Suction Through Small & Large Pipes

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    Pipes Suction
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Discussion Overview

The discussion revolves around the relationship between pipe size and suction power in vacuum systems, particularly focusing on how different diameters affect the effectiveness of suction. Participants explore theoretical and practical implications, including specific applications and design considerations.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Experimental/applied

Main Points Raised

  • One participant questions whether a larger or smaller pipe increases or decreases suction power, seeking a link between pipe diameter and vacuum effectiveness.
  • Another participant suggests that 'suction power' is not straightforward to define and relates to the volume of air moved and the speed of airflow, indicating that a smaller inlet may increase speed but reduce overall effectiveness.
  • A participant specifies a desired suction area of 70mm x 300mm for cleaning dirt and water, implying a need for effective suction in a specific application.
  • Another participant proposes that a standard carpet attachment might suffice for the described application, while also suggesting that industrial solutions may be necessary for continuous operation.
  • A different perspective introduces the concept of centrifugal pumps, noting that suction lines are designed to minimize friction losses to maintain sufficient net positive suction head (NPSH).

Areas of Agreement / Disagreement

Participants express differing views on the relationship between pipe size and suction effectiveness, with no consensus on a definitive answer or formula. The discussion remains unresolved regarding the optimal design for specific applications.

Contextual Notes

Limitations include the lack of a clear definition of 'suction power' and the dependence on specific applications and design requirements. The discussion also highlights unresolved technical aspects related to friction losses and pump design.

BradINewton
Hi,

I am wondering if suction power from a vacuum for example that has a set amount of power, is increased or decreased depending on the size of pipe. Does a large pipe decease/ increase the suction power, or does a small pipe decease/ increase the suction power? Is there a link to the size in diameter of a pipe and a vacuums suction power that gives the best results? To make the answer easier assume that the pipe is straight. Thanks for your help in advance and any help would be appreciated.
 
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Good question! Welcome to PF.
The answer probably won't be very satisfactory for you, though because (i believe) there is no simple formula for this. The problem is with the term 'suction power', by which you probably mean 'effectiveness as a vacuum cleaner'. That, I guess, will be a combination of volume of air shifted per second and the speed at which it moves into the nozzle. You will notice that, if you partly or fully block off the end of your vac hose, the more the speed will increase. That implies that it is not doing as much work on the air with a small inlet hole - i.e. it is probably less effective. The fan is the thing that does the work and it will have been designed (/chosen) to shift a certain volume of air at a pressure difference at the nozzle. So the 'best' result, for a given fan / motor will depend on what you want. Do you want a lot of air over a big area (carpet or floor cleaning) or a smaller amount of his speed air ('crevice tool)?
Electrolux salesmen used to demonstrate the 'power' of their cylinder vacuum cleaners by removing the hose and holding the device inlet up to the ceiling. It would stay there! "Nothing sucks like an Electrolux" was their catch phrase. language changes over the years!
Do you have a specific application in your question or is it just for interest?
 
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Hi,

Thanks for your quick response. I would say I want as good as suction as I can get from a rectangle area of 70mm x 300mm. The hose in question will travel into a head that is then spread across the area of 70mm x 300mm and will be used to suck up dirt (small/dust) and water. Thanks again.
 
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What yo describe seems pretty much like the standard carpet attachment. Wouldn't that do?
If you need something for continuous running then an ordinary vacuum cleaner wouldn't be suitable. You would need something 'industrial' with an induction motor.
Have you tried google for some ideas" The Images option can help a lot with getting ideas for this sort of practical requirement.
 
The suction pipe of a centrifugal pump is not necessarily a larger bore (diameter)than the discharge pipe.
Suction lines are generally designed to keep friction losses to a minimum. This is in order to ensure sufficient available Net positive suction Head (NPSHa) to meet the NPSH required (NPSHr) by the pump.
 

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