In 1972, after graduating from dental school, I equipped my brand new private practice in Spearfish, South Dakoata with a dental vacuum system powered by a Sears shop vac.
Now, why would I want to turn dental vacuum into a do-it-yourself project? Because I didn't like the idea of using a water ring pump. That was the popular type of dental vacuum pump commercially available at that time. I considered water ring pumps outstanding underachievers. They used a lot of water. They seemed kinda wimpy. And they looked like they could fail at any time and leave me hanging. Not a pleasant thought since back in ’72, Spearfish was 400 miles from the nearest dental dealer (Denver). Depending on water ring pump parts or service from so far away was definitely unappealing. I wanted a vacuum pump I could repair myself – using locally available parts.
So I built that first system using the Sears shop vac and discovered it didn’t work very well. In spite of wailing like a banshee and sounding like it might blow up at any moment, it wasn't very powerful. This did not inspire confidence.
My second attempt yielded better results. I replaced the not-too-trusty Sears with a “Surge” dairy pump – the type that had been used for decades by farmers to milk cows. The “Surge” pump was a beefy hunk of iron and gave me more performance than I knew what to do with. But it too was very noisy – not the shriek of the Sears – more like the roar and rumble of a Mack truck. In addition, it didn’t have the ancillary components needed for dependable, unobtrusive, long-term operation. It needed a better vacuum controller, and a better separating tank, and better protection from flooding. And it needed to be quieter. Much quieter.
Little by little the improvements came. The first was a vacuum controller to tame the beast. Next were the experiments with drive ratios that revealed I could slow down the pump without loss in performance and change the big truck roar to a small car's purring idle. That speed change also allowed a change to a smaller, more energy efficient motor. Separator improvements came more slowly. I found a lot of tubs and barrels that didn’t work. Many were strong enough in tension (they hold positive pressure), but vacuum doesn’t create that type of load. Even the light negative pressure (vacuum) I set my pump to produce caved in plastic shop vac tanks and flexed the ends of steel drums. The solution would come a number of years later when I finally decided to have a fiber reinforced resin (“Fiberglas”) tank custom fabricated.
There’s more to come. Please stay tuned.