How Emissions from painting are Determined & How to Calculate VOCS (Includes Calculators)
One common area of concern for a manufacturer to ensure they are meeting proper regulatory requirements is the degree of emissions they are producing. While there are a variety of sources of emissions, we will focus on emissions related to painting in this article. We will cover how paint emissions are calculated and then cover options you have to reduce your emissions.
How emissions from painting are determined
To understand how emissions from painting are determined first you have to understand the composition of a typical paint. Common components of paint include Volatile Organic compounds (VOCS), hazardous air pollutants (haps), and toxic air contaminants (tacs) among other components. A typical paint is made up of a portion that is primarily solid and a portion that is primarily liquid. Within the solid portion of paint, there can be some hazardous air pollutants and some toxic air contaminants. The haps and tacs in the solid portion of the paint are typically captured by paint booth filters. In contrast, the liquid portion of a coating which is often times made up of solvents contains haps, tacs, and vocs. Since these hazardous components are in liquid form they are able to pass through the filters of your paint booth and in general will be the main source of emissions from your paint process in your manufacturing plant.
To estimate the volume of emissions created there are a few key variables that you will have to know
Total Volume of Coating Applied – The first factor contributing to your annual emissions (which is what most states are measuring) is the total amount of coatings you will apply. You can take this based on an hour, a week, or even a year time frame to determine how much emissions you will generate
Pounds of VOC per Gallon – This will be listed on the product data sheets for your paint or material safety sheets (see example below) it is important to note that less exempt solvents is not typically used for calculating emissions
Hazardous ingredient composition calculation – This can typically be found on the MSDS sheet and will list how much of each given hazardous air pollutant component is found in your coating it will be used typically to determine the amount of certain haps you emit.
Used for Calculating Emissions
Important sometimes the label for VOC’s can be labeled a variety of ways for emissions use VOC’s listed as theoretical, calculated, total, as applied, or as mixed this is the right one to use.
Calculate Emission Rate
To determine the emission rate take all the paints you will be spraying, the volume you will spray, and VOC content of the coatings. Then plug them into the calculator below to determine the amount of emissions you will create. Remember you must also account for any thinner you add to your coatings which will add to your VOC content (unless your thinner is exempt). Certain thinners are exempt from counting toward your emissions count which you can review exempt thinners here. If you use a non exempt thinner you will have to account for the thinners VOC content just like any coating you are using.
Will say you are using 2 paints and a thinner with it. One has a voc content of 3.95 lbs per gallon, the other 2.5 lbs per gallon, and the last one 2.0 lbs per gallon. You plan on using and spraying 2 gallons of each. This would add up to a total of 16.9 lbs of VOCS. You can use this same math to compute annual emissions, hourly emissions, or a different amount of time just identify the volume of paint sprayed and the VOC content of the paint sprayed.
Annual Emissions Calculations
To determine tons of emissions you would calculate the total pounds of emissions created using the calculator above then divide the total number by 2000 to give you tons per year. For example, if you generate 4000 pounds of VOCs this is equivalent to two tons of emissions.
Calculating Individual Hazardous Air Pollutants and Toxic Air Contaminants
If you need to calculate the amount of a particular pollutant that you will emit you need to know an additional detail:
The composition of the hazardous ingredients of the coating which can typically be found on the MSDS (see below).
To determine the individual amount of a particular Hazardous air pollutant you take the total vocs * the % by weight of the chemical you are evaluating.
For example will say we are calculating HAPS from Methyl Ethyl Ketoxime. As a whole our coating has 3 lbs of VOCS in a gallon and we use a gallon. That means we produced .012 pounds of vocs. You can also use the calculator below.
What You can Do to Reduce Your Emissions
The portion of emissions that you can readily help control is the portion of your emissions total related to VOC’s that are trapped in the solids of your coating and your total VOCS. The VOC’s related to the solid portion of your coating can be determined by the following formula:
Total lbs of VOC’s in coating * % by weight of solid Hap of concern, * (1- transfer efficiency of paint equipment) * (1 – efficiency of paint booth filter)* amount used
So if your coating had 5 lbs of total VOCs and was composed of 2% of a Solid HAP, your equipment was 65% efficient and your filters 99.7% effective you would produce a total of .0001 pounds of emissions.
Typically the most common option to reduce your emissions will include a few different strategies. First you can consider a lower VOC paint (usually it consists of higher solids ) which will have less pounds of VOC’s listed. Second, you can consider a more efficient spray gun like an HVLP spray gun and paint booth filter that can help slightly reduce emissions related to the solids portion of your paint. Third and this is only if all other options have been considered, you could consider a booth that burns off VOC’s prior to leaving your facility (though this is a very costly solution). We can also help if you need additional assistance reducing VOC’s.
Additional Frequent Questions about Emissions
Do water borne paints count toward emissions – Yes most water based paints will still have some volatile organic compounds
Additional Resources on Emissions
VOC Exempt compounds list – This list gives you solvents and chemicals that are not counted toward your voc count.
List of Hazardous Air Pollutants – This is a list of hazardous air pollutants
Ultimately keeping emissions down is important for regulatory compliance, our environment, and your business costs. By knowing how much emission you may potentially create and what contributes to your emissions you can be better prepared to properly plan for emissions reduction