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There has been a lot of talk about these pumps just lately and they do have certain advantages, they are simple, reliable and will pump air or water (or oil or treacle for that matter) there flow rate is constant and they are not affected by depth or external pressure so current drain is more or less constant regardless of how hard they are working.
I designed and built this one around 1986 just to try the idea out and boy does it work, I used it to pump water into a closed vessel and it blew my 200psi pressure guage to bits in around 20 seconds. I figured that was not the sort of pressure I would like to invite into the pressure hull of my sub and so threw it onto a shelf for over twenty years. Seeing that a couple of you guys are having a go with them I thought perhaps this might be of help. The contruction is straifgt forward enough and is just as you see it here.
The size of mine is 2" dia but you can make them smaller or larger as suits application, the only thing to be careful with is the pressure on the silicon tube. To get it right I simply put the tube between the anvils of a micrometer and closed up until I could suck on the end of the tube and it would just stick to my tongue so I knew I had a good seal I could then adjust each roller by taking a tiny bit off the sleeves pressed over the bearings. To power mine up I had a couple of gears giving about 10:1 reduction
from a standard 540 motor but you can simply mount it onto the end of a pile gearbox.
If you are going to try one of these things out on a sealed system then I would strongly suggest
that you use the pump to empty a tank and work against a vacuum rather than fill a tank and generate
what could easily be very high pressure.
One last point, don't you just love this site, no bloody politics, just modellers sharing information and
maybe showing off a bit, but so what we have all earned the right.
I designed and built this one around 1986 just to try the idea out and boy does it work, I used it to pump water into a closed vessel and it blew my 200psi pressure guage to bits in around 20 seconds. I figured that was not the sort of pressure I would like to invite into the pressure hull of my sub and so threw it onto a shelf for over twenty years. Seeing that a couple of you guys are having a go with them I thought perhaps this might be of help. The contruction is straifgt forward enough and is just as you see it here.
The size of mine is 2" dia but you can make them smaller or larger as suits application, the only thing to be careful with is the pressure on the silicon tube. To get it right I simply put the tube between the anvils of a micrometer and closed up until I could suck on the end of the tube and it would just stick to my tongue so I knew I had a good seal I could then adjust each roller by taking a tiny bit off the sleeves pressed over the bearings. To power mine up I had a couple of gears giving about 10:1 reduction
from a standard 540 motor but you can simply mount it onto the end of a pile gearbox.
If you are going to try one of these things out on a sealed system then I would strongly suggest
that you use the pump to empty a tank and work against a vacuum rather than fill a tank and generate
what could easily be very high pressure.
One last point, don't you just love this site, no bloody politics, just modellers sharing information and
maybe showing off a bit, but so what we have all earned the right.
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