How to Build a Spirometer for a Science Fair Project
Doctors use spirometers to help determine a patient’s lung capacity. Patients are instructed to take a deep breath and then expel all air from their lungs into the spirometer mouthpiece; the spirometer will record the force of the breath and the time it took for the patient to empty his lungs.
As a science fair project, a handmade spirometer will help students learn how to conduct a lung-capacity test, record data and draw conclusions. Students can hypothesize about what type of person, such as boy, girl, or young or old person, might have the greatest lung capacity.
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Things You'll Need
- Empty 3-liter soda bottle with cap
- Measuring cup, marked in milliliters
- Marker
- Water
- Large bucket
- Plastic tubing
- Volunteers
Instructions
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Making the Spirometer
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1
Add 500 ml of water to the empty soda bottle, and use the marker to indicate the water level. Add another 500 ml and mark the water level. Continue adding water and marking the bottle until the bottle is completely full. Place the cap on the bottle.
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2
Hold the filled soda bottle so that about half the bottle is submerged in the bucket, and add water to the bucket until the water covers the soda bottle.
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3
Turn the bottle upside-down, in the water, and remove the cap. Keeping the bottle under the water prevents air bubbles from entering the soda bottle. Place an end of the 2.5-foot piece of plastic tubing inside the bottle, and have a volunteer hold the bottle inside the water.
Spirometer Breath Test
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4
Record the normal breath of a tester by having him take a normal breath in and then exhale normally into the plastic tubing. You should find that as the tester breaths into the tube, air is forced into the bottle and pushes the water out. Record the amount of air in the bottle. The amount of air inside the bottle is equivalent to the amount of air that was inside the tester’s lungs.
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5
Remove the bottle from the bucket and refill with water. Replace the cap, submerge in the bucket and remove the cap underwater. Then reinsert the plastic tubing.
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6
As a volunteer holds the bottle under the water, ask the same breath tester from Step 1 to inhale as much air as his lungs can hold and then exhale all his air into the plastic tubing. Record the amount of air left in the bottle.
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7
Retest the project with a variety of volunteers, such as young and old people or healthy vs. unhealthy people; analyze the data.
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8
Compare results between male and female testers, and between different age groups. Compare your hypothesis to the actual results and draw conclusions as to who has the largest lung capacity.
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Tips & Warnings
Consider expanding the project by retesting the volunteers after they have engaged in a brief exercise such as jumping jacks or running in place.
Science fair judges will look for the participant’s adherence to the scientific method and following the rules of the individual science fair.
Although some science fairs may not allow the use of liquids at the display table, bring the spirometer with your on judging day so that the judges can see your exact model.
Remember to take photos throughout the testing process, and consider video tape recording the results for review, and to help when analyzing the data.
In ensure cleanliness, use a new piece of plastic tubing for each tester. Keep in mind that the tubing must be the same length for each tester to keep the test accurate.
