A Fizz Keeper is a device that is sold to preserve the carbonation in soft drinks. We decided to see if they really work at maintaining pressure in bottles. We used a special soda bottle to which we attached tubing to connect to our Gas Pressure Sensor. We opened a bottle of soda, poured the contents into our special bottle, and then put the Fizz Keeper on the special bottle. Data collection was started. We quickly pumped up the pressure, and then let the bottle sit for 25 hours. As you can see, the pressure held fairly nicely.

Pressure data in a soda bottle capped with a Fizz Keeper

The more general question of whether a Fizz Keeper is effective at keeping the carbonation in an opened soda bottle is more complicated. It could be a good topic for discussion in a chemistry class. Since the Fizz Keeper pumps air, not CO2, into the bottle, does it really help at all in keeping the soda carbonated? For a good discussion on this, see http://en.wikipedia.org/wiki/Fizz_keeper