Leaving compressed air in air tank/ok or bad?

I have a 6.8 liter carbon fiber refill tank and sometimes when I shoot I have a lot of air left. Is it bad to leave the compressed air in the tank to use over a period of maybe a month of should it be drained everytime I am done. I read somewhere that leaving about 1000 psi is okay for the regulator but the article did not mention 3000 psi. Has anyone left that much air in their refill tank?

thanks for the great info Airgun Nation
 
Valves are not put under any pressure before selling so I cannot see any harm to leave the them unpressurized . There may be some chance of ingression of humidity into the tank but I think the problem is minimal. One advantage of putting tanks under pressure is that O rings will remain tightly seated so there will be less chance of having leakage due to bad seating. This is more true for old O rings that have lost some elasticity.
 
Valves are not put under any pressure before selling so I cannot see any harm to leave the them unpressurized . There may be some chance of ingression of humidity into the tank but I think the problem is minimal. One advantage of putting tanks under pressure is that O rings will remain tightly seated so there will be less chance of having leakage due to bad seating. This is more true for old O rings that have lost some elasticity.

The reason for the advice is a tank with positive pressure is unable to ingest anything undesirable and it proves that it has been stored in a sealed condition. Otherwise, it is impossible to predict the condition of and or the contamination of the internal space, without a light-scope.
 
Here's a good one... How's about a brand new Air Hog 88 CU FT CF 4500psi never ever been filled had all fittings installed since new roughly 20 years ago and never once filled and cosmetically TODAY is perfect that had been stored in a cool closet and forgotten. Still ok? Would it be considered as safe as a 2020 mtg tank? Yo!
 
Here's a good one... How's about a brand new Air Hog 88 CU FT CF 4500psi never ever been filled had all fittings installed since new roughly 20 years ago and never once filled and cosmetically TODAY is perfect that had been stored in a cool closet and forgotten. Still ok? Would it be considered as safe as a 2020 mtg tank? Yo!

I assume that this is a hypothetical question as I doubt that Air Hog has been around that long. If it's 20 years old then it's 5 years out of date. If you took it for a hydro test, you wouldn't get it back in one piece without a hole drilled in it. The clock starts ticking on the date of birth, not when it is filled for the first time. If it has been stored in a sealed condition with a valve installed and closed it will probably be perfectly safe but filling it will break the law. My advice in the previous post was for used SCUBA bottles but the same principles apply for all tanks designed and made for breathable gasses.
 
For maximum safety I always discharge my 20# LP/Propane tanks after lighting up the grill to avoid any potential explosion. I usually use about 1/2# of propane so I'm only safely discharging 18.5# of propane into the air, based on temperature, based on entropy, based on gas expansion.

*grin*

Now this begs the real question -- why can I store 1# LP tanks indoors but not 20#? Why does the NFPA highly recommend against it? What if I duct taped twenty 1# tanks together or stacked them in a similar fashion as a 20# tank?

Perhaps something for Myth Busters to figure out assuming they have actuarial tables for MTBF?
 
Here's a good one... How's about a brand new Air Hog 88 CU FT CF 4500psi never ever been filled had all fittings installed since new roughly 20 years ago and never once filled and cosmetically TODAY is perfect that had been stored in a cool closet and forgotten. Still ok? Would it be considered as safe as a 2020 mtg tank? Yo!

Send it to me. No laws here on the ranch. DOT only has jurisdiction on items transported on a highway and my tanks never leave the ranch. ;)



@LMNOP Discharging propane into the air? VERY wasteful to say the least and leaves a cloud of heavier than air flammable gas that could just ignite if the right conditions are met. Hope your downwind neighbor is not a smoker! lol

1 gallon of liquid released = 270 gallons of vapor which in turn makes
over 10,000 gallons of flammable fuel to air mixture. A 20 lb tank therefore makes 40,000 gallons of flammable fuel to air mix. BOOM!!!