Air flow splitting in two directions

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Discussion Overview

The discussion revolves around the issue of air flow splitting in two directions when inflating balloons using an air pump. Participants explore the mechanics of balloon inflation, potential causes for unequal inflation, and experimental approaches to address the problem.

Discussion Character

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

Main Points Raised

  • One participant notes that when the air pump is activated, only one balloon fills while the other does not, despite there being no visible leaks or blockages.
  • Another participant suggests that the inflation pressure is highest at the start, and as one balloon inflates, the pressure decreases, potentially preventing the other balloon from inflating.
  • A suggestion is made to use a pneumatic flow divider to ensure equal air distribution to both balloons.
  • One participant proposes switching the positions of the balloons to see if the issue persists, indicating that differences in balloon material or thickness might affect inflation.
  • An experimental approach is suggested where a deflated balloon is connected to an inflated one via a pipe to test if air can transfer between them, which may illustrate the imbalance in inflation.
  • Another participant reiterates the idea that constraining one balloon's expansion could help in understanding the flow dynamics.
  • There is an encouragement for the original poster to think creatively about mechanisms that could be added to ensure both balloons inflate properly.

Areas of Agreement / Disagreement

Participants express various hypotheses and experimental ideas, but there is no consensus on the exact cause of the unequal inflation or a definitive solution to the problem. Multiple competing views and suggestions remain present throughout the discussion.

Contextual Notes

Some assumptions about the uniformity of balloon materials and the effectiveness of proposed solutions are not fully explored, leaving room for further investigation.

Gurleen
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TL;DR
I need this pump to fill up two balloons at once, somethinf is wrong with the airflow?
Basically the air pump on the left turns on and when it does, the balloon on the right fills up but the other does not. I also tried putting the pump upright but the left one just doesn’t seem to fill? Any ideas of why? There’s no air leak or blockage or anything
 

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If you have ever tried tried to blow up a balloon by yourself, it gets easier as the balloon gets bigger.
 
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Try constraining the expansion of the one on the right and see what happens.
 
What you need is a pneumatic flow divider. It let's equal amounts of air through both branches when a line splits.
 
From:
http://scipp.ucsc.edu/outreach/balloon/labs/InflationExp.htm
BalloonPressure.png


As you can see, and @256bits said above, the required inflation pressure is highest at the start of inflation. As soon as one balloon starts to inflate the pressure decreases and, due to the variations between balloons, when one starts inflating it keeps the pressure low enough that the other one can't inflate.

Cheers,
Tom
 
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Gurleen said:
... Any ideas of why?...
I would try switching the locations of the balloons.

If the pink balloon still fills up first, being on the left side of the tee, the problem may be in slight differences in the thickness or material of the walls, since each balloon, being of different color, may have been manufactured in different machines or by different processes.

If you could stop the air pump and still keep some pressure in the system, the value of the static pressure inside the plastic hose, tee and each balloon at zero air flow should be exactly the same.
 
Last edited:
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Experiment: Blow up a single balloon. Take a short length of pipe that the neck of a balloon can slip over and seal. Slip a deflated balloon over one end of the pipe. Then slip the inflated balloon over the other end of the pipe while pinching the neck to prevent deflation. Now release the inflated balloon allowing it to drain into the other through the pipe. My guess is it won't inflate the other balloon which would support what is said in post #2 causing the imbalance.
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I think an orifice in-line with each balloon would balance things out assuming your pump is able to build enough pressure to get a significant drop across each orifice.
 
256bits said:
If you have ever tried tried to blow up a balloon by yourself, it gets easier as the balloon gets bigger.
phinds said:
Try constraining the expansion of the one on the right and see what happens.
It's kind of fun to think up mechanisms that could be added to the setup to ensure that both balloons end up fully inflated. Since the poster seems to be doing a home science experiment, maybe it's a good exercise for them to try to think up some ways that the setup could be made to work with some additions to it.

@Gurleen -- can you come up with a couple ways that you could add to your setup to make both balloons blow up? :smile:
 

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