What's stamped on the cylinder means very little. One of our distributers will couple a dozen or so full cylinders and several empty cylinders into a manifold bank and equalize the pressure by filling the empties from the full ones.
If this is your distributors words - get another distributors fast! Those stamped numbers and symbols mean EVERYTHING! No cylinder can be filled, sold or transported in the U.S. without them by penalty of FEDERAL law DOT)
Hers is the fill procedure for oxygen:
Check for contamination (dirt and oil on cylinder)
Odor test (crack valve and check for positive pressure and smell content for traces of acetylene, - if no pressure inject nitrogen and repeat)
hook to manifold (most tandem fill 10 to 30 cylinders per bank)
open all cylinders and blow down contents
vacuum pump to -20in mercury(?)
start Oxygen fill
at 1800 read cylinder temp and consult chart for finish fill pressure.
shut off at finish pressure
remove from bank
cap.
That was the "official" Linde/Praxair/Airgas methode
IF your distributor is "coupling a dozen or so full cylinders and several empty cylinders into a manifold bank and equalize the pressure by filling the empties from the full ones"
Then they are "cascade filling". This is often done by fire departments and ambulances to keep their equipment full.
Consider this: IF 5- 2400psi 100% filled cylinders are couple to 5- 0% full cylinders and "balanced" - the best you will get is 10 50% full cylinders at around 1200psi. So they took 5 full cylinders at their cost of say $5 each ($25 investment), transfilled them into 5 empties, balanced them to wind up with 10 "full" 1200psi (cough, cough) and sold each one for $25 ($250 gross), And they probably broke several federal laws to boot!
If your distributor is selling you a cylinder filled to anything less than stamped rated pressure, they are doing you a disservice and potential putting you in danger with improperly serviced cylinders(rupture hazard). You can cascade and fill a cylinder to full but that method is way more wastefully than productive. You are paying for waste ,laziness and profit gouging.
If you can't tell, I was in this business for a few years.