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I am trying to build a vacuum pump by myself and move rocks from one place to another. After some online search, I came across this video on Youtube. I am trying to build something like this. Can anyone explain the science behind it and tell me how I can make this by myself?

NMech
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Joy Karmoker
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1 Answers1

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What you are seeing in the video is a vacuum generator/vacuum ejector/aspirator.

enter image description here

Figure 1: Venturi effect (source: wikipedia)

It uses the principle of the Venturi effect. I.e. that for steady, incompressible, inviscid when there is an increase of speed there is a drop in static pressure. This is mathematically expressed as:

$$p_1-p_2 =\frac{\rho}{2} (v_2^2- v_1^2) $$

Application in vacuum generators.

This is used in vacuum generators, in the following way:

enter image description here

Figure 2: Application on Vacuum generators (source: COVAL)

Initially, Compressed air is driven through a nozzle. This increases the velocity (and the kinetic pressure) and drops the static pressure. At the exit of the orifice there is pressure drop which creates a negative pressure which sucks in air (and other small materials).

NMech
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  • To the OP: If you can make a good seal between the vacuum cup and object then a vacuum generator with low flow but high vacuum will do the job with efficient use of compressed air. If the object is leaky or there is a poor cup-object seal then you need a high flow vacuum generator. With 100% vacuum you can lift 1 kg/cm² of vacuum cup internal area. – Transistor Jul 11 '21 at 12:53
  • Can you tell me how much will be the cost of building such a system? – Joy Karmoker Jul 11 '21 at 13:07
  • You can buy it of a shelf for a few dollars.building it from scratch would not be cost effective. – NMech Jul 11 '21 at 13:32
  • What will the total setup cost? – Joy Karmoker Jul 11 '21 at 16:22
  • That will depend on the local market. I'm guessing that the highest cost will be the supply of compressed air. – NMech Jul 11 '21 at 16:32
  • Can you please suggest to me any specific compressor that will have enough power to do my job? – Joy Karmoker Jul 11 '21 at 16:49
  • @JoyKarmoker I'm afraid I don't have any experience with dimensioning analytically this type of systems. The few systems I've developed were trial and error, and there were for much grappling fruits (not for transferring material). What I did, was I went to a local developer, saw what was available, and had a lot of help with all the details. If I were to calculate it analytically, I think I would be at least +- 80%. – NMech Jul 11 '21 at 18:06