# Simple safety question: Can I leave a portable air tank pressurized for long periods of time? **URL:** \ **Category:** Factual Questions\ **Created:** [December 31, 2013, 11:41pm UTC](https://boards.straightdope.com/t/simple-safety-question-can-i-leave-a-portable-air-tank-pressurized-for-long-periods-of-time/677600 "2013-12-31T23:41:44Z")\ **Posts on this page:** 8\ **Page:** 2
**Author:** ![Gbro](https://avatars.discourse-cdn.com/v4/letter/g/c6cbf5/32.png) [@Gbro](https://boards.straightdope.com/u/Gbro)\ **Post date:** [January 9, 2014, 5:49am UTC](https://boards.straightdope.com/t/simple-safety-question-can-i-leave-a-portable-air-tank-pressurized-for-long-periods-of-time/677600/21 "2014-01-09T05:49:18Z")
> [@bubba001](#): > > There isn’t enough pressure and volume to worry about. I’ve had one for 20 years, I leave pressure in it frequently. I do drain the air compressor, when I think about it. Generally, the pump on consumer grade compressors will fail before the tank rots out. I worked in a factory for 30 years. They had huge compressors, feeding twin 48 inch lines, maintaining a minimum of 150 psi. It was stepped down to 90 psi for most lines. They still needed dryers on machines, water in the air was just something to be managed, you couldn’t totally eliminate it. Well that statement is not correct > [@](#): > > There isn’t enough pressure and volume to worry about. When i worked in the Iron mines we had well over 200 air receivers (tanks) on the property that were below 200 psi. every couple years we would have a air tank inspection that was done by the Insurance underwriters and that inspector would look for the ASME label that is fixed to the tank and insure the pressure relief valve matched the label and that there was absolutely no welding or improper mountings, damage etc. No lable, the tank was removed immediately. My work truck had an axillary air receiver for a stand alone compressor and there was a dent in the tank about as big as a golf ball and 1/2 inch indented. We knew the tank would be cited and tried to hide the truck, but it was on his list and the truck was then red tagged until that tank was removed. Here are a couple pictures of the “Not Enough Pressure statement” [Here](https://www.dli.mn.gov/ccld/BoilerIncidentsAir2.asp) [Here](http://www.tractorshed.com/gallery/trouble/r1959.jpg) ---
**Author:** ![Machine\_Elf](https://avatars.discourse-cdn.com/v4/letter/m/82dd89/32.png) [@Machine\_Elf](https://boards.straightdope.com/u/Machine_Elf)\ **Post date:** [January 9, 2014, 1:12pm UTC](https://boards.straightdope.com/t/simple-safety-question-can-i-leave-a-portable-air-tank-pressurized-for-long-periods-of-time/677600/22 "2014-01-09T13:12:04Z")
> [@bubba001](#): > > There isn’t enough pressure and volume to worry about. The OP’s 5-gallon tank, filled to 135 psi, has almost 5000 foot-pounds of stored energy. That’s enough to fire the tank across the garage at 89 MPH. So yes, there’s enough energy here to be concerned about - but as has been discussed, storing pressure in the tank for extended periods does not, by itself, present any unusual risk. A corroded tank OTOH is not safe to pressurize for any length of time, as **Gbro** ’s links demonstrate. ---
**Author:** ![Rhythmdvl](https://avatars.discourse-cdn.com/v4/letter/r/85f322/32.png) [@Rhythmdvl](https://boards.straightdope.com/u/Rhythmdvl)\ **Post date:** [January 9, 2014, 3:01pm UTC](https://boards.straightdope.com/t/simple-safety-question-can-i-leave-a-portable-air-tank-pressurized-for-long-periods-of-time/677600/23 "2014-01-09T15:01:27Z")
> [@Machine\_Elf](#): > > storing pressure in the tank for extended periods does not, by itself, present any unusual risk. I try and live life somewhere between “here, hold my beer” and “oh my god, why aren’t the tips of those bananas in bubble wrap?!” I got the feeling from the thread that storing a pressurized tank (particularly one that’s stored indoors and not banged about) does pose a risk, but a minimal one at best. I also realized that, in accord with public opinion, I am an idiot. Why am I keeping the \*compressor itself \*in the basement? I use it upstairs far more often than I use it downstairs. :smack: ---
**Author:** ![Iggy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/iggy/32/3364_2.png) [@Iggy](https://boards.straightdope.com/u/Iggy)\ **Post date:** [January 9, 2014, 9:41pm UTC](https://boards.straightdope.com/t/simple-safety-question-can-i-leave-a-portable-air-tank-pressurized-for-long-periods-of-time/677600/24 "2014-01-09T21:41:31Z")
> [@Napier](#): > > Isn’t this pretty rare? I’ve seen filters that include a passive moisture trap on compressors and other systems, but I don’t think I’ve ever seen a moisture trap on just a gas cylinder, ever - and I’ve been around them for 50 years. Am I missing something? My bad. I wasn’t as clear as I should have been. A moisture trap is needed for the compressor. As many auto shop low pressure compressors have their own pressure cylinder, I confounded the two. FWIW, a rusted high pressure scuba cylinder is a deadly threat. [Scuba cylinder explosion in a boat](http://www.scubaengineer.com/documents/j_botle_bang.pdf) (PDF with photo) This [2010 report from Atlanta](http://www.11alive.com/news/local/story.aspx?storyid=146114&catid=3) shows the results of leaving a CO[sub]2[/sub] cylinder in a hot car. ---
**Author:** ![Lare](https://avatars.discourse-cdn.com/v4/letter/l/53a042/32.png) [@Lare](https://boards.straightdope.com/u/Lare)\ **Post date:** [January 10, 2014, 7:44pm UTC](https://boards.straightdope.com/t/simple-safety-question-can-i-leave-a-portable-air-tank-pressurized-for-long-periods-of-time/677600/25 "2014-01-10T19:44:37Z")
In the “SCUBA cylinder explosion in a boat” picture, it says “Cylinder(s) in poor condition should not be moved or depressurized and should be roped off and warning sign(s) clearly displayed.” Maybe I’m just being too literal today, but isn’t that exactly what you’d want to do? Depressurize it and move it somewhere for disposal? Is “…by trained professionals” implied by their text? ---
**Author:** ![Machine\_Elf](https://avatars.discourse-cdn.com/v4/letter/m/82dd89/32.png) [@Machine\_Elf](https://boards.straightdope.com/u/Machine_Elf)\ **Post date:** [January 10, 2014, 7:50pm UTC](https://boards.straightdope.com/t/simple-safety-question-can-i-leave-a-portable-air-tank-pressurized-for-long-periods-of-time/677600/26 "2014-01-10T19:50:52Z")
> [@Lare](#): > > In the “SCUBA cylinder explosion in a boat” picture, it says “Cylinder(s) in poor condition should not be moved or depressurized and should be roped off and warning sign(s) clearly displayed.” > > Maybe I’m just being too literal today, but isn’t that exactly what you’d want to do? Depressurize it and move it somewhere for disposal? Is “…by trained professionals” implied by their text? If it’s on the verge of rupture, anything you do to it - including attempting to depressurize it - might cause it to rupture. If it’s just sitting there, then it’s at least stable (for the time being), so don’t mess with it; call in a pro. Cylinders that are already depressurized when they are found to be in poor condition are typically drilled through (to prevent them ever being filled again) before being discarded. ---
**Author:** ![Lare](https://avatars.discourse-cdn.com/v4/letter/l/53a042/32.png) [@Lare](https://boards.straightdope.com/u/Lare)\ **Post date:** [January 10, 2014, 7:54pm UTC](https://boards.straightdope.com/t/simple-safety-question-can-i-leave-a-portable-air-tank-pressurized-for-long-periods-of-time/677600/27 "2014-01-10T19:54:26Z")
Thank you. ---
**Author:** ![Rhythmdvl](https://avatars.discourse-cdn.com/v4/letter/r/85f322/32.png) [@Rhythmdvl](https://boards.straightdope.com/u/Rhythmdvl)\ **Post date:** [January 10, 2014, 8:54pm UTC](https://boards.straightdope.com/t/simple-safety-question-can-i-leave-a-portable-air-tank-pressurized-for-long-periods-of-time/677600/28 "2014-01-10T20:54:44Z")
> [@Machine\_Elf](#): > > If it’s on the verge of rupture, anything you do to it - including attempting to depressurize it - might cause it to rupture. If it’s just sitting there, then it’s at least stable (for the time being), so don’t mess with it; call in a pro. …who will then feed it to a shark, saying “smile you son of a bitch!” [Previous page](https://boards.straightdope.com/t/simple-safety-question-can-i-leave-a-portable-air-tank-pressurized-for-long-periods-of-time/677600.md?page=1)