Tank Filling Timings

[Roma88]

Hi,

I am new to scuba diving. I was wondering, if you had a powerful compressor, how long it would take to fill a 10 litre tank to about 300 bar?

I heard it was one bar per second.

Also, as the tank gets fuller does it take longer for one bar to be put into the tank (in comparrison to an empty tank?)

Thanks alot.

 

[spectrum]

I have local dive shop that can do 200 bar in 30 seconds, I timed them!!!! And I have a witness.

Given the lessening of the pressure delta between the source and tank beng filled I'm sure the velocity will tapper off.

You should be more concerned about how slowly you can get it filled. A fast fill will be a hot fill and after cooling leave you 10% or more short.

 

[fweber]

The slower the better. Ideally an Aluminum 80/11liter should not be filled any quicker than about 500psi/minute or .5 bar/second. I wouldn't worry about how fast a fill you can get, but how slow a fill you recieve. Slower results in less heating and subsequently less pressure loss do to cooling.

In absolute Life Or Death situations firemen are know to back up to truck mounted fill banks without removing their SCBA and go from 0 to 300 bar in under 60 seconds...:11:

 

[Roma88]

Wow, thats fast filling. How big are these compression machines? Got any make names or pictures? I want to look them up.

Thanks for all the help.

 

[pescador775]

Roma, a "bank" is not a compressor, it consists of several HP cylinders of large capacity. I hope that your questions have been answered satisfactorily. Good luck.

 

[Roma88]

Hi,

Yeah thanks, I know what a bank is. My post was more aimed at spectrums reply.

Anyways, Spectrum- This diving shop, do they fill tanks from banks or compressors?

Cheers in advance.

 

[spectrum]

Hi,

Yeah thanks, I know what a bank is. My post was more aimed at spectrums reply.

Anyways, Spectrum- This diving shop, do they fill tanks from banks or compressors?

Cheers in advance.

The dastardly deed was done from the banks. I can't fathom the compressor that could drive 4 cylinders to 3450 that fast.

Pete

 

[Rick Inman]

I have local dive shop that can do 200 bar in 30 seconds, I timed them!!!!

Cool.

Ah... I mean, hot. Very hot! :11:

 

[AndyA]

NIOSH recommends filling cylinders (without regard to type) at a rate below 600 psig per minute and refrain from over-pressurizing or fast filling. I fill at 300-400 psig

 

[meesier42]

I was trained by the Navy not to fill beyond 300psi/min this slower rate mimizes the adiabatic heating that then results in tank damage. If you read the studies of all the tank failures out there the most common reason is high filling rate. There are reasons that you are supposed to do a fill with the neck of the tank underwater while filling, and then max recommended is 500psi. Navy we where trained NTE 300psi/min wet, 200psi/ min dry.

If the shop does a hot fill like that you should make a HUGE stink about it, at least if it is your tank.