I get a lot of questions about whether or not it’s a good idea to implement an additional tank to a compressor, or people even ask, is it even possible? The answers to both questions is… yes! With some qualifications, of course.
One way you can improve the function of a small air compressor is adding a second tank to air compressor, building a greater reservoir of compressed air for you to draw on when you are using an air tool that outstrips the capacity of the compressor.
This page will serve as a guide on why and how to connect two air compressor tanks, the considerations you must take before resulting in a dual tank air compressor.
Table of Contents
- Why Connect Two Air Compressor Tanks Together?
- How to Connect Two Air Compressor Tanks
- Important Considerations When Connecting A Second Tank
- Where Shall I Add the Second Tank
- Connecting Two Air Tanks Together Parts Available on Amazon
- FAQs (Frequently Asked Questions)
- Reader Questions and Responses
Why Connect Two Air Compressor Tanks Together?
The key benefit on offer from adding or connecting another air receiver tank to your air compressor is the ability to have a larger storage of air! This allows the air compressor motor to run for a far longer period before reaching it’s cut out pressure and not allowing you to use your pneumatic tools for this period. Now that you have enabled the compressor pump to fill a larger volume of air (the two receiver tanks), you have a greater amount of CFM available!
This is by far, a great solution for increasing the CFM of your compressed air system. Not only this but adding a second tank will allow the compressor to have greater cooling time. Well, this is under the assumption that you’re not drawing more CFM from the air compressor system than your pump can actually generate. This greater cooling time is due to the greater volume of air that is keeping your air tool running for longer than it was before the cut in pressure is reached and the compressor restarts.
This can also be a great technique for reducing the stress on the air compressor as let’s say, for example, your compressor has a 50% duty cycle and it spends say 10 minutes working (on) and 4 minutes resting (off) then you’re over-stressing it!
Check out my guide to air compressor duty cycles for more information.
Note: It’s important to understand that adding a second air tank to your compressor increases the CFM of the compressed air system and NOT the air compressor pump CFM. The actual CFM available at the outlet of the air tank is separate from the air compressor pump CFM.
So on that note, you could get 20 CFM out of your 10 CFM rated air compressor by having a large enough set of air receiver tanks to hold the volume. This 20CFM would only be available for a fixed period of time, as the 10 CFM rated air compressor pump would not be able to keep up with this demand.
How to Connect Two Air Compressor Tanks
Now let’s get into the process. To connect two air compressors you can follow the following steps which I’ll expand on further below:
- Unplug your compressor
- Pick your location
- Install second tank (using couplers, tees and a hose)
Unplug Your Compressor
First of all pull the plug on your compressor, and void any compressed air in the tank to atmosphere by opening the tank drain valve and letting it drain out.
Pick Your Location
Where do you put the extra tank? Right next door to the existing compressor tank, or on the other side of the workshop?
For most DIY type applications it really doesn’t matter. Just remember that you need to have a hose or pipe long enough reach from one tank to the other.
An extra tank can be any shape or size, depending on the capacity of the compressor pump and motor.
Note: You will have to drain both air tanks regularly. Make sure you have access to the drain valves on both tanks to make this process convenient for you.
Installing the Second Tank
You could “hard plumb” the new tank, but the easiest way, and the one I will recommend, is connecting the two tanks together with a hose.
Use the existing coupler on the current air tank. This coupler allows you to plug a connector into it, and once you plug in the connector air will flow into the air line or hose.
You’ll need a length of air hose long enough to reach from the coupler of the main tank, to the inlet connector on the second tank. This air hose will have a coupler on one end, and a connector on the other.
Now, thread a Tee into the intake port on the new tank, and thread a coupler into one side of the Tee.
You can now push the coupler from your extension air hose onto this connect, effectively connecting the two air tanks together.
On the other side of the Tee, you could consider adding a nipple, an air filter, another nipple, and then another checked coupler. This allows the air to be filtered before it heads down the line from the secondary tank to the air tool.
You may note wish to have an air filter here, so instead you can just insert a coupler to the Tee, and then connect your air hose or line that connects to your air tool!
For further information on hoses, vist our Air Compressor Hose & Tube Guide – What Size? Air Tube & Hose Types & Fittings guide!
Note: Don’t plug the connector into the coupler until you have the hose connected at the new tank end!
Now, every time the compressor pressure switch calls for air, the compressor will start and run until it fills both air tanks to the high pressure cut out level providing you with the additional tank volume of air for your applications, between compressor cycles!
Just as the connector on your compressor tank has a checked coupling to keep air in the tank when there isn’t a connector attached to it, the coupler you’ve added to the Tee on the new tank will keep the air in both tanks until you’re ready to insert an air line connector into it.
Installing the Second Tank Steps:
- Plug an air line into the discharge coupler on the primary tank (the other end should have a coupler)
- Plug that coupler onto the Tee connector on the secondary tank
- Plug another air line into the discharge coupler on the secondary tank, so that your air can flow from both compressors down the line to your air tool
Important Considerations When Connecting A Second Tank
Be aware of a little thing called duty cycle. It would be a shame to have your compressor work so hard and so long to fill up the multiple tanks that it burned itself out because you didn’t give it a chance to cool off often enough! Ensure it is operating within its duty cycle limits.
It’s possible to decrease the ratio of working time vs idle time by adding a second tank to the air compressor system. This will result in a duty cycle reduction even if the pump in running for longer.
Adding a second tank is not ideal for continuous use applications as you have to stop-start so that the compressor can refill the tanks. It’s far more suited to intermittent uses where the compressor pump has time to “catch up” as such, with demand.
You must be aware that the air compressor will require a greater amount of time to refill the two tanks when the pressure drops below the cut in, this is due to the increased volume of the connected tanks.
This can be a very important consideration to be aware of as the compressors running time and idling time have duty cycle limits which are specified by the air compressors manufacturer. If you were to operate the compressor outside its recommended duty cycle then you could cause permanent damage to the system or even compressor pump and motor failure.
Important Considerations When Connecting A Second Tank Summary
- Not ideal for continuous use of air tools
- Great for intermittent use of air tools
- Need to size the tank correctly even for intermittent use (please visit how to size an air compressor tank here)
- Still need to check the duty cycle of the air compressors to size the air compressors correctly in relation to the air tool working CFM
Where Shall I Add the Second Tank
It’s absolutely crucial to insert the second air tank AFTER the first air tank due to the location of the check valve.
Where the air enters the tank on the compressor, there is normally a check valve installed. This allows air into the tank, but won’t allow air back out that way. For more information visit our Air Compressor Check Valve: How It Works, What It Does and Why It Exists guide!
This is a very important feature of any compressed air system, and is why the secondary tank is installed after the primary. This way the air from both tanks cannot escape back up the supply line when the compressor is stopped and escape through the unloader valve which is opened to atmosphere.
Connecting Two Air Tanks Together Parts Available on Amazon
Many parts for connecting two air tanks together are readily available on Amazon. The first is a Le Lematac air tool fitting set which includes couplers, plugs and connectors.
- Complete set of air hose quick connect that comes with two 2 female couplers, 3 female plugs, 3 male plugs, five 5 male to male connectors, 2 rolls of Teflon tape, and a plastic storage box.
Prices pulled from Amazon Product Advertising API on:
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on [relevant Amazon Site(s), as applicable] at the time of purchase will apply to the purchase of this product.
Another good set is the Milton 1/4″ NPT 12 piece coupler and plug kit.
- BASIC FLOW SIZE: All 1/4 body size air fittings. 1/4 NPT. Buna-N seals.
Prices pulled from Amazon Product Advertising API on:
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on [relevant Amazon Site(s), as applicable] at the time of purchase will apply to the purchase of this product.
A third set it the 18 piece air coupler and plug kit that includes tee pipe fitting.
- UNIVERSAL QUICK COUPLER - The 1/4 NPT universal couplers (male and female) which fit Industrial (I/M), ARO (A) and Automotive (T) so you do not worry about whether it is fitting or not. Heavy duty steel air fittings are ideal for general purpose applications and the brass has good solid and durability.
Prices pulled from Amazon Product Advertising API on:
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on [relevant Amazon Site(s), as applicable] at the time of purchase will apply to the purchase of this product.
FAQs (Frequently Asked Questions)
Yes, you can hook two compressors together to make a bigger reservoir of air. By connecting them with the correct fittings you can enable longer periods of use for your air tools however, it will also take your air compressor longer to get the pressure built up in two tanks rather than just the one.
Follow these simple steps:
1. Plug an air line into the discharge coupler on the primary tank and a coupler on the other end on the line/hose
2. Screw a tee onto discharge of the secondary tank
3. Plug that coupler onto the Tee connector on the secondary tank
4. Plug another air line into the discharge coupler on the secondary tank, so that your air can flow from both compressors down the line to your air tool
Adding a second tank to an air compressor will increase the CFM of the compressed air system but not the air compressor pump CFM. This is important to remember as the actual CFM available at the outlet of the air tank is separate from the air compressor pump CFM.
Reader Questions and Responses
Adding an air tank to increase volume?
Question:
by Ray
(Amarillo, Tx)
Adding second air tank to small compressor to increase volume
Where should the pressure regulator be located…if it stays in the same location, would back pressure from other tank be a problem?
Response:
Ray, if putting the second tank in series, then having a regulator before the second tank will mean that you are regulating the pressure going into that tank.
Since regulators only lower pressure, the secondary tank will only have air pressure in it equal too or lower than the first tank, so, no back pressure.
Still, it would make more sense to me to have the regulator installing in the line after the second tank, so you have full compressor pressure built up in both tanks for you to draw on.
Set the regulator at the lowest possible pressure that works for your air tools to reduce energy use and wear and tear on the compressor.
Sure. DeWalt does it, as does a number of compressor manufacturers as they try to get more volume capacity into a small compressor footprint.
I added a second tank and…
Question:
I followed your instructions on how to add a second tank to my compressor, I added a 26 gallon tank to a 30 gallon.
Everything is running fine but it seems the compressor is still turning on and off at the same rate as before. Is there an adjustment I need to do?
Response:
Not quite sure what this means.
Adding a tank gives you more pre-compressed air supply for your tools. It will not change the cut in or cut out pressure levels of the pressure switch.
What will happen is that when it cuts in, the compressor will run longer as it fills both tanks.
If that’s not the issue, please post a comment here letting me know.
Can i put two tanks on one compressor?
Question:
by walt meeks
(tenn humbouldt)
put the two tanks side by side and fill
Response:
Hi Walt…
Yup, you sure can.
Supply the second tank with air from the tank on your air compressor, and then plumb the air from the second tank to your workshop.
You’ll need to remember to drain both tanks regularly, as both will gather moisture.
Check out the new page on this website Add An Air Tank and review the pages on compressed air plumbing on this site, as well, if you want more information.
Remote air tank – how to install?
Question:
by steve
i have a compressor tank that i want to keep in my garage to use when i need more volume for bigger jobs. is there anything special i have to do to hook up a smaller compressor(6 gal.pancake style 1 1/2 hp)to the larger tank?
Response:
Steve…
If you have one 30 gallon tank on a compressor, or one on a compressor and another beside it, the compressor doesn’t care. The net result of the two tanks is 60 gallons of compressed air ready to use when both are full. You have more air to use, but it takes longer for the compressor to fill the two tanks.
Coupling two air tanks together?
Question:
by Scott Rich
I have a portable compressor and have received a larger tank from a old compressor.
Can I couple the two with a hose between them and increase my volume so I can run die grinders and sanders more efficiently?
What do I have to consider?
Could I burn up my portable from it running more often?
Response:
Hi Scott:
Yes, you can couple two tanks together to make a bigger reservoir.
When the compressor runs, air flows from the piston (assuming it’s a reciprocating compressor) through a tube into the tank. As the air travels downs the tube, it passes through a check valve.
This check valve keeps the air in the tank when the compressor stops, and the unloader valve operates.
So, if you are coupling two tanks together, you have to make sure that both of them are downstream from the check valve. In this way, air goes into both tanks from the compressor, and can’t flow back up the line to the unloader valve exhaust port.
Wander to the site map on this site, and check out “duty cycle” to give you some ideas so that you don’t burn out your compressor.
Thanks for writing in.
When two tanks are coupled together, the air pressure will equalize in each.
Add an additional compressed air tank to the system?
Question:
by Ed
(Orlando, FL)
I purchased a portable tank, but intend to add it to the system when plumbing my home garage/workshop.
Response:
Hi Ed:
You can add the tank anywhere it’s convenient in your garage / workshop.
Air from the compressor needs to be plumbed into that tank, and then you need to have a discharge from that tank to your workshop.
If (and you should) you have a filter / regulator from the existing compressor, you’ll want the air from both tanks to go through this unit before you plumb to your tools.
Don’t forget to drain the secondary tank too!
Visit this page: about-air-compressors.com/plumbing.html, to learn more about Plumbing compressed air.
Can I hook a second tank to my air compressor?
Question:
by bill
(lewisburg oh USA)
I am wanting to hook my new 60 gallon air compressor to my old 60 gallon tank that I took compressor and motor off for extra storage .I was told this was unsafe to do this, can this be done
Response:
Hi Bill. If the “old” tank is sound, I do not understand why someone would say that it is unsafe to do so, unless they are talking about the motor?
Whether your compressor has one tank of 60 gallons, one tank of 120 gallons, or two tanks totaling 120 gallons, is immaterial to the air compressor, as long as filling the two tanks does not overload the motor.
See the link from the sitemap regarding duty cycle.
Also see the link “add an air tank” from the sitemap.
Two Tanks, Two Different Burst Ratings…
Question:
by Andrew
(Costa Mesa, CA)
Hey Bill, you freakin’ ROCK by the way. Okay so, I have a 16g 200 psi compressor and I also just purchased a 15 gallon tank that’s rated to 150psi. Is it possible to add the 15 gallon tank as a slave tank for the compressor? The slave tank says not to exceed 150psi and I’m assuming that is its burst pressure. The compressors pressure switch doesn’t auto-off until a solid 205psi. How would I plumb the two together? Is it possible to add a small regulator in between the connection lines? Or is this not possible due to bursting the spare tank at its psi limit?
Thanks!
Response:
Andrew, if this were my set up, I would not put a tank rated for 150 PSI in series with an air source at 250 PSI, regardless of putting a regulator in line.
My opinion is, you either turn down the pressure output of the compressor to 150 PSI and run that pressure for both tanks, or you get a tank rated for the 250 PSI of the original compressor.
If you have any questions regarding adding or connecting a second tank to your air compressor system, please leave a comment here along with photos if applicable so that someone can help you!
Ok so this is my setup. My auxiliary tank is 33 gallons craftsman and I have a 10 gallon 2hp california air tools compressor. Same motor that’s on their 33 gallon. Assume both tanks are empty after assembled and connected. If I turn it on it will reach the 125 max and cut off. When I look at the guage on the 33 gallon aux it’s only at 50 psi. I know it can hold more air up to 165psi. Should I disconnect the line drain the 10 gallon run it again and continue to fill up the 33 gallon… Read more »
Sorry, insufficient info. How have you interconnected the machines? Are you running both or just the CAT? If you do it correctly, the tanks will be at the same pressure.
Ok so I figured it out and I think I have only one question. I emptied the air compressor and the aux tank to start fresh. I started by opening the regulator on the air compressor all the way so the aux tank can fill quickly. Aux tank only filled to 80psi and my air compressor filled to 125 psi (max) then turned off. My air compressor will kick on if it drops to 90psi. I hooked up a mini spray gun to the aux tank and depressed the trigger to see how long before the compressor kicks on. It… Read more »
OK. I just reviewed the stuff up top of this page, and while it’s not exactly wrong, it’s not right either. To get the result you want, re-plumb the connection between the tanks so that the TANKS are directly connected with no regulators involved. This can be done pretty much any way you want, if the tanks are rated for the expected pump cut-out pressure. You do want to be sure that you leave at least one PRV (safety valve). You’ll probably want one or the other or both regulators, depending. If you use just one regulator, you can put… Read more »
When plumbing a second tank to a compressor via a hose – does the second tank need the installed check valve – or can it be removed? Tank will not be consistently used – only when painting. Output will have a regulator.
If the tank is connected after the pump check valve, no. If the second tank is directly connected to the pump, yes it needs the check.
Can I make a pressure tank from an old well pressure tank?
If it has a pressure rating greater than the pressure you intend, yes.
It shoult also have a PRV to protect the tank in case the pressure tries to go too high for some reason.
Can we add one more compressor tank in truck and used as as air pump?
You can add as many as will fit and not overtax the pump. It will not be a pump, but it will allow more storage for air.
Looking at putting a high valume air compressor on a service truck (1 inch impact drains the tank fast). Is there any value to have lets say 5 10 gallon tanks VS 1 50 gallon or even 2 25 gallon tanks (all tank pressure ranting being the same) and i do know more tanks means more plumbing but i can wiggle multiple tanks in a tighter patern than one big one.
Yeah, you can do that. The caveat is use at least 1/2 inch pipe. and plumb as directly as possible toward the outlet, and the input from the compressor should likewise be near the out let tank, or manifold, as the case might be. As for a manifold setup, think alone the lines of what you see on the exterior fire hose connections for large buildings. E.G., if you have five tanks, that could be the other four tanks plumbed directly into the fifth one, where the pump and outlet would also connect. Don’t neglect providing a tank water drain… Read more »
I have very little technical knowledge on the ins and outs of compressors and what they can do other than plugging my nail guns in or filling up my tires. But I’ve got a project in mind that I need to know if the compressor part of the project is even do-able. Let’s see if I can describe it well enough. You plug in the compressor and fill it up. Once the compressor is filled to say 130psi, Is there a way to run a hose to another tank and have only a specified lower psi transferred to that spare tank… Read more »
Sure. Just put a regulator between the two tanks, set to 10psi.
Note that many regulators don’t do well at low pressure, so you may have to do a bit of research to find one that actually works.
Thanks Doug, I was wondering if that was the solution. I have an existing regulator on my compressor, am I to assume that will serve the purpose or do I need to add an additional regulator along the line?
Depends. Try it. If it works, great.
But you might find it goes bonkers at only 10psi, in which case you can set that one to something stable, and go looking for a regulator that specs down to say 5-7psi. Something like 0-120 is probably not what you want. Yes, it will go to 0, or 120, but maybe not 10
Play with your existing regulator and you’ll *probably* see what I mean. If not, then great. You’re done.
What Doug says, and do remember too that general purpose regulators are not terribly accurate, if accuracy is important. Depending on how precise the pressure required may suggest a more expensive precision regulator. Good luck.
One more thing:
We haven’t talked about the low pressure tank(s).
If it is rated at less than the the main tank, you need a PRV on the line such that it will blow before the low pressure tank can.
e.g., the main tank has a 150psi PRV.
If the rating of the lp tank is 150, you’re good.
If the rating of the lp tank is 100psi, you need a 100psi PRV ahead of that tank, if it doesn’t already have one built in.
Hello, I am trying to add another on board air system to my truck but tie them all together so they fill faster but one system is 200 psi and the other is 150 but burst pressure on the tanks is 250 the 150 psi system is for my train horn and the other is just for general use how do I tie them both together so I can still run 150 psi to my horns?
Read the above post. Just tee off the the 200 through a regulator to the 150. Leave the horn on the 150 tank.
Or are you talking three systems? Need more info about pump and tank capacity vs load demand.
Hi I have a 3 cylinder Air compressor I want to take the tank off and put a double the size larger tank on I will plumb it exactly the way the old one is can I do that
You can.
Be sure the tank has a PRV, and that it is rated for the pressure you want to put in it.
The only concern is that you don’t want to exceed the pump/motor duty cycle.
i was going to use the same PRV off the old compressor how would i check the pump motor duty cycle. Thank you
Well, you need to check the specs on the pump, and usually there’s info on the motor plate for the motor.
If you can’t find the pump info, usually 10-15 minutes on and 50% is safe.
You could post a pic of it…
We are trying to get a bank of tanks that would get a consistent output of 4500. We have multiple size tanks. 6000,4500,3600, and 3500 tanks. What is correct sequence of tanks for an output of 4500? The compressor runs right into the tanks from there the tanks run to a regulator than fill station.
4500 what? CFM? Can you either get a picture of what you have, or make a drawing showing how they are connected now? That would include where the compressor is connected and the connection between the tanks and regulator to fill station.
Also, the pipe sizes for the interconnections and the pressure/flow rate you’re after, for how long.
Right off the bat, the tanks should be in parallel, so there’s no ‘sequence’.
I can’t engineer it for you, but I can steer you in the right direction, if I haven’t already.
We want to add additional tanks to our bank. The tanks we will be adding are smaller than the four we currently have. We are just trying to get more output pressure of 4500. Just trying not to run the compressor all the time to achieve this.
We just received some tips. They mentioned that we would need to add the smaller tanks before the bigger tanks. Compressor – small tanks – large tanks – regulators – fill station
Thanks in advance
The attached is the better way.
But if you leave it serial, then yes, smaller to larger. Big pipes.
Good luck.
How about new compressor is 175 psi but old compressor was 150 psi new one is 21 gallons and old one 26 gallons craftsman new one is a McGraw the craftsman burned motor after 15 years but tank is still in great shape can I use that tank as extra storage
Yes. But first, insure that you have functional safety (PRV) valves on each tank. I can think of three possible ways, two of which are pretty straightforward: Set the pump cutoff pressure to 150 and connect the tanks either in series or parallel. Parallel is a bit more plumbing, but can give more air than a series arrangement. Run the output of the new compressor through a regulator set to 150 into the old tank, and take the output from there. Output will be limited by the inter-tank regulator in this arrangement. Is probably more trouble than it’s worth.… Read more »