Suction Through Small & Large Pipes

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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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  • #2
sophiecentaur
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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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BradINewton
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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  • #4
sophiecentaur
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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.
 
  • #5
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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