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  • Sanitizer mechanism.

    Everyone is making masks and foot pump sanitizers. I have been asked to look at making one with a difference. It flatters me that they asked me because I cant draw and lack creativity.
    Anyway the downfall I believe of most of these foot sanitizer pumps is the lack of bottle size and all the different type of bottles available.We want to try making one that uses a bigger bottle,say ten liter.

    We tried a simple petrol tank primer bulb used on boats outboard motors and a laser cut pedal box. The primer bulb is simply depressed by the action of your foot on a lever.
    It seems to work well but this is Africa and these things will be going to far away places so it needs to be Africa proof.

    What could we use to make this foot action sanitizer stand that would be stronger than a primer bulb. The volumes of liquid are really small that need to be displaced.Our other dilemna is the spray action.
    I drilled a one mm hole into a piece of brass to act as a spout .But one mm is too large. It seems as if the hand sanitizer nozzles seem to atomise the liquid. How small do you think a nozzle hole needs to be to atomize or is it the shape of the hole that does the trick.
    Also any dirt in such a small hole would become a problem. Remember these will go out to rural areas where some poor locals dont even have a water faucet.So they will battle to fix this if it gets blocked.

  • #2
    how about adapting a soap dispensing unit? why would you want to spray?

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    • #3
      Originally posted by plunger View Post
      so it needs to be Africa proof.

      .
      That my friend will be your major design problem. I live in Africa, my family lived here for two hundred years, and yeah, such a thing does not exist

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      • #4
        Use a nozzle off a pump sprayer.

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        • #5
          How about using some of the silicon tubing like that used in peristaltic pumps? You would need only an inch or so, a couple of simple check valves, and a spring loaded lever to transfer pressure to the tubing. that would protect it from being stomped on. As for a foolproof spray nozzle, sorry, best idea I can come up with ie a short length of thinwall silicone tubing with a 1/4" slit, lengthwise , in it, plugged on the end. About as close to selfcleaning as possible.

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          • #6
            5 liter garden pesticide spray bottles in a metal frame where a foot pedal moves the plunger up and down? The bottles will not last long but are cheap and can be seen as a consumable

            We also experimented with water pumps where old soft tyres were used as the bellows. A lot like a blacksmiths air bellows. They did last a long. Probably too big for your application but maybe a small 12 inch tyre? I would advise against using brass, it tend to grow feet exceedingly fast.

            Maybe a light air suspension airbag in place of the bulb? A lot harder to pump, but you can make the lever longer to compensate. Not sure what the alcohol will do to the rubber.

            Where in Africa will it be used? In South Africa, Namibia and Botswana sourcing parts and materials is not a big problem, but the further north you go the worse it gets.

            Edit - Just now saw you are from the RSA, please ignore me stating the obvious
            Last edited by Blouwildebuffel; 06-30-2020, 08:47 AM.

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            • #7
              I'm 60 years away from Africa (further north) and know that a lot has changed in that time. But in looking for universally available components, what about bicycle inner tube sections. If the pump was made to have clamps on each end of a section of tube, it could be replaced as needed from a discard. Alternatively, building on the peristaltic pump proposal, in British Africa bicycle tire valves used a short piece of rubber tubing that was replaceable and someone in a market everywhere would have some tubing. If that design has been replaced by Schrader valves or another design, that idea is out the window.
              .
              "People will occasionally stumble over the truth, but most of the time they will pick themselves up and carry on" : Winston Churchill

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              • #8
                Originally posted by Blouwildebuffel View Post

                That my friend will be your major design problem. I live in Africa, my family lived here for two hundred years, and yeah, such a thing does not exist
                Yes said with a sense of humour. You need to live in Africa to understand it.Where are you from.

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                • #9
                  Lol, Windhoek

                  Although a fact of life here, it was said in jest, but I actually expected a flaming!

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                  • #10
                    Okay so you are from Namibia.I have only had the privilege of visiting your country when it was called South West Africa. But I went to places like Ondangwa ,eenhana and Ogongo.I spent fifteen months up there.

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                    • #11
                      When it comes to nozzle design, the formulation of the sanitizer may be an issue because of the impact on viscosity. I have sanitizer that ranges from very thin (like whole milk) to thick (warm butter). Obviously those two formulas will require different nozzles.

                      The only one that I have that would atomize would be the straight ethanol that has a touch of something that makes it undrinkable. The silicon tube with a slit in it may well be the best bet.

                      Dan
                      At the end of the project, there is a profound difference between spare parts and extra parts.

                      Location: SF East Bay.

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                      • #12
                        Trying to keep it simple. A plastic jug can be squeezed a small amount to force the liquid in it out through a tube. A simple L shaped lever could be used; someone steps on the horizontal part of the L and the vertical part squeezes the jug. Easy to adjust for different sizes of jugs. I envision two L shaped sides with flat boards between then: one board for the foot pedal and the other board to press against the jug.

                        Cork or screw-on top with two tubes. One tube goes to the bottom to pick up the liquid. The other tube only goes through the cap to admit some air when the foot pedal is released. Both of those tubes would have a simple, one way valve. These valves could be made with a widened chamber that is drilled to accept a ball bearing ball which would move up to open when fluid or air flows and down by gravity to close. A "nut" on that ball chamber with serrations/ribs to allow fluid/air to flow around the ball when pumping and a hole leading to a hose (tubing) barb. The tube for admitting air would need a U turn to preserve the gravity closure by the ball. This part would be somewhat exposed to damage so some kind of protection/enclosure would be needed to protect it.

                        One of the tubes only passes air so cleaning would only be on well spaced occasions. The valve in the other tube would be separated from the outside air by a length of tubing (flexible) so it also should only need occasional cleaning. Cleaning could be performed by soaking in water and/or forcing water through the various parts. A well designed ball based, check valve should not clog up easily as small grains of sand would just flow around the ball. If the ball seat is made well, then the pump action should be self priming.

                        The parts for these valves could be made on a lathe from brass or aluminum or even by 3D printing with a suitable plastic. I would recommend SS for the balls to prevent corrosion. In any event, they should be easy to replace, even in Africa.

                        One advantage here would be that the discharge "nozzle" can be made fairly large because it only had to drip the solution into the user's hands. In fact, if the size of the tubing is chosen carefully, then no actual nozzle would be needed at all. If dirt getting in through the air tube becomes a problem, a simple filter over it's opening could be made with a scrap of cloth or a cotton ball in a simple device like a pipe or tubing end cap with a hole drilled in it. I am sure that fabric is available in Africa.

                        If flexing of a plastic jug is not a good option, then a section of larger, flexible tubing could be inserted in that air admitting line. Again, it would be squeezed by the foot pedal: round the edges of the board that presses against it. It would be between the top of the jug and the air check valve. And it would be easy to replace if it wears out.

                        Well, that's one idea. I am sure it could be improved with some discussion. Or lets hear some others. Come on guys. Think up!
                        Last edited by Paul Alciatore; 06-30-2020, 04:26 PM.
                        Paul A.
                        SE Texas

                        Make it fit.
                        You can't win and there IS a penalty for trying!

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                        • #13
                          No clue as to what is available but I would try to make a pump to emulate a hydraulic jack pump. Small plastic rod for piston inside plastic tube, or more heavy duty, small metal rod inside metal tube. Variation - screw leather washer etc on for replaceable packing. Length of stroke limits amount dispensed. Ventilated reservoir feeds the pump. Any piece of hose that resists whatever the sanitizer is made of, and a sports inflating needle pin nozzle to dispense. Spring return foot petal sucks in next shot on return. Best if nozzle is high.

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