Use household items to approximate human lung capacity

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Spinnor
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I would like suggestions for using household items to approximate human lung capacity. Thinking my lung capacity was at issue (quick research showed it to be about 4.8 liters) I thought how I might measure it using household items and I came up with the following.

The opening of a thin plastic bag was wrapped tightly around a short piece of plastic hose and then a rubber band wrapped tightly around that with care to not inflate the plastic bag. The top of a plastic 1 gallon water container was removed and the un-inflated plastic bag was inserted into the container. Inhaling as much air as I could I then inflated the plastic bag in the container and was surprised that I was able to easily inflate the plastic bag completely inside its 1 gallon enclosure. I needed more capacity so I repeated the experiment with both a gallon container and a quart container and was able to just inflate both bags, one in the gallon container and one in a quart container, roughly measuring average lung capacity.

Suggestions on how to improve this measurement using common and inexpensive materials appreciated.

https://www.lung.org/lung-health-diseases/how-lungs-work/lung-capacity-and-aging
 

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Find a rigid transparent container with a neck. Fill it with water and hold it inverted with the neck submerged. Blow your air into that with a short hose. The water level in the inverted container now indicates the volume expelled.

It can be done with a cup, say half liter. Just fill the thing multiple times until you run out of air. A cup might work better than a drink bottle due to the speed at which it can be refilled with water on each iteration.
 
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Merlin3189
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I used to use a demijohn filled with water and inverted in a bowl of water. Then simply blow air in through a plastic tube. Two easy ways to measure the volume. Rough measurement can be marked on side as you fill with water. More accurately, measure the full volume, then measure the water left after expt.

As you say, 4.5 l is not enough for a fit adult male. I used two jars and switched the tube when one was nearly filled with air.
 
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Spinnor
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I like that method, very precise. The weight of the water will slightly lower the pressure of the water over estimating volume but high school physics gives the correction?
 
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An improvement of my technique? Get 10 gallon trash can plastic bag liner and seal a short length of hose as in post 1. Then using a bucket of know volume see how many lungfuls of air it takes to inflate the plastic bag in the bucket, the last lungful will need to be estimated.
 
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Spinnor
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I had to Google demijohn, I have one:smile:.
 
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I like that method, very precise. The weight of the water will slightly lower the pressure of the water over estimating volume but high school physics gives the correction?
Pressure on the water in the container can be eliminated by having it level with the water surface when you note the air level at the end of the exhale. The air then will be at normal pressure and will fill the volume as marked on the container.

As for the trash bag, do you really know where it needs to be tied off to hold exactly 10 gallons? Also, you're likely to pass out if you take say 8 full lungfulls to get that bag inflated. I once had to inflate an air mattress by blowing, and I had to run laps while holding my breath between blows in attempt to not over-oxygenate myself.
 
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Spinnor
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As for the trash bag, do you really know where it needs to be tied off to hold exactly 10 gallons?
That is where the container of known volume comes in. You inflate the bag in the container and when the inflated bag fills the container you will approximate the volume, a "lid" helps.

Just did 4 lungfuls each over two experiments to displace 5 gallons (minus about a cup of water) and did not get faint.

1589910804082.png


1589911105384.png
 
  • #9
Spinnor
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16 liter bucket with 10 gallon trash bag and lid, dog for a sense of scale.

1589911547548.png


16 liter bucket with 10 gallon trash bag.

1589911622345.png


With some care, 2 3/4 lungfuls then 2 7/8 lungfuls to fill bag in 16 liter bucket.
 
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The weight of the water will slightly lower the pressure of the water over estimating volume but high school physics gives the correction?
Okay, or you could just lower (or raise) the bottle until the water levels line up, then cap it.
 
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  • #12
Baluncore
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I would like suggestions for using household items to approximate human lung capacity.
You are not measuring lung capacity. You are measuring the tidal volume.
 
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