CFt3 To Ltrs

[JBFG]

My current tanks are marked in cubic feet (HP100) and with a rated pressure of 3442 PSI but I prefer to dive in bars and litres.

Anyone has a quick formula (or the answer) to translate these 2 data points into litres and bars?
I would like to set up my computer and AI with the correct information.

Thanx in advance!

 

[tbone1004]

@racanichou are they relatively new Fabers? If so 12.9L
https://kaplanindustries.com/wp-con...-Faber-Steel-Cylinder-Specifications-2019.pdf

 

[JBFG]

@tbone1004 Born in 2019!
Thank you for the link, 12.9 it is.
I just need to figure out that working pressure now. I think 237 Bar?

 

[Compressor]

1 bar is roughly 14.5 psi. You can round to 15.
Memorize a few pressure numbers:
3442 psi is about 237 or 240 bars
3000 psi is about 206 or roughly 200 bars. This is easy to remember. You can divide this by factor of 2 or 3 to figure out the next 2 in your head.
2000 psi is about 137 or roughly 140 bars.
1000 psi is about 68 bars or roughly 70 bars.
500 psi is about 35 bars.

You can take a sharpie than write this on your spg or tank.

 

[JBFG]

thanx!
I like the idea of writing it on the tank but my Perdix will also remember it for me once I make the necessary input.

 

[tbone1004]

@racanichou
you can go to the search bar in google and type in "3442psi in bar" and it will bring you to the google unit conversion and spit it out.
237bar

You can do the same from cubic ft to liters, however there is non-linear compression due to a compressibility factor that becomes significant above 3000psi. For air it's about 1.067 at the working pressure of that tank and room temp. Linear would call out 108cf or 3057 liters, however in reality it's about 101cf or 2865L

Isn't this fun?

 

[Compressor]

thanx!
I like the idea of writing it on the tank but my Perdix will also remember it for me once I make the necessary input.

I sharpied it on my spg (back of it).

 

[Diving Dubai]

@tbone1004 Born in 2019!
Thank you for the link, 12.9 it is.
I just need to figure out that working pressure now. I think 237 Bar?

We tend to round down to nice easy numbers, so you'd have a 12l at 230bar which means you're carrying 2760 litres (volume x Pressure)

Conveniently because that's how metric works - that means 1 bar = 12 litres

I dive 15l tanks and round my SAC up to 15l/m which means at 1 ata I'm breathing 1 bar/min, 2 bar/min at 2 ata etc etc. Thus on the fly gas time remaining calcs are really easy

 

[JBFG]

I like the way you think @Diving Dubai

@Compressor i only run transmitter on my SM tanks so no SPG to sharpie on and I won’t write on my transmitter. Tank it is.

 

[JBFG]

Conveniently because that's how metric works - that means 1 bar = 12 litres

and that’s why I want to do the permanent switch. I dove both metric and imperial and I find that metric just makes more sense and is so much easier to do on the fly.