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Been researching peristaltic pumps, but cant find an industry standard in designing them.

Wiki (http://en.wikipedia.org/wiki/Peristaltic_pump) has a little bit of maths on the occlusion, and a basic idea on calculating the flow rate

and this article explains a little of the theory

http://www.coleparmer.com/TechLibraryArticle/579

but there doesnt seem to be much in the way of a set of rules in designing one.

I came up with a little bit of methodology and wondered whether you guys could comment - or had a better way of dealing with it:

Anyone agree/disagree or have a good reference - would love the comments, thanks So if I put a tube on the table a metre long, and put one end in a bucket of water (assuming no height changes anywhere for now), then squeezed it in the middle (@ 0.5m) and dragged your fingers down towards the other end (not in bucket) what would be occuring:

I.e assuming a perfect squeeze (completely sealed) and I know the inner/outer diameters, young's modulus, and density of fluid (water), distance of drag is 0.5m I need to know my flow rate and "effort" required to pull some water up the pipe

flow rate is (pi*ID^2/4)*[speed I drag at) (iD is inner diameter)

work is force required * 0.5m,

Force required is...??? The effort to "suck" water up the pipe? Thats gonna be this equation: resulting in the change in pressure inside the pipe, which can be converted into a force by multiplying by the cross sectional area of the pipe:

[itex]\Delta P=f.\frac{L}{D}.\frac{\rho V^{2}}{2}[/itex]

?

If L is 0.5m D is inner diameter (at non squeezed point) and f comes from a moody diagram

Then as my fingers that are squeezing the pipe reach the free end, my other hand squeezes at 0.5m and does the same thing, I keep repeating this technique and I have peristaltic motion.

So now thinking of a peristaltic pump, i.e

the distance moved is half the circumference, the torque on the motor is the force required to "suck" * distance to pivot

The available speed is from Power = T* rotational velocity

therefore I now know the speed at which I can move that amount of fluid, so I have a flow rate???

If I increase the number of squeeze points to 4 (like the picture) then my force required increases by 4?

However the distance that I am sucking is now the distance between squeeze points

And what happens if I dont have "perfect squeeze"? Im thinking the force required (and flow rate) may fall away with a 1/r^2 rule? what do you think?

Perfect squeeze can only be considered depending on the tubing used - to stiff and creating a perfect squeeze may crack (damage) the tube, so maybe I would just want a 50% squeeze...

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# Designing a Peristaltic Pump

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