How do you measure the air pressure inside a balloon?

[thecooltodd]

Unfortunately when I google the answer, the results are just how to use a balloon to measure air pressure. I want to be able to monitor the internal pressure of a balloon using a digital barometer.

1) How would I go about setting up such a system?
2) Would the barometer have to be on the inside of the balloon or are there ways of measuring the air pressure inside by letting out some air?
3) What type of digital barometer should I use?
4) What is the typical air pressure of a balloon?

 

[berkeman]

Unfortunately when I google the answer, the results are just how to use a balloon to measure air pressure. I want to be able to monitor the internal pressure of a balloon using a digital barometer.

1) How would I go about setting up such a system?
2) Would the barometer have to be on the inside of the balloon or are there ways of measuring the air pressure inside by letting out some air?
3) What type of digital barometer should I use?
4) What is the typical air pressure of a balloon?

You would use an "Absolute" pressure sensor, as described at this wikipedia page:

http://en.wikipedia.org/wiki/Pressure_sensor

You could use a relative/gauge pressure sensor if you could pass atmospheric pressure air through a tube that goes through where the knot normally goes on the balloon (like seal it with a rubber band around the tube).

 

[Chestermiller]

If you know the deformational mechanical properties of the rubber comprising the balloon, the uninflated surface area of the balloon, the undeformed thickness of the rubber, and, if the balloon is close to a perfect sphere, then you can calculate the gas pressure inside the balloon as a function of the balloon diameter. Then, for any measured diameter, you will know the pressure inside the balloon.

The pressure inside a balloon will typically be less than 2 psi above atmospheric.

 

[DrZoidberg]

You would need a digital pressure gauge, not a barometer. But those can cost several hundred dollars.
Why not instead simply use some aquarium tubing plus water to measure the pressure. Take a bottle with a plastic screw on cap (coke bottle), make two holes in the cap, put two tubes through and glue them in with epoxy or super glue. Then you fill the bottle halfway with water. One of the two tubes should reach all the way to the bottom, the other should not touch the water. Then you connect a filled balloon to the shorter tube and see how far the water rises in the other. If it rises by 1 meter that means the pressure is 1N/cm^2 = 10000 N/m^2 = 10 kPa
Most toy balloons have around 5kPa. Modelling balloons have 10 - 20 kPa.

 

[PJC01]

1) To set up a system for measuring the air pressure inside a balloon using a digital barometer, you would need to first attach the barometer to the balloon. This can be done by using a small piece of tape or adhesive to secure the barometer to the surface of the balloon. You may also need to attach a small tube or straw to the barometer to ensure that the sensitive sensor is not directly exposed to the air inside the balloon.

2) The barometer should be placed inside the balloon in order to accurately measure the internal air pressure. This is because the pressure inside the balloon is likely to be higher than the outside pressure, and letting out some air could affect the accuracy of the measurement.

3) When choosing a digital barometer for this purpose, it is important to select one with a high level of sensitivity and accuracy. This will ensure that you are able to get precise readings of the air pressure inside the balloon. Additionally, it may be helpful to choose a barometer with a data logging feature, which will allow you to track changes in pressure over time.

4) The typical air pressure inside a balloon can vary depending on a number of factors, including the type of balloon, its size, and the amount of air inside. However, a general range for the pressure inside a balloon could be between 1-2 pounds per square inch (psi). Keep in mind that this is just an estimate and may vary in different situations.