I'm thinking of buying a CO2 cartridge bike pump to take with me on trips. I'm looking for opinions, I don't have any experience with them. Thanks!
@stfn Don't not bring your minipump if you're going on a long trip. You don't want to end up popping a tube and then being stuck without enough air to finish your trip. Yes you can bring multiple cartridges, but CO2 can pass through the valve a lot easier compared to regular air so you'll end up with a flat in the morning anyway
It has higher density: ideal gas (which air and co2 are well approximated by at room temperature and reasonable pressured) has the same number of moles per unit volume in the same pressure and temperature. CO2 has molecular mass of ~44, whereas nitrogen has one of ~28 (and oxygen ~32). So, the density of CO2 as a gas will be higher than that of air.
Density (mass density) has little to do with leakage rates through small holes. That's controlled by viscosity and/or by mean free travel distance (the average distance molecule travels before colliding with another one) at different scales, and maybe by something related to interaction with the material the sides of the hole are made of. I think that for ideal gases that aren't adsorbed by the wall of the hole the only meaningful property is molecule diameter.
That said, see the sibling comment: it appears that these leaks are not through the valve but through the tube itself (as in, the tube's rubber is somewhat co2-permeable in a way I don't really understand).
A set of random people on the internet (after excluding ones that say things that can't be real) is reasonably unanimous in claiming that it's because co2 is in some way "soluble" in solid rubber. See e.g. https://www.madsci.org/posts/archives/may98/895552329.Ch.r.html
Thank you, I learned something new.
@robryk @brandon @stfn co2 has lower density than classic air composition if i good remember