Different cylinder sizes

[time2dive]

My steel 72's are roughly 6.65x25 and my 38's are roughly 6.75x20. That being said I have a number of tanks that are not....

I have a tank that is 6.75x24 1800psi, one that is 6.5x21 2015 psi and a set of doubles that have concave bottoms and are 7.75x23 1800 psi.
Does anyone know what size these other tanks are?

[SurfLung]

- I think there's a formula for figuring it out but you first need to know the internal volume... Which I think you get by filling up the tank with liquid and then measuring how much liquid it took... cubic inches or cc's. I didn't want to find out bad enough to do all that...

[sitkadiver]

You're best bet is to check the tank chart in Basic Scuba. I'm at work, so I cannot referrence it now for you. Mr. Roberts, I beleave, also has the equation in the book.

There are a ton of size charts on the internet, so you can always check the size of a comparable tank and then use working pressure to find a close percentage of your tank size - or vice versa. Your search will be easier if you go by manufacturer, but you'll still get a bunch of hits.