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Painting/Coating Operations: Instructions for Emission Calculation Spreadsheet

This method may be used to develop an editable spreadsheet containing detailed emissions calculations for painting and coating operations at your facility. These instructions are used to calculate potential particulate matter (PM), volatile organic compounds (VOCs) and individual and total hazardous air pollutants (HAPs). Potential emissions of other pollutants from the painting/coating operation will also need to be included in the permit application (e.g., emissions from fuel combustion in a curing oven). Each step in your calculation(s) needs to be clear and easy to follow.

Include the following information with your calculations:

  • AQ Facility ID No. — Include your Air Quality (AQ) Facility identification (ID) Number (No.). This is the first eight digits of the permit number for all permits issued under the operating permit program. If your facility has never been issued a permit under this program, do not include it at this time.
  • AQ File No. — Include your AQ File Number, if known. This number can be found in the “cc” section of correspondence from the Minnesota Pollution Control Agency (MPCA). If you don't know or can't find this number, do not include it at this time.
  • Facility name — Include your facility name.
  • Emission unit or other identification number(s) — Include the identification number of the emission unit(s) (EU). Obtain this number from Form GI-05B or the appropriate form related to the permit you are applying for, or your existing permit.
  • Stack/Vent designation number(s) — Fill in the designation number of the stack(s) or vent(s) through which the unit will exhaust into the atmosphere. Obtain these numbers from form GI-04 or the appropriate form related to the permit you are applying for, or your permit.
  • Control equipment — Include a description of the type of control equipment. Use the designation number of the control equipment (CE) through which the equipment will exhaust. Obtain this number from Form GI-05A, or the appropriate form related to the permit you are applying for, or your existing permit. If none, indicate no control equipment. If you are applying for a registration permit Option D, just provide a description of the control equipment.
  • Application Method Indicate the coating application method (e.g., Air atomization spray, Airless spray, Electrostatic/Air atomization, Electrostatic/Airless). If painting or coating is done by dipping, use this method to calculate volatile organic compound (VOC) emissions and volatile HAPs. There are no particulate matter (PM/PM10/PM2.5) emissions from dipping. If painting or coating is done by brush or with spray cans, this method is not applicable.
  • Number of Spray Ports in the Booth Indicate the number of spray gun hook-up ports in the booth. If there are more than one, specify any physical limitation that would prevent the simultaneous use of all the spray gun hook-up ports in the booth.
  • Ovens, if applicable If oven(s) are used to dry or cure the coating, fill in the number of ovens, the fuels which can be used, and the total rated heat input of the ovens. Be sure to calculate emissions from the ovens as shown on the webpage for External Combustion Units. If the ovens use electric heat or UV curing, there would be no emissions.
  • Coating Information — For each paint, coating and mixture that could reasonably be used in this coating operation, provide the density, VOC content, solids content, each individual HAP content, and total HAPs content. This information should be provided in the spreadsheet (an example format is shown in Table 1 below). Use an abbreviation or code number for each material, if needed.
  • Density Indicate the coating density in lbs/gallon for each coating. This information can be obtained from the Material Safety Data Sheet (MSDS).
  • Determine VOC Content For each coating that you use, indicate its VOC content in pounds per gallon (lbs/gallon). To determine the VOC content of the coating, consult the (MSDS), VOC data sheet, or contact the coating manufacturer. If the MSDS gives a range (e.g., 1-5%), use the highest number in the range (e.g., 5%). Include all MSDSs in the application or submit the MSDSs electronically (disk or CD). If the VOC content is listed in the MSDS in weight percent, calculate the lbs/gallon by weight using the following formula: VOC content (lb/gallon) = VOC content (weight %) x coating density (lb/gallon)

    If the MSDS or other source does not give the VOC content in lbs/gallon or in weight %, it may be given in volume %. In this case the VOC content of the coating in lbs/gallon can be calculated by using the following formula: VOC content (lb/gallon) = [VOC content (volume %) ÷ 100] x VOC density (lb/gallon)
  • Determine Solids Content For each coating, indicate the solids content in lbs/gallon. Solids content will be used to calculate PM/PM10/PM2.5 potential emissions. To determine the solids content of the coating or the coating density, check the MSDS or contact the coating manufacturer. If the MSDS gives a range (e.g., 50-60%), use the highest number in the range (e.g., 60%). Attach the MSDS to your calculations, or submit the MSDS electronically (disk or CD). If the solid content is not listed in pounds per gallon in the MSDS, use the following formula: Solid content (lb/gallon) = [Solid content (weight %) ÷ 100] x coating density (lb/gallon)
  • Determine HAPs Content For each coating that you use, indicate the content of each individual HAP and total HAPs in pounds per gallon (lbs/gallon). To determine the HAPs content of the coating, consult the MSDS or contact the coating manufacturer. If the MSDS gives a range (e.g., 1-5%), use the highest number in the range (e.g., 5%). Attach the MSDS to your calculations, or submit the MSDS electronically (disk or CD). If the HAP content is listed in the MSDS in weight percent, calculate the lbs/gallon by weight using the following formula: HAP content (lb/gallon) = HAP content (weight %) x coating density (lb/gallon)

Table 1. Example format for Coating Information

  Coating   

Density (lb/gal)

VOC Content (lb/gal)

Solid Content (lb/gal)

Total HAPs Content (lb/gal)

HAP 1 Content
(lb/gal)

HAP 2 Content
(lb/gal)

Continue for each HAP

Coating A

Coating B

  • Minimum Transfer Efficiency Indicate the transfer efficiency, as a percentage. Please note that if an applicable federal regulation specifies a transfer efficiency, that efficiency must be used. If no applicable federal regulation applies, and if no site-specific data is available (e.g., gun manufacturer data), use Table 2 below. Note that when doing the calculations (i.e., Step 5), the maximum emission rate of PM/PM10/PM2.5 will not necessarily occur at the minimum transfer efficiency. You may need to analyze each type of coating and its transfer efficiency to determine the combination that results in maximum emissions.

    Table 2. Minimum Transfer Efficiency

Application Method

Transfer Efficiency

Air atomization spray

0.30

Airless spray

0.45

Electrostatic/Air atomization

0.70

Electrostatic/Airless

0.75

HVLP (High Volume Low Pressure)

0.75

Electrode deposition

0.95

Powder

0.95

  • Formula/Equation — The formula and/or equation needs to be available in the spreadsheet cell for each calculation step (for example, Steps 5, 6, 8, 9, 10, 11 and 12 below).
  • Operating limitations — Describe in detail any permit limits you plan to take to restrict your potential-to-emit (hours of operation, bottlenecks, etc. - see Proposing Synthetic Minor Permit Limits). Attach additional information, as needed. Describe the limiting factors, cite any rules that apply (e.g., Standards of Performance for Stationary Sources [NSPS, 40 CFR part pt. 60], Best Available Control Technology [BACT]). The associated limit must be used to calculate your potential-to-emit after permit limits in Step 11. If you used vendor certification or stack test data to limit your potential-to-emit, the factor you used will become your permit limit. Include all proposed limits on Form CD-01, and anywhere else as instructed in the application forms.
  • Additional Emissions Calculations for this unit(s) — If the emissions units described by these calculations include other types of emissions, calculations for those emissions should be included on a separate worksheet. For example:
    • If this process/unit combusts fuel, include fuel combustion emissions.
    • If this process/unit uses clean-up solvents in addition to the process described by these emissions calculations, include emissions calculations for clean-up activities.
    • If this process/unit emits greenhouse gases, include greenhouse gas emissions as described in PDF Document MS Word File Form EC-17 (Greenhouse Gas Emissions).

Emissions Calculations

Follow these steps for calculating your emissions for each spray coating operation at your facility. Generally, each column of your spreadsheet will correlate to each step indicated below. Additional columns can and should be included in the spreadsheet to indicate additional steps or information specific to your coating operation.

Step 1. Pollutant

Include each of the following pollutants that your coating operation emits.

  • PM = particulate matter
  • PM10 = particulate matter smaller than 10 microns in aerodynamic diameter
  • PM2.5 = particulate matter smaller than 2.5 microns in aerodynamic diameter
  • VOC = volatile organic compounds
  • HAPs = hazardous air pollutants – each individual hazardous air pollutant. See EPA's Web site Exit to Web for more information.
  • Total HAPs = All HAPs added together

Step 2. Maximum Pollutant Content [lb/gallon]

Indicate the highest or maximum pollutant (VOC, PM, PM10, PM2.5, or HAP) content as identified in the Coating Information above.

Step 3. Maximum Coating Application Rate [gal/hr]

Indicate the maximum coating application rate that can occur in the booth, in gallons per hour. This is the maximum amount of coating that can be applied by each gun that can be operated simultaneously (i.e., if there are 4 guns each capable of spraying 4 gallons per hour, and up to 3 can be used simultaneously, the maximum coating application rate is 3 guns x 4 gallons per hour per gun = 12 gallons per hour).

Step 4. Transfer efficiency

Indicate the transfer efficiency.

Step 5. Emission Rate [lb/hour]

Calculate the maximum uncontrolled hourly emission For VOCs and volatile HAPs, use the following equation:

  • Emission Rate [lb/hr] = maximum pollutant content [lb/gal] x maximum coating application rate [gal/hour]

For PM/PM10/PM2.5 and particulate HAPs, use the following equation:

  • Emission Rate [lb/hr] = maximum pollutant content [lb/gal] x maximum coating application rate [gal/hour] x (1-transfer efficiency)

Step 6. Maximum uncontrolled emissions

Calculate the maximum uncontrolled emissions by multiplying the hourly emission rate by 8760 hours per year, and dividing by 2000 pounds per ton. This is the ‘maximum unrestricted emissions’ in tons per year to be included in the middle column of item 3e on Form GI-07.

  • Maximum uncontrolled emissions [tons/year] = Emission rate [lb/hour] x 8760 [hour/year] x [1 ton/2000 lb]

Step 7. Pollution control efficiency

Include the pollution control efficiency. The pollution control efficiency is the product of the capture efficiency and the destruction/collection efficiency indicated on Form GI-05A (or other similar form, depending on the type of permit you are applying for), or in your existing permit. Enter this number here and remember to include on Form CD-05 a plan to demonstrate and maintain the destruction/collection efficiency. The efficiency should be expressed for each pollutant. If there is no control for a particular pollutant, indicate “zero” as the control efficiency.

Step 8. Maximum controlled emissions rate [lb/hr]

This is the maximum controlled lb/hr required in the first column of item 3e on form GI-07.

  • Maximum controlled emissions rate [lb/hr] = Emission rate [lb/hr] x {[100 - Pollution control efficiency] ÷100}

Step 9. Maximum controlled emissions [tons/year]

Calculate the maximum controlled emissions using the following formula:

  • Max. controlled emissions [tons/year] = Max. uncontrolled emissions [ton/year] x {[100 - Pollution control efficiency] ÷100}

Step 10. Hourly Emission Rate Allowed by State Rule or Federal Regulation

Include the maximum hourly emission rate allowed under 40 CFR pt. 60, 40 CFR pt. 61, 40 CFR pt. 63 or Minn. R. ch. 7011. (See Form GI-09 for information on applicability of the various regulations.)

Step 11. Limited controlled emissions [tons/year]

(Skip this Step if applying for Registration Permit Option D)

Limited controlled emissions are calculated by taking into account all limitations on operation of the source you are proposing to comply with in this application. These limitations include limits on hours of operation, on the amount of material used. You start the calculation of limited controlled emissions by repeating the calculation of emission rate [Step 5] but taking into account the limits you propose. This is the limited controlled emissions in tons per year in the right column of item 3e on Form GI-07.

If an emission unit is subject to an emission limitation specified in 40 CFR pt. 60, 40 CFR pt. 61, 40 CFR pt. 63 or Minn. R. ch. 7011, you must show this requirement in the calculation of limited controlled emissions and take this into account in calculating the limited controlled emissions. If you choose to propose to comply with more a stringent limit, you should state this clearly and show the resulting allowed emissions in this calculation.

Step 12. Actual emissions

If this is an existing operation and historical records exist, calculate actual emissions using the average of the previous two calendar years or usage data, or average the previous two emission inventory reports, if an inventory was submitted. [Note, if you are calculating actual emissions for a Registration Option D permit, you may base the actual emissions on the previous 12 months of operations.] If this is a new unit or no records exist, use a reasonable estimate of the amount of coating material used.

For VOCs and volatile HAPs, use the following equation for each coating, then sum the actual emissions for each pollutant:

  • Actual Emissions [ton/year] = pollutant content [lb/gal] x actual amount of coating used [gal/year] x [(100% - Pollution control efficiency) ÷ 100] x [1 ton/2000 lb]

For PM/PM10/PM2.5 and particulate HAPs, use the following equation for each coating, then sum the actual emissions for each pollutant:

  • Actual Emissions [ton/year] = pollutant content [lb/gal] x actual amount of coating used [gal/year] x [1-transfer efficiency] x [(100% - Pollution control efficiency) ÷ 100] x [1 ton/2000 lb]
Last modified on April 11, 2012 10:20