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## Emissions Calculations 101

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Title: Emissions Calculations 101

1
Emissions Calculations 101
• Tim Trumbull
• Iowa Air Emissions Assistance Program
• Iowa Waste Reduction Center
• University of Northern Iowa

2
Estimating Emissions
• Developing emission control strategies
• Determining affects of sources and mitigation
strategies
• Emissions Inventories
• Permit Applications

3
Estimation Hierarchy
4
Preferred Method of Estimating Emissions
• Continuous Emission Monitoring
• any monitoring effort that continuously
measures ( I.e. very short averaging time) and
records emissions
• Very expensive but most accurate

5
Second Best Method of Estimating
• Stack Test Data
• Short term scientific tests to quantify an
emission rate
• Results are applicable only to the conditions
existing at the time of the test
• Reliable and somewhat expensive

6
Third Method of Estimating Emissions
• Material Balance
• Reliable average emission rate
• For use when a high percentage of material is
lost to the atmosphere
• May be inappropriate when a material is consumed
or combined in a process
• Need to account for all materials going into and
coming out of a process

7
Fourth Method of Estimating Emissions
• Emission Factors
• Ratios that relate emissions of a pollutant to an
activity level that can be easily measured .
• Given an emission factor, simple multiplication
can yield an estimate of emissions
• Represent typical values for an industry, not
necessarily representative of a specific source

8
Fifth Method of Estimating Emissions
• Engineering Estimates
• Term applied to the best approximation that can
be made when stack testing, material balance, or
emission factors are not available.
• Usually made by an engineer familiar with a
specific process, and is based on process
information

9
Material Balance
• Commonly used for surface coating operations
• Required Process rates, material used, material
properties (from MSDS), and knowledge of process
• Example Spray Paint Booth

10
Material Balance
• Sample Exercise

11
ACMEs Spray Paint Booth
• ACME Corp. applies a base coat and a top coat to
each wagon it produces. The paint is sprayed
directly from the container with no thinning or
mixing. ACME has a federally enforceable paint
usage limit of 2000 gallons per year. ACME
sprayed 1,300 gallons last year (500 gallons of
base coat and 800 gallons of topcoat). An HVLP
spray gun with a maximum capacity of 7 gal./hr is
used. The paint booths filters have a 95
percent particulate removal efficiency.

12
MSDS Information
All percents are weight percents and expressed as a percent of total paint weight Top Coat Base Coat
Paint Weight (lbs/gal) 8.75 7.21
VOC 25 42
Solids 75 58
Xylene 8 2
Toluene --- 15
MEK 2 ---
13
Step 1- Determine paint usage
• Since ACME has a usage limit of 2,000 gal/yr,this
is the maximum amount of paint that they can use.
• If this limit was not in place potential usage
would be calculated as follows
• Gun capacity x hours/yr gallons / year
• 7.0 gal/hour x 8760 hr/yr 61,320 gal./yr.

14
Step 2- Calculate Potential VOC and HAP emissions
Top Coat Base Coat
Paint Weight (lbs/gal) 8.75 7.21
VOC 25 42
Solids 75 58
Xylene 8 2
Toluene --- 15
MEK 2 ---
• Use the highest constituent amount of VOC and
HAPs from the base or top coat to calculate
potential emissions.
• First, determine which paint has the highest
amount of VOC.
• Base7.21lb/gal x .42 3.02 lb/gal
• Top 8.75 x .25 2.01 lb/gal

15
Step 2- Calculate Potential VOC and HAP emissions
(cont)
• Density (lb/gal) x Usage Limit (gal/yr) x Max.
VOC x ton/2000 lb
• (7.21 lb/gal) x (2000 gal/yr) x 0.42 VOC x (1 ton
/ 2000 lbs)

• 3.02 Tons / year VOC
• Use the same formula for each HAP but replace VOC
with the highest specific HAP from the two
coatings
• Xylene 8.75 lb/gal x 2000 gal/yr x 0.08 x
ton/2000 lb 0.7 tons/yr
• Toluene 8.75 lb/gal x 2000 gal/yr x 0.15 x
ton/2000 lb 1.31 tons/yr
• MEK 8.75 lb/gal x 2000 gal/yr x 0.02 x ton/2000
lb 0.18 tons/yr

16
Step 3 Calculate Potential PM-10 Emissions
• To calculate PM-10 emissions the spray transfer
efficiency (TE) of the spray gun and the control
efficiency (CE) of the filter must be inserted
into our earlier formula for VOC.
• Transfer Efficiency is the percentage of paint
from the gun that adheres to the part being
painted.

17
Step 3 Potential PM-10 Emissions (Sample
Transfer Efficiencies)
Method of Spraying Flat Surface Table Leg Surface Bird Cage Surface
Air Atomized 50 15 10
Airless 75-80 10 10
Electrostatic Disk Airless Air Atomized 95 80 75 90-95 70 65 90-95 70 65
18
Step 3 Calculate Potential PM-10 Emissions
(cont)
• The HVLP gun has a transfer efficiency of 65
• The filter control efficiency (CE) is 95
• In ACMEs process, 65 of the paint sprayed hits
the part and 35 enters the exhaust stream.
• The filter captures 95 of the solids in the
exhaust.
• The remaining 5 is discharged up the stack

19
Step 3 Potential PM-10 Emissions (cont)
• Calculations
• Density (lb/gal) x Usage Limit x Max solids x
(1-TE) x (1-CE) x ton / 2000 lbs.
• ton/yr PM-10
• 8.75 lb/gal x 2000 gal/yr x 0.75 x (1-.65) x
(1-.95) x ton/2000 lbs 0.11 tons/yr PM-10

Top Coat Base Coat
Paint Weight (lbs/gal) 8.75 7.21
VOC 25 42
Solids 75 58
Xylene 8 2
Toluene --- 15
MEK 2 ---
20
Step 4- Calculate Maximum Hourly Emissions
• Multiply the capacity of the gun by the weight of
the heaviest paint and by the highest percentage
amount of each constituent.
• The paint density multiplied by the percent of
the pollutant (by weight) equals a pound per
gallon emission factor.
• To calculate hourly PM-10 emissions the transfer
efficiency and collection efficiency must be
included in the formula

21
Step 4- Calculate Maximum Hourly Emissions (cont.)
• Gun Capacity (gal/hr) x Density (lb/gal) x Max.
VOC/HAP VOC or HAP
• Gun Capacity (gal/hr) x Density (lb/gal) x Max
PM-10 x (1-TE) x (1-CE) PM-10
• VOCs 7 gal/hr x (8.75 lb/gal x 0.42) 25.73
lb/hr VOC
• Xylene 7 gal/hr x (8.75 lb/gal x 0.08) 4.9
lb/hr Xylene
• Toluene 7 gal/hr x (8.75 lb/gal x 0.15) 9.19
lb/hr Toluene
• MEK 7 gal/hr x (8.75 lb/gal x 0.02) 1.23 lb/hr
MEK
• PM-10 7 gal/hr x (8.75 lb/gal x 0.75) x (1-.65) x
(1-.95) 0.8 lb/hr PM

22
Step 5- Calculate Actual Annual VOC and Toxic
Emissions
• Emissions from each coating must be calculated
• Paint used (gal/yr) x Paint Weight (lb/gal) x
Pollutant x ton/2000 lbs. Actual Tons/
year
• VOC-Top Coat
• 800 gal/yr x (8.75 lb/gal x 0.25) 1,750 lb/yr x
ton/2000 lb 0.875 TPY VOC
• VOC- Base Coat
• 500 gal/yr x (7.21 lb/gal x 0.42) 1,514 lb/yr x
ton/2000 lb 0.75 TPY VOC

• 1.63
TPY VOC

23
Step 5- Calculate Actual Annual VOC and Toxic
Emissions
• Xylene -Top Coat
• 800 gal/yr x (8.75 lb/gal x 0.08) 560 lb/yr x
ton/2000 lb 0.28 TPY Xylene
• Xylene- Base Coat
• 500 gal/yr x (7.21 lb/gal x 0.02) 72.1 lb/yr x
ton/2000 lb 0.04 TPY Xylene

• 0.32 TPY
Xylene
• Toluene -Top Coat
• 800 gal/yr x (8.75 lb/gal x 0.0) 0.0 lb/yr x
ton/2000 lb 0.00 TPY Toluene
• Toluene- Base Coat
• 500 gal/yr x (7.21 lb/gal x 0.15) 540.75 lb/yr x
ton/2000 lb 0.27 TPY Toluene

• 0.27 TPY
Toluene

24
Step 6- Calculating annual PM-10 Emissions
• Use the same formula with the incorporation of
Transfer and Control Efficiencies
• Top Coat
• 800 gal/yr x (8.75 lb/gal x 0.75) x (1-.65) x
(1-.95) 122.5 lb/yr x ton/2000 lb
0.05 Tons/yr PM-10
• Base Coat
• 800 gal/yr x (7.21 lb/gal x 0.58) x (1-.65) x
(1-.95) 63.09 lb/yr x ton/2000 lb
0.02 Tons/yr PM-10

• 0.07 TPY PM-10

25
Emission Factors
26
Emission Factors
• An emission factor is a representative value that
attempts to relate the quantity of a pollutant
released to the atmosphere with an activity
associated with the release of that pollutant.
• In most cases, EFs are an average of all
available data of acceptable quality and are
generally assumed to be long-term averages for
all facilities in the source category.

27
Emission Factors
• General Equation for Emission Estimation
• E A x EF x (1-ER/100)
• Where
• E emissions
• A activity rate
• EF emission factor
• ER overall emission reduction efficiency,
• further, ER is the efficiency of the control
system

28
Sources of Emission Factors
• AP-42- includes descriptions of activities that
produce emissions
• FIRE- The Factor Information Retrieval Data
• Air CHIEF 9.0 CD-ROM- includes AP-42 and FIRE
• TANKS- estimates VOC HAP emissions from tanks
• CHIEF Bulletin Board System- includes latest
guidance and information on air emission
inventories and emission factors
• available at www.epa.gov/ttn/chief

29
Other Sources of Emission Factors
• State Published Emission Factors
• Vendor Supplied Emission Factors

30
Emission Factor Example
• ACME Company has a welding station that it uses
to construct wagons.
• Process Gas Metal Arc Welding, E308 electrode
• Maximum Feed Rate 30 lb. electrode per hour
• Actual Throughput 40,000 lbs. Electrode per
year

31
Air CHIEF to find Emission Factors
32
(No Transcript)
33
ACMEs Welding Station
• SCC No. 30905212
• Emission Factors
• (HAPs from table 12.19-2)
• PM-10 5.4 lbs/1000 lb of electrode consumed
• Cr 0.524 lbs/1000 lb of electrode consumed
• Mn 0.346 lbs/1000 lb of electrode consumed
• Ni 0.184 lbs/1000 lb of electrode consumed

34
Step 1- Calculate Annual Potential
• Make sure units of rate and emission factor
match.
• 30 lb/hr x lb/1000 lb 0.03 1000 lb/hr
• 0.03 1000 lb/hr x 5.4 lb/1000 lb x 8760 hr/yr x
ton/2000 lb
• 0.71 tons/yr PM-10
• Potential Chromium 0.07 tons/yr
• Potential Manganese 0.05 tons/yr
• Potential Nickel 0.02 tons/yr

35
Step 2- Calculate Actual Emission
• Actual PM-10 in tons per year
• 40 1000 lb/yr x 5.4 lb/1000 lb x ton/2000 lb
0.11 tons/yr
• Use the same formula for the other HAPs with
their corresponding emission factors
• Actual Chromium 0.01 tons/yr
• Actual Manganese 0.01 tons/yr
• Actual Nickel 0.00

36
Emission Factor Cautions
• Because emission factors are an average, 50
percent of sources will have rates above or below
the factor used
• Emission factors are neither emission limits nor
standards
• If a factor for a pollutant is not available from
EPA, this does not mean that the source does not
emit a pollutant

37
Questions? Contact Info
• Phone 800-422-3109
• E-mail trumbull_at_uni.edu