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Portable Air Tank Expiration Date


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#1 dthomp17 OFFLINE  

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Posted July 30, 2016 - 08:55 PM

I learned something today that I was totally unaware of and possibly some of you guys were unaware as well. I was cleaning up a portable air tank, a friend recently gave me, and I noticed it had stamped on it "Discard after 2004". The tank looked to be in great shape and I'm thinking, why throw away a perfectly good air tank? I had always thought that portable tanks and compressor tanks would eventually develop small pin hole leaks from rust and wouldn't hold air any more. At that point they would be discarded and you would have to buy new. After searching the internet for additional information, it appears you can't really tell much about a portable tank's condition by it's outward appearance. Because of water condensation (and no easy way to drain it), it can look great on the outside and rusted almost through on the inside resulting in a potential explosion when pressurized. They can also develop metal fatigue from repeatedly being pressurized and depressurized resulting in a weak spot. I believe the potential for injury from an exploding portable tank would be greater than that from an exploding compressor tank because when working with a portable tank, or filling the tank, you are usually very close to the tank.

From the information I got off the internet, tanks can be tested and re-certified and the expiration date extended. However, re-certification cost would probably approach that of buying a new tank.

After learning this, I now have to decide what to do with my freebie air tank. An old converted tank, that I've used as a portable air tank for the last 20+ years, will be thrown away very soon.
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#2 shorty ONLINE  

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Posted July 30, 2016 - 08:59 PM

Hmm. I wonder what my tank might tell me. Need to check it this week.

#3 boyscout862 OFFLINE  

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Posted July 30, 2016 - 09:09 PM

One of my tanks is from a WWII bomber(70+ years). No expiration date on it. Good Luck, Rick
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#4 JBRamsey ONLINE  

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Posted July 30, 2016 - 09:24 PM

All pressure tanks have expiration dates--oxygen, acetylene,your propane tank for your gas grill. Locally they've been enforcing the expiration date at propane filling stations and won't fill an expired tank.
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#5 ol' stonebreaker OFFLINE  

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Posted July 30, 2016 - 09:32 PM

One of my tanks is from a WWII bomber(70+ years). No expiration date on it. Good Luck, Rick

  Sounds like mine, all stainless steel= no rust. I have two plumbers straps around it attached to a  carry handle. 

                                  Mike


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#6 dthomp17 OFFLINE  

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Posted July 30, 2016 - 10:17 PM

Do you think it would be possible to look inside a portable air tank with an endoscopic camera, that attaches to your computer or smart phone, and tell if there was significant rust damage present????? You can get a camera in the $10 to $20 range off of ebay but don't know how good the resolution and picture quality would be. You could unscrew the air fitting and I believe the camera would fit through the hole.  Just a thought before I throw away the tank.


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#7 secondtry OFFLINE  

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Posted July 30, 2016 - 11:13 PM

  Getting the camera to focus properly would be a real trick. Being sure you inspected the the entire tank would be impossible. I am by no means an expert but I understand that re certification of a pressure tank involves filling the tank with water and pressurizing that water to several times the rated pressure of the tank.  Hydrostatic test. Since the tank is full of uncompressable water it can rupture without exploding.    Don


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#8 Cat385B ONLINE  

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Posted July 30, 2016 - 11:30 PM

Do you think it would be possible to look inside a portable air tank with an endoscopic camera


Sure, the trick is convincing a doctor to do it.
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#9 chieffan OFFLINE  

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Posted July 31, 2016 - 08:17 AM

Have heard of expiration dates on propane equipment like tanks, grill bottles and regulators.  That is for prevention of explosive gases from escaping.  Never heard of it on air tanks.  The chance of an air tank "exploding" I think would be null.  Might leak air some place.


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#10 chieffan OFFLINE  

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Posted July 31, 2016 - 08:19 AM

Do you think it would be possible to look inside a portable air tank with an endoscopic camera, that attaches to your computer or smart phone, and tell if there was significant rust damage present????? You can get a camera in the $10 to $20 range off of ebay but don't know how good the resolution and picture quality would be. You could unscrew the air fitting and I believe the camera would fit through the hole.  Just a thought before I throw away the tank.

If the tank isn't leaking don't worry about it.  Never heard of an air tank exploding.  Leaking yes but exploding, no.


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#11 ol' stonebreaker OFFLINE  

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Posted July 31, 2016 - 08:32 AM

If the tank isn't leaking don't worry about it.  Never heard of an air tank exploding.  Leaking yes but exploding, no.

  I beg to differ!! I had one rupture( there is a difference) about 6 1/2 yrs ago when I was kneeling beside it monitoring the pressure and checking the pressure relief valve. Cracked the left tibia and femur and shattered the bones in the left hand, so just because you haven't heard of it doesn't mean it didn't happen.

                                          Mike 


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#12 KC9KAS OFFLINE  

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Posted July 31, 2016 - 08:33 AM

The chance of an air tank "exploding" I think would be null.  Might leak air some place.

WRONG!

An explosion is "a rapid release of pressure", and an air tank can do this easily and become an un-guided missile!

 

Our fire department SCBA tanks had to be hydro tested every 6 years...maybe more often with the new composite materials.


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#13 JBRamsey ONLINE  

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Posted July 31, 2016 - 09:42 AM

Ok, so let's think through this. You buy a $ 20 camera, get it inside a tank and see a few spots of rust. How do you know if the rust is surface rust or affects the tank integrity? You don't.

Secondary is right about the testing procedure. KC9KAS is also right about them exploding. It's not whether the gas inside is flammable or not. A pressurized cylinder of any gas is a bomb. Everytime you fill the tank, it fatigues the metal just a little. Let it sit in the hot sun and it expands even more. That's why tanks have pressure reliefs on them.

As far as the old tanks not having expirations on them, we didn't know as much back then either. Look at all the things we know today that we didn't years ago--asbestos, loud noises damaging our hearing, sun and skin cancer. The list goes on and on.

Ol'Stonebreaker's family is lucky that he only had broken bones. A high school friend had a bike tire explode on him. He almost lost vision in one of his eyes.

Last summer my boys and the neighbor boys took a water bottle and with a bunch of duct tape connected it to their bike pump. After a bunch of pumping the bottle exploded. Like a bomb. You would be surprised how loud it was. My oldest was the designated pumper. He felt the blast. Now take a five or seven gallon STEEL tank with a 110 psi or more in it and explode it two feet from you. Most often when I'm using my portable tank at least part of me is touching the tank.

A five gallon portable tank from Harbor Freight is 29.99 before the 20% off coupon which drops it to $ 24.

I think I'd go for a new tank for the difference. The $ 24 is much less than most medical co-pays and cheaper than an undertaker.
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#14 dthomp17 OFFLINE  

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Posted July 31, 2016 - 03:17 PM

Ok, so let's think through this. You buy a $ 20 camera, get it inside a tank and see a few spots of rust. How do you know if the rust is surface rust or affects the tank integrity? You don't.

Secondary is right about the testing procedure. KC9KAS is also right about them exploding. It's not whether the gas inside is flammable or not. A pressurized cylinder of any gas is a bomb. Everytime you fill the tank, it fatigues the metal just a little. Let it sit in the hot sun and it expands even more. That's why tanks have pressure reliefs on them.

As far as the old tanks not having expirations on them, we didn't know as much back then either. Look at all the things we know today that we didn't years ago--asbestos, loud noises damaging our hearing, sun and skin cancer. The list goes on and on.

Ol'Stonebreaker's family is lucky that he only had broken bones. A high school friend had a bike tire explode on him. He almost lost vision in one of his eyes.

Last summer my boys and the neighbor boys took a water bottle and with a bunch of duct tape connected it to their bike pump. After a bunch of pumping the bottle exploded. Like a bomb. You would be surprised how loud it was. My oldest was the designated pumper. He felt the blast. Now take a five or seven gallon STEEL tank with a 110 psi or more in it and explode it two feet from you. Most often when I'm using my portable tank at least part of me is touching the tank.

A five gallon portable tank from Harbor Freight is 29.99 before the 20% off coupon which drops it to $ 24.

I think I'd go for a new tank for the difference. The $ 24 is much less than most medical co-pays and cheaper than an undertaker.

 

Thanks for all the comments and I've decided that even though the explosion risk may be very small, there is a risk involved (as verified by ol' stonbreaker) and it's not worth  trying to save the $20-$30 for a new tank


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#15 petrj6 OFFLINE  

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Posted July 31, 2016 - 07:08 PM

     Re-certifying a tank is pretty basic but is still expensive due to the ASME stamp required by the tank shop.  Generally they UT the tank for thickness to verify there are no thin spots below the threshold or tolerances, then they fill full of water and test to 1-1/2 times the capacity to verify no leaks and then it is good to go.  for the $30 you are better to get  new tank and have peace of mind.

                                                                                                    Pete


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