Have you ever met with a colleague or customer on the production floor to discuss a problem they were experiencing, only to see it happen first hand while you were there? It continually surprises and amazes me how often I have had this experience.
I recall one particular example from my early days in the industry. The application was potting electrical components with epoxy resin. For those unfamiliar with this process, basically vacuum is used to degas and then cure components in an epoxy resin. Depending upon the type of vacuum pump used and the pressure obtained, this material can be vaporized and pulled directly into the vacuum pump. The vapors will condense in the pump oil, contaminating the oil to the point where pump performance is compromised. Over time, this can lead to pump failure.
I received a call from a customer, (we’ll call him Tom), who was using a belt drive, 2 stage rotary vane vacuum pump. He was having problems with the epoxy resin contaminating the oil, and causing premature vacuum pump failures. He was hoping I could come in and look at the set up and make recommendations for a foreline trap to remove the epoxy resin vapors.
I decided to pay Tom a visit . The first thing I noticed was a very dated industrial production area with black iron piping for vacuum lines and drop legs scattered throughout. Tom explained their process in detail. He mention that their biggest problem was operator error. Apparently it was not uncommon for an operator to accidentally turn the manual valve the wrong way and actually suck liquid epoxy resin directly into the pump. When this unfortunate accident occurred, the epoxy would set in the pump. It would take a crowbar to open it up and trying to clean it was a nightmare. In some cases it was easier for them to just dispose of the pump and replace it with a new one. Obviously this was a costly and undesirable situation.
As (bad) luck and Murphy’s Law would have it, as soon as I started to make my recommendations, an operator turned the valve the wrong way and we watched in horror as the epoxy resin was sucked into the pump and started oozing out of the pump exhaust. The pump bound up in a matter of seconds. Tom just threw his hands up in the air as if to say “this is the last straw.” After a few awkward moments of silence, we both turned, looked at each other, and burst out laughing. At that point, there wasn’t much more we could do.
I made recommendations for a single stage rotary vane pump that ran at a higher ultimate pressure to eliminate vaporizing of the epoxy resin, an appropriate pneumatic valve, and a trap to protect the vacuum pump in case of valve failure.
After that, Tom became a very good customer and a friend. I never did find out how the unfortunate operator fared.