tank fill rate

[HeatCker]

what is the correct or usual rate at which an empty tank is filled .... ie ???? psi per minute

 

[tbone1004]

luxfer says to fill between 300-600psi/min. Not sure I've seen one out for steel tanks though they get quite hot even at a 500psi/min fill rate

 

[Basking Ridge Diver]

I have been know to fill between 100 and 200 per minute - I have lots of time on my hands and generally only fill 4 bottles at a time. I am lucky I have access to my own compressor - I try to keep the tanks as cool as I can. I fill both aluminum and LP steel tanks.
I have occasionally gone over 500 psi but that is too hot for my liking and only when I am really in a hurry. I want my tanks to last - this is not official this is what I do based on past experience and limited knowledge on tank expansion and heat transfer.

 

[spectrum]

The 600 PSI/ minute number is common. I think I have seen CGA guidance more like 300-400 PSI/minute.

SCBA rapid refills have become quite common on the order of 45 seconds for aluminum and composites. See here.

I have a LDS that ca do a 30 second fill.

Pete

 

[bl6394]

Also depends upon what you are filling the tank with... O2 (50-60 psi/min). Nitrox (200 psi / min). Air (400-600 psi/min)

 

[bl6394]

The 600 PSI/ minute number is common. I think I have seen CGA guidance more like 300-400 PSI/minute.

SCBA rapid refills have become quite common on the order of 45 seconds for aluminum and composites. See here.

I have a LDS that ca do a 30 second fill.

Pete

The gas temperatures you get from compression heating are considerable - approaching 700 degrees F. Not good for the cylinder. And when it cools - you'll loose 15% of the pressure (e.g. 3000 hot may cool to 2600). Not a good practice.

 

[DEdiveguy1]

In its Fill Station Operator Hazmat training, PSI recommends filling air at 300-600 psi/min, nitrox at 200 psi/min, oxygen at 60 psi/min.

 

[HeatCker]

thanks for the info guys

 

[nadwidny]

In its Fill Station Operator Hazmat training, PSI recommends filling air at 300-600 psi/min, nitrox at 200 psi/min, oxygen at 60 psi/min.

Do they say why they recommend those rates?

 

[bl6394]

Do they say why they recommend those rates?

It's not just PSI - it's also a recommendation from a number of agencies (TDI, PADI) with respect to blending technique.

Slow fills for O2 prevent compression heating (adiabatic compression) that could result in ignition. The lower the concentration of oxygen - the lower the risk of igniting hydrocarbons or seals in the system. Hence the faster fill rates for lower fractions of O2.

But that is a qualitative argument. And no, I have not seen a quantitative argument to why 60 for O2 is better than 40 or not as good as 100.