Why add another air tank to your air compressor? What are the ramifications?
This is page two of an article about I need more air! Page one about I Need More Air is here. Page one begins our discussion about the benefits of adding another air tank.
If an air tool draws more air than the air compressor can deliver even when running full out the supply and pressure of compressed air to the air tool will decrease to the point where the air tool will not do the job it was designed to do.
Adding another tank might resolve that.
Add another air tank
When you add another air tank, when you are not using compressed air, your air compressor will run and fill both tanks – the one that came with the compressor and the one you have just added.
This means that the air compressor motor will run longer before reaching cut out pressure and stopping. The compressor pump is now filling a larger volume.
Note that you must make sure that your air compressor will handle the increased run time. If the duty cycle of the air compressor is too low – that’s the maximum run time allowable to avoid compressor overheating – then adding a tank may make your compressor run too long at any one time, and that may damage the compressor motor.
The manuals for the lower cost DIY air compressors may not even show you what your compressor duty cycle is. If your air compressor manual does not indicate the duty cycle of your brand and model, then our rule of thumb is that your air compressor should only run for a maximum of ten consecutive minutes. If it needs to run longer to fill the tanks, the we shut it down and let it cool for fifteen minutes before running the compressor again. After the compressor motor has cooled down, we will run the compressor again for the maximum ten minutes or until both tanks are full to the cut out pressure setting and the compressor stops automatically, whichever comes first.
Having the extra tank, means that you now will have a much larger reservoir of pre-compressed air to use when you next run your higher demand air tool.Just watch out for compressor overheating.
Plumbing your new air tank
You can use one similar to the “air pig” shown in the image.
Plumbing would need to be modified so that air from the compressor pump would flow both into the main tank on the compressor and this new tank at the same time.
Plumbed this way the one pressure switch on the air compressor would monitor the pressure in both tanks and shut the air compressor off when the pressure reached in both tanks reached the normal cut out setting of the original compressor and tank.
To add a tank to your DIY type air compressor, the simplest way is to add a tee to the tank. See the sketch below.
- The first air line is plugged into the discharge coupler on the compressor
- The other end of that air line has a coupler
- Plug that air line coupler onto the connector on the secondary tank
- Since the coupler on the other side of the Tee on the portable tank is checked, air will not flow out until a mating connector is inserted into the coupler on the secondary tank
- When you need air at the job, plug a second air line into the discharge coupler on the secondary tank, and air from both compressor tank and secondary tank will flow down the line to your air tool
Place Second Air Tank Near Job
Another benefit of having a secondary tank is that the secondary tank can be placed nearer the job site more easily.
To use an air nailer for shingles on a roof for example, it would be so much more convenient to leave the heavy air compressor at ground level, run an air line from it up to the secondary portable tank on the roof, and then run an air line from the secondary tank to the nail gun. More convenient to move around and more air supply closer to the nail gun are significant benefits.
If you add another air tank to your air compressor, you will be able to use higher demand air tools for a longer period of time. If, however, the air supply and pressure diminishes still, and your air tool starts to wind down, then stop, take a break, and let the air tanks come back up to cut out pressure.
Just be mindful of the duty cycle.
Hi there. I know this is an old post, but I’ve just stumbled on it and its exactly what I want to do.
I have two compressors, one is a harbor freight 1.8HP, 26 gallon, 150psi max.
The other one is a campbell hausfeld 4hp, 13 gallon, 120psi max.
I intend to make both tanks run off the 4hp motor, but, use the pressure switch of 120psi. That way, I don’t over pressure the smaller tank because the larger tank can accept more psi. I’ll default to the lower pressure for safety.
Having said that, there is a brass/copper hard pipe that has compression fittings, appear to be 3/4″ from the motor to the tank itself. Then from there, the air goes through the pressure gauges, safety, regulator as most do.
On the larger tank, the whole gauge/regulator, etc. setup is directly mounted (no pipe) to the tank itself on a 3/4″ male nipple.
My first idea was to find piping, ‘t’ it the smaller tank and run the pipe to the larger tank. Then, I thought, why do I need piping when hoses will do?
So, I plan to run a female 3/4 fitting with a quick disconnect nipple with a hose (short, about 17″ or so-found a swivel end hose that should work) to the ‘t’, and then of course ‘t’ from there with a 3/4″ male to to 3/4 quick disconnect fitting.
I’ll do the same on the opposite side with the quick disconnect fitting, plug in another hose run of 25′ hose (shortest I found) to the larger tank.
At that tank, I’ll use a 3/4″ female to male adapter, screw it onto the nipple of the tank, then insert a quick disconnect nipple there to plug onto the hose.
For use, it will be primarily to support air tools for automotive work, but it is a home setup, not professional use so load on the system won’t be that much. The reason I’m doing this is it seems like I can’t get a full run down of the lug nuts (16 in total) before the compressor comes on. I then have to wait for recharge, and check the tightness again just to make sure I’m good.
Unless you tell me all this is a horrible idea and it will only end up to being a lot of work for the coroner to locate all my body parts. lol
I realize the run time of the motors too that you mentioned and I believe the 4hp motor will do fine to power both tanks.
Thank you for taking time to help.
Not sure if you require extra information hopefully this is correct.
Wanting to know if installing a 50L Receiver is large enough for a Compressor that operates but with power surges will stop that compressor however want to continue the pressure flow with the Receiver?
Question is how long to hold above 1bar when releasing pressure at 2 ltrs per min? Do we need a bigger Receiver than a 50Ltr?
I have a 75 ltr tank can i ad a 50 litr auxiliary tank
Thanks for a very informative and useful set of articles. The information assisted in updating a couple of small portable hobby and light work compressors. Attaching a manifold to a couple of small volume air storage tanks have really improved the output and increase productivity on some projects. The recommendation to factor in the duty cycle and tool CFM can often be overlooked and are very valuable points as required to extend service life on these small compressors. Thank you again for providing this information. It will be well referenced and passed on.
I have a pump and motor that work great. But the tank is rotten. I also have another complete compressor. Can I hook up the two pumps to the same tank to get the boost in CFM?
Hi I am a bit confused and hope you can help. I have 50ltr compressor with a discharge pressure of 115psi/8bar but the tank fills to 10bar , firstly what’s the difference, and can I use an 8bar tank as a secondary tank. Hope this makes sense.
Hello, great idea. I have a Rhyas 50l V-Twin 3HP 14,6 CFM engine which would probably (?) suit a twin tank set up. On the basis of aesthetics alone, I have seen very visually similar motors used on 100l tanks and, therefore, have some grounds to believe the motor would be sufficiently capable…?
Is a spares or repair compressor the only avenue for obtaining a candidate for additional expansion 50l tank? Or could used automotive LPG tanks be suitable (only where they have been emptied by qualified LPGA fitters as the gas expands 20x by volume at room temperature and is extremely flammable!)
I hope you may be able to help but superb idea you have suggested.
Regards,
Matt
Like this idea. I have a 90 PSI compressor and want to add my 100 psi portable tank to it to increase volume. I’m going to try this so my pneumatic tools will run better, but like you said the cycle time is critical so you don’t cook your compressor.
Would you need a pressure regulator at the outlet of the reserve tank, of would the regulator at the compressor serve that function?
I’m looking to build a 300 psi system and I want to know if I could run 2 air tanks rated at 150 psi to meet my 300 psi goal. Thanks.
What would you estimate a Kobalt 8 gal compressor maximum extra tank size be?
I have a Werther TC-108 Special compressor with an 1.5liter air tank. I want to add a second tank in order to achieve higher air brushing times without the need of turning on again the compressor. Is it possible to auto switch to the second air tank when the 1.5L gets full? What kind of materials I’ll need and the second air tank how much pressure must withstand ? Thanks
Compressor
Bar 3.8/psi 55
L/min 23/cfm 0.74
Okay so I have 2 compressors both 30-40gal. Compressor a had bad motor good tank. Compressor b has good motor and tank.
If I take compressor b line from motor and put a tee coupler with a line going to tank a and b and the two going into shut off regulator, and then put my quick connect on compressor a, I will have doubled my capacity, correct?
In my effort to add a tank, i want to tee off just before the check valve threaded into the tank.
What i am finding is that while it is a compression fitting, the discharge line is NOT a true 3/8″ or 1/2″ line, and the nut is 3/8″ PIPE threads!
So, based on the pic i included with this question, how would i still be able to use a compression fitting tee for both the discharge line AND the Auxiliary tank line AND thread the third tee opening onto the check valve inlet?
I have a porter cable pancake 6 gal for jobs on site. But I want a bigger and more powerful compressor in my basement workshop that will be static.
Somebody gave me a porter cable compressor 20gal 135psi 5.3cfm@90psi with a cracked tank. The compressor is almost brand new(he didn’t drain the tank and wasn’t using it often).
And I have an other porter cable 6gal pancake which the compressor is busted.
My question is is it possible to build a station in my workshop using 2 portable 10 gal tank with my 6gal pancake tank plugged on my compressor who was on the 20gal tank. That would give me 26 gal. I’d use it for nail gun and spray paint etc wich I guess would be plenty enough.
will my compressor run less by doing this with a smaller compressor to larger tank
So i have an old twin tank compressor with the motor shot. I ripped the motor off and ran a line in from the compressor at the bottom and a line out at the top to the gun. The piggy back tank is in series with the compressor. That probably will not give me the desired affect will it? What i need to do is cap off the bottom and then put a tee at the top for air in and out so it can use the same pressure switch? Or should it work the way i have it set up?