Spray Coating Operations

A spray booth

Do I Need a Permit to Install a Spray Booth?
In many cases you will need to obtain a permit, or amend your current permit, before installing a paint spray booth. Spray painting and associated paint spray booths are of concern due to the volatilization of the solvents used to carry the paint solids as well as the overspray paint solids themselves and the hazardous constituents of both.  A permit is required if your proposed total coating usage at the facility will result in five (5) tons per year or greater of air emissions.  Yes, volatile gaseous emissions still have weight.  A permit may still be required even if emissions are less than this if the coatings contain significant volatile or particulate hazardous constituents.  Most auto body spray painting operations tend to be small enough as not to require a permit.  You should contact the AQCD Permits & Engineering Section  to confirm permit applicability before conducting spray painting operations or installing a spray booth of any size.

How Do I Know if My Spray Coating Operation Will Exceed Five Tons of Emissions?
The Safety Data Sheets for each of your coatings should provide the coating density in pounds per gallon and the percent volatile by weight.  If you coating weighs ten pounds per gallons and is 80% volatile by weight you could use 1,250 gallons total per year and remain under five tons per year of volatile emissions.

[1,250 gpy * 10 lbs/gal * 0.80 volatile emissions /2,000 lbs/ton = 5 tpy]

 Review your Safety Data Sheets carefully.  Sometimes they list the product density as a specific gravity as it relates to water or some other solvent.  If the value is related to water and gives a specific gravity of 1.2 then the weight per gallon would be 8.334 lbs/gal water * 1.2 = 10.0 pounds per gallon.  The Safety Data Sheets may also provide multiple values for the volatiles fraction.  From a regulatory standpoint we are only interested in the photochemical reactive volatile organic compounds (VOCs) and hazardous constituents.  Some coatings contain various amounts of water, which is volatile, but not of concern.  You will want to use the “VOC pounds per gallon” or “percent VOC by weight per gallon”.  Avoid the values “VOC pounds per gallon less water and exempt solvents” or “VOC by volume per gallon”.  You can contact the AQCD Permits & Engineering Section  if you have questions on how to read your Safety Data Sheets.

What Do I Need to do to Obtain an Air Permit?
A Permit to Construct application must be submitted with the appropriate application fee  to the AQCD.  The Permit must be issued before the applicant can commence construction of the project.  This would be required before installing or operating a paint spray booth at the site.   Please refer to our Permit to Construct Application Guidance webpage for more information. In addition to the information required to be submitted for a Permit to Construct Application, please also submit the following equipment specifications and designs.

Equipment Specifications & Designs
Please submit the following information to the Permitting and Engineering Section when applying for a permit.

  • Manufacturer, Model No.
  • Date of Installation
  • Spray Booth Type (dry filter, water wash, etc.)
  • Spray Booth Outside Dimensions (width, length, and height)
  • Method of Coating Application: (air atomization spray, airless spray, air assisted airless spray, electrostatic/air atomization, electrostatic/airless, electrostatic/air assisted airless, High Volume Low Pressure spray)
  • Number of exhaust fans and maximum air flow rating for each fan
  • Number and dimensions of exhaust filter elements (width, height and thickness of each element)
  • Capture efficiency of the filter elements for a specific particle size
  • Will ovens or heaters be utilized to speed curing of applied product?
  • Estimate of transfer efficiency
  • Filter face velocity (feet per minute)
  • Describe how pieces are placed and removed
  • For each coating or solution to be applied: manufacturer, product name, list of all constituents contained in the product, percentage of each constituent in the product (% by weight or volume, please specify), product density (lbs/gallon), usage rate (gallons per hour), volatile organic compound content (% VOCs as applied, excluding water) Clean up solvents (same as listed for coatings)

Particulate Emissions  
VOCs and volatile hazardous constituents are not the only concern with spray coating operations.  Spray painting by its very nature generates liquid particulate droplets of paint.  The total mass of particulate overspray emissions tend to be minor in comparison to the mass of volatile emissions given that much of the paint solids are deposited on the part being painted and much (but not all) of the overspray is captured by the spray booth filters.  But if the coating solids contain hazardous constituents, like heavy metals often used as pigments, very small amounts of emissions can still be of serious concern.

Spray Booth Filters and Spray Guns  
Regardless of permit applicability, you will need to equip the spray booth with overspray particulate filters.  Please note that not all overspray filters are equal.  In some cases as noted below you will need higher efficiency filters.  The spray booth exhaust should also vent vertically above the roofline and without a raincap  that would obstruct the upward dispersion of the exhaust.  Standard high pressure spray guns are also being phased out in favor of high volume low pressure (HVLP) spray guns.  HVLP guns provide higher paint transfer efficiency, reducing wasted overspray and the amount of coating you need to use.  Many coating operations are now prohibited from using traditional spray guns and are required to use only HVLP guns or their equivalent. 

Further Regulations 
You should also review your Safety Data Sheets carefully and avoid using coatings that contain chromium (Cr), lead (Pb), nickel (Ni), cadmium (Cd), or manganese (Mn) compounds.  Use of coatings in any amount containing these compounds may make you subject to the federal regulation for Paint Stripping and Miscellaneous Surface Coating Operations (40 CFR Part 63 Subpart HHHHHH)  that requires higher efficiency overspray filters, use of HVLP guns, spray painter training and certification, recordkeeping and reporting requirements.  You should also avoid coatings that contain hazardous constituents which when used in significant enough quantities would cause you to exceed chemical emission Action Levels found in the Vermont Air Pollution Control Regulations Appendix C.

What other permits or requirements may be applicable to my project?
The Department of Environmental Conservation Environmental Assistance Office has permit specialists that can provide assistance in determining what other state permits or programs may be applicable to your project.  You can find more information about this service at the following website:  http://dec.vermont.gov/environmental-assistance/permits

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