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A Technical Guide to Airbrushes

Choosing the Right Air Source

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In the grand scheme of airbrushes and sprayguns choosing the right airsource is the least important step and, possibly, the most expensive step.

People who make the best choices answer these three questions first.

  1. How much capacity do you need?
  2. Will a noisy compressor be an issue?
  3. Is electrical power an issue?

How much capacity do you need?

Here's the basic formula to determine how much air flow capacity you need.

Total Air Volume Needed x 1/(Duty Cycle) = Compressor CFM Requirement

Look at your setup.  How many airbrushes and sprayguns will you use at the same time?  One after the other in succession doesn't count.  This gives you your Total Air Volume Needed.

Total Air Volume Needed is the bare minimum.  No less.  Don't get anything that pumps out anything less than this number.  Bad.  Very Bad.

But there's still something else to consider here.

Duty Cycle, normally given as a percentage, means the compressor engine should only run for that percentage of every hour the compressor is in use.  It's a good recommendation to follow as best you can to keep your compressor running for a long time to come.

Examples
50% Duty Cycle = 30 minutes running for an hour's use.
25% Duty Cycle = 15 minutes running for an hour's use.

Will a noisy compressor be an issue?

Compressors, especially big ones, can be loud.  Very,very loud.  There are four  ways to handle the noise.

  1. Give it the fairy tale treatment--in a land far, far away.
  2. Muzzle it, like the loud, barking dog it is...
  3. Don't buy a noisy compressor.
  4. Avoid compressors all together and use compressed gas canisters.

Give it the fairy tale treatment in a land far, far away

In fairy tales everything always happens in a land far, far away--Snow White and the Seven Dwarfs, Cinderella, Sleeping Beauty, even modern fairy tales like Star Wars (I don't know if I'd call Yoda a fairy god mother though...).

Lock your compressor away in the dungeon, or the tower, or banish it to New Jersey.  The garage, shed, or even a closet work great if you don't have you very own dungeon or convenient access to Trenton.

All of these methods work because noise gets softer with distance.

If you decide to get medieval on you compressor make sure your choice allows great ventilation, compressors use air after all.

Also, keep compressors out of the elements.  Most compressors put up with the rain and snow.

Potential un-fairy-like problems.

Don't offload your own noise problems onto your neighbors. Waking up the neighborhood in the dead of night because inspiration slammed you upside the head with a 2x4 is not nice.

Don't forget to keep your compressor maintained.  Out of sight, out of mind.  Don't fall into that trap.  You'll still need to drain the tank and moisture traps, check oil levels if applicable, blah blah blah.

Muzzle it like the loud barking dog it is!


If you're the handyman, Do-It-Yourself, I-don't-need-to-pay-someone-else-to-do-what-I-can-do-myself, person then you might build a noise box around the loud beastie.  

I've seen untamed, very loud compressors become nothing more than  the occasional dull rumble.

Just like the fairy tale treatment air flow is the problem.  
Compressors use LOTS of air.  Make sure they can breathe.

Don't buy a noisy compressor


Quiet and even silent compressors exist out there.  They range from low rumbles to a little louder than your refrigerator.

It's story time!

Silent compressors can fool you about how loud they really are.  Many times the fan that cools them is louder than the engine pumping the air. How do I know?

When you start work on a compressor you depressurize the air tank first.

I opened the air tank drain valve.  The air rushed out (incidentally the compressor was shipped full of compressed air).  Air tanks don't take long to depressurize, a few seconds, maybe ten.  The air kept hissing out. I stared, puzzled, at this compressor after a full minute of flowing air.  How can an air tank have that much air in it?  What's going on?  I'd turned it off!

My instructor looked at me.  Rolled his eyes and flipped the power strip off.  The tank stopped spewing out air.  Heh heh...umm....whoops.

Yes, the compressor was running while I was working on it.  Talk about embarrassment...

These compressors do tend to be small.  They can range from a few pounds on up to 50 or 60 pounds.

Smaller sizes make them far more portable than bigger, louder compressors.  The smaller the compressor the less capacity that compressor has, but depending on your application that could be a very acceptable trade off.

There is one major down side to quiet and silent compressors.

  •  They are expensive.
Quiet and silent compressors are usually underpowered for high prices.  Consider the proverb, "Silence is golden."  You pay for the lack of noise.

Use compressed gas.


This is an elegant solution.  Why?

  • Compressed gas is completely quiet.  The loudest noise is the escaping air's hiss.
  • There's no need for power.  The tank starts already full.  Take it wherever you need it to go.  Then work your magic.
  • It's very portable.  Though possibly unsightly, the little oxygen carts for the elderly can easily carry a tank of CO2 or N2 or a repurposed SCUBA tank.
  • Compressed gas has very low up front equipment costs.
If compressed gas is so great why doesn't everyone use it?

Technically, everyone uses compressed gas.  Compressors pressurize whatever gas they're pressurizing and pressure cylinders (tanks) store the compressed gas for use later.   But that's getting technical.

There's no engine.  The engine is what makes the noise, uses electricity, and compresses the air.  It's just a tank of high pressure air.

Compressed gas has three big flaws


  1. Tanks eventually empty making tank refills a way of life.

     
    Experienced users horde an extra tank or two for the inevitable 'I just ran out of gas in the middle of what I'm doing!' moment.  Local welding supply, and beverage supply companies are your friend.
     
  2. Suffocation 

     
    The risk is really, really small.  This risk so small that it's a non-issue.  I mention it because if you do suffocate yourself, it's completely your fault, because it's easy to avoid.
     
    Here's how to avoid suffocation.  Ventilation.  You shouldn't spray in an enclosed space anyway, so you shouldn't be able to drown yourself by displacing all the breathable oxygen.
     
  3. Knocking off the tank's head.

     
    This is another very small risk that's completely avoidable.
     
    Rough handling that knocks or shears off the head allows all the pent up gas to escape turning the docile air tank into a torpedo.
     
    Avoid this problem by not handling the air tank roughly.  If you can strap the tank against something else upright to avoid the tank falling over.

Is power an issue?

For whatever reason, if you discover problems finding or running power to your compressor do one of these two things.

Purchase a generator for the compressor.

Make sure the generator will put out enough power for your compressor.  You might want to talk to the compressor's manufacturer and ask them about the start up power surge.  Your generator will need to put out enough power to cover that initial surge.

or

Use Compressed Gas.

Finding good steady power at the fair grounds or for a mobile service is murder.  A #20 CO2 or N2 tank frees you from the power grid nightmare.

Other thoughts

Air Tanks

An air tank on a compressor is a good thing.  Your compressor with a tank will run longer than a compressor without an air tank.  It might cost more, but it's a good thing.

Trapping Moisture

Compressed gas users don't need this advice.  Welding supply or beverage supply stores sell dry gas.

Air compressors must have a moisture filter and an air filter, but they might not come with the compressor you purchase.  

Moisture filters remove the compressed air's water vapor before the aerosol spray mixes with it.   The paint type you use determines what kind of bad results you'll get.  But no one wants bad results.  Unless you live in  New Mexico, deep in the Sahara, or in Antarctica, get a moisture trap.  

If you live in extremely humid places like Hawaii, on or near any body of water's coastline, or in the tropics, you might need to do more than purchase a moisture trap.

Dry air beats humid air every time.  Don't forget it.

Air Regulators vs Bleed Valves


Both control the amount of air delivered to your tools.  But they control airflow very differently.  

Bleed valves adjust the pressure by removing air from the pressurized air system before you have a chance to spray it.  They bleed air like medieval doctors bleeding their patients.

Air regulators adjust the pressure by allowing controlled amounts of air from one part of the pressurized air system into another.  It's like the on-ramp traffic lights on many freeways.  The lights regulate traffic onto the freeway.  Regulators regulate pressure into the air line.

You need enough air to run your equipment.  Choosing the right air source will keep you on the right track to starting airbrushing right.