Ask the Expert Question-and-Answer Archive

by Ron Joseph

October, 2000

NESHAP and Paint Spray Guns

Q. NESHAPs for my industrial classification have yet to be promulgated. According to what I have read, our NESHAPs will be similar to ship & shipbuilding requirements. My question is, since we use mainly air atomized spray for current applications, will replacement with alternative coating processes probably be required? I assume that, since we will have to use higher solids coatings, perhaps air assisted airless or some other application process will be needed. Your advice is appreciated.

A. First, what is the industry classification under which you fall? I have studied the Aerospace MACT in minutest detail and have also seen outlines of the MACT for the Miscellaneous Metal Parts (MMP) and Plastic Parts (PP) industries which will be proposed by the EPA in 2001, and so I will base my answer on those.

If you fall into the MMP or PP industries, then I doubt that air-assisted airless or airless applications will be allowed, but you will undoubtedly be required to use either HVLP or electrostatic spray guns. With regard to air-assisted airless, some manufacturers, such as Graco and perhaps also Kremlin (and perhaps other of whom I am nit familiar) sell air-assisted airless guns that meet the definition of HVLP in that their "atomizing" air pressures are less than 10 psig.

With regard to coatings, you will be required to use low VOC coatings (solvent or water based), much like those that are currently being used today. However, the MACT standards are written specifically to control emissions of Hazardous Air Pollutants (HAP) and limits are placed on the HAP content, rather than their VOC content. From what I have seen, the new standards will be written differently from what we have been used to in the past, namely in terms of lbs HAP/gal of solids! That does not change what we have been doing before, except the calculations are very different and are based on the density of the solvents in the coating formulation.

Please bear in mind that when a MACT standard is written it is based on what is known as MACT floor. In other words, the EPA first surveys the industry for which the MACT is being written, and the standards are usually based on what 12% (the number can change) of the industry is ALREADY doing! Therefore, the EPA doesn't simply draw numbers out of a hat and regulate haphazardously. The limits are based on EXISTING technologies! What does change are record keeping and monitoring requirements, which tends to be more rigorous.

If you are interested in getting yourself prepared for the new MACTs, regardless of your industry, please be aware that I am giving a 4-day training program in January in the San Jose, CA. The purpose of the class is to prepare all participants with a full understanding of the regulations, and especially the calculations that will be required. In addition we will discuss spray gun and spray booth requirements, which in some regards will be different from current practices.