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Adding Air Storage?

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imagineer

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Ohio
Is it worth the effort to add another air storage tank to my shop air system?

Quite some time ago, I built a media blast cabinet and still use it on occasion. The compressor supplying it has a 60-gallon tank. A rough estimate for the pipe loop adds about 1.5 gallons of storage. Although the compressor can keep up, I’m thinking of adding a 20-gallon tank to the line feeding the media blast cabinet.

FWIW, there’s a water filter/regulator before the media blaster that’s set for 90psi.

I have an unused Coleman 20-gallon “oil-free” compressor. 8-10 years ago, I broke off the drain valve. The compressor has been idle since, but I’m fairly certain the tank is in good shape.

There’s space under the media blast cabinet to install this tank. I’m just wondering if there’s a benefit to adding extra air storage?
 
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dchawk81

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20 extra gallons would give you 1/3 extra capacity for 1/3 more runtime.

Like going from a 60 to an 80 gallon compressor. That's a decent jump for continuous air tools. Probably wouldn't make a lot of difference for an impact gun.

Downside is you have a compressor for a 60 not an 80 gallon tank so it'll take longer to refill.
 
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Jswain

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Calgary, AB
First thing is the second tank needs to be rated for the same or more pressure as the first tank

If you installed it right at the blast cabinet that would be best, especially if you have a long run of lines from the compressor to the cabinet.

It will also help keep the air dryer as the air will cool when it hits the tank.

You won't get more CFM as you are at the mercy of the pump for that, you will get more initial run time though.
 
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P

phred

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Apr 23, 2009
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NC
I don’t see an issue with your idea. I have a 40 gallon reciever plumbed in along side of a 60 gal 5 hp single stage compressor. The extra receiver has a fan cooled after cooler above it so the receiver serves as storage and a place for moisture to drop out of the air.
 
S

SwissMetric

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Dec 28, 2024
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Switzerland
Even many factories have undersized compressed air storage which leads to frequent starts and here I mean expensive screw compressors while it would be wise to increase the total volume and maybe also use VSD (variable speed) screw compressors, also a lot of energy is wasted as the unloaded compressor still needs to run some time to cool down.
When checking the start counter sometimes one would be surprised how many starts are performed per year, it even happens that load cycles are so short that the motor doesn't even stop.

One important point are mandatory periodic pressure vessels inspections by a specialist (regardless of fluid, also hydraulic accumulators and other gases), details depend on local regulations. Often there's a limit defined by the volume multiplied by the pressure.
Here it's 3000, ie.g. 300 l (liters or litres) at 10 bar (barg) (0.3 m3 at 1 MPa and yes, in Switzerland we mostly use the dot as decimal separator) for compressed air, values are different for liquids and also if the medium is heated but as said details depend on regulations.
That explains why where possible often a couple of smaller tanks are used instead or a single large one. Of course it won't make sense if you require e.g. a 250 kW screw compressor.

Many compressor manufacturer websitse feature online calculation tools but the effectively required flow is not always easy to estimate. For example sandbalsting ***** if the compressor is undersized and sellers are often a bit too optimistic when it comes to compressor sizing.

Increasing the storage volume increases the lifetime of the compressor as each start stresses both the compressor unit and the motor.
It's also extremely important to purge correctly (preferably automatically and not into a hose which can end clogged by frozen water) and design piping where water can't end trapped at a non-purgeable low point.

As I'm more used to screw compressors I don't know conventional compressors well, excepted that direct power-switching pressostats seem to all fail after some time, it's so stupid to not use a contactor (no idea how many such lame pressostats I saw failing).

Used tanks should be carefully inspected, especially checking internal rust. Sometines water can even remain in the tank during a long time if not purged. A tank can look great while being dangerously damaged by rust. Also small tanks don't have those oval handholes which makes controls even more tricky.
 
T

ToolsRCool

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Plymouth, MI
Not hijacking OP's thread, I'd like to throw away my standard vertical 60g steel tank, and switch over to a few smaller stainless, aluminum, or fiberglass tanks hidden up and around the rafters, then move the motor and pump up there as well. For sure using it less with the advent of battery tools, but it is still necessary.
 
N

no704

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Apr 27, 2016
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If you have a long run from compressor to blast cab it might help to have it near the cab. Might put a valve to disconnect it when not in use.
 
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