Fresh Air Supply

HobbyAir also available at autobodystore.com.

I haven't seen anything less expensive for a commercial product than these two manufacturers. I think they represent the floor in cost for supplied-air systems catering to the DIY. You might also check out some on-line automotive painting forums and/or ebay for the possibility of a used one showing up. I would expect there are some DIYs out there that will purchase something like that to paint their car, would not have a further need for it and would be interested in selling it to recover some of the expense. I don't know that to be true but its worth checking into.

I've never used a PAPR but I'll give you my opinion on them. A PAPR would be better than a normal, cartridge style, negative pressure respirator since it forces air to the mask under pressure. It does not rely on the negative pressure caused by breathing in to force air through a chemical cartridge/filter. The mask therefore operates under a slight positive pressure, caused by the unit on your belt. Because of that, the face fit would not be as critical and it could be possible for people with facial hair to use one successfully - although I'm not sure if any manufacturer actually recommends that. You also would not have the bother of dragging around a second hose for your breathing air as you would with a fresh air unit. However, those are the only advantages that I see (for painting). The PAPRs still rely on a filter/chemical cartridge to get rid of the bad stuff - e.g. isocyanates. They also require a battery pack to power the blower unit.

The biggest thing I have against them is the requirement for processing the bad air using a chemical cartridge/filter. As far as I know, no manufacturer makes a chemical cartridge with an end-of-service-life indicator (ESLI) for isocyanates. So the user has no specific way of telling when the cartridge needs to be replaced. Isocyanates have no odor so any sense of smell is not reliable. Furthermore, no manufacturer that I am aware of makes a cartridge that they recommend for isocyanates without pre-conditions that are unrealistic for a DIY to meet. For instance, 3M does make a cartridge they suggest can be used with isocyanates but ONLY when the air concentration is less than 10 times the permissible exposure limit. They specifically DO NOT recommend it if the air concentration is unknown - which is always the case for DIY painting. The National Institute of Occupational Safety and Health (NIOSH) doesn't recommend cartridges for isocyanates at ANY concentration, even less that 10 times the permissible limit. Air concentration for a DIY is not only unknown but can be expected to be highly variable. There is a major difference between a DIY, even when painting outside, and a person in a professional down draft paint spray booth that serves, by design, to minimize iso concentration in a painter's breathing zone.

For the above reasons, my preference for DIY painting is for a fresh air type of continuous flow respirator that can take the source air from a known location. I'd much rather breathe known, good fresh air than rely on some filter to remove the bad stuff from contaminated air. Not to mention the continuing maintenance costs of prefilters, chemical cartridges and batteries/battery packs. Having used a fresh air respirator for many years, I have no interest at all in a PAPR for my painting needs. I have no idea what the life-cycle cost difference between a fresh air respirator and a PAPR might be. Whatever it is, it wouldn't change my opinion. I admit dragging around a breathing air hose is somewhat of a pain. But it's a bother I'm gladly willing to put up with to guarantee fresh air to breathe.

Rod