how long to keep air ?

[Corlett]

Hello all
Just a quick question, once a tank is full is there a `` use by date ´´ before the oxygen becomes compromised, if it does so ?

 

[Dive Right In Scuba 2]

My personal rule is a year at the most...just stick to the VIP date on the inspection sticker. I'm sure some of the others will chime in with some science on the subject, but this rule has always worked for me.

 

[Subcooled]

78% of air is nitrogen (inert) and 1% is argon (noble). Only the remaining 21% oxygen could react (with the metal - think of rust). As long as the contents have 21% oxygen; all is well. Keep the inside of the cylinder dry (maintain the compressor and its filters).

Just make sure that nothing grows inside the cylinder

It's healthy to look inside once a year.

 

[GrumpyOldGuy]

Its not really a question of if the air is good or not. Even with a good amount of oxidation (rust) , the amount of oxygen consumed is small. The question is if you have a wet fill, how long do you want to leave it in your tank?

 

[Corlett]

Thanks for the answers.
I am more of a seasonal diver due to projects I am involved with, or for 2 months each year projects are on holt, and combined with bad weather it is the perfect time to do all maintainance on the equipment..
Will be looking at compressor soon.

 

[Peter69_56]

Thanks for the answers.
I am more of a seasonal diver due to projects I am involved with, or for 2 months each year projects are on holt, and combined with bad weather it is the perfect time to do all maintainance on the equipment..
Will be looking at compressor soon.

Don't buy a cheap Chinese special, I did and regretted it. I now have a Bauer and am very happy. Probably lost about $1200 in the changeover. The Chinese special I and could never have met air standards and could not be considered a breathing air compressor even though it was sold as one. Filter element was small, no priority valve and badly built etc etc.

 

[Corlett]

I have one all ready, a coltri, which I need to plumb in and get inspected and serviced, one more thing is PADI allways says to never competeley empty your tank, but does not specify exactly what is an acceptable amount to leave in the tank, 30 / 40 / 50 Bar ?
Speaking to a tank inspector today he explained to me that only 3 / 5 Bars is enough and if not better, explaination : the more oxygen left in the tank the more oxidization or oxygen to ```feed ´´ rust, 3 to 5 Bar is ideal because if any oxidization or rust starts it will soon consume all the oxygen in the tank.

Might have a valid point...

 

[daz88]

doesn't matter, just as long as there is positive pressure in the tank

 

[Peter69_56]

I have one all ready, a coltri, which I need to plumb in and get inspected and serviced, one more thing is PADI allways says to never competeley empty your tank, but does not specify exactly what is an acceptable amount to leave in the tank, 30 / 40 / 50 Bar ?
Speaking to a tank inspector today he explained to me that only 3 / 5 Bars is enough and if not better, explaination : the more oxygen left in the tank the more oxidization or oxygen to ```feed ´´ rust, 3 to 5 Bar is ideal because if any oxidization or rust starts it will soon consume all the oxygen in the tank.

Might have a valid point...

Its more about keeping moisture out of the tank. If positive pressure moisture cannot get in unless introduced as wet air when filling. If the air is dry you should not get rust in the tank. If there is rust in the tank, its either wet air or not blowing the salt water out of the valve fitting before filling. Thus when air is pumped in the remaining water in the valve head is taken into the tank, thus immediately promoting rust.

 

[Corlett]

Its more about keeping moisture out of the tank. If positive pressure moisture cannot get in unless introduced as wet air when filling. If the air is dry you should not get rust in the tank. If there is rust in the tank, its either wet air or not blowing the salt water out of the valve fitting before filling. Thus when air is pumped in the remaining water in the valve head is taken into the tank, thus immediately promoting rust.

Most probably `` wet air ´´ :thumbdown:

---------- Post added November 21st, 2014 at 06:05 PM ----------

One last question, allthough a bit off the subject, but I might as well get my answered questioned all in the one go.

Why does ice form when emptying a cylinder & is there a danger of freezing and stressing, should you release the air in seperate blasts or constantly and slowly, or does it not matter ? ?

:cold: