Convert a tire inflator-type air compressor into a vacuum pump

Picture of convert a tire inflator-type air compressor into a vacuum pump
A vacuum pump is just an air pump, like a compressor, where you use the input side for suction, rather than using the output side for blowing.

Many air compressors make good vacuum pumps if you can find the air intake, enclose it, and attach an appropriate hose or fitting.

In this instructable, I'll show how to convert a 12-volt "tire inflator"-type air compressor into a vacuum pump. This makes a vacuum pump suitable for vacuum bagging laminates and composites (like fiberglass), or for evacuating a tank for a small vacuum former.

The vacuum created is several times stronger than any vacuum cleaner can produce, and most of the way to a perfect vacuum. (About 25 "inches of mercury" out of a possible 29.9, or 12.3 pounds per square inch---or 1768 pounds per square foot.)

It is strong enough to achieve professional-quality results for many processes that require vacuum.

I got my little air compressor for $2 at a Goodwill Blue Hanger store (a.k.a. "Goodwill Outlet Store"). New, it would cost about $20. Converting it to a vacuum pump required a few dollars worth of parts & glue.

In addition to the pump, I used:
a few feet of 1/4" inside diameter braided PVC tubing
a nylon fitting with a hose barb for 1/4" I.D. tubing, and
some J.B. Weld steel-filled epoxy

All of these things are available at home improvement stores.

Since this is a 12-volt device that draws almost 4 amps, it requires a fairly hefty (DC) power supply. I run it off my 6-amp car battery charger. (Or sometimes off of a 12-volt deep cycle, trolling motor-type battery, for vacuum forming in locations where A.C. power isn't available.)

Thanks to Doug Walsh and his book "Do It Yourself Vacuum Forming for the Hobbyist" for the basic idea.

I've done very similar conversions of "nebulizer" air compressors (for medical equipment) from thrift stores. They're quieter, but don't pull as hard a vacuum. (About 17 inches of mercury or 8 pounds per square inch.) That's still several times harder than a vacuum cleaner can suck, and good for vacuum-bagging things like RC model airplane wings, but only a little more than half the ideal vacuum.) The upside is that they're quieter and run cooler, and will likely last longer.

NOTES(added in light of comments below):

If you use a really, really cheap tire inflator, such as the $10 "mini air compressor" from Harbor Freight, don't expect too much. Really dirt cheap inflators may only run for a few minutes before overheating. (Better inflators can run for up to an hour. ) Err on the side of not running your pump for too long at a stretch. If you don't know if it's rated for more than 15 minutes, only run it for 5 or 10 minutes at a time, giving it 5 minutes to cool down before restarting it. Ideally, you'd like a pump with a heavy finned aluminum cylinder, a cooling fan, and a powerful motor, rated for continuous long runs. (Really ideally, you'll get it for $2 at the Blue Hanger.) Failing that, be gentle with your cheap little pump.

Some tips on keeping the workload within your pump's limitations:

For vacuum bagging: (1) don't expect to use this pump for things like full scale airplanes, or to cope with substantial leaks, (2) use a modest-sized vacuum reservoir so that you don't need to run the pump all the time, or for a long time just to build up vacuum in the reservoir. Either use a vacuum switch to top off the vacuum automatically now and then, leaving the pump off most of the time, or do it by hand. If the pump is running most of the time, something is wrong.

For vacuum forming: (1) don't expect to empty a 30-gallon water heater tank with this thing. (I use a 7-gallon $20 Wal-Mart air carry tank for my 12 x 18 inch vacuum formers.) (2) Use a two-stage plumbing system to reduce the load on the vacuum pump and make your small tank go much further. (Like this one, using a vacuum cleaner to suck most of the air out, and an evacuated tank to pull the plastic down hard: .) (3) Don't run the pump until it tops out at 25 inches of mercury or so unless you're forming thick plastic around tight details. 20 inches is plenty for most vacuum forming purposes, and the last few inches take longer, and wear out your pump that much faster.

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vicvelcro1 year ago
I modified one of these just a few weeks ago. I drew enough vacuum to boil water. The gauge I tried to measure with was not properly calibrated, so I can't give any exact numbers.

If anyone else gives this a try, I suggest looking for the 'Slime' brand of mini compressor. I bought mine at the store with the smiley face for $10 USD.
Higgs Boson2 years ago
How high of a vacuum can this create?
I just made one with a 110v compressor that was like the one in the ible, but about twice as big, it went to 29.5 in hg, about 99% of a complete vacuum.
Wow! That's pretty good for moding a compressor. unfortunately I need a pump which can get down to about 15 - 10 microns. I guess I will just have to buy a 15 micron refrigeration service pump and give it high quality oil to boost performance.
Woa, what do you need 15-10 microns for, that sounds like a awesome and dangerous project, are you making X-rays?

Those things are really expensive.

I got a more accurate measurement based off when water at a certain temp starts to boil in the vacuum, I get more like 29.02, but that is only running it for 10 seconds after the gauge stops, so if I try running it longer it might get lower.

I got a question for you, you seen to know something about vacuum, it seems to me that when my pump is pulling a full vacuum, that would be about the same strain on the motor as if it was pumping 14 psi, or 1 atmosphere right?

I need high levels of vacuum for constructing electron accelerators, and to tell the truth I haven't actually used a pump yet. I have been researching which is the best to buy, and where to buy it as well as how I should use it. Sorry, I wish I could help you with your question but as of now I don't have experience.
Does the level need to be that high? From what I understand from my research into vacuum tubes is that it is like trying to shoot a bullet through an ultra dense asteroid field, when there is no vacuum, it isn't going to happen, and with a high but not ultra high vacuum it is like shooting bullets through a super thin asteroid field, most of the bullets will go through and there will be very little loss of electrons.
I hope that makes sense.

I haven't made the pump I put a link to, but he says he got down to 150 microns, you might try building something like that to play around with before purchasing a big expensive one.

All I got to get is a flyback transformer and I'm on my way to making an osciliscope completely from scratch.
Well you don't need that high of a vacuum to get it to actually start to discharge, but the more air you pull out the more experiments you will be able to do with it. Hertz actually didn't get accurate results from his cathode ray tube experiments because he didn't have a high enough vacuum in his tubes. He was looking for deflection of the electron beam in a presence of an electric field, but was unable to detect it because his vacuum was not deep enough. It took another experiment in a vacuum of 33 microns to see this. A lot more affects can be seen in the CRT if you have a deeper vacuum.

i just wanted to know would this work with concentrates ? enough to pull all butane out of the product? after a heat bath :) please let me know any inforrmation would be grealy appreciated

fcharest14 months ago

I have one question do we need to keep the one way clapet intact ?

This looks like an excellent Instructable! I do wonder, could you use this for vacuum forming? I was going to need a Shop Vac for the project I'm looking at, but if I could use this, it would be preferable.

RadiantOnyx5 months ago

Awesome, I'm going to apply the same idea for making a desoldering iron. I could replace the bulb type desoldering iron assembly, add the vacuum tube where the bulb was, have a momentary switch glued to the soldering iron controlling a relay for the pump, and voila!

-copper tube-6 months ago

Great vacuum tips: take a container, put marshmallows, one balloon or a sealed soda can and watch the results.

patrickm7 months ago
I built one out of a compressor that was identical to this with the only difference being mine had a pressure gauge in the front panel. The best I can get with it is a whopping 18 in. Hg! In fact, that's a lot more than I really thought it would do, but still far from being anything close to what I need. So, I ended up converting an old Harbor Freight pancake compressor I had sitting out in the garage, and I can get 24-25 in. Hg with that. Not sure it that's going to be high enough either, but will give it a try.

I have no idea how the rest of these people are getting anything close to 20 in Hg with these little things, there is no way they are capable of that! That's why people end up spend hundreds of dollars for a real vacuum setup in the end.

Anyway, just my 2 cents.
ajoj1 year ago

with this pump is it possible to suck the oxygen out of a water tank where the water is 4 inch away from the lid?
batman962 years ago
Thank You!
I have regular 50 gallon air compressor, and somebody gave me a little air compressor like this one, but it is 110v 150 psi, but very well made, it has a 6 inch long motor with a fan at each end, and the cylinder head has fins on it, the intake was in a depression like yours, so I used a right angle hose barb and epoxy putty and installed it, hooked it up to a vacuum gauge and it went all the way down to 29.5 In Hg!
I couldn't believe it almost a complete vacuum!
Thank you for these instructions, I was going to take the thing apart and turn it into a steam engine, because I had no use for it, now I can finish gas discharge tubes that I tried to make with a hand pump, but it just didn't have enough vacuum, it only went down to about 24 In Hg.
mdenunzio2 years ago
do you think this set up would work to operate a power booster on a car? aftermarket vacuum pumps usually run over 200! i could make this for free today. just mounting is the only issue.
ikes97113 years ago
Will this work with water?
skaar ikes97112 years ago
till water gets in the pump... perhaps it would be possible to pulse it, pull water into a container, let vac off, pump again. you could use it as a sprayer, air through a constricted tube, a source of water put in at the middle, like a bulb pump perfume sprayer, or carburetor.
skaar3 years ago
how about... put the entire thing into a box, and seal the out tube... no noodling, and there would be a vac reserve, use a vac switch to switch it on and off...
detchells skaar2 years ago
The problem with that would be that the pump itself (motor, piston/cylinder, etc) would be operating in a vacuum, so the heat generated couldn't be conducted away by the surrounding air. - It'd almost certainly fry the motor, pump assembly or both in fairly short order.
skaar detchells2 years ago
unless it went really really really low pressure, i rather doubt there would be a problem with heat conductance. if there's concern, a circulation fan could be put in.
detchells skaar2 years ago
Good point - I was thinking "vacuum," but these little tire inflators aren't able to pull a very strong one. Still, the author says his unit can reach a vacuum of ~12.3 psi, so that means the pressure inside the box would be only ~14.7-12.3 = 2.4 psi vs normal atmospheric pressure of ~14.7. That's only about 16% of normal, so you can figure only ~~16% of the heat could be carried away vs normal operation. A fan would help some, and the unit might be OK for short runs, but you wouldn't want to leave it running for very long.
skaar detchells2 years ago i don't feel very well today, so... ended search here. someone there has a link to a table, but, another says it's irrelevant at low pressures... perhaps low pressure differential is intended, and not important till the differential is large, dunno.
egunawan13 years ago
can I use this kind of vacuum pump to boil a water?
FloydV5 years ago
Have any of you tried a aspirator vacuum pump. Basically, water sucks the air in as it flows out a pipe. Cheap ($20.00), and high volume and high suction (28.5" Hg). I've used these before and they work really well.

A link for a Nalge pump is:
johnny3h FloydV3 years ago
Hi Floyd,

I too have used the waterhose aspirator vacuum pump for YEARS for servicing automotive air conditioning systems and it has worked well [down to 28 to 28.5 in Hg], and what I really like about it is that with good, high water pressure, it works FAST!!!!! MUCH faster than "store bought" commercial, OR refrigerator compressors converted. Over the last 45 years I've tried 'em all.
Would you be willing to make an instructable on how to use a water aspirator? I want to build a vacuum degasser for resins and a water aspirator vacuum pump seems like the cheapest way to do it.
I looked up the link: Product Code NL-LP-6140-0010 List Price $35.95 Sale Price $31.95 Must have raised the price...
troppoforte3 years ago
Nice little project here!

I love those small pumps with those tiny pistons, the likes of which are in small gas plane engines.

I've actually been pondering turning one of my vacuum pumps into a compressor for an air-powered engine project I have been planning.

I bought three vacuum pumps from my local University surplus warehouse for $5-15 each. One of them is a dual-cylinder pump. It has a direct-drive to the crank as does another of my older ones. My oldest, a Fisher Scientific with a 1/2 HP GE motor, is powered through a belt. That's probably the stongest one I have.
Mattrox5 years ago
Does anybody know how to change the copressor plug from being car cigerrete lighter powered to mains or run it off a car battery Pleaz Coment
miiwii3 Mattrox4 years ago
easy buy a 12 volt wall wart you know 120v to 12v and splice the wires together white or dashed wire to white or dashed wire black to black. i believe black is ground or negative ohh and your wall wart must be dc voltage
air compressors use more power than a wall wort can usually supply, and will either burn up your wall wort, not supply enough power to run the compressor or both. A computer power supply does work ok though. In general, they probably run around 8-10 amps for the model shown in this instructable.
Mattrox miiwii34 years ago
miiwii3 Mattrox4 years ago
no problem
rada194 Mattrox4 years ago
a really easy way is to hook it up to a 12.0 volt drill battery thats what i did and its rechargeable and portable its great
bomihdar3 years ago
thank you
noledude443 years ago
Would be strong enough to use with a vacuum bag? I'm going to be making a longboard and i'm just checking out different ways to do it.
there is an instructable on making a vacuum seeler
corbin5694 years ago
does anyone know if this would pull a big enough vaccum for a fusor reactor/fansworth reactor... i,m only wanting to make the plasma not introduce a new gas and make actual fusion
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