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MOS95B t1_iy4dj6q wrote

Reply to comment by Sleepdprived in can you run an ethernet cable through an empty conduit in your house on your own? by VanillianArt

Works the other way too with a vacuum cleaner, but you're pulling rather than pushing

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Sleepdprived t1_iy4dro2 wrote

For vacuum I always want short fat pipes, for long pipes pressure works better, because air is stretchy.

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xhephaestusx t1_iy4f42d wrote

That doesnt really make sense to me, could you explain?

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Sleepdprived t1_iy4hkka wrote

Have you ever heard the term "thin air"? When you pull on air it stretches. The more air between you and what you want to pull the more space air has to stretch, and the more air there is to stretch. This overworks your vacuum. The longer the pipe, the less efficient the vacuum is. The air has friction against the surface area of the pipe and adds drag which stretches the air thin.

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xhephaestusx t1_iy4wu2w wrote

This makes some sense, and plays into the pressure differential example the other commenters gave, thanks for taking the time!

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dominus_aranearum t1_iy4op69 wrote

If it helps, water in a tube can only be 'vacuumed' up 10.3 meters before a literal vacuum is created. Whereas the distance water can be pushed vertically through the same tube is only limited by the pressure pushing the water. The more pressure, the higher the water goes.

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ajandl t1_iy4qxm5 wrote

The difference in pressure on the 2 sides of the wad is what pushes it.

If you use a vacuum, your high pressure side is roughly 15 psi and the other is maybe 0 (probably more, but whatever). So the max difference is 15 psi.

If you use pressure, the low pressure side is 15 psi, but the high side can now be whatever your compressor gives. Maybe 90 psi or more. So the pressure difference is much higher.

When pushing long distances where there will be more drag due to the line being pulled, the higher pressure difference will help more.

While the air is "stretchy," that's not really what matters.

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Sleepdprived t1_iy4t1ph wrote

Fair point, I am an hvac guy so Intake=short, fat, output= long pipe

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Robin_the_sidekick t1_iy4py0o wrote

When you feel wind, that air is pushing on you and compresses a bit against you. Air can stretch and thin out, or it can compress and push.

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