The toilet bowl: A priceless process control case study
Patrix feels that a toilet bowl could well be a piece of art owing to its “smooth rounded and elegant curves.” As a control engineer, I want to comment on another aspect of the toilet bowl, as well as the septic tank. It might well be amongst the oldest automatic control system still in use close to its original form.
There are so many control elements in that single, relatively simple, system. First the flush: the water in the tank has to flow into the bowl until the tank is drained. The level of water in tank triggers the outflow valve in “off” position. When the water flows into the bowl, the bowl should not overflow. When the water gushes in at a high rate, the bowl has to empty its contents. Water then partly fills up the bowl so that there is some of it remaining in the bowl at the end of a flush. Finally, the tank has to fill up. When the water is at a certain level, the inflow automatically switches off.
Isn’t it amazing how many control elements are packed in that single humble device that we use everyday?
Some people say, correctly, that the kitchen is the most automated part of an American house. But the automation of a toilet bowl amazes me due to its simplicity.