The fact that the bucket being used was plastic didn’t help things any as the bucket with the oil in it basically became a large capacitor with a couple of thousand volt static charge. Had this been done in an explosive vapor environment it could have been a major disaster.

We called the local rep for the oil who had also sold us the filtering rig. He said that he had run across this recently with one other customer using this type of oil and filtering setup. According to the rep, the combination of this particular oil and the fiberglass filter media being used becomes a very effective static electricity generator. He was looking into an anti-static additive that could be used with the oil. We have currently shut down this particular system until a suitable additive or substitute oil can be found.

Jay Gamerman is project engineer in the Maryland area who has worked in the consumer, medical, industrial and military industries for over 30 years (yeah I’m getting to be an old timer). He graduated from the Rochester Institute of Technology in 1977 with a BS in Electrical Engineering and is a Senior Member of the IEEE (Institute of Electrical and Electronics Engineers).