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777funk 02-24-2012 08:26 PM

Is shop air safe for a fresh air breathing system?
I just found a hood that's made for a fresh air system and plugged it into one of my air lines. The hood was super cheap as a surplus item on ebay. But as I did a little homework it looks like there are all sorts of filters to be used to breathe shop air and LOTS of money to be spent on the filters (around $1k for DeVillbiss' filter system).

Currently I have my compressed air running through the HF blue air line filter, then through the airline plumbing with drains every 10 feet or so, to my booth's regulator with a water trap, then through a 10 micron fuel filter for a diesel/gas pump (my particulate filter).

Seems like my missing piece(s) are an oil vapor filter and a coalescing filter. I'm not sure I have much oil in my lines but I'm sure there's some. I'm guessing it's not safe breathing air.

Is anyone on here using shop air for their fresh air respirator? Seems to be common these days but I kind of wonder if it's safe.

In the compressed air system I can think of a few things it's got against it:
1. The compressor gets hot and I can smell the paint heating on the cylinder walls. This paint smell is getting into the intake.
2. Drain the compressor and it's a musty nasty water smell. All compressors have this smell. Some of this fungus and mold has to be in the compressor's air.
3. Oil vapor leaking past the piston rings is hot and atomized. I'm sure a little of this gets in the lines.

All of that makes me a little bit nervous. But then again breathing paint fumes isn't safe either.

Seems like most oil vapor filters are carbon (charcoal) types that absorb contaminants. I'm guessing they work to a decent degree. That's also what the NIOSH resporator masks are so they must work.

Maybe I'm nervous for no reason on this... but I have to admit I'm a little leary of breathing from my compressed air line. Is there something better or am I just nervous for no reason?

OneMoreTime 02-24-2012 09:11 PM

You need the proper filters to use shop air and yes they are expensive...the better option is to go with a dedicated fresh air system such as the Hobby aire or similar and picking up fresh air from an outside source..
Just my take


Powork 02-24-2012 09:21 PM

I know when the divers came to clean the bottom of my boat they just had a little oil less compressor that they set on the dock. Don't know the brand or anything. Sure didn't look like an expensive setup.

TucsonJay 02-24-2012 09:30 PM

I was asking the same question, and found out that "oil-type" air compressors produce carbom monoxide.... because there is oil in the cylinder during compression.

You would need to use a diaphram-type, also known as "oiless" compressors. I switched over, and now do what you were talking about. I will add that they are not inside the booth sucking paint fumes. :-)

Irelands child 02-25-2012 05:51 AM

By the time you get that shop air system sorted out and the material needed there is a pretty good chance that you have come close or could have paid for a Hobby Aire system seen here. From personal use, these work just fine. I pulled my fresh air from a cool basement and used a 50 foot RV water hose that I have as the hood air supply - it's quite a bit more flexible then the one supplied.

That Harbor Freight air separator will need a further separator after it as it really doesn't do a good job. I used one of them along with a Sharpe - absolutely no water carry over.

This wasn't the final configuration as I added this pressure regulator and straightened out the plumbing:

.....and it worked for me :D

777funk 02-25-2012 03:06 PM

I've thought about trying to use the blower fan from a car as the fresh air supply. I'm sure it'd be more than enough CFM's. But the 12V thing is what's held me back on that.

Maybe an old hotel air conditioning unit blower. The guy who owns our hardware is always scrapping those things.

ogre 02-25-2012 08:40 PM

either fan will work, but you will need a 4'' duct to carry enough air to stay alive.
imagine dragging a 30 ft length of duct while trying to paint a car...

777funk 03-07-2012 10:27 AM


Originally Posted by ogre
either fan will work, but you will need a 4'' duct to carry enough air to stay alive.
imagine dragging a 30 ft length of duct while trying to paint a car...

You're right, I can't see much air getting through the 1" hose on most air hoods.

I tried a Coleman air mattress inflator (like a small blow dryer) years ago, it worked but it tended to blow hot air and it smelled pretty bad like plastic. I eventually retired it to being a blower to help my charcoal grill heat up faster.

fireboat 03-07-2012 07:39 PM

I think the others are right, unless you spend the big bucks for good quality filters, it is best not to go the compressed air route.

I'm sure I will get some flak, but I built my own fresh air system and have been using it for years. I bought a new vacuum cleaner motor on ebay for about $70, the impeller is sealed from the motor so you are not breathing air that passed through the motor. I built a wooden box with a switch, an inlet air filter, discharge pipe and a bypass valve. I use the cheap corrugated medical blue ventilator hose connected to my surplus fire department Scott full face mask. All told, I guess I have about $150 in it.

It is noisy, but the air is cool and clean. Still the easiest way is to simply buy a Hobbyair. It seems like a lot of money but the peace of mind is great not to mention your body will thank you too.

777funk 03-08-2012 10:15 PM

The ShopVac Bucket max is around $20 and has the blower fan separate from the motor. It's got a pair of filters (foam and cloth). I'd bet it'll work. I just bought one tonight so we'll see.

777funk 03-13-2012 11:31 AM


Originally Posted by 777funk
The ShopVac Bucket max is around $20 and has the blower fan separate from the motor. It's got a pair of filters (foam and cloth). I'd bet it'll work. I just bought one tonight so we'll see.

So far it seems to work well and I'd think is enough air. I have 12' of ebay CPAP (for people with sleep apnea) hose connected to the shop 1.25" hose with duct tape and the other end in my fresh air hood (an actual fresh air hood I found on ebay from a surplus place cheap).

My only worry is that I could forget to turn the air supply on. I suppose I'd smell paint soon enough as a reminder.

Of course this is jerry rigged and definitely not tested or commercially designed as such, but I'd bet it's healthier than paint fumes. I can't smell even a hint of paint with this on.

777funk 03-14-2012 07:02 AM

I wish there were an easy way to measure Co2 levels in the hood. I'm going to measure the flow rate of the incoming air to at least see what that is. So far I feel fine with this on for 10-15 minutes at a time (as long as I usually spray). I may add a snorkel and breathe out through it in order to keep carbon dioxide out of the hood.
I definitely smell ZERO paint. So that's a good thing!

AutoGear 03-22-2012 12:40 PM

The fumes you smell aren't the ones to be worried about most. Isocyanites are odorless and tasteless (apparently). In fact most home respirators guys use to paint a car (the NIOSH type) aren't recommended for what we do. has beat this to death for years it seems (in fact, thats where I first ran into MartinSR).

777funk 03-29-2012 01:09 PM

Measured the CFM of the bucket max shopvac head and it's way high. I'd guess around 10 CFM or more (pegged in a big way a small 6 CFM gauge). Seems like the airflow should be enough to keep me alive. We'll see!

boatbob2 03-29-2012 01:54 PM

Huh ???
Hi,let us know if it kills you, so we wont try it,,,,,, :nono: :nono:

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