We all have triumphs and tragedies in our work life. Mine is no exception. I’ve had a few, of course some stick out in my memory more than others. I think those are the ones that smarted the most.
I worked at the South Carolina plant which manufactured silicon wafers, discs in six and eight inch diameter sizes. The discs were sold to the likes of Intel and Motorola who then sliced the wafers in to chips. The process was rather lengthy, from pulling a six or eight inch diameter rod about three feet long, to cleaning, slicing, polishing, more cleaning, and finally, packaging.
One of the last projects I engineered before I left the company for self-employment, involved design and installation of a new slice cleaner. A small front-loading rotary washer was adapted to hold a cartridge of a dozen or so slices. I designed a bank of three or four of these rotary washers tied together with one pumping system and washing chemicals. A requirement to provide heated water to the system meant the inclusion of an inline heater. This piece was carefully specified so that it would provide the heat needed without going overboard.
Our on-site construction contractor built the unit, which consisted of various piping, pumps, washers and electrical service. Finally the big day came to water batch it. This is a term commonly known in the chemical industry meaning to introduce water into the system ahead of any chemicals. Water doesn’t hurt anything or anyone if the system gets out of control. Not that that ever happens. Much.
The water batching operation was a success and so the operations folks added the soaps and began cleaning the slices. It wasn’t long before I was called down to the area. The water was overheating and nothing could control the temperature, short of turning off the system.
I reviewed my calculations and conferred with other engineers. At this point I had been out of school for about ten years and this kind of project was one I’d not experienced since then. This issue really stumped me. I was sure the design was solid.
One of my co-workers, could have been my manager, time has blotted out that part of the memory, asked if I had allowed for the heat input into the system by the pump itself. Well, of course…oh. One of the basics of thermodynamics, enthalpy and exothermic processing, had been forgotten. Thermo had been a favorite of mine in college. Time wiped away the knowledge. Use it or lose it, kind of.
The pump applied pressure to the system, expanding the water creating an exothermic process raising the temperature of the fluid, which then flowed through the inline heater. What an idiot! I was so embarrassed. I don’t think anyone likes to be shown up, especially by a piece of equipment. We removed the inline heater and the system worked, finally.
Up to that point my accomplishments had been many and my track record pristine. Sometimes it takes a fall from grace to humble us into knowing that not all the bases are covered all of the time. I moved on to my self-employment adventure, but I never forgot how vulnerable designs could be. Short-term successes can be fleeting, but the long-term growth that is available due to these hiccups is immeasurable. Get over the embarrassment, laugh about it and learn.