Coming soon to this page: the science bit, complete with the theory, the diagrams and the long words.
While you're waiting for that, you might want to check out these sciency distractions
Fizzkeeper chemistry paper
Here's a paper all about fizzkeepers
The Fizz Keeper, a Case Study in Chemical Education, Equilibrium, and Kinetics (Reed Howald, Montana State University, 1999)We didn't write it. We just found it on the web and thought it was a cool title. Sadly you have to subscribe to the Journal of Chemical Education in order to read any more than the abstract. We have not yet been able to convince ourselves that it's worth $60 to read one paper.
It does look pretty interesting though. The writer claims that because fizzkeepers only introduce air, not CO2, they are "...effective for storage of resealed pop containers for hours, but not for periods of weeks or months."
Could make an interesting (and rather controversial) read.
Fizzkeepers and physics
Fizzkeepers are often used to demonstrate physics concepts in the classroom. This article in The Physics Teacher describes how "your class can measure the molecular mass of gases to an accuracy of about 10% using a device that costs only a few dollars". You guessed it, he's talking about a fizzkeeper. The introduction to the article describes how fizzkeepers work.
These are just some of the fizzkeeper related highlights from the US Patent database.
Willard A Saxby & Robert D Pikula (January 9, 1984) US patent # 4,524,877 Pressurizing and closure apparatus for carbonated beverage containers
Tommy R. Robinson and Michael B. Beyer (February 9, 1988) US patent # 4,723,670
Pump closure for carbonated beverage container
Paul M Chamberlain (February 1, 1994) US patent # 5,282,495
Beverage container pressurizing system
Dion P DiFelice (Mar 5, 2002) US patent # 6,352,165
Replacement cap and pressurizing mechanism for bottle