Homestead mailing list

[Bill Jones <billj AT harborside.com>]

steve jones wrote:

> Hi Bill,
>
> I have been trying to contact you re details about your 'well pump  
> breakthrough'. I've tried several times to send you an email without  
> success. I have now joined this homestead thing to see if I have better  
> success. The info you posted on the net is not quite detailed enough for  
> me to build one. I am trying to install a small irrigation system here in  
> Morwell Victoria Australia. I am hand drilling a number of 25 metre  x 100  
> mm (80 ft x 4 in) wells in a fine sandy aquifer. There is plenty of water  
> but it doesn't flow very quickly so linking several with compresed air  
> pumps to produce a reasonable flow of water would be a good idea.  
> Unfortunately the commercially available pumps are at least $1000 each and  
> this makes for financial problems. If I could build them for $100 each as  
> you suggest I would be very grateful. My email address is  
> stevendella AT finnsheep.com I hope you are able to help.
>
> Cheers,
>
> Steve & Della Jones.
>  
Hi Steve.  Your email is probably buried on my hard drive, but I've had 
several system crashes, so who knows?

Indeed, an air-displacement pump can just wait as long as necessary for 
the well to refill, so low flow rate is no problem.

Well, it's just a vertical tube submerged in the water.  At the bottom, 
an inlet port lets water in through a check valve.  A second check 
valve, also at the bottom, serves as the water outlet, and connects to 
the return tube.  These two check valves face in opposite directions.  
Now, if there were a piston at the other end of the tube, water would be 
forced upward through the return tube when the piston compresses, and 
new water would be pulled in when the piston draws back.

In these respects it's just like any other piston pump.  But instead of 
a piston, air is injected into the top through a long tube.  The bubble 
of air acts exactly like a piston.  It forces the water out the outlet 
valve.  Gravity is the only thing keeping the air in the top of the 
tube, and the water in the bottom, so that's why the tube must be held 
vertical.  No need to have a piston pull back to draw in the water, 
since it will just flow in by itself through the inlet valve once the 
pressure's off.

Now you only have to find a way to make the air turn on, and disconnect, 
every few seconds.  We're using a simple 3-way solenoid valve, and a 555 
timer circuit.  We have no particular skills in electronics, but we were 
still able to hook up a 555 chip with no problem.  The system will be 
somewhat less efficient to operate if the solenoid valve is placed above 
ground, because of the long tube of air that's lost during each cycle, 
but we like the idea of not having electricity and solenoids down in the 
humid well shaft.

This is as simple as it gets.  There are commercial models that have a 
pair of water-level detectors inside, so they "know" when it's time to 
change to the other state.  This seems like overkill to me.  Since it 
always takes the same amount of time to refill, and a different (but 
always the same) amount of time to empty out, this feedback isn't really 
necessary.  There are models that pulse the air flow on and off using 
purely mechanical means, but they're much more expensive, and I've heard 
they have troubles with stalling out.  Either way I'm always amazed at 
the huge prices and sophisticated stuff, when it's really just a giant 
keg tapper.

Bill
S. Oregon coast