2
$\begingroup$

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?

$\endgroup$
4
  • $\begingroup$ blow compressed air down the pipe $\endgroup$
    – jsotola
    Jul 11 at 4:00
  • 1
    $\begingroup$ How big are these rocks? $\endgroup$
    – Solar Mike
    Jul 11 at 7:13
  • $\begingroup$ It is quite big actually, 6 inches in diameter on average $\endgroup$ Jul 11 at 16:25
  • $\begingroup$ You can rent a small front-end loader for less than the rental cost of the air compressor necessary to generate the venturi suction. $\endgroup$ Jul 11 at 20:18
1
$\begingroup$

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).

$\endgroup$
7
  • $\begingroup$ 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. $\endgroup$
    – Transistor
    Jul 11 at 12:53
  • $\begingroup$ Can you tell me how much will be the cost of building such a system? $\endgroup$ Jul 11 at 13:07
  • $\begingroup$ You can buy it of a shelf for a few dollars.building it from scratch would not be cost effective. $\endgroup$
    – NMech
    Jul 11 at 13:32
  • $\begingroup$ What will the total setup cost? $\endgroup$ Jul 11 at 16:22
  • $\begingroup$ That will depend on the local market. I'm guessing that the highest cost will be the supply of compressed air. $\endgroup$
    – NMech
    Jul 11 at 16:32

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.