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  • From: Bill Jones <billj AT harborside.com>
  • To: homestead AT lists.ibiblio.org
  • Subject: Re: [Homestead] Well Pump Breakthrough
  • Date: Mon, 16 Oct 2006 16:07:19 -0700

Bill Jones wrote:


The only remaining (easy) task is to come up with a circuit that will turn on a 3-way solenoid valve (or off, depending on which type of valve it is), to turn off the air pressure when the pressure switch cuts out, and then delay for a fixed length of time before resetting, to allow the top ball to fall and the chamber to refill.


That will definitely work, but today I mastered the secret of pure mechanical control. When the pressure rises, indicating that the chamber is full of air and ready to reset, a pressure-relief valve releases the air from the line. This would work by itself, but poorly. My buddy Orlando was happy with this arrangement, but I see only inefficiency as the air blows uncontrollably, first out the valve, and then out the top of the chamber, whose top ball will have now fallen, perhaps even interfering with the top ball as it tries to seat itself.

So I had an idea to use a valve that would shut when the air flow goes above a certain rate. It would be like the pneumatic equivalent of a circuit breaker, one that resets itself. It turns out that the valve I need is precisely the one that James was talking about for the hydraulic ram pump a few months back. It's actually a one-way valve, the pneumatic equivalent of a diode, placed backwards in the line, which allows only a low rate of flow in the "wrong" direction. This one has to work for air, but it's the same principle.

The one tiny problem remaining is how to make this valve reset. It stays shut until the pressure on both sides nearly equalizes, I would think. Well, here's how to solve that problem. A second air tube is connected directly from the pressure supply to the chamber, bypassing the "circuit breaker" valve, but through a valve that barely leaks air in at all (the pneumatic equivalent of a large electrical resistance). This way, very little air is wasted during the reset of the system, but when the top ball plugs the hole, only a little air needs to seep in through the second tube to repressurize the chamber, and that allows the built-in spring to reset the fancy valve, allowing air to flow freely into the now sealed chamber.

Mr. Stauffer deserves a patent for this device, unlike so many other patents I've been embarrassed to learn of. After all, it took me ten years of off-and-on cogitating to figure it all out. But the hour is late, and the ecovillagers don't deserve to starve to death because they can't afford $800 for a water pump. Wasn't all that *simplicity* supposed to help lower the price? So now I'm happy to announce that anyone can build one for under $100.

Bill
S. Oregon coast




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