Can I leave an air tank pressurized?

[THansenite]

I just bought a portable air tank for rallycross and autocross this season. The 12V pump doesn't work well so I figured I'd just bring a tank with me. I'm just curious if you guys leave them pressurized for long periods of time or is it better to empty them out. I am not planning on filling it to max pressure by any means, but can I keep it pressurized in my garage between racing events?

[Newk_Rally]

we i was younger and my family was racing there was all ways and air tank in the garage we would take with us i don't ever remember emptying it and refilling it before an event. i think you should be okay

[carl]

so is it an aircompressor or just an air-tank? air-tanks are meant to be filled by a compressor and then left full so if it's that, it's fine obviously. if it's an aircompressor it probably fine to leave full of air for a while - my compressor doesn't stay filled over night though, it has a small leak

[Daniel B]

In theory... no.

The concept is that compressors make the air hot. You pump the hot iair into your tank (on it's own, or attached to a compressor) and it will cool. When it cools the moisture in the air condenses and you are now risking rust inside your tank.

Rust ~can~ be very,very dangerous on a high pressure air tank for obvious reasons.

On my compressor I always drain the tank. Every decent air compressor I have ever used has a drain fitting at the lowest point in the tank. Most compressor manufacturers recomend discharging the tank if it will sit for mare than a week.

All of that being said... I have a 7-gallon air hog. It was cheap Princess Auto brand (Canadian Harbour Freight). I have pulled all of the fittings off and added teflon tape. It holds pressure for months. I drain it every once in a while, or if it's low anyway. I try to drain the pressure through a kleenex to see if any moisture or Rust colouring comes out. I've been leaving that thing full on and off for a few years now and never had an issue. Your mileage may very...

[carl]

In theory... no.

The concept is that compressors make the air hot. You pump the hot iair into your tank (on it's own, or attached to a compressor) and it will cool. When it cools the moisture in the air condenses and you are now risking rust inside your tank.

Rust ~can~ be very,very dangerous on a high pressure air tank for obvious reasons.

On my compressor I always drain the tank. Every decent air compressor I have ever used has a drain fitting at the lowest point in the tank. Most compressor manufacturers recomend discharging the tank if it will sit for mare than a week.

All of that being said... I have a 7-gallon air hog. It was cheap Princess Auto brand (Canadian Harbour Freight). I have pulled all of the fittings off and added teflon tape. It holds pressure for months. I drain it every once in a while, or if it's low anyway. I try to drain the pressure through a kleenex to see if any moisture or Rust colouring comes out. I've been leaving that thing full on and off for a few years now and never had an issue. Your mileage may very...
I always empty mine out when I'm done but even if you didn't it would take quite a while before the tank rusted out - the compressor would probably quite before that happened anyway

[MilesFox]

if you are just filling it to take with you where there is no air access, then you are good to go.

[WAM]

If this is a portable tank with no drain fitting on the bottom, then letting the air out just leaves the water inside. And the more often you fill it, the more water you pump in. I wouldn't be just dumping the air between uses. But maybe inverting the tank once in a while to try to drain the water would be useful.

My Jeep has on-board air (engine-driven compressor), with a small tank mounted under the body. We drilled and tapped a #6 hole in the bottom of that tank and plugged it with a common screw and a little grease on the threads. A couple times a year I drain the water through the screw hole. I have Jeep friends who drill a much tinier hole in the tank and just leave it open. The tank slowly loses pressure, but it takes the water with it. Just to give you an idea of what other people do.

[sniper1rfa]

I've got a tank here that's been at 2000 PSI for the better part of two years. I wouldn't worry about it.

[Hairy Sheep]

we use ours a couple of times a week, its a 10 gallon tank that has a slow leak in the lines, so it only stays full for a day or so. but even if its not full you need to drain the water out occasionally, maybe once a month depending on how much it is used.

we didnt drain ours for 2 years, ran it a couple of times a week, when i finally thought to drain it last year it didnt have a hole lot of water (maybe a quart or so) but it was pretty muddy from all the dust and crap that gets past the filter over the years.

[ProRallyCodriver]

Leave a pressurized tank in the rallycar for the train horns.

[Hairy Sheep]

Leave a pressurized tank in the rallycar for the train horns.

+100000

http://trainhorns.net/Hot-Rods-Deluxe/El-Diablo/675206/
this kit comes with a compressor, tank, everything!

[u3b3rg33k]

Most portable tanks have a destroy date stamped into them. Mine says "DESTROY BY 2009"


I didn't listen, and it hasn't blown my chest cavity to bits yet. Of course, we also leave it empty most of the time.

But seriously, If you can fill your with dried air, it won't matter a bit, because there's no / insignificant moisture left in the system.

[socalwrench]

I think it depends on how much pressure is in it. A 100 psi in a metal tank isn't a big deal at all. I leave my garage air compressor filled up most of the time. However, I still empty it out to let the moisture out; that collects on the bottom of the tank (from the compressor operation).

[THansenite]

Yea, the tank I have is a 125 Harbor Freight special. Not super high quality, but not real high pressure either. It doesn't have a drain fitting in it, so the inverting the tank every once in a while and pulling the valve is a good idea. Thanks everyone.