Compressor in Garage & Car Emissions Questions

[realdiver7]

Just wondering if any special precautions for air quality need to be taken when using a compressor with air banks in the same garage where two cars are parked. I would think that carbon monoxide, carbon dioxide, hydrocarbons, and other emissions would use up filters quickly, and pose the potential problem of getting contaminated air mixed in with the good air that goes into the banks or scuba tanks.

Any ideas, precautions, ventilation techniques, time periods to wait before pumping air after cars are removed from garage, etc.? Is this something significant to consider or worry about?

Any expertise/experience in this matter would be greatly appreciated.

Thanks!

 

[fppf]

You should route your compressor intake high and outside the building.
Even our dive shop where the compressor is inside the building has the intake routed up and outside. This helps ensure the cleanest air intake as possible.

Also, if your pumping your own tanks you should have your air tested by a service.

 

[captain]

As long as you are not running the cars and the compressor at the same time and the garage door is open I don't see a great problem.

 

[pescador775]

Either run a food grade plastic tube as above or open the garage doors to clear the air. "Testing" is mostly irrelevant except as a CYA. If the air in the SCUBA carries an odor or if the SCUBA tanks have developed rust problems it is the responsibility of the diver and compressor operator to rectify the problem. Notably, the contaminant toluene cannot be detected by some outfits who claim to test air, but this gas can be detected by the diver simply by breathing in and exhaling through the mouth. This was indicated when Mike Barnett's odiferous air came back "clean" when submitted to a tester. He almost passed out during the dive and only the second tester hired for this purpose was able to find the contaminant, and then only when prompted to look for it. The air came from a dive shop who had a "test" sticker posted on the wall. How does one know that the results of a test on Monday will be the same as a sample taken on Friday? One needs to recognize that a properly maintained filter system produces clean air and simple precautions will keep it that way. Fortunately, a private owner, as evidenced by your question, may be more sensitive to air quality than some shops. Bad air is rare but not restricted to private owners by any measure.

 

[oxyhacker]

I'm often surprised when I visit home mixing stations at how often they are in garages where there are conspicuous off smells in the air ranging from mouse droppings and mold to gas, oil and solvents.
The nose is very sensitive, and can detect many contaminants in concentrations far too small to be a problem, but all the same, you don't really want to be putting this kind of air in your tanks. So an outside intake should be considered an essential part of any indoor compressor installation. Hydrocarbons are bad but CO is the worst of all so be sure your intake is up high and not in a place where CO can accumulate. There's been at least one CO fatality where a shop had an outside intake in an alley and someone left a vehicle idling nearby.

If you don't have an outside outlet, either move the compressor outside when in use, or at the very least, open the garage doors wide to air it out before you start pumping to air out the garage. A fan will considerably speed up the process.

 

[fppf]

You can not smell CO or CO2.
As depth increase the PP of these gasses also increases. Gas that is ok on the surface can kill you at depth.
That is why you don't want to get your tanks filled at your local fire dept. They do not hold to the same testing standards.

 

[pescador775]

We often hear that one cannot smell CO or CO2. However, these gases are rarely present alone. They are the result of combustion or chemical reactions and typically there are odors entrained with the carbon monoxide or other byproducts. However, if a stream of this stuff enters the compressor it is possible that the contaminated intake air will be "cleaned" of odors but not CO. This can happen because the activated charcoal is much more tolerant of moisture than is hopcalite catalyst. If the catalyst gets wet and stops working, an unusual situation can come into play as described. Usually, this involves an engine driven compressor. Therefore, a compressor operator, especially with a portable machine, should adhere to operating and maintenance instructions for the filter system, and observe the wind direction.

 

[realdiver7]

I appreciate all of the great advice and opinions submitted here. It looks like I'll be running an intake from the outside to play it safe.

Please continue with these discussions.

Thanks!

 

[fppf]

Higher the better, less chance of a pocket of bad air.

 

[rjack321]

Car exhaust is ~350 ppm CO. The CGA limit is 10 although 2 is better/more protective esp. for nitrox blending and or deeper diving. Basically you don't want any car exhaust getting entrained in your intake, it will quickly exceed safe limits for breathing at depth. A CO monitor like this is a good idea.
http://www.denninger.net/diving/co-analyzer.htm

And hopcalite in your final filter.

Do not, even with hopcalite, back up to a running compressor - even for just a second before turning the car off. My wife did this once and got a 16ppm spike of CO even with the hopcalite.