Co2 like n2o is a liquid and is based on volume which is measured by weight. The weight(or volume) is just the source of the product, the application of the prodcut is determined by pressure. Pressure is determined by a combination of volume and temperature. Temperature can change from pressure release(purging or use) as well as external modifiers like bottle warmers and/or cooling packs(or I use co2 bottles now to cool over pressure co2 and n2o bottles as it doesn't lower the volume when attempting to lower the pressure). The pressure reduction from purging is not all from lowering the volume, but also(or even moreso imo) from the temperature drop by releasing product (product increase raises temperature and pressure, while product decrease lowers temperature and of course pressure).
As many have said, filling is done by volume which is measured by weight. But monitoring those bottles for safe and cosistent use or storage should be done by pressure which can be done by having a capped gauge on hand that you can easily screw on any bottle in question. Solenoids don't like to be outside their pressure range of use for consistency reasons... anymore then the bottles, valves, lines and rupture discs like to be over their reccomended pressure ranges for safety reasons.
I had a bottle loaned to Deb and I this weekend from a fellow racer on here that just bought it from another racer on here that has been using it for for some time now.. it will be hitting the dumpster in the morning as it is not round nor straight(fottballed in one directiona dn hourglassed int he other). Weakness to these bottles can be from torching, over filling and heating as well as from over tightening clamping/mounting systems... if they aren't round adn concentric then they aren't worth the risk in my opinion.
800-1500psi is nothing to play with as Bill has showed in this thread(probavbly closer to the 2200-2500psi range in his case I'd imagine). If using high pressure equipment of any kind, I reccomend getting at least enough knowledge about it that you don't put your family members, friends, other racers or your self in jeapordy by being around your equipment... no less imnportant then handgun knowledge should something go wrong.
It's easy (at least for me) to get complacent with thsi stuff so I for one am thankful for the reminder caused by this thread and personally thanked Bill this weekend for sharing this here
Todd
