Wednesday, November 14, 2007
Sunday, September 30, 2007
More of April's excellent photos of the first day of pump operation can be seen at http://psu.facebook.com/album.php?aid=20610&l=9d3d2&id=635241284.
So, what's left to do? A lot. The pump is after all a prototype. Rick is using the pump, as are others, and Jim and I are receiving periodic updates as to what needs to change and what needs to be improved. Once we have the design more tuned than it is now, we intend to publish pump plans, and make them available to anyone. There is already talk under way about how to introduce the pump in Haiti, but that is still far from settled, and a much more difficult undertaking than designing the pump.
Tuesday, September 4, 2007
In the second photo Winston provides instructions in the finer points of pump construction.
Next we see Jobert studying photos. Jim took photographs of the pump at each stage of disassembly. Viewed in reverse order, they form our instruction manual. That was the intent, anyway. Somewhere along the way, the guys hit a snag, and Kathy was called in to provide translations and what looks like a drawing. That's Rick in the right foreground.
Things are straightened out now, and the pump is almost finished. Jenner is installing a piston and it's seals into the cylinder. The last photo show Jobert and Jenner priming the now assembled pump by filling the cylinders with water.
Tomorrow, plans are to try the pump out at one of the project areas in the hills. Thanks to Kathy for the photos, and many thanks to Winston and his group for hauling the pump all the way from North Carolina.
It's hoped that today, the pump will be moved to one of the project areas further up the mountains, and used there. We're also promised some photos, and I'll upload those and publish them as soon as they arrive.
Sunday, September 2, 2007
There are several points of interest. The first is the terrain itself. It's usually decscribed as mountainous. These aren't the rockies, but if you're carrying water or anything else on your back, or as is the custom there, on your head up these hillsides, they qualify as mountains. You'll also notice that there are no trees. The trees that used to cover these mountain sides have been cut and used for the most part to make charcoal. Much of Haiti's population, estimated to be as high as 8.7 million, uses charcoal to cook three meals a day. That's a lot of people demanding a lot of charcoal, in a small country, resulting in mountains denuded of any vegetation of any size. Haiti also enjoys periodic torrential rains as a result of passing tropical weather systems, ranging from tropical depressions to hurricanes. Over the years, these rains have carried away feet of topsoil, flushing it into the Caribbean Sea. One of the activities pursued by CODEP is erosion control in the form of terraces, or contour ditches. You can see one new terrace in the left foreground of the photo. The basin in the center of the terrace catches and conserves rain. The berm that forms the downhill lip of the terrace has been planted with Vetiver grass. This grass can form a dense hedge along the contours that hold and stabilize the soil, and filter the the rain water, preventing further erosion.
Photo Credit: Rick Land
Sunday, August 19, 2007
Tuesday, August 7, 2007
Finally, we hit on ordinary automotive type rubber heater hose. It's flexible enough to install and remove easily, readily available, and cheap enough. The only problem is that it collapses under vacuum. This little conundrum was solved by making a coil out of galvanized 14 ga steel wire. Almost any wire of sufficient stiffness will do, even if it wants to rust. A wire coat hanger would work. The coil was made by winding the wire around a 3/4 inch steel rod. Again, what one uses for a mandrel is not critical. As long as the result fits inside the heater hose fairly closely, and prevents it from collapsing under the vacuum produced by operating the pump, it's all good. Only the hoses on the vacuum side of the pump need to have a coil installed.
We tested our cheap and dirty vacuum hose arrangement on 08/06/07. It works. We'll be posting the results of the testing later, probably with more videos. We're still looking for a cheaper substitute for the pretty stainless steel hose clamps we've been using to secure the hoses. They're kind of expensive. There are a number of possibilities, and as soon as we know what we're going to do, we'll post it here.
Sunday, August 5, 2007
Saturday, August 4, 2007
We were expecting the pump to be much harder to operate with this increased length and elevation. Instead, it was about the same; just the strokes per minute were slower. It is not necessary to use leg muscles to force the treadles down. Your body weight provides the force. At the end of each stroke, you just have to raise your body weight high enough to step up on the other treadle. To accommodate people of different weights, one can just move their feet position further away from or closer to the pistons to change the mechanical advantage. We measured the volume of water per minute pumped and knowing the total lift, we could calculate the work required. Rate was 4 gallons per minute which is about 50 watts. According to several studies by others, this an easy output for people to maintain almost continuously. Larry operated the pump for 2 hours on a very hot day and was not excessively fatigued. Realizing that we probably weigh more than the average person who will be using this pump, we decided to add several additional inches to the treadle length to accommodate people that weigh less. We feel that except for some minor changes in the way we interconnect the piping so that it is more easily disassembled for cleaning, we have arrived at the final pump design. The following video is about 2 minutes long and shows the pump being tested at the stated pipe length and elevation. There is a short video following the first one that shows Larry operating the pump at this length and elevation after he has been at it for 2 hours. These test results were very encouraging. Our next step will be to get a prototype pump to our CODEP project in Haiti and begin creating drawings and instructions for how copies can be made by others.
Sunday, July 29, 2007
Sunday, July 15, 2007
The new plumbing worked just fine, as did the new check valves. I was holding my breath about the new valves. The easy up-and-down mast worked too. The new plywood braces were plenty rigid. That leaves the paraffin valves. Results there were less than stellar. Without going too much into the gory details, the paraffin seals were almost impossible to prime, and once primed, the upper seals, the ones that should provide a seal on the vacuum stroke, were excessivly leaky, and wouldn't hold their prime. After a half hour fighting with the balky seals, I retreated to the older molded seals, primed the pump, and everything else worked.
Except the pulleys. The pulleys that hold the cable that raises the treadles on each vacuum stroke have been something we've sort of neglected till now. We were using a pair of old brass pulleys that I had lying about from an attempt to hang a bird feeder where the squirrels couldn't get at it. That endeavor failed by the way. Anyway, the pulleys were too small for the task we had applied them to, and they didn't survive. All the vigorous jumping up and down I did while trying to use the paraffin based seals didn't help any.
The pulleys have since been replaced with three inch diameter pressed steel pulleys with a ball bearing in the center, intended to help raise a garage door. If you click on the photo, you should be able to see the new pulleys and get a better look at the metal bails that hold the mast.
We still have a working pump. In fact, plans are to take the pump to Jim's house, plumb it to his pond, and try to pump the pond dry. No, really, we're going to take advantage of the water his pond can supply to work the pump for as many hours as he and I can make ourselves pump, so as to identify any part that is prone to premature failure. We're also going to play some games involving feeding the pump sand and mud to see how the seals and check valves handle that. We've got some strainers to test as well. Until now, we've been pumping clear water.
There's been some preliminary talk about shipping this pump to Haiti. Should all this testing we've planned work out with no big setbacks, I hope this can happen. The sooner the better. The sooner we can manage to get a pump on the ground in Haiti, the sooner we'll know what works, what doesn't and what needs to be changed.
Saturday, July 14, 2007
The seals, which are sticking out in front of the cylinders to dry are molded using melted paraffin. The pump cylinders have new homemade check valves. The valves are installed both on the same side of the cylinders, which allowed us to reduce the amount of plumbing required, and simplified the routing. The plywood braces have been cut down, to minimize weight and save materials. A cleat has been added on the left end of the pump, to act as a treadle stop, and keep the treadles from beating the plywood brace on the end of the pump to bits. A lot of the extra holes have diasappeared. We needed them earlier so we could change the position of things easily. The design has firmed up now to the point that those adjustments are not needed any more. One last feature that was Jim's idea was to mount the mast with metal loops that allow it to be raised and lowered without tools or any hardware. That's the mast lying across the top of the pump. If you look closely, you can see the metal bails that it slides through. The one on the left rotates with the mast to a vertical position, and allows the mast to slide down and seat on a bracket between the pump bases that you can't see, but is there. In the lowered position, the mast projects past the vertical supports and provides a carry handle on each end. How handy. More tests coming soon.
Sunday, July 8, 2007
The valves are made from one 1 1/4" coupler and two 1 1/4" x 3/4" flush reducers. A 7/8" delrin ball fits nicely in the throat of one of the reducers, and stops flow in that direction. When flow reverses, the ball would travel back to the other reducer, and stop flow in that direction too, except that it's stopped by what I'm going to call a spider, which is what those two complicated looking star shaped objects are in the front of the photo. One is made out of aluminum, which I didn't like too much. The other is made out of a piece of the PVC that both spiders are sitting on. The PVC came from a short section of PVC pipe that was slit down one side, and heated in a 300 degree oven for about five minutes. At that temperature, PVC is as pliable as putty, and can be flattened between two boards and held till it cools. After that, it can be cut, filed and drilled. The spiders look complicated to make, but they're not. You cut a square the right size, and drill a half inch hole in the center. Then you use a half round bastard file such as you see in the photo to file the half round recesses in the four sides of your PVC square. It's easy, and it only takes a few minutes. To the left you see a Delrin ball sitting on it's spider, inside a spacer cut from a piece of pipe to provide space in the valve for the ball to travel back and forth, and retain the spider. The second photo shows a cut away copy of the valve so readers can see how all this goes together inside. In quantities, the cost of this valve should be less than three dollars each. I'll let you know how they work as soon as I can get them installed in the pump.
The base and and piston are made out of old countertop material. They could be made out of anything, even wood. The rings are short sections of the same four inch PVC pipe that's being used for the pump pistons. There's a large 45 degree bevel at the top of the rings to help ease the leather into the mold without tearing it up. Today, I finally got around to molding seals. Five inch diameter leather circles were soaked in melted paraffin, and placed in the molds. The bolt through the center of the mold was used to tighten down on the leather and force it into the mold. It worked like a charm. The only problem was that I made the rings a little too short. I improvised by taping the rings together with masking tape, and using one mold at a time. I'll make taller rings later. The second photo shows one of the seals out of the mold, and one of the seals still wrapped around the piston, waiting to be trimmed. I trimmed the edges of the seals with the razor knife to the left, using the top of the piston as a guide. I have no idea how well these will work. We've read that these seals will be self lubricating, and less prone to rot and swell from absorbing water. We'll try these seals the next time we take the pump out for a walk, along with the new check valves we made today. That's what the next post is about.
Sunday, June 24, 2007
Thursday, June 21, 2007
To make the seals I first marked five inch circles on the leather using an ordinary compass. The circles were cut out with a sharp knife, and a 3/8 inch hole cut in the center. The leather circles were then soaked in warm water for about half an hour. I used the pump pistons and seal retainers to hold the seals, and forced them into two short sections of four inch PVC pipe of the type we're using for the cylinders. The first photo shows the seals in the molds. The edges of earlier seals were convoluted, or accordian shaped. This leather is much more pliable than what we've been using, and I was able to smooth out the humps and bumps using my fingers.
In the background of the second photo (click on the photos to enlarge them for better viewing) you can see a piece of the leather that I used, and the short sections of PVC that were used for molds. In the foreground are two of the now cup shaped seals , dried and with their edges trimmed, more or less. In the middle are the two pistons. One has the new seals installed, and the other is positioned to show as best I can the piston and seal retainers. The piston is machined to a close fit to the cylinder. The retainers are quite a bit smaller than the piston, with generously radiused edges. Their purpose is to loosely hold the leather seals without forcing them against the walls of the cylinder. Pressure or vacuum in the cylinders formed as the pump operates forces the seals against the cylinder walls. If all goes well, tomorrow we'll try another version of the pump, with these very seals.
Sunday, June 17, 2007
Saturday, June 16, 2007
Wednesday, June 13, 2007
Wednesday, June 6, 2007
In the last post I promised another treadle pump with three inch pistons. Here it is. If you compare it with the first version, you'll see the cylinders are larger in diameter, shorter, and installed at a different location in the treadle frame. The treadles and treadle stops are lower too. The purpose for locating the pumps where you see them was to provide greater mechanical advantage to the operator. The pump works great. The larger piston diameters required the mechanical advantage we built in this time as expected. This time I talked my wife into acting as one of our test subjects. One of our concerns is that people shorter and lighter than Jim and I must be able to operate the pump. My wife fits the small size requirements, and she had no problem moving water to a height of 25+ feet.
The second photo shows one of the three inch pistons. The commercially manufactured check valves can be plainly seen. The pumps are mounted to the treadle bases with short sections of all thread rod secured under the bases with "t" nuts and passed thorough plywood donuts made to closely fit the outside diameter of the cylinders. Nuts and washers tighten down the donuts against the pump bases and hold everything secure and upright.
Last time we were too busy and disorganized to make videos. This time, due to popular demand, we have videos to post, which I will do as soon as I can get them uploaded.
Tuesday, June 5, 2007
Friday, June 1, 2007
Wednesday, May 9, 2007
Monday, May 7, 2007
Sunday, May 6, 2007
What you see is an experiment with using leather washers to make a piston seal. Two washers were used, one to seal against vacuum, the other to seal against pressure. The cylinder is a piece of 2" PVC pipe, with a cap on the end. The cap was drilled and tapped for a ball valve so that I could vary the resistance to flow. Long story short, the seals worked, surprisingly well. The addition of vegetable shortening to the leather improved the seal, and greatly reduced resistance to motion.
The results of the piston seal experiment was encouraging enough that a search for check valves was begun.
So, you may be asking, what's a treadle pump? It's a foot powered water pump used for irrigation. It usully has two pedals, called treadles, that the pump operator stands on and operates with a walking motion. These treadles are connected to two cylinders with valves at the bottom that comprise a pump. There are two basic types of treadle pumps, lift pumps, and pressure pumps. Lift pumps have a practical limit to the distance they can lift water of seven or maybe eight meters. In Haiti, crops are grown on terraces at greater distances above the water source than that, so a pressure type pump is what's required, and that's what we're trying to design and build.