# Air Receiver tank for Storage?



## ElkRiverFJ (Mar 19, 2013)

Hello,

I've been a lurker for over a year and appreciate all the assistance and info I've learned here.

My question is, is there any reason I shouldn't use large air receiver tanks for pressurized storage? I am looking at two similar size tanks in the 240 gallon each range that I can tee together. Benefit is they are already piped with all the ports I need (so no welding), typically already located at the top and bottom, with smaller ports that will be handy for temp/pressure gauges, and they are space savers by standing vertical with a base already attached.  I should add that this is only because I've seen some local deals on used tanks that make this cost effective..new air receiver tanks typically would be too high in price.

Something like the attached pic (hopefully the pic works...)








Thanks!


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## Coal Reaper (Mar 19, 2013)

I cant imagine how that could be a problem. Anything thats designed to hold pressure should work.  Propane tanks are ussually in the ballpark of a doller per gallon size so consider that when comparing to the air recievers you are looking at.


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## ElkRiverFJ (Mar 19, 2013)

I've about exhausted my options trying to find a propane tank. When I did find one at a reasonable price, it was in someones yard and he couldn't prove that he owned it..plus I was informed by a colleague that you need to have a hazmat license to move it if the tank has not been decommissioned (I researched this and it is the case). I know a lot of guys just go get them, but I decided it wasn't worth the risk.  Not to mention the cleaning, welding, etc..


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## maple1 (Mar 20, 2013)

Go for it - there are guys on here using them.


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## Floydian (Mar 20, 2013)

maple1 said:


> Go for it - there are guys on here using them.


 
I agree with maple1, as long as you can give the insides of the tanks a visual inspection to be sure that corrosion hasn't been issue.

How old are the tanks?

Noah


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## Tennman (Mar 20, 2013)

I've considered air tanks. Typically the working pressure for a standard air tank is 125-150 psi and then there is a Safety Factor of at least 1.5 and most commercial tanks probably go to a SF of 2.0. That's a pressure vessel of 250-300 psi before something really ugly happens. Your boiler system pressure relief should be set to about 25-30 psi. My only reluctance for using like your standard home use air tanks vs a commercial grade is the wall thickness. If you've found commercial grade air tanks I'd feel more comfortable since thicker material to add conservatism for corrosion was never seriously considered in the shop air/home use types. There's a big difference in tank weight between our commercial compressors and what you find at Tractor Supply. That's the only reason I'm committed to finding propane tanks in the next month or two, not the pressure limits, but insurance against corrosion for 30 years. The good thing is when a 25 psi, water filled pressure system lets go it's mostly a mess, not an explosion. Interesting comparison: 250 gal propane tank = about 670 lbs; 250 gal air compressor tank = about 300 lbs. Both WAY exceed our pressure requirements. Look at how your expansion tank's built, much like an air compressor tank. But I regard an expansion tank as a replaceable item, not my 1000 gal of spray foamed storage. Just information for you, not trying to muddy your waters, just sharing my decision path on components I'll never change for the rest of my life. But boy will my grandkids be busy.


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## Armaton (Mar 20, 2013)

Air reciever tanks are usually ASME. Build sheet says, 165 psi @400 degrees for the particular one you posted, us em! If the tanks you are interested in still have their ID plates, you can call/e-mail the company and get the exact build sheet for them if you want piece of mind. My tank is a Sylvan, approx 850 gallons,112" tall and 48" diameter, one of six built for a special order, and I picked it up at the scrap yard for $400. Contacted Sylvan, they emailed me the build sheet with all the specs and certifications it had when new. And the inside was clean as a whistle.


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## ElkRiverFJ (Mar 21, 2013)

Appreciate all the input. The tanks I am looking at are from industrial facilities. I've put a few feelers out to some guys that basically salvage out machinery from plants that have shut down or done upgrades. Right now I've got a line on two identical 400 gallon tanks that are 36" x 102" that came off of a large plant compressor system, mfg in 1995 I think. More storage than I thought I would get (have to get another expansion tank now) but if the price is right I might jump on them. 

I had just done some searching and couldn't find anyone that had used one. I didn't want to post a pic after it was installed and get the "OMG, you used THAT!".  I've learned never to assume anything will just work, always ask first.


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## JP11 (Mar 21, 2013)

My opinion they are BETTER than propane.  No stink, rated for real high pressure.  I went with what I could get quick, and free, and that was propane.


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## Armaton (Mar 22, 2013)

They would be perfect, if you make sure the piping is correct, they should charge evenly, stratify well, and will easily fit in a 10 ft building.


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## Fred61 (Mar 22, 2013)

I am no expert on this subject but any air receiver tanks that I have come in contact with over the years that had any corrosion at all, had it on the outside. There is usually enough blow by on the piston rings over the years of use that will coat the interior of the tank with a layer of oil thus protecting it from corrosion. That's why you see oil traps on process air lines.


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## Gasifier (Mar 22, 2013)

ElkRiverFJ. I have a 400 gallon air receiver tank. Works great. ASME stamp and the Wood Gun heats it up quick. I just wish I had two, no wait, three of them!


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## Karl_northwind (Mar 22, 2013)

I've used and spec'd air reciever tanks for boiler use.  the only thing you need to worry about is making sure you take care of your boiler water.  in reality your boiler will corrode out before the tanks if your water chemistry is bad.
the lighter weight is great when it comes to moving, standing, and not having to weld or clean is awesome. 

used LP tanks are in the $1 per gallon range, but you have to clean and weld.   air receivers are 2-3 per gallon new, no cleaning, welding etc.

karl


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## Tennman (Mar 22, 2013)

You're right Fred. Our compressors have auto drains due to high humidity and the water always looks filmy and milky. Long term in 180F water the coating will be gone. No disagreement with anything said above Elk. My point was a 500 gal propane tank has a wall thickness of .245" vs .165" for the above air tanks. Does it make any practical or safety difference in our lifetimes? No.


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## Karl_northwind (Mar 22, 2013)

Tennman said:


> You're right Fred. Our compressors have auto drains due to high humidity and the water always looks filmy and milky. Long term in 180F water the coating will be gone. No disagreement with anything said above Elk. My point was a 500 gal propane tank has a wall thickness of .245" vs .165" for the above air tanks. Does it make any practical or safety difference in our lifetimes? No.


 
I figure something built to hold flammable gas and be backed into by UPS trucks and folks in tractors has to have heavier shell requirements for puncture protection.


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## Floydian (Mar 22, 2013)

As much $$$ as we have in these systems, it would be silly to not use a decent chemical precleaner, IMO. This will remove oils, flux, gunk etc. And it's cheap.
Then take care of your water chemistry, as Karl says. Again, relatively cheap. I recommend talking to Mike @ http://www.woodboilersolutions.com/ He is very helpful. I paid $200 for the precleaner and boiler treatment chemicals for my 1060 gallon system.



Tennman said:


> My point was a 500 gal propane tank has a wall thickness of .245" vs .165" for the above air tanks.


 
Tennman, if you really want to over do it, look for anhydrous ammonia nurse tanks. Typically 1000 gallons with a shell thickness of .3125" and the domed ends are .375". Yeah, it's heavy at 2400 lbs. Mine was very clean and had various 1.25" fittings already. If you go this route have an appropriate mask and goggles when you open any fittings for the first time as there could still be vapor. Fill with water, drain and the ammonia is gone.

Another storage option, but my first choice would vertical if possible though I have no issues maintaining very good stratification with my horizontal tank.

Noah


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## Tennman (Mar 22, 2013)

Geez... I'm having enough trouble locating propane tanks in my area let alone ammonia tanks, Noah. Two 500 gal propane tanks vertical will give me, I guess, somewhat better stratification, but mainly it's a smaller footprint in my boiler barn vs stacking them horizontally. I have the height to have them vertical. Getting pretty jazzed about adding storage... if only I could find those propane tanks down here. Kinda like big bucks. Ya see them all year long until December, then they vanish. Craigslist is just dry of propane tanks for quite a radius around me. But, I'll get them, I'm patient.... up to a point. Then I'll just head off to Ohio if I have to.


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## NE WOOD BURNER (Mar 22, 2013)

http://www.blttanks.com/salvage-tanks

Tennman, this guys are west of you I believe.


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## Tennman (Mar 22, 2013)

Thanks NE! 12 hrs west via MapQuest but dawgone it there they are! Ya know I've googled the life out of propane tanks but don't think I ever did salvage tanks..... Geez.... he's got a BUNCH! May be a road trip in my future. Great find!


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## Fred61 (Mar 22, 2013)

If you make the trip to pick them up, try to use an enclosed truck or trailer. Any vehicle transporting these tanks needs to have a haz mat certified driver and be placarded with the appropriate symbols.


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## ElkRiverFJ (Mar 23, 2013)

Thanks for all the info guys. Looks like I will be getting these:





400 gallon each. It is worth it to me for the extra expense because I don't have to weld, no mercaptan stink, and they are already setup to be vertical. Though, they are 8' 6", and my basement is just a wee bit taller than that to the bottom of the I-joists, so it might take some excellent shoehorn work to get them in. If all else fails, I can likely shorten the bottom support ring..which is some fab work but I'll tackle that if needed when I get them here.


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## Floydian (Mar 23, 2013)

ElkRiver,

Those look like nice tanks. How much? I'd still like to see inside them before I hand over the cash but that's me.

What kind of boiler will be heating those tanks?

Noah


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## ewdudley (Mar 23, 2013)

ElkRiverFJ said:


> Thanks for all the info guys. Looks like I will be getting these:
> 
> 400 gallon each. It is worth it to me for the extra expense because I don't have to weld, no mercaptan stink, and they are already setup to be vertical. Though, they are 8' 6", and my basement is just a wee bit taller than that to the bottom of the I-joists, so it might take some excellent shoehorn work to get them in. If all else fails, I can likely shorten the bottom support ring..which is some fab work but I'll tackle that if needed when I get them here.


Be aware that if you use the side ports then all the volume above the top port and below the bottom port will be lost for heat storage purposes.  Using the dome top and dome bottom ports is good, but a major pain to plumb, especially if headroom is tight.  Some guys have made dip tubes and risers that angle off inside closer to the bottom and top of the tanks to reclaim plenty of the dead volume.


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## Floydian (Mar 23, 2013)

EW, can you link any threads with pics of your boiler to storage piping?

I am curious what you did with your vertical tanks.

Noah


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## ewdudley (Mar 23, 2013)

Floydian said:


> EW, can you link any threads with pics of your boiler to storage piping?


Can't find a thread just now, I suppose here's as good a place as any.

I used a manifold top and bottom with separate boiler  and load connections teed into the manifolds in 'reverse-return' configuration.  Having separate connections to the manifolds for boiler and load seems pointless to me now.  Neither do I think it was necessary to tap into the manifolds at those points between the tanks.  

I think I could have simply gone straight into the left end of the bottom manifold for both boiler return and load return teed together, and then could have gone down to a U-turn on the right end of the top manifold for reverse-return purposes.  

Since then I've seen the dip tube/riser tube idea using side ports and I think that could be a lot easier and would perform quite well, although in my particular situation with the tank and boiler positioning, having a straight-shot from the middle of the tanks to the back of the boiler worked out nicely.


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## Gasifier (Mar 23, 2013)

EW,

How many gallon tanks are they? How much does each one of those tanks weigh when full?


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## ewdudley (Mar 23, 2013)

Gasifier said:


> How many gallon tanks are they? How much does each one of those tanks weigh when full?


They're 250 gallon, about 2500 lb each.  Vertical wooden legs are 1.5" x 6.0" rough cut scraps.  Blue board is 3" high density 70 psi stuff.  Pound per square inch at base of wooden legs is 70, so whatever load spreading is provided by the 3/4" plywood is gravy.


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## Floydian (Mar 23, 2013)

Thanks for the pics, EW.

Reverse return really seems like the best way to get even flow thru multiple tanks but I admit I hadn't read up on it much as I have the one big tank. 
I kinda figured piping tanks in parallel was the norm but after some searching this site I realize RR makes a lot of sense.

Learned something new today, thanks!

Noah


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## ElkRiverFJ (Mar 24, 2013)

Floydian said:


> Those look like nice tanks. How much? I'd still like to see inside them before I hand over the cash but that's me. What kind of boiler will be heating those tanks? Noah


 
Well, I got them for $600 each, but I paid a little more to have them freighted to me. I did the math and I would only be ahead about $150 with the gas and trailer rental plus a day of my time. I would have liked to look at them first, but wasn't possible.

I will have a BioMass 25 for these.



ewdudley said:


> Be aware that if you use the side ports then all the volume above the top port and below the bottom port will be lost for heat storage purposes. Using the dome top and dome bottom ports is good, but a major pain to plumb, especially if headroom is tight. Some guys have made dip tubes and risers that angle off inside closer to the bottom and top of the tanks to reclaim plenty of the dead volume.


 
Hmmm.. I knew it was a good thing I posted as I learn something all the time. I didn't think those small distances would have much affect.  I've looked at dip tubes in the past, guess I will need to go back and look a little closer.


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## Floydian (Mar 24, 2013)

ElkRiverFJ said:


> I would have liked to look at them first, but wasn't possible.


 
I'm sure you will be fine. I'll admit I can get paranoid about things I can't see, like corrosion or termites, or deer ticks.

The Biomass boilers look nice. I was close to choosing the 40 but in the end I fell for another-of the Swedish variety. 

Noah


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