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Is there a positive displacement pump that experiences only rolling resistance? One with no sliding friction and diaphragm stretching?

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  • $\begingroup$ Are you thinking of a peristaltic pump? $\endgroup$
    – Solar Mike
    Oct 17 '21 at 14:18
  • $\begingroup$ the flexing of the "hose" is esentially equivalent to streching of a diaphragm $\endgroup$
    – Francis L.
    Oct 17 '21 at 15:11
  • $\begingroup$ peristalic pumps also have frictional losses besides ones at the bearings of the rollers - the deformation of the tube doesn't give back all the energy you put into it $\endgroup$
    – Pete W
    Oct 17 '21 at 15:19
  • $\begingroup$ @FrancisL. The flexing of the hose is it being crushed, not stretched. $\endgroup$
    – Solar Mike
    Oct 17 '21 at 15:32
  • $\begingroup$ @PeteW so what do you suggest? Axial, centrifugal? Piston? Mercury? $\endgroup$
    – Solar Mike
    Oct 17 '21 at 15:33
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Rolling diphragms have been around for many years now. See... https://www.diacom.com/rolling-diaphragm-theory

rolling diaphragm

With or without the spring.

(With enough vacuum in the top you can get the membrane to slip upwards, but it is easily reset by cycling.)

Fabric reinforcement helps prevent stretch, but generally everything is elastic to some extent.

Additionally, https://www.airpot.com/ has made some innovative low friction graphite/glass piston/tube cylinders that I haven't tried with fluids other than air.

airpot dashpot

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Our body has several examples, our throat when swallowing, our intestines would be another example.

Arteries in our legs pump the blood by our leg muscles squeezing them.

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  • $\begingroup$ Isn’t the swallowing action peristalsis? Which is why peristaltic pumps were discussed above. Or you missed the comments. $\endgroup$
    – Solar Mike
    Oct 17 '21 at 19:08
  • $\begingroup$ @Solar Mike, i stand by mu answer. Swallowing and pushing the food down the intestines is done by rolling action, no rotating or spinning, or difragms involved. $\endgroup$
    – kamran
    Oct 17 '21 at 20:57
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Progressing cavity pumps. The rotor executes a rolling motion in the stator, because of the different auger like shapes of rotor and stator the cavity between moves along the axis. This video shows the movement.

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