Two years ago we bought a Berkey water filter, and we are very happy with it. However, it created a twice-daily chore for me to fill it. So this past spring I thought I'd make a system that would fill it automatically. What seemed simple up-front project turned out to be a little bit of a challenge, and quite educational for me. Here is a little of the puzzle, then I'll show the solution.
The Problem: The filter system consists of two 2.5 gallon containers, one on top of the other, and two candle filters. Water is added to the top container, and gravity slowly causes the water to drip down into the lower container. At first I thought I'd install a float type valve (think: carburetor or toilet water tank type valve) but that wouldn't work: If the float was on the top container, the bottom would eventually overflow, and if the float was on the bottom, the top would overflow before the bottom would fill and shut the water off (that is an abbreviated synopsis of unworkable solutions, there were many more).
The Solution: Weight the whole filter unit, and as water is drawn out, it weighs less, and will replenish the same weight that was drawn. The idea seemed valid but I did not have the technology to implement the concept until this spring; I was introduced to micro-controllers. A micro-controller is like a little computer that can be programed to do simple functions (see Arduino). So I bought one, and after some trial and error (no floods yet!) have a working filter filler!
How it works: There are four pressure sensitive resisters under an aluminum pie-plate. They allow electricity to pass thru them in proportion to the weight upon them. The little controller sense the electricity decrease when the filter gets lighter, and turns on a solenoid (electrically activated water valve, taken from a discarded dish-washer). As the filter fills with water, the weight increases until the resisters reach a determined value, and the valve shuts off. If the filter overflows, it will spill into the pie-plate, and two wires there will sense that spillage, turn off the valve, and turn on an alarm. 
Still to do: Neaten up the wires, box it up, and put the lid on the filter. This is just to show you the "works".
5 comments:
very nice! I have always admired the engineering prowess of the men in my family. You and Dan and Dale each approach things a little differently, but you all have that amazing mind for machines and putting things together in innovative ways that actually work, and work well! Very impressive!
Awesome!!! I love it! You are a genius!
Ok... I kind of get it.
So do you have just one weight that you use as a trigger? Is there a delay anywhere? I am assuming you allow for some margin somewhere. Do you have a low weight threshold that then triggers the pump until you reach the high weight cutoff, or are you in some way keeping track of the water in both chambers? I assume that the filtering process isn't instantaneous. So that if you filled the unit until it weighed more than 2.5 gallons you could conceivably overfill the top container. Wondering at your exact solution?
Now, if you could solve my Berky problem... the ants keep climbing in and committing mass suicide. Can't seem to keep them out (of the filtered water). Very frustrating!
Very Cool!
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