Multiple air tanks in the rafters?

[dgolgert]

I'm building a new shop with a loft and have a section of the loft with a 2-½' ceiling. My latest thought is to put multiple small air tanks along the short wall, plumbed into the air header. By small, I'm talking 10-13 gallon tanks and I'd have 5-6 in a row. These tanks are $35 ea at HD or HF. I save space and money, and I can locate the compressor outside to reduce noise. The tank savings will likely get spent on a better compressor.

System: I'm going to have a ring header for compressed air regardless. The air compressor would be located outside in a separate shed with no receiver tank.

Drainage: The tanks would be plumbed in so they drain into the air header, which will be set up with low point drains.

Plumbing: All copper. ¾" for the air header, with ½" drops.

Unloader: The unloader valve for the compressor will be tied in ahead of the check valve at the entrance to the air header.

What's wrong with this plan?

 

[fitz11]

The problem I see is that the portable air tanks you are talking about using usually only have one port on the top of the tank. You would need a rack to mount them upside down and then use a "t" for your air in/out and drain.

 

[dgolgert]

The single connector shouldn't be a problem. The air header will be the drain path too. Since the tie-in from the compressor is away from the tanks, condensation in the tanks should be minimal.

The tanks will likely get mounted with OSB form boards, so orientation is of little consequence. I have plenty of ⅝" and ¾" OSB left over from the sheathing.

 

[akdiesel]

your going to have moisture in the tank or in the line to the tank, unless you have a desicant system. (I think I spelled that correctly). Even then moisture still has to collect somewhere.
Might think about keeping one of the tanks down low and use it as a knock out drum then feed your other tanks. And then as you said tie in the drain lines together and control it with the lower tank or have an auto drain system.

 

[DekeT]

Lot of plumbing for 55-60 gallon @ 125 psi max, Is that enough? Especially if you want to get a better compressor someday.

 

[CNGsaves]

Lot of plumbing for 55-60 gallon @ 125 psi max, Is that enough? Especially if you want to get a better compressor someday.

+1 on too many small tanks. Likely be better with qty 3 tanks from say 26 to 33 gal tanks from very common Craftsman or CH oil-less (thus, lots of these for sale on CL). These generally had 150 psi operating pressure so tanks would be better.

 

[justanengineer]

Keep your eyes open on Clist and you can probably find a 60 or 80 gallon tank for less than youre spending on multiple smaller tanks. Personally, if youre going to do it right eventually, you might as well do it right now.

 

[Charles (in GA)]

I can see problems with this type of system. The pressure switch will have to be in the line near the compressor, or you will have to run lots of wire from the pressure switch in the header to the compressor. If it is close to the compressor, and the line is not real large, the pressure switch may trip off, and as air continues to flow thru the header and tanks, trip back on again.

Thinking about it, the pressure switch will have to be close to the pump to allow it to operate the relief valve that dumps the pressure off the head of the compressor at shutdown (unless you were using a centrifugal or oil pressure operated system as used on some large Champion, Quincy, etc systems.

Another issue is that you will not have a leak free system, that is virtually impossible. When you leave the shop, you will shut off power to the compressor and then the system will leak down, and then when you power the compressor back up, it will have to pump up those tanks and header again. With a regular compressor, you shut off the valve at the outlet of the tank on the compressor, and if it is leak free, then it holds pressure till you need it the next time, without pumping the whole thing back up again.

Lastly, if you put a rather large volume system, 60 to 80 gals total in and have a rather small pump to begin with, the compressor will seem to run forever to pump up the system. A quality large compressor does not make a huge amount of noise. You can either have it in the shop, or outside under a shed, supplying a header system, but the need for numerous small tanks is not there, if you size the plumbing correctly.

Really sounds like you might be solving a problem that doesn't exist.

Charles

 

[Sureshot]

I know you can build a leak free system. My compressor has only been shut off for extended vacations for 13 years and I have many outlets, hoses, and an underground system to my house. I think you can do it but is it worth it in the end with extra fittings etc.
Sounds like you may be built but you can buy 24" or 30" pipe and ends and could have built a major tank in place. You could also look at modding propane tanks after a flush and pressure test with fluid before putting into use. Lots of people will say you can't but it has been done many times before.

I do believe those cheap tanks are thinner than regular tanks.

 

[mayday0017]

Cool idea, no way you will "save" any money doing this though... you will go broke buying fittings... If you are going to build something outside for the compressor why not build it tall/big enough for a tank and just buy a complete unit and save yourself a ton of headache?

 

[OldNeons]

Save yourself lots of work and headaches now and later. bargain shop and buy a good old 80 gal 2 stage unit and put it outside. You'll never look back and never think about air again.

 

[kbs2244]

It will work.
Is it practical?
Maybe.

I would go with at least a 1.5 or 2 inch vertical leg up to the loft with a drain on the bottom.
The larger size will slow down the air flow and give the moisture a chance to condense out before it gets to the tanks.

 

[volaredon]

I too was wonndering about this; my current setup is a 5HP 2 stage 80 gallon upright in a shed on teh west side of the house and my garage on the east side with 3 50 foot hoses coupled together across the front yard any time I work in the garage. I have a cousin that has either a 60 or an 80 (cant remember which) gallon tank collecting dust... from a compressor that died at his work and they got rid of... I was thinking of building like a little "outhouse" behind the garage for teh compressor (already have 220 in the garage "for" a compressor) with this 2nd tank in the attic... I have plenty of room up there as I can stand up in the attic and I am 5'11.

 

[JJThrasher]

I too was wonndering about this; my current setup is a 5HP 2 stage 80 gallon upright in a shed on teh west side of the house and my garage on the east side with 3 50 foot hoses coupled together across the front yard any time I work in the garage. I have a cousin that has either a 60 or an 80 (cant remember which) gallon tank collecting dust... from a compressor that died at his work and they got rid of... I was thinking of building like a little "outhouse" behind the garage for teh compressor (already have 220 in the garage "for" a compressor) with this 2nd tank in the attic... I have plenty of room up there as I can stand up in the attic and I am 5'11.

If I were you, I'd get that tank and tie them together. The build a small shed against your garage and put them both in there.

 

[Jere]

I like the idea of keeping the air tanks in the attic out of the way. Instead of a bunch of small tanks I would hunt for bigger or couple of medium tanks. Propane tanks get pretty big and sell for next to nothing on CL,maybe just vent and change the fittings?

 

[CNGsaves]

I like the idea of keeping the air tanks in the attic out of the way. Instead of a bunch of small tanks I would hunt for bigger or couple of medium tanks. Propane tanks get pretty big and sell for next to nothing on CL,maybe just vent and change the fittings?

Would NOT recommend using any kind of propane tank for what the OP wants to do in attic. Those LPG tanks only have one port opening at top so there would be no way to have drain = = = = = RUST = = = = TANK FAILURE.

Those little 20 lb propane tanks work well to become portable air tanks (when properly converted), but that's about it.

If you're going to lay vertical ASME air tanks on their side, then you'll need to have the normal output port to act as drain (ie gravity force downwards). The ********* at bottom (ie when stood up vertical) will now become your inlet port.

However, fittings will force up cost of this idea.

 

[eadieryzv]

You would need a rack to mount them upside down and then use a "t" for your air in/out and drain.

 

[softailgarage]

I guess I'm getting old and slow, but, what's the point of all this ? Seems like extra work and extra dollars for what? reserve air? Whats wrong with just running a line thru out the shop? BTW, how big is the compressor your going to put outside?

 

[Jere]

Would NOT recommend using any kind of propane tank for what the OP wants to do in attic. Those LPG tanks only have one port opening at top so there would be no way to have drain = = = = = RUST = = = = TANK FAILURE.

Those little 20 lb propane tanks work well to become portable air tanks (when properly converted), but that's about it.

If you're going to lay vertical ASME air tanks on their side, then you'll need to have the normal output port to act as drain (ie gravity force downwards). The ********* at bottom (ie when stood up vertical) will now become your inlet port.

However, fittings will force up cost of this idea.

I haven't looked up the fittings so you might be right and that could sink the whole idea. I have seen tanks setup in-line before with an ac condenser where I think only the first tank gets water build up.

Found an example on the internet

It is a little more work and cost but would make for a more efficient compressor set up with the cooler air. Do you think about a set up like that plumbed into sideways tanks would work CNGsaves?

 

[ratdoggy]

Save yourself lots of work and headaches now and later. bargain shop and buy a good old 80 gal 2 stage unit and put it outside. You'll never look back and never think about air again.

I have a vertical 60 gallon in my basement and piped it into the garage. rubber pads under the feet and it's fairly quiet.

 

[MoonRise]

Doable? Sure, sort-of.

A 'good' plan? Not really, IMNSHO.

Usage of compressed air depends on two main factors, the pump to make the compressed air and the storage tank(s) to store that compressed air until use.

The duty cycle of the pump/motor combination is (usually) matched up with the general usage envisioned and the air storage capacity of the tank.

So a small pancake or hotdog compressor unit made to run a small brad or finish nailer can have a relatively small motor to run the relatively small pump that fills the relatively small air tank in a 'reasonable' amount of time and runs the pump/motor within their (usually 50%) duty cycle so that they don't overheat and burn-up/fail.

Take that same, perfectly adequate to run a brad nailer, unit and try to continuously run a high-demand air tool like maybe a die grinder or DA sander or large(r) spray gun or media blaster and you just don't have enough pump or motor or air tank capacity to run the tool(s) properly or for very long at all.

You just can't add more air tank capacity, because you still have the original 'small' pump/motor trying to fill up the larger volume of tank capacity. Result is that the pump/motor runs longer trying to fill the bigger tank(s) and overheats (either just a little bit or a whole lot ending in a burned up pump/motor.)

More air tank capacity lets you use a high-air-demand tool for a brief period of time before the tank runs out of air. Then you have to wait for the pump to refill the tank and then you briefly use the air tool again. example: an impact wrench. Those handy beasts can **** down air at greater than 20 CFM (medium-to-heavy duty 1/2" impact wrench) but are often used for just a short burst to tighten/loosen the fastener. So while you move over to the next fastener, the pump can be refilling the air tank. If you are continuously running the impact, not many 'homeowner' sized air compressors can keep up with that sort of air demand on a non-stop basis.

Also, related to the above mentioned gotcha about those small 'portable' air tanks not having a drain valve, is that all of the ones I've seen also have a limited design/use pressure limit of just 125 psi and those tanks also have (or are supposed to have, based on the thinner tank wall metal and the lower design pressure and the lack of a tank drain) a mandated 'short' shelf/use life of IIRC either 5 or 10 years. Yeah, those portable air tanks are supposed to be scrapped after just 5-10 years.

Next, let's look at the math for a minute. Say six 5-gallon tanks at $40 each. That's $240 for 30 gallons of tank capacity. Add in another say $10 in fittings and pipe runs per 'unit' (a T fitting for each, plus some elbows and drip legs and adapters to get all the pieces to connect, oh and some drain valves on each drip leg and some isolation valves so you can shut off just a tank or two if they have a problem or whatnot, and I easily see $10 in parts costs per 'unit' to rig things together, unless you happen into a 'deal' on all the fittings and piping and valves and so forth) and you have another $60 in piping costs for those five small tanks all manifolded together.

So that's ~$300 to rig up 30 gallons of tank storage capacity.

A brand-new, full retail price, 'industrial' supplier Grainger has a 26 gallon 175 psi ASME horizontal tank at $551. Inlets, outlets, drain.

https://www.grainger.com/Grainger/SPEEDAIRE-Air-Tank-1TZZ4


And no matter what, you still have to have a compressor pump and motor and rig all that up.

It's usually simpler to just go and buy a 'decent' air compressor unit with the pump and motor already sized to the tank capacity and the entire unit picked to meet your 'needs'. (btw, try to more CFM capacity than you think you need. Air tools can make your life and 'chores' go faster and easier, but only if you have enough CFM capacity to 'feed' them.)

Most of the time, for a home hobby/shop, a 60 or 80 gallon unit (with the 3 or 5 hp electric motor) is enough for -most- tasks. Overkill for filling up a bicycle tire and might not be quite enough to run a 'big' media blaster or other really air-hungry tool. YMMV.

Determine what air tool(s) you want to run. Find a compressor unit (pump and tank) that will meet the CFM demands to run those air tool(s) and meets your price/quality/durability point.

 

[smokem2020]

I had a big DeVelbiss 4 cylinder, 10 hp, 80 gallon tank, two stage compressor that would run less than a minute. I put 4 100# propane tanks in the attic upside down hanging from the rafters for drainage. I also plumbed it into a 60 gallon back-up compressor. After the added tanks the compressor ran just under 5 minutes. I turned the pressure down to 150 from 175 cut off to kick on at 105. I was so happy that It worked well. Only bad thing was the air smelled a little like propane at time.

 

[Jere]

I had a big DeVelbiss 4 cylinder, 10 hp, 80 gallon tank, two stage compressor that would run less than a minute. I put 4 100# propane tanks in the attic upside down hanging from the rafters for drainage. I also plumbed it into a 60 gallon back-up compressor. After the added tanks the compressor ran just under 5 minutes. I turned the pressure down to 150 from 175 cut off to kick on at 105. I was so happy that It worked well. Only bad thing was the air smelled a little like propane at time.

Great idea! What did you do for fittings for the propane tank?

 

[APEowner]

That seems like a rather complex solution for something that's not really even a problem. Just size the compressor and plumbing appropriately and forget about it.

 

[Sureshot]

Great idea! What did you do for fittings for the propane tank?

I believe they are 3/4" NPT.

 

[smokem2020]

I used Iron fittings in the propane tanks. Then 3/4" barbed push lock brass fittings and high pressure hose. All running down hill so there was no moisture traps. I put a few ball valves in so I didn't have to blow down the whole system for filter maintenance. The compressor was so big it needed a tank like you see on the TV show
'Overhauled".

 

[dgolgert]

I have space under the short roof for the storage tanks. I'd use 10-13 gallon tanks, plumbed with the connector facing down to allow for drainage. I'm not sure what y'all are paying for fittings, but ¾" tees and such aren't that expensive.

The compressor would be a 2-stage suitable for a 60-80 gallon tank and I'd have 60-80 gallons of storage capacity. The piping in from outside connect to the shop ring header. That would allow most of the heat to dissipate before the air hit the storage. The ring header will have low point drains.

 

[machine_punk]

As someone who has thought way more about air delivery systems in small shops than anybody ought to, my first thought was, "Hmmm...interesting idea."

My first question was, "Which problem is he trying to solve with this?"

With a 3/4" airline and 1/2" drops, you will have all the flow you need from WHEREVER your main air tanks are. Having small tanks throughout the system won't make "more air available," with the diameters of pipes you are going to use. I've seen a couple of large air systems and I don't remember any of them using 'remote tanks' to solve an airflow issue.

The other issue that concerns me about this design is how much compressor you are going to have, with how much storage. Having a ton of air storage (really big tanks) is cool, until you try to fill those back up with an undersized compressor (and wait even longer for the tank to fill than the 120 volt/30 gallon portable systems).

Now, of course, if you are like me, doing something unusual like this is, just to have something to talk about. It is a class 2C intervention...won't hurt, might help. I've never seen a design like this, but that doesn't mean it won't work.

Now, if you are just trying to use a cheap resource to it's fullest (the tanks are on a 'fire sale'), then you have to ask yourself how much you are going to spend to make these cheaper tanks work, over the cost of using a larger, central reservoir. Pipe fittings are not cheap right now and may change the economics of your plan. Then, you are going to need a compressor large enough to refill your system anyway. Those usually come with pretty large tanks to start with.

I would start with a clear statement of the "problem," then sort out the best solution for that problem. If you think 'airflow' is your problem, then I think you've got that covered with the large distribution pipes. If you think 'air volume' is the problem, then you're going to have to fix that with a bigger pump...which usually comes with it's own, appropriately-sized air reservoir.

Whichever way you go, I want to see pics of what you end up doing!

Kev

 

[smokem2020]

There is a problem for us snow bound people putting our air compressors out side. When the temperature gets really cold they don't like to start all that well. Also the moisture will freeze. I keep mine in the shop so I can hear it. I know its loud but if somethings not right I can address right now. Not when I find out I don't have any air or didn't smell the thing overheating. That being said. my buddy just bought one that was outside, on a west wall with little protection or insulation and it looked like new.

 

[dgolgert]

My problems:
Floor space is at a premium, 24x24 garage on a small in-city lot. I'm trying to use all the nooks and crannies. City code restriction on roof height meant a low ceiling on half the loft. The ceiling starts at 2-1/2' at the wall and goes to 6-1/2' at the center line. Tucking a row of tanks behind a false wall seemed like a solution.

Noise is an issue, putting the compressor outside is much preferred. Having the compressor located in a sound-proof box, possibly wall mounted above head height, is more practical if I don't have a 60 or 80 gallon tank attached.