TECHNICAL SUPPORT DOCUMENT (UPDATED) 

FOR EMISSIONS FROM 

PRODUCTION OF FLUORINATED GASES: 

PROPOSED RULE FOR MANDATORY 

REPORTING OF GREENHOUSE GASES 

Office of Air and Radiation 

U.S. Environmental Protection Agency 

March 22, 2010 
i 

Table of Contents 

1. Source Description ................................................................................................................ 1

A. Facilities Subject to the Rule ........................................................................................... 1

B. How Fluorinated GHGs are Generated and Released at Fluorinated Gas Production 

Facilities .......................................................................................................................... 1

C. Background on Uses of Fluorinated Gases ....................................................................... 2

D. Potential Overlap Emission Points for Production and Suppliers. ..................................... 3

E. Total U.S. Production and Associated Emissions ............................................................. 4

2. Options for Reporting Threshold ........................................................................................... 5

A. Uncontrolled Emissions Threshold .................................................................................. 5

B. Controlled Emissions Threshold ...................................................................................... 6

C. No Emissions Threshold (i.e., All-in)............................................................................... 7

3. Monitoring Methods, Data Collection and Current Plant Practices ......................................... 7

A. Scoping Test and Options for Characterizing Emitted Streams......................................... 7

i. Reliance on previous bench- and pilot-scale testing.................................................... 7

ii. Initial Scoping Test (including discussion of analytical methods) ............................... 8

B. Options for Developing Emissions Estimates ................................................................. 10

i. Default Emission Factor........................................................................................... 10

ii. Mass Balance ........................................................................................................... 10

1. Error Limits ....................................................................................................... 11

2. Mass Balance Approach Equations. ................................................................... 13

3. Choice of Reactant Whose Yield Is Measured. ................................................... 17

4. Frequency of Measurement and Calculation. ...................................................... 17

5. Reactant and Byproduct Emissions. ................................................................... 18

6. Alternative approach based on measurements of balanced element ..................... 18

7. Current Plant Practices for Mass Balance ........................................................... 22

iii. Monitoring of Process Vents .................................................................................... 22

1. Process-Vent-Specific Emission Factor Approach. ............................................. 23

2. Process-Vent-Specific Emission Calculation Factor Approach. .......................... 28

3. Obtaining and Maintaining Representative Emission Factors ............................. 30

4. Updates to emission factors and emission calculation factors. ............................ 35

5. Potential Process Vent Emission Threshold. ....................................................... 35

6. Process Vent Preliminary Emission Estimates. ................................................... 37

7. Current Plant Practices for Process Vent Monitoring .......................................... 37

8. Potential use of continuous emissions monitors to measure emissions from 

vents. ................................................................................................................. 39

9. Equipment Leak Emissions Estimates. ............................................................... 39

10. Destruction Efficiency Testing ........................................................................... 41

C. Other Potentially Significant Emission Points ................................................................ 41

4. Procedures for Estimating Missing Data .............................................................................. 43

5. QA/QC Requirements ......................................................................................................... 43

6. Reporting and Recordkeeping Procedures............................................................................ 44

7. References ........................................................................................................................... 44 
1 

1. Source Description 

A. Facilities Subject to the Rule 

This source category, fluorinated gas production, covers emissions of fluorinated 

greenhouse gases (GHGs) that occur during the production of fluorinated gases. It also covers 

emissions of fluorinated GHGs that occur during transformation of fluorinated gases and 

destruction of fluorinated GHGs when those processes are co-located with fluorinated gas 

production processes. Fluorinated GHGs include hydrofluorocarbons (HFCs), perfluorocarbons 

(PFCs), sulfur hexafluoride (SF6), nitrogen trifluoride (NF3), and other fluorinated GHGs such as 

fluorinated ethers. Fluorinated gases include fluorinated GHGs, chlorofluorocarbons (CFCs) and 

hydrochlorofluorocarbons (HCFCs). However, the source category excludes generation and 

emissions of HFC-23 during the production of HCFC-22, which is covered by subpart O of the 

Mandatory Reporting Rule. 

Producing a fluorinated gas includes the manufacture of a fluorinated GHG, CFC, or 

HCFC from any raw material or feedstock chemical. This includes the manufacture of 

fluorinated GHGs for use in a process that will result in the transformation either at or outside of 

the production facility. Producing a fluorinated gas does not include the reuse or recycling of a 

fluorinated gas, the creation of HFC-23 during the production of HCFC-22, or the creation of byproducts that are released or destroyed at the production facility. 

B. How Fluorinated GHGs are Generated and Released at Fluorinated Gas 

Production Facilities 

Fluorinated GHGs can be generated and emitted from production, transformation, 

destruction, and other processes at production facilities in a number of ways. Emissions from 

fluorinated gas production include fluorinated GHG products that are emitted upstream of the 

production measurement and fluorinated GHG by-products that are generated and emitted either 

without or despite recapture or destruction. Emissions from fluorinated gas transformation 

include emissions of fluorinated GHG feedstocks and possibly by-products of the transformation 

process. Emissions from fluorinated GHG destruction include fluorinated GHGs that survive the 

destruction process. Other emissions sources are discussed further below. 

Many reactions producing fluorinated GHGs, CFCs, and HCFCs also generate significant 

quantities of chemically related by-products, e.g., through over-fluorination or side reactions. 

Table 1 provides an overview of some commonly produced fluorinated GHGs, CFCs, and 

HCFCs and their known fluorinated GHG by-products. Note that production of CFCs and 

HCFCs can generate and emit fluorinated GHGs such as various HFCs and some PFCs. These 

fluorinated GHG by-products occur due to the chemical similarities between HFCs, PFCs, 

HCFCs, and CFCs and the common use of halogen replacement chemistry to produce them. 

Also note that Table 1 is not exhaustive. It omits the most commonly known product and 

byproduct, HCFC-22 and HFC-23, which are covered by subpart O of the Mandatory Reporting 

Rule. In addition, it does not include all of the by-products and products that have been 

identified by fluorinated gas producers. 
2 

Table 1. Some Fluorinated Products and their By-products 

Product By-product(s) Source of information 

HFC-134a HFC-143a Italy National Inventory Report, 2009 

SF6 CF4 Italy National Inventory Report, 2009 

Electrochemical 

fluorination plant 

that produces a 

broad range of 

fluorochemical 

products, mainly 

for electronics 

industry 

SF6, CF4, 

C2F6, C3F8, 

C4F10, C5F12, 

C6F14, CF3SF5, 

C7F16, C8F18 

and C8F16O 

Belgium National Inventory Report, 2009 

http://unfccc.int/files/national_reports/annex_i_ghg_inventories/national_inven

tories_submissions/application/zip/bel_2009_nir_15apr.zip

CFC-11, CFC-12 CF4 2006 IPCC Guidelines 

CFC-115 C2F6 Italy National Inventory Report, 2009 

http://unfccc.int/files/national_reports/annex_i_ghg_inventories/national_inven

tories_submissions/application/zip/ita_2009_nir_15apr.zip

Trifluoroacetic acid 

(TFA) 

CF4, HFC-125 French National Inventory Report, 2009 

http://unfccc.int/files/national_reports/annex_i_ghg_inventories/national_inven

tories_submissions/application/zip/fra_2009_nir_7apr.zip

The quantities of by-products generated, as a share of the product, depend on the product 

and the process. Based on conversations with fluorinated gas producers, by-product generation 

rates generally range between one and five percent but can sometimes be higher or lower. 

Emissions of products, by-products, and feedstocks may occur from process vents, from 

equipment leaks from flanges, connectors, and other equipment pieces in the production line, 

from storage tanks storing either raw materials or products, from wastewater streams, from 

control devices (e.g., thermal oxidizers), and during the filling of tanker trucks, railcars, 

cylinders, or other containers that are distributed by the producer. Undesired by-products may be 

deliberately vented, and some product (or reactant) may be vented at the same time due to 

imperfect separation of by-products, products, and reactants. Emissions can also occur during 

scheduled maintenance and occasional service work on production equipment, during the 

blending and recycling of fluorinated GHGs, and during the evacuation of containers used to 

distribute products. EPA estimates that total emissions from this source category were 

approximately 10.6 million metric tons CO2e (mt CO2e) in 2006.1

C. Background on Uses of Fluorinated Gases 

Fluorinated gases are man-made gases used in several sectors. As noted above, they 

include fluorinated GHGs (HFCs, PFCs, SF6, NF3, and a number of fluorinated ethers), CFCs, 

and HCFCs, all of which are manufactured through various chemical processes. 

Hydrofluorocarbons (HFCs) are the most commonly used fluorinated GHGs, used primarily to 

replace ozone-depleting substances in a number of applications, including air-conditioning and 

refrigeration, foams, solvents, and aerosols. PFCs are used in fire fighting and to manufacture 

semiconductors and other electronics. SF6 is used in a diverse array of applications, including 

electrical transmission and distribution equipment (as an electrical insulator and arc quencher) 

and in magnesium casting operations (as a cover gas to prevent oxidation of molten metal). 

 

1

 Fluorinated GHG production data were from 2006; CFC and HCFC production data were from 2008. 
3 

Nitrogen trifluoride (NF3) is increasingly used in the semiconductor industry, to reduce overall 

semiconductor GHG emissions through processes such as NF3 remote cleaning and NF3

substitution during in-situ cleaning. Fluorinated ethers (HFEs and HCFEs) are used as 

anesthetics (e.g., isofluorane, desflurane, and sevoflurane) and as heat transfer fluids (e.g., the HGaldens). The manufacture of CFCs and HCFCs for emissive uses is being phased out under the 

Montreal Protocol, but production of these materials for use as feedstocks is permitted to 

continue indefinitely. As discussed further below, the volume of CFCs and HCFCs used as 

feedstocks in the U.S. is significant; even excepting HCFC-22, this volume is actually larger than 

the volume of fluorinated GHGs produced in the U.S. Fluorinated GHGs are powerful 

greenhouse gases whose ability to trap heat in the atmosphere is often thousands to tens of 

thousands of times greater than that of CO2, on a pound-for-pound basis. Some fluorinated 

GHGs are also very long lived; SF6 and the PFCs have lifetimes ranging from 3,200 to 50,000 

years (IPCC, 2006). 

D. Potential Overlap Emission Points for Production and Suppliers. 

The facilities that are covered under the fluorinated gas production source category are 

many of the same facilities that are covered under the industrial gas supply source category. In 

general, the industrial gas supply source category is intended to cover or capture the quantities of 

fluorinated GHGs that are entering and leaving the U.S. supply of industrial gases, (i.e., amount 

of product), while the fluorinated gas production source category is intended to cover or capture 

the quantities of fluorinated GHGs emitted at fluorinated gas production facilities. Specifically, 

the industrial gas suppliers source category is meant to track the quantities of fluorinated GHGs 

that are (1) produced, (2) transformed, (3) destroyed, (4) imported, and (5) exported. The 

industrial gas suppliers source category would essentially track the amount of final product made 

(produced) at a production facility but not the emissions of fluorinated GHG from the production 

steps from raw material to final product. 

There are several areas of potential overlap between the emissions that are reported under 

the industrial gas suppliers source category and those that could be reported under the fluorinated 

gas production source category. The areas of overlap concern “downstream” emissions, meaning 

they occur at the fluorinated GHG production facility after the fluorinated GHG product 

measurement. Downstream emissions include those from fluorinated GHG transformation 

processes, destruction of fluorinated GHGs that are removed from the U.S. supply, recycling or 

reclamation of fluorinated GHGs, and evacuation of fluorinated GHG heels from returned 

cylinders or containers. (“Upstream” emissions occur at the fluorinated GHG production facility 

prior to the fluorinated GHG product measurement.) 

Fluorinated gas production facilities sometimes make a fluorinated GHG product that is 

later used as a raw material in making another product. For example, fluorinated GHG product is 

used as a raw material in transformation processes to produce fluoropolymers (the fluoropolymer 

product would not be considered a fluorinated GHG). Emissions of fluorinated GHGs that occur 

from transformation processes are an area of overlap, since these transformation processes may 

occur at the same site where fluorinated GHG products are produced, or they may occur at 

another fluorinated GHG production facility to which the fluorinated GHG feedstock is shipped. 

The emissions of fluorinated GHG from destruction processes used to remove fluorinated 

GHG from the U.S. supply is another area of overlap. The fluorinated GHG is returned to the 
4 

facility and subtracted from the U.S. supply, however some emissions may occur from the 

destruction process, either as fugitives from the handling of the fluorinated GHG or as 

undestroyed emissions at the outlet of the destruction device. 

Filling cylinders or other containers (loading emissions) with fluorinated GHG product 

and blending of fluorinated GHG with other gases will most likely occur after the production 

measurement, classifying emissions for cylinder filling (loading) and blending as downstream 

processes. 

Recycling of used gas may be performed by the producers of new gas or by offsite 

recycling firms. Emissions may occur during handling and purification of old gas and during 

packaging of recycled gas.2 Since the used gas has already been counted as produced (used gas 

is removed from, and then added back into, the gas supply), recycling emissions are considered 

to be downstream of the production measurement. 

Evacuation of fluorinated GHG from returned cylinders or containers results in emissions 

that vary depending on process type and the composition and amount of the heel (residual gas) 

present. 

In theory, it might be possible to track emissions from transformation and destruction 

simply using quantities reported under 40 CFR part 98 subpart OO. However, this would require 

that (1) fluorinated GHGs that are produced only to be transformed or destroyed be tracked 

separately, (2) production, transformation, and destruction be measured to very good precision 

and accuracy (e.g., 0.2 percent), and (3) that no by-products be formed or emitted during these 

processes. If all of these conditions were met, emissions could be equated to the differences 

between production and transformation and production and destruction. In practice, however, it 

would be difficult to meet all of these conditions. 

E. Total U.S. Production and Associated Emissions 

The production of fluorinated gases includes production of fluorinated GHG (HFCs, 

PFCs, SF6, and NF3, HFEs), CFCs and HCFCs (except for HCFC-22 production processes). In 

2006, 12 U.S. facilities collectively produced over 350 million mtCO2e (170,000 tons) of HFCs, 

PFCs, SF6, and NF3. EPA estimates that an additional six facilities collectively produced almost 

1 million mtCO2e of fluorinated anesthetics (HFEs) in 2006. The total U.S. production of CFCs 

and HCFCs (except HCFC-22) in 2008 was estimated to be approximately 266,000 tons. The 

majority of the CFC and HCFC production processes are co-located at facilities that also produce 

fluorinated GHGs. Another 2 facilities that produce CFC and HCFC products were identified 

that were not already included in the 12 facilities identified above for HFC, PFC, SF6, and NF3 

production. Fluorinated gas production processes are sometimes co-located with fluorinated gas 

transformation processes or fluorinated GHG destruction processes. The total amounts of 

fluorinated gases transformed into other products or destroyed are not known. 

Fluorinated GHG emissions (actual emissions, following application of control 

techniques where applicable) from U.S. facilities producing fluorinated GHGs are estimated to 

range from 0.8 percent to 2 percent of the amount produced, depending on the facility. An 

 

2

 2006 IPCC, Chapter 3.10. 
5 

emission rate of 1.5 percent is assumed for fluorinated GHG production processes. At an 

emission rate of 1.5 percent, the 12 fluorinated GHG facilities together are estimated to have 

emitted approximately 5.3 million mtCO2e of HFCs, PFCs, SF6, and NF3. The six additional 

HFE production facilities are estimated to have emitted approximately 15,000 mtCO2e of 

fluorinated anesthetics, using an emission rate of 1.5 percent. 

The quantity of emissions of fluorinated GHGs from production of CFCs and HCFCs is 

uncertain. However, the magnitude of by-product generation during F-GHG production (e.g., 

quantities equivalent to one to five percent of the mass of the product) suggests that significant 

quantities of by-product F-GHGs may be generated during production of chemically similar 

substances. Given the substantial amounts of CFCs and HCFCs that are produced in the U.S., 

emission rates could be relatively low and still result in significant emissions. In 2008, the 

combined tonnage of U.S. HCFC and CFC production was higher than that of all fluorinated 

GHG production in 2006 (the latest year for which data were available), with CFCs produced as 

feedstocks comprising the majority. (Although production of HCFCs and CFCs is limited under 

the regulations implementing Title VI of the CAA, production of these substances for use as 

feedstocks is permitted to continue indefinitely.) Assuming that this production resulted in 

emissions of fluorinated GHG by-products equal to one percent of the mass of CFCs and HCFCs 

produced,3 and that these byproducts had an average global warming potential (GWP) of 2000, 

emissions from CFC and HCFC production are estimated to have totaled 5.3 million mtCO2e in 

2008, the same as estimated emissions from fluorinated GHG production in 2006. (No estimate 

of fluorinated GHG emissions from transformation processes, or fluoropolymer production 

processes, is available.) These emissions, combined with those from fluorinated GHG 

production, lead to a total for the source category of 10.6 million mtCO2e. 

2. Options for Reporting Threshold 

EPA evaluated a range of threshold options for fluorinated gas production facilities. 

These included 1,000 mt CO2e, 10,000 mtCO2e, 25,000 mtCO2e, and 100,000 mtCO2e. 

Emission levels on both an uncontrolled and a controlled basis were evaluated. Because EPA 

has little information on combustion-related emissions at fluorinated gas production facilities, 

these emissions were not included in the threshold analysis. 

A. Uncontrolled Emissions Threshold 

Facility-specific uncontrolled emissions (i.e., pre-control) were estimated for fluorinated 

GHG production processes (including fluorinated anesthetics production processes) by 

multiplying a factor of 3.0 percent by the estimated production at each facility. For CFC and 

HCFC production processes (except for HCFC-22 production processes), uncontrolled emissions 

were estimated by multiplying a factor of 2 percent by the estimated production at each facility. 

Uncontrolled emissions are strongly influenced by by-product generation rates, which are known 

to vary between zero and several percent for fluorinated gas production processes; thus, these 

estimates are uncertain. The results of the analysis for uncontrolled emissions from the 

production of HFCs, PFCs, SF6, NF3, CFCs, and HCFCs are shown in Table 1. (No emissions of 

 

3The emission rate from CFC and HCFC production is assumed to be lower than that from fluorinated GHG 

production because only by-products are included in the former, while both products and by-products are included in 

the latter. 
6 

fluorinated GHG from transformation processes, such as fluoropolymer production processes, 

are included in the analysis.) 

All or most production facilities would be covered by uncontrolled emission thresholds, 

i.e., 14 of 14 or 13 of 14 facilities would be covered depending on the cutoff level. Use of the 

uncontrolled emissions threshold would not allow for applying reductions from destruction 

devices, which may or may not be achieving the demonstrated destruction efficiency on a 

continuous operating basis. Under the uncontrolled emissions threshold option, emissions 

reductions would not be overstated and emissions to the atmosphere would not be understated. 

(It is uncertain where the emission levels of the individual anesthetic facilities would fall, and the 

anesthetic facilities and emissions are not included in Table 2. There are 6 anesthetic facilities 

that are estimated to generate a total of approximately 30,000 mt CO2e.) Emissions from 

combustion sources at facilities are not included in the emissions estimate shown in Table 2. 

Table 2. Threshold Analysis for Fluorinated GHG Emissions from Production of HFCs, PFCs, SF6, 

NF3, CFCs, and HCFCs (Uncontrolled Emissions) 

Threshold 

Level 

(mt CO2e/r) 

Total National 

Emissions 

(mt CO2e) 

Number of 

Facilities 

Emissions Covered Facilities Covered 

mt CO2e Percent Number Percent 

1,000 10,600,000 14 10,600,000 100% 14 100% 

10,000 10,600,000 14 10,600,000 100% 14 100% 

25,000 10,600,000 14 10,600,000 100% 14 100% 

100,000 10,600,000 14 10,600,000 100% 13 93% 

B. Controlled Emissions Threshold 

Facility-specific controlled emissions (i.e., those following the control device, if in place) 

were estimated for fluorinated GHG production processes (including anesthetics production 

processes) by multiplying a factor of 1.5 percent by the estimated production at each facility. 

For CFC and HCFC production processes (except for HCFC-22 production processes), 

controlled emissions were estimated by multiplying by a factor of 1.0 percent by the estimated 

production at each facility. Controlled emissions were assumed to be half of uncontrolled 

emissions at each facility. The results of the analysis for controlled emissions from the 

production of HFCs, PFCs, SF6, NF3, CFCs, and HCFCs are shown in Table 2. No emissions of 

fluorinated GHG from transformation processes (other than those that produce fluorinated 

GHGs) are included in the analysis. 

All or most of the production facilities would be covered by controlled emission 

thresholds, depending on the cutoff, although fewer facilities would be covered under the 

controlled emission threshold option (10 facilities) than under the uncontrolled emission 

threshold option (13 facilities) at the highest cutoff (i.e., 100,000 mtCO2e). Use of the 

controlled emissions threshold option would allow facilities to account for emission reductions 

achieved by destruction devices that had a demonstrated destruction efficiency. It is possible 

that emission levels may be understated using the controlled emissions option. (It is uncertain 

where the emission levels of the individual anesthetic facilities would fall, and the anesthetic 

facilities and emissions are not included in Table 3. There are 6 anesthetic facilities that are 
7 

estimated to emit a total of approximately 15,000 mt CO2e.) Emissions from combustion sources 

at facilities are not included in the emissions estimate shown in Table 3. 

Table 3. Threshold Analysis for Fluorinated GHG Emissions from Production of HFCs, PFCs, SF6, 

NF3, CFCs, and HCFCs (Controlled Emissions) 

Threshold 

Level 

(mt CO2e/r) 

Total 

National 

Emissions 

(mt CO2e) 

Number of 

Facilities 

Emissions Covered Facilities Covered 

mt CO2e Percent Number Percent 

1,000 10,600,000 14 10,600,000 100% 14 100% 

10,000 10,600,000 14 10,600,000 100% 14 100% 

25,000 10,600,000 14 10,600,000 100% 14 100% 

100,000 10,600,000 14 10,300,000 97% 10 71% 

C. No Emissions Threshold (i.e., All-in) 

Under an “all-in” approach, no emissions threshold level would be included in the rule 

and all facilities in the fluorinated gas source category, including facilities producing anesthetics, 

would be subject to the rule regardless of emission levels. The all-in approach would ensure that 

all facilities identified and quantified their fluorinated GHG emissions, even if they initially 

believed those emissions to be small. Some facilities that initially believed their emissions to be 

small could find that those emissions actually exceeded 25,000 mt CO2e (e.g., because a 

previously unidentified fluorinated GHG with a high GWP was being generated and emitted as a 

by-product). Facilities whose emissions remained below 25,000 mt CO2e or 15,000 mt CO2e 

could cease reporting after five or three years respectively. In addition, an all-in approach would 

provide an essentially level playing field because all facilities in the source category would be 

subject to the rule and be subject to the same economic impact from the reporting rule. 

However, an all-in approach would also increase the burden on facilities with uncontrolled 

emissions below 25,000 mt CO2e. This could result in higher reporting costs per metric ton CO2e 

for these facilities than for higher emitting facilities. 

3. Monitoring Methods, Data Collection and Current Plant Practices 

A. Scoping Test and Options for Characterizing Emitted Streams 

i. Reliance on previous bench- and pilot-scale testing 

During research and development of a fluorinated gas product, companies develop 

laboratory, bench-scale, and pilot-scale processes to manufacture new products. During 

laboratory and bench-scale development of the process, companies generate small quantities of 

the product. The companies monitor and measure all aspects of the process, including rates and 

extent of reaction, reactant and full product and byproduct identity and compositions, and 

physical characteristics of the compounds. This testing and analysis of compounds in the various 

process streams generally identifies the product and all byproducts generated in the process. 

During these laboratory or bench-scale processes, process optimization is addressed by defining 

operating conditions that generate the best product yields and least byproducts, considering the 

most efficient use of resources. Following the laboratory and bench-scale level of process 

development, a process may be scaled to a larger basis, i.e., pilot-scale basis, to continue 

research and development of the process and to continue to refine process optimization. The 
8 

pilot-scale process, meant to simulate a full-scale production process, generates a larger quantity 

of product than the laboratory scale process but less than a full-scale production process. The 

equipment used in pilot-scale processes is similar in design to what the full-scale process might 

be, and is used to continue research on the process, as the data available from earlier laboratory 

and bench-scale systems are applied. However, some data may not be directly applicable to the 

pilot-scale system. As part of the continued research, the company continues to test and analyze 

the products and byproducts from the pilot-scale process to confirm what compounds are 

generated in the process as operating conditions are refined (i.e., changed). 

The findings regarding the identities of the compounds generated during these stages of 

process research and development may be used to help understand the identities of the 

compounds present in emission and waste streams for the full-scale production process. The 

analyses are typically rigorous as the company is eager to know and learn as much as possible 

and limit side reactions and increase yields. A potential drawback to use of the laboratory and 

pilot scale compound and composition analyses is that there may be some differences in the 

products and byproducts as the process is scaled from laboratory/bench-scale to pilot-scale to 

full-scale production units. The earlier data may not be fully applicable to the larger scale 

processes. Differences are likely to occur between the laboratory and pilot-scales, and streams 

may need to be tested and analyzed again to detect changes between the pilot- and full-scale 

production processes. 

ii. Initial Scoping Test 

To ensure that all fluorinated GHGs that occur in emitted streams are accurately 

identified, an initial scoping test on vents and streams from fluorinated gas processes may be 

conducted. The initial scoping test would be conducted using methods that allow detection and 

identification of all compounds in the vent or stream. The identity of the specific compounds 

that are generated during the fluorinated gas production process is important to the emissions 

estimate. Some facilities have indicated that even with extensive laboratory and bench-scale 

compositional and quantitative analysis from research, development, and design stages of the 

process, unexpected F GHGs can be found in emissions streams.

4

 

The results of the scoping test can be used to inform both the mass-balance and emissionfactor approaches (described further below). In the mass balance approach, the amount of 

product recovered is compared to the amount of reactants and the expected product quantity; the 

differences are assumed to be product lost to emissions. However, byproducts are created and 

knowledge of these informs the emissions estimate so that product and byproduct compounds are 

appropriately represented in the mass balance equations. For example, for facilities using the 

mass-balance approach, the scoping test can be used to determine whether some emissions 

assumed to occur in the form of the product are actually occurring as by-products. For those 

facilities using an emissions factor approach, the results from the scoping test will ensure that 

emissions factors are appropriately developed for all byproduct compounds. The scoping test 

will identify byproducts that should be measured in subsequent emissions testing to develop 

emission factors. 

 

4 Based on conversations with Fluorinated GHG producers, as referenced in section 7. 
9 

Accurately identifying the compounds emitted provides for a better fluorinated GHG 

emissions estimate and also a better CO2e emissions estimate because the appropriate GWP are 

applied to the emitted compounds. If there is a difference between the GWPs of a product and a 

byproduct and if the emissions are assumed to consist exclusively of the product, the CO2e 

emissions could be overestimated or underestimated. Underestimation is a particular concern 

where the process unexpectedly generates a fluorinated GHG that is difficult to destroy (e.g., 

CF4). In this case, applying the destruction efficiency (DE) of the destruction device to the 

emissions may overestimate destruction and underestimate emissions. 

Facilities would conduct an initial scoping test on each fluorinated gas process at the 

facility. EPA evaluated emissions cutoffs on a process basis so that only those processes with 

expected fluorinated GHG emissions above a cutoff level would conduct the initial scoping test. 

We considered a limit of 10,000 mtCO2e on an uncontrolled basis for each process, and note that 

a cutoff based on fluorinated GHG (rather than CO2e) emissions may be appropriate because the 

identity and the GWP of some fluorinated GHG compounds may not be known. Based on a 

conservative assumption of an average GWP of 10,000, the fluorinated GHG emissions cutoff 

would be 1 metric ton fluorinated GHG. The estimate of emissions from each process could be 

determined using standard engineering calculations, previous measurements, and engineering 

assessments (i.e., similar to preliminary emission estimates discussed under process vent specific 

emissions calculation factors below). Because the specific fluorinated GHG byproducts may not 

be known, it may be appropriate to apply the 1-metric-ton-fluorinated-GHG-emission cutoff to 

uncontrolled emissions. As noted above, the application of the destruction device’s DE may 

underestimate emissions (and therefore fail to trigger testing) if difficult-to-destroy fluorinated 

GHGs occur unexpectedly in the stream. 

For each process with fluorinated GHG emissions above the cutoff level, facilities would 

select those process vents or streams for testing that are most likely to contain all of the 

fluorinated GHG compounds anticipated to be generated or emitted. Sampling and analytical 

methods capable of detecting and speciating fluorinated GHG compounds and capable of 

identifying multiple compounds simultaneously would be the best choices for the initial scoping 

test. For example, methods that use gas chromatography with mass spectrometry (GC/MS) are 

capable of detecting and identifying multiple fluorinated GHG compounds. Another example of 

an appropriate sampling and analytical method includes Fourier transform infrared (FTIR) 

analysis. There are several EPA reference methods and other consensus vetted methods that may 

be used to sample and analyze fluorinated GHG; these methods include EPA Method 18 - 

Measurement of Gaseous Organic Compound Emissions by Gas Chromatography (GC/ECD, 

GC/MS), EPA Test Method 320 Measurement of Vapor Phase Organic and Inorganic Emissions 

by Extractive Fourier Transform Infrared (FTIR) Spectroscopy, and ASTM D6348-03 (FTIR) 

Standard Test Method for Determination of Gaseous Compounds by Extractive Direct Interface 

Fourier Transform Infrared (FTIR) Spectroscopy. Each of these is briefly described below in the 

section on Process-Vent-Specific Emission Factor Approach. If EPA Method 18 is conducted, 

the facility would also conduct an EPA Method 1 series (Sample and Velocity Traverses for 

Stationary Sources), Method 2 series (Determination of Stack Gas Velocity and Volumetric Flow 

Rate), Method 3 series (Gas Analysis for Carbon Dioxide, Oxygen, Excess Air, and Dry 

Molecular Weight), and Method 4 (Determination of Moisture Content in Stack Gases). If a 

facility is not able to conduct EPA Method 2, alternative flow rate methods may be used, such as 

OTM 24 (Tracer Gas Protocol For the Determination of Volumetric Flow Rate Through the Ring 
10 

Pipe of the Xact Multi-Metals Monitoring System) or ALT-012 (Emission Measurement Center 

Approved Alternative Method). 

B. Options for Developing Emissions Estimates 

i. Default Emission Factor 

One option for characterizing fluorinated GHG is the use of default emission factors. 

These factors would provide a rough estimate of the quantity of fluorinated GHGs emitted. 

Although the default emission factor approach is simple and easily-implemented, it is also highly 

imprecise; emissions of fluorinated GHG products in U.S. plants are estimated to vary from 0.8 

percent to 2 percent of production, more than a factor of two (RTI, 2008).5 Thus, applying a 

default factor (1.5 percent, for example) is likely to significantly overestimate emissions at some 

plants while significantly underestimating them at others. 

Under a somewhat more rigorous default emission factor approach, emission factors 

would be developed for similar types of emission points at multiple facilities within a source 

category. The emission factors for each type of emission point would be averaged to develop an 

industry-wide emission factor for that type of emission point. Because these EFs would represent 

average values over multiple facilities, some facilities would be above the EF and some would be 

below. As a result, such factors may not provide an accurate emissions determination for a 

single facility. Default EFs would not account for inter-facility variability that can occur due to 

the age of facility and equipment, equipment sizes, equipment design, differences in raw 

materials and suppliers, different typical operating parameters, and variations in the process 

operation that may not be readily apparent or known. In addition, default EF would not provide 

information that EPA may need to compare the best and worst performers, or provide insights 

into which facilities have the most or fewest opportunities to obtain additional reductions. 

ii. Mass Balance 

In the mass-balance approach, facilities weigh or meter the reactants fed into the process, 

the product resulting from the process, and any byproducts and wastes that are removed from the 

process (i.e., sent to the thermal oxidizer or other equipment, not immediately recycled back into 

the process). Facilities then calculate the difference between the mass of reactants fed into the 

process and the sum of the masses of the main product and those of any byproducts and/or 

wastes. This difference is then assigned to loss of reactants, loss of product, and/or conversion to 

byproducts. As discussed further below, it is EPA’s understanding that some facilities perform 

these measurements and calculations to monitor their processes and yields. 

Because the mass-balance approach relies on the calculation of relatively small 

differences between relatively large numbers, measurements must have good precision to avoid 

large uncertainties in the emissions estimates. EPA evaluated methods to estimate the error 

associated with the mass balance approach. 

 

5

 The emission rates cited were estimated for HCFC-22, which is an ozone-depleting substance and therefore 

excluded from the proposed rule. However, the production processes for many fluorinated GHGs are similar to 

those for HCFC-22 (2006 IPCC Guidelines, Volume 3, section 3.10.2.1), and therefore their emission rates are 

likely to be similar as well. 
11 

1. Error Limits 

Precision and Accuracy Requirements for Individual Measurements 

One approach to limiting the error associated with emissions estimates developed using 

the mass-balance approach is to establish specific precision and accuracy requirements for each 

measurement used in the mass-balance equation. These measurements include mass 

measurements for reactants, products, and fluorinated GHG by-products, including feed streams, 

final product streams, emitted streams, and destroyed or recaptured streams. In addition, they 

include concentration measurements where products or by-products occur in streams with other 

substances. To limit the uncertainty of the emission estimate to ± 30 percent of the estimate, 

devices used to measure masses (e.g., flowmeters and scales) would need to be able to achieve 

precisions and accuracies near ± 0.2 percent or better, at least for streams with a large impact on 

the mass-balance calculation. Concentration measurements would need to be conducted with 

precisions and accuracies of ± 10 percent or better.This approach limits error and is 

straightforward to implement and enforce. However, it may require substantial expenditures to 

obtain accurate and precise measurements of quantities whose errors have little impact on the 

overall error of the emissions estimate. For example, under this approach, facilities might be 

required to upgrade flowmeters in streams that affect the emission estimate (and its uncertainty) 

only slightly. The approach also limits flexibility. Even a facility with a relatively large error in 

one stream may be able to bring the total error of its emissions estimate to a tolerable level by 

improving the accuracy and precision of other measurements that are used in the mass-balance 

equation, such as the mass flows of reactants and products. 

Error Limit for the Emission Estimate as a Whole. 

Another approach to limiting the error of the mass-balance approach is to establish a limit 

on the error of the overall emission estimate. To estimate the statistical error associated with use 

of the mass-balance approach, facilities would be required to use error propagation, considering 

the accuracy and precision of their measurements and the calculation methods of the massbalance approach. Under this approach, EPA would not specify precision and accuracy 

requirements for individual mass or concentration measurements. Instead, EPA would require 

that the error associated with the overall estimate of fluorinated GHG emissions fall under a 

specific limit. This limit could be expressed in terms of a fraction of the emissions estimate 

(relative error) or as a specific quantity (absolute error). Facilities could achieve this level of 

precision and accuracy however they chose. 

A maximum relative error of ± 30 percent would be comparable to that cited by a facility 

that has used an emission factor approach to estimate its fluorinated GHG emissions. It is also 

comparable to the error that EPA calculates for a facility with an emission rate of two percent 

and with good precisions and accuracies for its mass flow measurements (± 0.2 percent) and for 

its concentration measurement (± 10 percent) of a waste stream constituting five percent of the 

process’s fluorinated GHG output flow. For facilities whose emissions constitute a very small 

share of their inputs and outputs (e.g., one percent or less), a relative error of ± 30 percent would 

be very difficult to achieve using a mass-balance approach. At the same time, the absolute error 

of such a facility’s estimate may be smaller than the absolute error of a facility that meets the 

relative error test but that has a higher emission rate. It may therefore be appropriate to establish 

a maximum permissible absolute error of 3,000 mtCO2e for facilities whose estimates have 
12 

relative errors greater than 30 percent. This absolute error is equivalent to 30 percent of the 

10,000 mtCO2e threshold that is used elsewhere in the subpart to establish requirements for 

different sources (e.g., process vents). Under this approach, processes whose emissions were 

lower than 10,000 mtCO2e could have relative errors higher than 30 percent so long as they met 

the limit on absolute error. This approach would avoid penalizing processes and facilities with 

low emissions. 

Another approach that would avoid penalizing facilities with low emission rates would be 

to express the maximum relative error as a fraction of the total mass of reactants fed into (or 

consumed by) the process. For a given process, this mass would remain relatively constant 

regardless of the emission rate. For the model facility described above, with errors of 0.2 percent 

in its mass flow measurements and of 10 percent in its concentration measurements, the error of 

the emissions estimate relative to the total mass of reactants is about 0.3 percent. One advantage 

of this approach compared to the absolute limit is that this approach limits the relative errors for 

processes with small throughputs, while the absolute limit could permit very large relative errors 

for processes with small throughputs. 

The absolute and relative errors associated with using the mass balance approach on a 

process may be estimated using equations L-1, L-2, L-3, and L-4 in conjunction with equations 

L-7 through L-12. To perform the calculation, facilities would calculate the absolute and relative 

errors associated with the quantities calculated using equations L-8, L-9, L-10, and L-11. Once 

errors have been calculated for the quantities in these equations, those errors would be used to 

calculate the errors in equations L-7 and L-12. Where the measured quantity is a mass, the error 

in the mass could be equated to the accuracy or precision (whichever is larger) of the flowmeter, 

scale, or combination of volumetric and density measurements at the flowrate or mass measured. 

Where the measured quantity is a concentration, the error of the concentration could be equated 

to the accuracy or precision (whichever is larger) of the analytical technique used to measure the 

concentration at the concentration measured. 

Equation L-1 provides the general formula for calculating the absolute errors of sums and 

differences where the sum, S, is the summation of variables measured, a, b, c, etc. (e.g., S = a + b 

+ c): 

 eSA = [(a*ea)

2

 + ((b*eb)

2

 + (c*ec)

2

 ]1/2 (Eq. L-1)

Where: 

eSA = absolute error of the sum, expressed as one half of a 95 percent confidence interval. 

ea = relative error of a, expressed as one half of a 95 percent confidence interval. 

eb = relative error of b, expressed as one half of a 95 percent confidence interval. 

ec = relative error of c, expressed as one half of a 95 percent confidence interval. 

Equation L-2 provides the general formula for calculating the relative errors of sums and 

differences: 
13 

( ) a b c

e

e

SA

SR

+ +

= (Eq. L-2) 

Where: 

eSR = relative error of the sum, expressed as one half of a 95 percent confidence interval. 

eSA = absolute error of the sum, expressed as one half of a 95 percent confidence interval. 

a+b+c = sum of the variables measured. 

Equation L-3 provides the general formula for calculating the absolute errors of products 

(e.g., flow rates of GHGs calculated as the product of the flow rate of the stream and the 

concentration of the GHG in the stream), where the product, P, is the result of multiplying the 

variables measured, a, b, c, etc. (e.g., P = a*b*c): 

 ePA = (a*b*c)(ea

2

 + eb

2

 + ec

2

)

1/2 (Eq. L-3) 

Where: 

ePA = absolute error of the product, expressed as one half of a 95 percent confidence 

interval. 

ea = relative error of a, expressed as one half of a 95 percent confidence interval. 

eb = relative error of b, expressed as one half of a 95 percent confidence interval. 

ec = relative error of c, expressed as one half of a 95 percent confidence interval. 

Equation L-4 provides the general formula for calculating the relative errors of products: 

( ) a b c

e

e

PA

PR * *

= (Eq. L-4) 

Where: 

ePR = relative error of the product, expressed as one half of a 95 percent confidence interval. 

ePA = absolute error of the product, expressed as one half of a 95 percent confidence 

interval. 

a*b*c = product of the variables measured 

2. Mass Balance Approach Equations. 

The following set of equations summarizes the mass-balancing method for estimating 

fluorinated GHG emission. 

The total mass of each fluorinated GHG product emitted annually from all fluorinated gas 

production processes would be estimated by using Equation L-5 of this section: 

∑ ∑= =

=

m

i

Pip

n

p

EP E

1 1

 (Eq. L-5) 
14 

Where: 

EP = Total mass of each fluorinated GHG product emitted annually from all production 

processes (metric tons). 

EPip = Total mass of the fluorinated GHG product emitted from production process i over 

the period p (metric tons, defined in Equation L-7 of this section). 

n = Number of concentration and flow measurement periods for the year. 

m = Number of production processes. 

The total mass of fluorinated GHG by-product k emitted annually from all fluorinated gas 

production processes shall be estimated by using Equation L-6 of this section: 

∑ ∑= =

=

m

i

Bkip

n

p

EBk E

1 1

 (Eq. L-6) 

Where: 

EBk = Total mass of fluorinated GHG by-product k emitted annually from all production 

processes (metric tons). 

EBkip = Total mass of fluorinated GHG by-product k emitted from production process i over 

the period p (metric tons, defined in Equation L-8 on this section). 

n = Number of concentration and flow measurement periods for the year. 

m = Number of production processes. 

The total mass of each fluorinated GHG product emitted from production process i over 

the period p would be estimated by calculating the difference between the expected production of 

the fluorinated GHG based on the consumption of one of the reactants (e.g., HF or a 

chlorofluorocarbon reactant) and the measured production of the fluorinated GHG, accounting 

for yield losses related to by-products and wastes. This calculation shall be performed using 

Equation L-7 of this section. 

∑( ) ∑ = =

= − − −

u

k

Bkip

q

j

P Dj

R R

P P

Pip P C W L

MW SC

R MW SC

E

1 1

*

*

* *

 (Eq.L-7) 

Where: 

EPip = Total mass of each fluorinated GHG product emitted from production process i over 

the period p (metric tons). 

P = Total mass of the fluorinated GHG produced by production process i over the period 

p (metric tons). 

R = Total mass of the reactant that is consumed by production process i over the period p 

(metric tons, defined in Equation L-8). 

MWR = Molecular weight of the reactant. 

MWP = Molecular weight of the fluorinated GHG produced. 

SCR = Stoichiometric coefficient of the reactant. 

SCP = Stoichiometric coefficient of the fluorinated GHG produced. 
15 

cP = Concentration (mass fraction) of the fluorinated GHG product in stream j of 

destroyed wastes. If this concentration is only a trace concentration, cP is equal to 

zero. 

WDj = Mass of wastes removed from production process i in stream j and destroyed over the 

period p (metric tons, defined in Equation L-9 of this section). 

LBkip = Yield loss related to by-product k for production process i over the period p (metric 

tons, defined in Equation L-10 of this section). 

q = Number of waste streams destroyed in production process i. 

u = Number of by-products generated in production process i. 

The total mass of the reactant that is consumed by production process i over the period p 

shall be estimated by using Equation L-8 of this section: 

R = RF − RR (Eq.L-8) 

Where: 

R = Total mass of the reactant that is consumed by production process i over the period p 

(metric tons). 

RF = Total mass of the reactant that is fed into production process i over the period p 

(metric tons). 

RR = Total mass of the reactant that is permanently removed from production process i 

over the period p (metric tons). 

The mass of wastes removed from production process i in stream j and destroyed over the 

period p would be estimated using Equation L-9 of this section: 

WDj = WFj* DE (Eq. L-9) 

Where: 

WDj = The mass of wastes removed from production process i in stream j and destroyed over 

the period p (metric tons). 

WFj = The total mass of wastes removed from production process i in stream j and fed into 

the destruction device over the period p (metric tons). 

DE = Destruction Efficiency of the destruction device (fraction). 

Yield loss related to by-product k for production process i over period p would be 

estimated using Equation L-10 of this section: 

( )

( ) Bk P

kip P Bk

Bkip MW ME

B MW ME

L

*

* *

= (Eq. L-10) 

Where: 

LBkip = Yield loss related to by-product k for production process i over the period p (metric 

tons). 
16 

Bkip = Mass of by-product k generated by production process i over the period p (metric 

tons, defined in Equation L-11 of this section). 

MWP = Molecular weight of the fluorinated GHG produced. 

MWBk = Molecular weight of by-product k. 

MEBk = Moles of the element shared by the reactant, product, and by-product k per mole of 

by-product k. 

MEP = Moles of the element shared by the reactant, product, and by-product k per mole of 

the product. 

If by-product k is responsible for yield loss in production process i and occurs in any 

process stream in more than trace concentrations, the mass of by-product k generated by 

production process i over the period p would be estimated using Equation L-11 of this section: 

= ∑

q

j

kip Bjk S j B c * (Eq. L-11) 

Where: 

Bkip = Mass of by-product k generated by production process i over the period p (metric 

tons). 

cBkj = Concentration (mass fraction) of the by-product k in stream j of production process i 

over the period p. If this concentration is only a trace concentration, cBkj is equal to 

zero. 

Sj = Mass flow of process stream j of production process i over the period p. 

q = Number of streams in production process i. 

If by-product k is responsible for yield loss, is a fluorinated GHG, occurs in any process 

stream in more than trace concentrations, and is not completely recaptured or completely 

destroyed; the total mass of by-product k emitted from production process i over the period p 

would be estimated using Equation L-12of this section: 

∑ ∑ = =

= − −

x

l

Dj Bkl Rl

q

j

EBkip Bkip cBkj W c S

1 1

* * (Eq. L-12) 

Where: 

EBkip = Mass of by-product k emitted from production process i over the period p (metric 

tons). 

Bkip = Mass of by-product k generated by production process i over the period p (metric 

tons). 

cBkj = Concentration (mass fraction) of the by-product k in stream j of destroyed wastes 

over the period p. If this concentration is only a trace concentration, cBj is equal to 

zero. 

WDj = The mass of wastes that are removed from production process i in stream j and that 

are destroyed over the period p (metric tons, defined in Equation L-9 of this section). 
17 

cBkl = The concentration (mass fraction) of the by-product k in stream l of recaptured 

material over the period p. If this concentration is only a trace concentration, cBkl is 

equal to zero. 

SRl = The mass of materials that are removed from production process i in stream l and that 

are recaptured over the period p. 

q = Number of waste streams destroyed in production process i. 

x = Number of streams recaptured in production process i. 

3. Choice of Reactant Whose Yield Is Measured. 

EPA has considered use of one reactant to estimate emissions under the mass-balance 

approach (rather than both as originally proposed). Some fluorinated GHG producers have noted 

that, for various reasons, it is sometimes considerably more difficult to track the yields of some 

reactants than others (e.g., HF vs. an organic feedstock). EPA notes that facilities estimating 

their emissions based on the yield of one reactant would still need to be able to demonstrate that 

their estimate met the statistical error test that might be required. 

If an alternate reactant was measured, it would be necessary for facilities to be extremely 

thorough in the monitoring approach and calculations in order to account for all potential 

emissions. The reactant whose yield is measured and its relationship to fluorinated GHG 

emissions for a particular process must be fully analyzed to ensure that it provided an accurate 

representation of the emissions. 

4. Frequency of Measurement and Calculation. 

EPA considered several measurement and calculation frequencies for the mass balance 

approach. The total mass of each fluorinated GHG product emitted from production process 

could be estimated on a daily or monthly basis by calculating the difference between the 

expected production of the fluorinated GHG based on the consumption of one of the reactants 

(e.g., HF or a chlorofluorocarbon reactant) and the measured production of the fluorinated GHG, 

accounting for yield losses related to by-products and wastes. The daily measurement requires 

additional man hours to conduct more frequent measurements; however, in situations where 

input or output flows are estimated by multiplying concentrations by total mass flow rates of 

streams, and where one or both of these vary, frequent measurements will lead to more accurate 

and precise estimates than less frequent. A number of fluorocarbon producers have noted that 

daily measurements are burdensome and lead to large errors in the estimates of daily emissions. 

Many streams may contain acidic and reactive constituents such as HF, and sampling from these 

streams can create safety hazards. Daily yield measurements can also vary significantly 

(sometimes exceeding 100 percent) for three reasons. First, when continuous processes are 

initially started, there is a lag time between the time the reactants are fed into the process and the

time products emerge. Second, even after the process has been running for a while, the quantity 

of material in the process can vary based on weather, changes in production rates, and other 

conditions. Third, the relatively large errors in measurements of in-process product holding 

tanks (e.g., based on sight-glass readings) have a significant impact on daily mass balances. Over 

time, all of these effects smooth out, making longer term mass balances more reliable than daily 

mass balances. 
18 

Some fluorinated GHG producers have stated that it is difficult to measure fluorinated 

GHG concentrations in some streams. In some cases, this is because waste streams contain 

hydrofluoric acid (HF), which, due to its acidity and reactivity, can damage sampling and 

analytical equipment. To the extent that these approaches could be relatively difficult or 

expensive to implement, however, it might be appropriate to permit very infrequent 

measurements. The disadvantage of this approach is that it might lead to larger errors, 

particularly for processes that vary over time. A series of measurements might be required to 

(l) reduce the error and (2) quantify the error for purposes of the statistical error test. Such 

measurements would be analogous to those used to develop emission factors. 

5. Reactant and Byproduct Emissions. 

EPA recognizes that the proposed mass-balance approach would assume that all yield 

losses that are not accounted for are attributable to emissions of the fluorinated GHG product. In 

some cases, the losses may be untracked emissions or other losses of reactants or fluorinated byproducts. In general, EPA understands that reactant flows are measured at the inlet to the 

reactor; thus, any losses of reactant that occur between the point of measurement and the reactor 

are likely to be small. However, reactants that are recovered from the process, whether they are 

recycled back into it or removed permanently, may experience some losses that the proposed 

method does not account for. 

Fluorocarbon by-products, according to the IPCC Guidelines, generally have “radiative 

forcing properties similar to those of the desired fluorochemical.” However, EPA is aware of at 

least one facility where byproducts often have much larger GWPs than the products. In this case, 

assuming by-product emissions are product emissions would lead to large errors in estimating 

overall fluorinated GHG emissions. EPA believes that the initial scoping test of emitted streams 

that is discussed above would help to determine whether this was an issue for a given process. If 

it was, then the facility could elect to pursue the PSEF approach rather than the mass-balance 

approach for that process, or, if the facility was still interested in pursuing the mass balance 

approach, it could perform more emissions testing to develop a robust break-out among the FGHGs assumed to be emitted under the mass-balance approach (e.g., by increasing calculated 

by-product emissions by some percentage). Such emissions testing would be similar to that 

performed for the PSEF approach below, except it would focus on the partitioning of emissions 

among the various F-GHGs. 

6. Alternative approach based on measurements of balanced element 

Another variant of the mass-balance approach would not require facilities to speciate 

their by-product and/or waste streams on a periodic basis. Instead, facilities could measure the 

total fluorine (or other element of interest other than carbon) in the by-product and/or waste 

streams, e.g., by burning them. An initial emissions test would be conducted to ensure that 

emissions were properly allocated among the reactant, product, and by-products, but this testing 

could be repeated at longer than monthly intervals, e.g., annually or every five years. The total 

fluorine approach could be particularly useful for processes with multiple by-products. 

The following equation, Equation AMB-1, is analogous to Equation L-7, but it provides 

emissions in terms of fluorine rather than the fluorinated GHG product. This equation describes 

a relatively simple case in which only one reactant contains the fluorine (or other element of 
19 

interest), but it could be generalized by summing over Rn, where n is the number of reactants. 

As discussed further below, EF needs to be multiplied by another term to obtain emissions in 

terms of the product and byproduct. 

∑ ∑ = =

−

















= − +

u

k Bk

F

k Bk

P

F

P

q

j

P Dj

R

F

F R MW

AW

B MF

MW

AW

P C W MF

MW

AW

E R MF

1 1

* * * * * * * (Eq. AMB-1) 

Where: 

EF = Total mass of fluorine emitted from production process i over the period p (metric 

tons). 

P = Total mass of the fluorinated GHG produced by production process i over the period 

p (metric tons). 

Bk = Mass of by-product k generated by production process i over the period p (metric 

tons). 

R = Total mass of the reactant that is consumed by production process i over the period p 

(metric tons). 

MWR = Molecular weight of the reactant. 

MWP = Molecular weight of the fluorinated GHG produced. 

MWBk = Molecular weight of by-product k. 

AWF = Atomic weight of fluorine. 

MFR = Moles fluorine per mole of reactant. 

MFP = Moles fluorine per mole of product. 

MFBk = Moles fluorine per mole of by-product k. 

cP = Concentration (mass fraction) of the fluorinated GHG product in stream j of 

destroyed wastes. If this concentration is only a trace concentration, cP is equal to 

zero. 

WDj = Mass of wastes removed from production process i in stream j and destroyed over the 

period p (metric tons). 

q = Number of waste streams destroyed in production process i. 

u = Number of by-products generated in production process i. 

This equation needs to be multiplied by another term to obtain emissions in terms of the 

product: 

F

F

P

P

P E

AW

MW

MF

E * *

1

















= (Eq. AMB-2) 

Where: 

EP = Total mass of fluorinated GHG product emitted (metric tons). 

MWP = Molecular weight of the fluorinated GHG produced. 

AWF = Atomic weight of fluorine. 

MFP = Moles fluorine per mole of product. 
20 

EF = Total mass of fluorine emitted from production process i over the period p (metric 

tons). 

Note that when Equations AMB-1 and AMB-2 are multiplied, they result in Equation L-7. 

As noted above, the advantage of the fluorine-balancing approach is that destroyed 

product and byproduct streams do not need to be speciated if their total fluorine contents can be 

measured. We can revise Equation AMB-1 to reflect this. We can also revise Equation AMB-1 

to express quantities in terms of mass fractions of fluorine. The following Equation AMB-3 

reflects these changes. 

EF = R MFFR − P MFFP − FD* (Eq. AMB-3) *

Where: 

EF = Total mass of fluorine emitted from production process i over the period p (metric 

tons). 

P = Total mass of the fluorinated GHG produced by production process i over the period 

p (metric tons). 

R = Total mass of the reactant that is consumed by production process i over the period p 

(metric tons), calculated in equation L-8. 

MFFR = Mass fraction of fluorine in the reactant, equal to 

R

F

R MW

AW MF * . 

MFFP = Mass fraction of fluorine in the fluorinated GHG product, equal to

P

F

P MW

AW MF * . 

FD = Mass of fluorine measured in destroyed or recaptured streams containing fluorinatedGHG product and byproducts. 

Equation AMB-2 assumes that all of the fluorine is emitted in the form of the fluorinatedGHG product. In fact, the scoping test and subsequent emissions testing may show that some of 

the mass emitted consists of fluorinated GHG byproducts. In this case, the mass of fluorine 

emitted should be allocated among the reactant, product, and byproducts (including GHGs and 

non-GHGs). 

To do this, we would begin with the results of the most recent emissions test, that is, with 

the fractions of the emitted fluorinated compounds that consist of the reactant, product, and each 

byproduct. These fractions would be adjusted to reflect the shares of the masses of the reactant, 

product and by-products that consist of fluorine. The sum of the adjusted fractions, multiplied 

by the total emissions from the process, are equal to the emissions of fluorine from the process 

calculated in Equation AMB-3. 













= + +∑=

u

k

EF T FER MFFR FEP MFFP FEBk MFFBk

1

* * * * (Eq. AMB-4) 
21 

Where: 

EF = Total mass of fluorine emitted from production process i over the period p (metric 

tons). 

T = Total mass emitted from the process, including emitted reactants, products, and byproducts 

FER = The fraction of the mass emitted that consists of the reactant (from the most recent 

emissions test). 

FEP = The fraction of the mass emitted that consists of the fluorinated GHG product (from 

most recent emissions test). 

FEBk = The fraction of the mass emitted that consists of by-product k (from most recent 

emissions test). 

MFFR = Mass fraction of fluorine in the reactant, equal to 

R

F

R MW

AW MF * . 

MFFP = Mass fraction of fluorine in the fluorinated GHG product, equal to

P

F

P MW

AW MF * . 

MFFBk = Mass fraction of fluorine in by-product k, equal to 

Bk

F

Bk MW

AW MF * . 

Since T*(FER) = ER, T*(FEP) = EP, and T*(FEBk) = EBk, we can solve Equation AMB-4 

for T and multiply by FER, FEP, and FEBk, as appropriate, to obtain Equations AMB-5, AMB-6,

and AMB-7, respectively. 













+ +

=

∑=

u

k

R P k Bk

F

R

FER MFF FEP MFF FEB MFF

FER E

E

1

* * *

*

 (Eq. AMB-5) 













+ +

=

∑=

u

k

R P k Bk

F

p

FER MFF FEP MFF FEB MFF

FEP E

E

1

* * *

*

 (Eq. AMB-6) 













+ +

=

∑=

u

k

R P k Bk

k F

Bk

FER MFF FEP MFF FEB MFF

FEB E

E

1

* * *

*

 (Eq. AMB-7) 

Where: 

EP = Total mass of fluorinated GHG product emitted (metric tons). 

EBk = Total mass of by-product k emitted (metric tons). 

ER = Total mass of Emissions of the fluorinated GHG product. 

FER = The fraction of the mass emitted that consists of the reactant (from the most recent 

emissions test). 
22 

FEP = The fraction of the mass emitted that consists of the fluorinated GHG product (from 

most recent emissions test). 

FEBk = The fraction of the mass emitted that consists of by-product k (from most recent 

emissions test). 

MFFR = Mass fraction of fluorine in the reactant, equal to 

R

F

R MW

AW MF * . 

MFFP = Mass fraction of fluorine in the fluorinated GHG product, equal to

P

F

P MW

AW MF * . 

MFFBk = Mass fraction of fluorine in by-product k, equal to 

Bk

F

Bk MW

AW MF * . 

u = Number of by-products generated in production process i. 

7. Current Plant Practices for Mass Balance 

A few facilities indicated that they conduct a form of the mass balance approach for 

determining fluorinated GHG emissions. Facilities noted overall that the difficulty of the mass 

balance approach depends on how sophisticated or complex the process is, i.e., how many input 

and output streams there are, and whether there are by-products generated and how many. 

Facilities that use a form of the mass balance approach indicated that it is often used in 

conjunction with an emissions factor based approach, to track yields and subtle or incremental 

changes in the process. These facilities conduct a “material balance” on the process, tracking the 

product yield, using the emission factor for some emission points, and the composition and 

concentration of the streams to determine if something in the process has changed. Generally, 

facilities have a good understanding of the chemistry for all processes and understand what raw 

materials are fed to the process, what side reactions occur, and what products and by-products 

are created. Facilities have laboratory-scale, pilot-plant, and full-scale stream analysis results. 

Facilities stated that with the original plant design, the mass balance equation is predicted. 

Facilities noted in particular that at the bench-scale phase of product and process development, 

they analyze every/all streams to identify all species and compounds. However, one facility 

indicated that while they do regularly measure byproduct concentrations in the product as a 

quality check, they do not regularly measure byproduct concentration across all process vents 

and streams. 

Some facilities indicated that they conduct the mass balance on the fluorinated organic 

component only. 

Facilities noted, in particular, that they reconcile and calculate the production levels on a 

monthly basis rather than on shorter time frames such as daily or weekly. 

iii. Monitoring of Process Vents 

The emissions from process vents may be determined by a number of methods. These 

include emissions testing, engineering assessments, or calculations based on chemical 

engineering principles. All three methods may also be used to develop a site-specific emissions 

factor based on the emissions estimate and the process activity observed during the test or 
23 

assumed for the calculations. These methods or approaches to determining emissions from 

fluorinated gas production processes provide emissions estimates of varying accuracy and 

precision. 

1. Process-Vent-Specific Emission Factor Approach. 

One method for estimating fluorinated GHG emissions is based on monitoring or 

estimating the composition and flow rate of the process vent streams along with the production 

activity parameter to develop a site-specific, process-vent-specific emission factor. Fluorinated 

gas producers have indicated that they develop and apply emission factors to estimate emissions 

from a range of processes. Typically a facility conducts an initial emissions test or engineering 

calculation to develop an emission factor or emissions calculation factor and updates the 

emissions factor as needed with process changes. Site-specific, process-vent-specific emission 

factors can be developed based on either measurement of process vent emissions or calculation 

of process vent emissions. The measurement of process vent emissions to develop an emissions 

factor is addressed in this section, and the calculation of process vent emissions is discussed 

below in Process-Vent-Specific Emission Calculation Factor approach. 

Under this approach, facilities would develop a process-vent-specific emission factor for 

each fluorinated GHG from each process vent by emissions testing. There are several EPA test 

methods available to sample and measure fluorinated GHG from processes in the fluorinated gas 

production source category, including EPA Method 320 (ASTM D6348-03) and EPA Method 

18. Method 1 or 1A, Method 2, 2A, 2B, 2C, or 2D, 2F, or 2G, Method 3, 3A, or 3B, and Method 

4 must be conducted along with EPA Method 18. 

Method 320 and ASTM D6348-03. For Method 320 a gas sample is extracted through a 

heated gas transport and handling system and analyzed using FTIR spectroscopy to identify and 

quantify the gas stream components. It is applicable only for vapor phase analysis of organic or 

inorganic compounds. The sensitivity of this method can be adjusted based on the reference 

standards used to configure the FTIR, but also depends on the gas composition, moisture content, 

and sampling losses. The ASTM D6348-03 FTIR method utilizes the same principles as Method 

320 but has some improved calibration requirements.

Method 18. Method 18 utilizes gas chromatography (GC) and flame ionization, 

photoionization, electron capture, mass spectroscopy, or another applicable detection method to 

identify and quantify gaseous organic compounds. For the fluorinated GHG gas industry, 

electron capture and mass spectroscopy and possibly photoionization are the most appropriate 

detectors for identifying fluorinated GHG compounds. The identity and concentration levels are 

determined by comparison to known standards, which are used to calibrate the GC. Stack gas 

samples may be collected through direct interface sampling, dilution interface sampling, 

adsorption tube sampling, or bag sampling. One needs to consider whether significant temporal 

changes in flow rate and/or concentration occur in the process (e.g., batch processes) when 

selecting and applying the sampling approach for this method. The direct interface, dilution 

interface, and adsorption tube sampling are not designed for sources that vary in concentration, 

and therefore may not be appropriate for batch processes. Instead, an integrated bag sample with 

proportional sampling (sample rate adjusted proportionally with changes in stack gas flow rate) 

would be appropriate for an emission source with a varying flow rate and concentration, such as 

a batch process. If the direct interface method is used, the timeframe of temporal changes of 
24 

concentration in relation to the analytical timeframe needs to be considered. For example, if 

significant changes in concentration are expected to occur rapidly (e.g., 10-minute time frame), 

but the GC analytical cycle is 30 minutes, a representative sample analysis may not be obtained; 

on the other hand, for this situation, if the analytical cycle is 5 minutes, a representative sample 

would be obtained. Variations in vent gas flow rate also need to be considered; for example, if 

vent flow rates and concentration are varying with time and the direct interface method is being 

used, the vent flowrate should be continuously monitored so that the flowrate and concentration 

can be correlated to determine mass emissions. For any of the sampling methods, all samples 

must be analyzed within a few hours of collection. 

Method 320, ASTM D63248-03 and Method 18 also require that the flow rate be 

relatively constant during sampling. If the flow rate varies significantly over the course of the 

sampling, then this fluctuation must to be accounted for when measuring concentration and 

calculating mass emissions. 

OTM 24, the Tracer Gas Protocol For the Determination of Volumetric Flow Rate 

Through the Ring Pipe of the Xact Multi-Metals Monitoring System (OTM 24) uses a GC 

equipped with an FID to measure the concentration at a specific point. A tracer gas is introduced 

into the process to perform a volumetric flow rate determination, which depends on the flow 

tracer flow rate, concentration at the measurement point and calibration and analysis data. 

The Emission Measurement Center Approved Alternative Method (ALT-012) is designed 

for measuring particulate emissions in situations where gas velocities are low and difficult to 

measure and subject to variations over time. ALT-012 can also be used to measure ducts and 

stacks that are not subject to stratification. First, locations are identified upstream, for injection

the tracer gas, and downstream, for the tracer gas measurement. For a complete measurement, 

three ten-minute long sampling intervals must be completed at the downstream location. 

Nuclear magnetic resonance (NMR) spectroscopy is a commonly used analytical 

technique in organic chemistry. Organic compounds are placed in a magnetic field and exposed 

to electro-magnetic energy, usually in the form of radio frequency (RF), and the nuclei of certain 

atoms absorb the radiation, which causes the nuclear spin to realign in the higher energy 

direction. The wavelength the atom absorbs is dependent on the neighboring atoms in the 

compound, and the resulting spectrum is called the NMR spectrum. This is a complex laboratory 

analytical method used to determine the structure of molecules. Much like using infrared 

spectroscopy (IR) to identify functional groups, analysis of a NMR spectrum provides 

information on the number and type of chemical entities in a substance. Also, the dependence of 

the transition energy on the position of a particular atom in a molecule makes NMR spectroscopy 

extremely useful for determining the structure of molecules. 

Using the applicable method(s), process activity (e.g., production or feed) would be 

monitored at the same time as emissions; the emission factor would be developed by dividing the 

emissions by the activity. Both continuous and batch processes are used in the fluorinated gas 

production source category. Typically, for continuous processes, facilities would measure and 

determine the fluorinated GHG emission rate based on test runs of at least 1 hour duration. For 

batch processes, a facility would typically measure and determine the fluorinated GHG 

emissions either over full batch cycles or during all emission episodes over the batch. Emissions 
25 

testing over the full batch may require significant effort and cost, depending on the length of the 

batch. For continuous processes, facilities would use Equation L-13 and for batch processes 

would use Equation L-14 to determine emission rates from processes. 

1

60 *

10

1

*

1

* * *

106 3

SV

MW Q

C

E PV

PV

ContPV = (Eq. L-13) 

Where: 

EContPV = Mass of fluorinated GHG f emitted from process vent v from production process i 

during the emission test during test run r (kg/hr).

CPV = Concentration of fluorinated GHG f during test run r of the emission test (ppmv). 

MW = Molecular weight of fluorinated GHG f (g/g-mole). 

QPV = Flow rate of the process vent stream during test run r of the emission test (m3/min). 

SV = Standard molar volume of gas (0.0240 m3/g-mole at 68°F and 1 atm). 

1/103 = Conversion factor (1 kilogram/1000 gram). 

60/1 = Conversion factor (60 minutes/1 hour). 

6 3

1

10

1

*

1

* *

10

* *

SV

MW

C Q D

E

ee

PV ee PV ee ee

BatchPV

∑ − −

= (Eq. L-14) 

Where: 

EBatchPV = Mass of fluorinated GHG f emitted from process vent v from production process i 

during the emission test during test run r (kg/batch). 

CPV-ee = Concentration of fluorinated GHG f during emission episode ee during test run r of 

the emission test (ppmv). 

QPV-ee = Flow rate of the process vent stream during emission episode ee during test run r of 

the emission test (m3/min). 

Dee = Duration of emission episode ee during test run r of the emission test (minutes). 

MW = Molecular weight of fluorinated GHG f (g/g-mole). 

SV = Standard molar volume of gas (0.0240 m3/g-mole at 68°F and 1 atm). 

1/103 = Conversion factor (1 kilogram/1000 gram). 

ee = Number of emission episodes ee from process vent v during process i. 

To develop the site-specific, process-vent specific emissions factor, facilities would track 

the process activity during the emissions testing and combine it with the emissions. For 

continuous processes, a facility would divide the fluorinated GHG emissions during the test by 

the process activity during testing. Equation L-15 would be used to estimate the average 

emission factor. 

r

Activity

E

EF

r

EmissionTest

PV

PV

∑ 















=

1

 (Eq. L-15) 
26 

Where: 

EFPV = Average emission factor for fluorinated GHG f emitted from process vent 

v during production process i (kg emitted/kg product). 

EPV = Mass of fluorinated GHG f emitted from process vent v from production 

process i during the emission test during test run r, for either continuous or 

batch (kg emitted/hr for continuous, kg emitted/batch for batch). 

ActivityEmissionTest = Process feed, process production, or other process activity rate during the 

emission test during test run r (e.g., kg product/hr for continuous, 

calculated in Equation L-13 of this section, kg product/batch for batch, 

calculated in Equation L-14 of this section). 

r = Number of test runs (i.e., batches) performed during the emission test. 

Development of the emissions testing program requires testing during representative 

process operation. To develop a representative emission factor for the process vent, the facility 

should give some consideration to what process variability might be present in the process. For 

each operating scenario of the process, the emissions test data must be representative of the 

typical process operation while also including process variability.6 The full range of process 

operating conditions should be included. The typical process operation conditions would include 

yield, temperature, pressure, and flow rates. The operating conditions and the process 

production activity should be measured during the emissions test. See section 3.B.iii.3 below for 

more information on representativeness. 

Using the process-vent-specific emissions factor method, a facility would estimate 

emissions using the emission factor and would track process activity on an on-going basis. To 

estimate annual fluorinated GHG emissions from each vent, facilities would multiply each 

emission factor by the appropriate activity data and account for the use (and uptime) of 

destruction devices. Equation L-16 would be used to estimate emissions for each individual 

process vent if the process vent is not vented to a destruction device, and Equation L-17 would 

be used if the process vent is vented to destruction device. 

EPV −RptPeriod = EFPV* ActivityRptPeriod (Eq. L-16) 

Where: 

EPV-RptPeriod = Mass of fluorinated GHG f emitted from process vent v from production 

process i, for the reporting period, either monthly or annually (kg/month 

or kg/year). 

EFPV = Average emission factor for fluorinated GHG f emitted from process 

vent v during production process i (kg emitted/activity)(e.g., kg emitted/kg 

product). 

ActivityRptPeriod = Process feed, process production, or other process activity during the 

reporting period. 

 

6

 Operating scenarios and other issues associated with developing representative emission factors are discussed 

further below under “Obtaining and Maintaining Representative Emission Factors.” 
27 

E EF *(Activity Activity 1(* DE)) PV −RptPeriod = PV RptPeriod −U + RptPeriod −C − (Eq. L-17) 

Where: 

EPV-RptPeriod = Mass of fluorinated GHG f emitted from process vent v from production 

process i, for the reporting period, either monthly or annually, considering 

destruction efficiency (kg/month or kg/year). 

EFPV = Emission factor for fluorinated GHG f emitted from process vent v during 

production process i (kg emitted/kg product). 

ActivityRptPeriod-U = Total process feed, process production, or other process activity during the 

reporting period for which the process vent is not vented to the destruction 

device (e.g., kg product). 

ActivityRptPeriod-C = Total process feed, process production, or other process activity during the 

reporting period for which the process vent is vented to the destruction 

device (e.g., kg product). 

DE = Demonstrated destruction efficiency of the destruction device (weight 

fraction). 

The fluorinated GHG emissions for all vents at the facility would then be summed to 

obtain the total emissions from process vents for the facility as a whole. Equation L-18 would be 

used to sum fluorinated GHG emissions over all process vents for the process, and Equation L19 would sum the emissions from all processes to estimate total fluorinated GHG process vent 

emissions. Other emission points at the facility such as equipment leaks, storage tanks, or 

wastewater would have to be accounted for separately and added in to the facility total. 

= ∑ −

v

EPfi EPV RptPeriod

1

 (Eq. L-18) 

Where: 

EPfi = Mass of fluorinated GHG f emitted from production process i, for the 

reporting period, either monthly or annually (kg). 

EPV-RptPeriod = Mass of fluorinated GHG f emitted from process vent v from production 

process i, for the reporting period, either monthly or annually, considering 

destruction efficiency (kg/month or kg/year). 

v = Number of process vents in production process i. 

= ∑

i

EP EPfi

1

 (Eq. L-19) 

Where: 

EP = Mass of fluorinated GHG f emitted from all process vents at the facility, for the 

reporting period, either monthly or annually (kg). 

EPij = Mass of fluorinated GHG f emitted from production process i, for the reporting 

period, either monthly or annually (kg). 
28 

i = Number of production processes i at the facility. 

2. Process-Vent-Specific Emission Calculation Factor Approach. 

As mentioned above, another method for estimating fluorinated GHG emissions is based 

on use of engineering calculations to determine the composition and flow rate of the process vent 

streams. These emissions estimates are divided by the production activity parameter to develop 

a site-specific, process-vent-specific emission calculation factor. A variation of this method 

includes use of engineering assessments to develop process-vent-specific emission calculation 

factor. Facilities have indicated that they regularly use engineering calculations and engineering 

assessments to estimate fluorinated GHG emissions. 

Engineering calculations use chemical engineering principles and component property 

data to calculate emissions. Acceptable calculation methods for uncontrolled and controlled 

process vent emissions are included in a number of rule texts and EPA guidance documents. 

Other promulgated rule texts that contain appropriate calculation equations include the MON 

NESHAP in §63.2460(b)(1) through (4) (the MON rule text also refers to equations in the 

Pharmaceutical NESHAP in §63.1257(d)(2)(i) for uncontrolled and §63.1257(d)(3)(i) for 

controlled emissions with some noted exceptions). These rule texts include process calculation 

methods and equations for vapor displacement, purging, heating, depressurization, vacuum 

systems, gas evolution, air drying, and empty vessel purging. An even more recent guidance 

document that provides appropriate calculations for chemical manufacturing operations is the 

Methods for Estimating Air Emissions from Chemical Manufacturing Emissions, Volume II: 

Chapter 16, of the Emission Inventory Improvement Program. 

Engineering assessments may be conducted using previous emissions test data or other 

information available on the process. Facilities typically have component and composition data 

available from the original research and development activities on the process and from the 

process’ lifetime of operation. If the facility performed a scoping test as described in section 

3.A.ii above, the results of that test should also be considered. For process vent emissions 

determinations, facilities could conduct an engineering assessment to calculate uncontrolled 

emissions for each process vent and for each emission episode. Various rules for other types of 

emissions include use of engineering assessments to estimate emissions from processes and 

process vents. Other promulgated rules that allow use of engineering assessments include 

NESHAP rules in 40 CFR part 63, such as subpart GGG for Pharmaceutical Manufacturing in 

§63.1257(d)(2)(ii) and subpart FFFF for Miscellaneous Organic NESHAP (MON) in 

§63.2460(b). Engineering assessments include use of previous emissions test data where the 

emissions are representative of current operating practices; bench-scale or pilot-scale streams 

analysis results for identifying stream components and composition for products, byproducts, 

and wastes; design analysis based on chemical engineering principles, measurable process 

parameters, or physical or chemical laws or properties. These previous emissions data, analysis, 

and calculations may be used to identify fluorinated GHG compounds and their concentrations in 

various streams. 

To develop the site-specific, process-vent-specific emissions calculation factor, facilities 

would first calculate the fluorinated GHG emissions and divide them by the appropriate process 
29 

activity associated with the emissions calculation. Equation L-20 would be used to estimate the 

emission calculation factor. 

presentative

PV

PV Activity

E

ECF

Re

= (Eq. L-20) 

Where: 

ECFPV = Emission calculation factor for fluorinated GHG f emitted from process 

vent v during production process i (kg emitted/kg product). 

EPV = Average mass of fluorinated GHG f emitted, based on calculations, from 

process vent v from production process i during the period or batch for 

which emissions were calculated, for either continuous or batch (kg 

emitted/hr for continuous, kg emitted/batch for batch). 

ActivityRepresentative = Process feed, process production, or other process activity rate 

corresponding to average mass of emissions based on calculations (e.g., kg 

product/hr for continuous, kg product/batch for batch). 

As with the process-vent-specific emissions factor, a facility would estimate emissions 

using the emissions calculation factor and would track process activity on an on-going basis. To 

estimate annual fluorinated GHG emissions from each vent, facilities would multiply each 

emission calculation factor by the appropriate activity data and account for the use (and uptime) 

of destruction devices. Equation L-21 would be used to estimate emissions for each individual 

process vent if the process vent is not vented to a destruction device, and Equation L-22 would 

be used if the process vent is vented to a destruction device. 

EPV −RptPeriod = ECFPV* ActivityRptPeriod (Eq. L-21) 

Where: 

EPV-RptPeriod = Mass of fluorinated GHG f emitted from process vent v from production 

process i, for the reporting period, either monthly or annually (kg/month 

or kg/year). 

ECFPV = Emission calculation factor for fluorinated GHG f emitted from process 

vent v during production process i (kg emitted/activity)(e.g., kg emitted/kg 

product). 

ActivityRptPeriod = Process feed, process production, or other process activity during the 

reporting period. 

E ECF *(Activity Activity 1(* DE)) PV −RptPeriod = PV RptPeriod −U + RptPeriod −C − (Eq. L-22) 

Where: 

EPV-RptPeriod = Mass of fluorinated GHG f emitted from process vent v from production 

process i, for the reporting period, either monthly or annually, considering 

destruction efficiency (kg/month or kg/year). 
30 

ECFPV = Emission calculation factor for fluorinated GHG f emitted from process 

vent v during production process i (kg emitted/kg product). 

ActivityRptPeriod-U = Total process feed, process production, or other process activity during the 

reporting period for which the process vent is not vented to the destruction 

device (e.g., kg product). 

ActivityRptPeriod-C = Total process feed, process production, or other process activity during the 

reporting period for which the process vent is vented to the destruction 

device (e.g., kg product). 

DE = Demonstrated destruction efficiency of the destruction device (weight 

fraction). 

The fluorinated GHG emissions for all vents at the facility would be summed to obtain 

the total emissions from process vents for the facility as a whole. Equation L-23 would be used 

to sum fluorinated GHG emissions over all process vents for the process, and Equation L-24 

would sum the emissions from all processes. Other emission points at the facility such as 

equipment leaks, storage tanks, or wastewater would have to be accounted for separately and 

added in to the facility total. 

= ∑ −

v

EPfi EPV RptPeriod

1

 (Eq. L-23) 

Where: 

EPfi = Mass of fluorinated GHG f emitted from production process i, for the 

reporting period, either monthly or annually (kg). 

EPV-RptPeriod = Mass of fluorinated GHG f emitted from process vent v from production 

process i, for the reporting period, either monthly or annually, considering 

destruction efficiency (kg/month or kg/year). 

v = Number of process vents in production process i. 

= ∑

i

EP EPfi

1

 (Eq. L-24) 

Where: 

EP = Mass of fluorinated GHG f emitted from all processes at the facility, for 

the reporting period, either monthly or annually (kg). 

EPij = Mass of fluorinated GHG f emitted from production process i, for the 

reporting period, either monthly or annually (kg). 

i = Number of production processes i at the facility. 

3. Obtaining and Maintaining Representative Emission Factors 

Process conditions 
31 

Emission rates from a process depend on the operating conditions of that process. Thus, 

to ensure that emission factors are representative, facilities should define the operating scenario 

that encompasses the typical range of operating conditions for the process. If the process has 

multiple operating scenarios, the facility should develop a representative emissions factor for 

each operating scenario. To define the process operating scenario, a facility could include 

information on the process description and the specific process equipment used; the process 

vents, emission episodes and durations, and the quantity of uncontrolled fluorinated GHG 

emissions; the control device or destruction device used to control emissions; and the 

manifolding of process vents within the process and from other processes. Alternative operating 

scenarios should also be defined for differences in operating conditions that affect emissions. 

Examples of situations where process differences may warrant separate operating scenarios 

include the following: making small volumes of a product in one set of batch process equipment 

part of the year and making larger volumes in larger batch process equipment part of the year; 

use of two different types of catalyst in the same process; deliberate alterations in process 

conditions such as temperature or pressure to shift the reaction to a particular product; and 

making small volumes of a product in a batch process part of the year and making large volumes 

in a continuous process part of the year. A facility would need to develop a representative 

emissions factor for each process operating scenario because each operating scenario for a 

process will result in different emissions levels. 

Prior to developing an emissions factor, facilities should observe the operating conditions 

of the process over a period of time and note how changes to the operating conditions affect 

emissions rates. The time periods may vary from facility to facility and perhaps from process to 

process, but typically may include an examination period of one year or one month and could 

include examination of startup and shutdown periods. An examination of the previous year of 

process operating conditions might take note of whether there is month-to-month or seasonal 

variability in the process. For example, seasonal variability might be caused by production rate 

changes or might be caused by changes in the ambient temperature from summer to winter. An 

examination of one month of process operating conditions might reveal some short-term process 

variability. A review of startup and shutdown process operating conditions may include an 

assessment of how frequently startups and shutdowns occur, what effect startups and shutdowns 

have on emission rates, and whether or not the impact on emissions can be quantified. 

In general, emissions testing during process startups and shutdowns would not be 

expected to lead to representative emission factors, because emission rates tend to fluctuate 

during such events. Exceptions to this could include long-term monitoring that would not overrepresent startup or shutdown conditions in the resulting emission factor, and monitoring 

specifically to obtain emission factors for startups and shutdowns conditions. Several companies 

indicated that they have analyzed the emissions profile during startup events and during 

shutdown events. They found that the emission rates during these events departed from those at 

steady state conditions, but that emissions profiles were consistent between one startup event and 

another. 

Number of samples 

Emission samples should be taken over the full range of process conditions within a 

given operating scenario. To assess the variability of emission rates within the operating 
32 

scenario, a minimum of three emission test runs is appropriate. If the emission factors based on 

the three test runs show relatively little variability, i.e., if their relative standard deviation (RSD) 

is low, then the three sample emission factors can probably be averaged to obtain a robust, 

representative emission factor for the process. However, if the emission factors based on the 

three test runs show high variability, that is, a high RSD, then the average of the three emission 

factors may be a poor estimator of the actual mean emission rate from the process. In this case, 

additional samples should be taken to develop a robust emission factor.7 The equation to 

estimate the RSD is shown in Equation RSD-1. 

EF

s

RSD = (Eq. RSD-1) 

Where: 

RSD = Relative standard deviation, fraction 

s = sample standard deviation, calculated in Eq. RSD-2 

EFbar = average emission factor for all test runs combined 

Equation RSD-2 is used to estimate the sample standard deviation, s. 

( ) ( ) ( )

1

...

2

3

2

2

2

1

−

− + − + − +

=

n

EF EF EF EF EF EF

s (Eq. RSD-2) 

Where: 

s = sample standard deviation 

EFi = the individual emission factor value from test run 1, 2, 3, etc. 

EFbar = average emissions factor across all test runs (sample mean emission factor), 

calculated in Equation RSD-3 

n = number of test runs 

Eq. RSD-3 (which corresponds to equation L-15 in the regulatory text) is used to estimate 

the mean emissions factor, EFbar. 

n

EF EF EF EF ... 1 + 2 + 3 +

= (Eq. RSD-3) 

Where: 

 

7

 The fact that emission rates from a process show high variability does not mean that a representative emission 

factor cannot be developed; it simply means that more samples must be taken to do so. Note, however, that if the

variability of the process can be attributed to the variability of a controllable and measurable process parameter, it is 

probably appropriate to develop one or more additional operating scenarios, each with its own emission factor, to 

capture this variability. 
33 

EFbar = average emissions factor for all test runs combined (sample mean emission factor) 

EFi = the individual emission factor value from test run 1, 2, 3, etc. 

n = number of test runs 

In general, more samples are required to characterize the mean of a population or 

parameter that has high variability than are required for a population or parameter that has low 

variability. The number of samples required to estimate the mean of the parameter with a given 

level of confidence can be calculated based on the RSD of the samples and on some assumptions 

about the distribution of the parameter. Where the set of samples is relatively small and only the 

sample standard deviation “s” is known (rather than the true standard deviation of the 

parameter), the appropriate statistic is often the Student’s t test. The Student’s t test presumes an

approximately normal, bell-shaped distribution of the underlying parameter, which implies that 

the distribution of the average is the Student’s t distribution. 

For this situation, the Student’s t test can be written: 

( )

statistic CI

T

statistic CI t

n

s

EF EF

t

−95% < + −95%

























−

− < (Eq. RSD-4) 

Where: 

EFbar = Average emission factor across all test runs (sample mean emission factor) 

EFT = True mean emission factor of the process 

s = Sample standard deviation 

n = Number of samples 

tstatistic-95%CI = Value of student’s t statistic chosen to represent a 95-percent confidence 

interval with n-1 degrees of freedom. For a sample size of 3, this value is 

4.30. 

Dividing through by the sample mean emission factor, EFbar, we obtain: 

( )

statistic CI

T

statistic CI t

n

RSD

EF EF EF

t

95% 95%

/

− < + −

























−

− < (Eq. RSD-5) 

To choose a RSD above which we will require more than three samples, we first decide 

how much error we are willing to tolerate in our emission factor. Suppose we want the emission 

factor to have a 95 percent chance of being within 30 percent of the true mean emission rate of 

the process. The requirement for the emission factor to be within 30 percent of the true mean 

emission rate can be expressed as follows: 

((EF − EF /) EF) < 3.0 T (Eq. RSD-6) 
34 

Equation RSD-5 can also be rearranged as follows: 

( ) T statistic CI t

n

RSD EF EF EF 95%

( /) * − < −

 (Eq. RSD-7) 

Subtracting Equation RSD-7 from Equation RSD-6, we obtain: 

statistic CI t

n

RSD

95%

0 3.0 * < − −

Plugging in the values for t and n and solving for RSD, we obtain 

> RSD

4.3

3.0 * 3

12.0 > RSD

We conclude that if the RSD exceeds 0.12 (or12 percent), we should test more than three 

samples. Unfortunately, it may be difficult to obtain an RSD of less than 0.12 even when the 

real emission rate is nearly constant. This is because the error of the concentration 

measurements used in the testing can be near 10 percent. Thus, we might want to consider 

whether we can tolerate a somewhat higher error in our emission factor.8 If we require that the 

emission factor be within 40 percent of the true mean emission rate and solve the above 

equation, we arrive at the conclusion that we should test more if the RSD exceeds 0.16 (16 

percent). If we require that the emission factor be within 50 percent of the true mean emission 

rate (with 95-percent confidence) and solve the above equation, we arrive at the conclusion that 

we should test more if the RSD exceeds 0.20 (20 percent). 

With an additional three samples (n=6), the uncertainty of the emission factor declines 

significantly. For n = 6, Equation RSD-5 becomes: 

( ) 57.2

6

/

57.2 < +

























−

− <

RSD

EF EFT EF

Plugging an RSD of 0.20 (20 percent) into this equation, we find that after six samples, 

there is a 95 percent chance that the sample mean (emission factor) is within 21 percent of the 

true mean (average emission rate of the process). 

 

8

 Another approach to minimizing the error is to require more samples initially, e.g., 4 instead of 3. With 4 initial 

samples, the emission factor has a 95 percent chance of being within 30 percent of the true mean emission rate if the 

RSD is less than 19 percent. 
35 

4. Updates to emission factors and emission calculation factors.

The emission rate from a process is likely to change as the process evolves or is altered. 

Process changes that can affect the fluorinated GHG emission rate include changes in raw 

materials, equipment, production levels, or operating conditions. These changes can occur all at 

once or gradually, over time. Facilities that have measured and re-measured their emission 

factors over a period of several years have found that gradual, incremental changes to the process 

(e.g., to improve yields) have significantly changed emission factors9. To ensure that emission 

factors and emission calculation factors continue to accurately represent emission rates, they 

should be updated when significant process changes occur. In addition, it may be appropriate to 

update emission and emission calculation factors at regular intervals (e.g., five to ten years) to 

capture the cumulative impact of small changes to the process. 

5. Potential Process Vent Emission Threshold. 

In discussions with EPA, representatives of fluorinated gas producers stated that more 

effort and resources should be expended to accurately estimate the size of large emission streams 

than to estimate the size of small ones. Consistent with this principle, EPA evaluated process 

vent emissions cutoffs above which facilities would be required to conduct emissions testing to 

develop a site-specific emissions factor and below which facilities could conduct emissions 

calculations to develop a site-specific emissions factor. 

There are various rules for other types of emissions that have established emission cutoffs 

above and below which there are different control, monitoring, and reporting requirements. For 

example, there are process or process vent cutoffs in various NESHAP rules in 40 CFR part 63, 

such as subpart GGG for Pharmaceutical Manufacturing, subpart FFFF for Miscellaneous 

Organic NESHAP (MON), and subpart VVVVVV for Chemical Manufacturing Area Source 

rule. Because some producers mentioned the rule requirement cutoffs in subpart FFFF, 

Miscellaneous Organic NESHAP (MON), the initial step in the cutoff development was 

reviewing the 10,000 lb/yr (i.e., 5 ton/yr) of uncontrolled organic HAP emissions cutoff for 

process vents in that rule. (While these data and facility practices for the MON source category 

may not be completely analogous to the data and practices at fluorinated gas production 

facilities, this information was used to inform the reporting rule-making process.) Similar to the 

fluorinated gas production industry, the MON source category includes both continuous and 

batch processes. At the MON facilities, we looked at the emissions levels of MON process vents 

to identify the number of vents covered and the emissions covered by various cutoffs. For 

continuous processes, approximately 26 percent of process vents have emissions greater >10,000 

lb/yr and more than 99 percent of the total organic HAP emissions from continuous process 

vents occur from these vents. For batch processes, 13 percent of batch process vents have 

emissions >10,000 lb/yr and the organic HAP emissions from these vents are 96 percent of the 

total organic HAP emissions from batch process vents. The 10,000 lb/yr organic HAP cutoff for 

requiring control of the process vent in the MON rule provides a good balance for minimizing 

the number of process vents required to implement control and maximizing the emissions 

covered or captured by the rule. 

 

9 Based on conversations with Fluorinated GHG producers, as referenced in Section 7.
36 

In evaluating cutoffs for the process vents in the fluorinated gas production source 

category, we began by analyzing a 10,000 lb/yr fluorinated GHG uncontrolled emissions cutoff. 

Because the quantities of these emissions in terms of CO2e would vary significantly depending 

on the specific fluorinated GHG compound emitted and its GWP, we decided to evaluate the 

cutoff in terms of CO2e. We assumed an average GWP of approximately 2,000 for the 

fluorinated GHG, and given the cutoff value of 10,000 lb/yr fluorinated GHG, we developed a 

cutoff of 10,000 mt CO2e. Process vents above the 10,000 lb/yr limit would be required to 

conduct an emissions test to develop a site-specific emissions factor for the vent, and process 

vents below the 10,000 mt CO2e could develop a site-specific emissions calculation factor based 

on engineering calculations or engineering assessments. 

Depending on the specific fluorinated GHG emitted, the emissions of the fluorinated 

GHG in terms of the actual gas could vary significantly. In Table 4, the emissions in terms of 

the fluorinated compounds that are translated from the CO2e cutoff are shown. The fluorinated 

compounds are shown in order of increasing GWP. For example, for fluorinated GHG 

compounds as diverse as HFC-134a to SF6, the cutoff of 10,000 mt CO2e would translate into 

fluorinated GHG emissions ranging from 16,962 lb/yr to 923 lb/yr, respectively. However, the 

detection limits of fluorinated GHG are likely sufficiently low to allow detection and 

quantification of these compounds at these emission levels. 

Another potential approach for selecting a process vent cutoff might include a combined 

approach, i.e., meeting both a CO2e emissions cutoff and also a cutoff in terms of pounds of 

fluorinated GHG. For example, if a process vent had emissions less than 25,000 mt CO2e and 

also less than 10,000 lb of fluorinated GHG emissions, i.e., the process vent meets both criteria, 

then it would be considered below the cutoff. 

An issue related to setting a process vent cutoff based on CO2e is related to fluorinated 

GHGs that do not have published GWP. In this instance, a lower level cutoff could be 

established for those fluorinated GHG whose GWP does not appear in Table A-1 of 40 CFR part 

98subpart A compounds, for example, less than 1 metric ton for emissions that include a 

compound without GWP. 
37 

Table 4. Analysis of Process Vent Cutoffs: Translate Emissions from CO2e to Pounds of 

Fluorinated GHG, and vice versa.1

Vent limit in 

mtCO2e 

In pounds of fluorinated GHG: 

HFC-134a HFC-125 HFC-143a CF4 C2F6 NF3 SF6 

Convert CO2e vent cutoff to lb of fluorinated GHG 

25,000 42,404 * 19,688 * 14,507 * 8,481 5,992 3,205 2,306 

20,000 33,923 * 15,750 * 11,605 * 6,785 4,793 2,564 1,845 

10,000 16,962 * 7,875 5,803 3,392 2,397 1,282 923 

5,000 8,481 3,938 2,901 1,696 1,198 641 461 

Vent limit in 

pounds of 

fluorinated 

GHG 

In mtCO2e: 

HFC-134a HFC-125 HFC-143a CF4 C2F6 NF3 SF6 

Convert lb of fluorinated GHG to mt CO2e 

10,000 5,896 12,698 17,234 29,478 * 41,723 * 78,005 * 108,390 * 

5,000 2,948 6,349 8,617 14,739 20,862 39,002 54,195

1 The GWP for fluorinated GHG are HFC-134a is 1,300; HFC-125 is 2,800; HFC-143a is 3,800; CF4 is 6,500 C2F6 is 

9,200; NF3 is 17,200; and SF6 is 23,900. 

* denotes that the level exceeds a 10,000-lb cutoff (in top table) or a 10,000-mtCO2e cutoff (in bottom table). 

6. Process Vent Preliminary Emission Estimates. 

To determine whether a process vent is above or below the 10,000 mt CO2e threshold, 

facilities could use any of several emission estimation methods discussed above. In this 

preliminary step, it seems reasonable to allow use of engineering calculations or engineering 

assessments similar to those identified in Section 3.B.iii.2 to determine the emissions of 

fluorinated GHG from the process. Acceptable calculation methods for uncontrolled and 

controlled process vent emissions may include those from various rule text or guidance 

documents, such as the MON, Pharmaceutical, and other examples provided in Section 3.B.iii.2 

above. 

Engineering assessments are another reasonable approach to determining preliminary 

emissions from process vents. Engineering assessments include the types of information 

discussed in Section 3.B.iii.2 above (previous test data, bench-scale or pilot-scale test data, 

design analysis, etc.) Facilities typically have component and composition data available from 

the original research and development activities on the process and from the process’ lifetime of 

operation. For process vent emissions determinations, facilities could conduct an engineering 

assessment to calculate uncontrolled emissions for each process vent and for each emission 

episode. 

7. Current Plant Practices for Process Vent Monitoring 

Several facilities with fluorinated gas production processes have indicated that they 

conduct monitoring and analysis on individual process vents and that they characterize streams 

from processes. They typically develop facility-specific or process-specific EFs and track 

production activity data to estimate fluorinated GHG emissions. 

Facilities indicated that a variety of approaches are used to estimate fluorinated GHG 

emissions and develop process-specific emissions factors, including sampling and measurement 
38 

(i.e., direct testing) and chemical engineering calculations and estimates. At most facilities, a 

combination of these approaches is used to estimate fluorinated GHG emissions from the various 

process vents at the site. Some facilities indicated, for example, that facility staff measure the 

concentrations and flows for reactor vessel process vents and conduct engineering calculations to 

estimate concentration and flows from process dryers. Engineering calculations are based on 

common chemical engineering principles and empirically based data and process knowledge. 

The engineering calculations may also be based on emission estimation equations contained in 

rules, for example in the Pharmaceutical NESHAP, or may be conducted using purchased 

process modeling software packages, such as ASPEN and EmissionsCalculator. 

Facilities indicated that each of these approaches, emission testing and engineering 

calculations, are valid and produce reasonable fluorinated GHG emission estimates and that 

flexibility in which approach is applied to any particular process vent is appropriate. Facilities 

particularly noted that they match the level of effort and “rigorousness” in the emissions 

determination approach with the emissions source size. That is, they devote more effort to 

characterizing emissions from relatively large fluorinated GHG emissions points, pursuing 

emissions testing for these sources, and less effort to characterizing emissions from relatively 

small fluorinated GHG emissions points, applying engineering calculations to these sources. 

Some facilities noted that certain process vents are not measured directly because the emission 

stream contains a compound that is hazardous for plant and personnel safety, e.g., if HF is 

present in a stream. The facilities noted that emission points that are not safe to measure are 

typically estimated from chemical engineering calculations and from process design data. In 

using FTIR instruments, some vendors have noted that specialty glass sample cells are available 

that are more resistant to HF. Some facilities noted that measuring fluorinated organics can be 

done easily if the HF can be removed from the sampling stream. One option may be to flow the 

sample stream through containers of water to remove HF prior to measuring the fluorinated 

organic. While this approach may be successful at measuring the fluorinated organic, the flow 

rate of the stream cannot be determined with any accuracy. This approach also does not alleviate 

the personnel safety concerns. 

Facilities further expanded on the use of previous stream analysis results as appropriate 

data to be used. Generally, facilities have a good understanding of the chemistry for all 

processes and understand what raw materials are fed to the process, what side reactions occur, 

and what products and by-products are created. Facilities have laboratory scale, pilot plant, and 

full scale streams analysis results. Facilities noted that in particular, at the bench-scale phase of a 

product and process development, they analyze all streams to identify all species and compounds 

such as product, byproducts, and waste. The process design from when the process was 

originally developed and built is detailed, and more recently installed processes will have 

excellent design and chemistry documentation available. Older processes may tend to have less 

detail. 

Facilities indicated that they typically conduct an initial analysis to develop the processspecific emission factor or emission calculation factor and do not continuously measure and 

calculate emissions from process vents and streams. When there is a process change, i.e., a 

change in the operating conditions or a change in the process equipment used, they will conduct 

a reanalysis of the process. Facilities pointed out that prior to making process change, they 

analyze the theoretical chemistry and predict the likely changes in the set of fluorinated GHG 
39 

compounds generated and in the fluorinated GHG emissions levels. They typically begin with 

engineering calculations to determine the impacts of the change on species generated or emission 

levels, and follow that with retesting and recalculations when appropriate. Some facilities noted 

that after a process change, they will sample and analyze to identify every species or compound 

generated, in either process vents or process streams. 

8. Potential use of continuous emissions monitors to measure emissions from vents. 

Another potential monitoring option EPA considered was requiring that facilities measure 

emissions from fluorinated gas production facilities using continuous emissions monitors 

(CEMS). If properly selected and maintained, CEMS would be expected to provide estimates of 

emissions more accurate than either the mass-balance or the process-vent approach. Under this 

approach, facilities would install and operate CEMS capable of measuring fluorinated GHGs to 

measure process emissions. The requirements for the CEMs would be similar to those in subpart 

C, adjusted, as appropriate, to accommodate CEMS for fluorinated gases. One possible option is 

to use Fourier Transform Infrared Spectrometers (FTIRs) CEMS in scrubber stacks to measure 

emissions. FTIR spectroscopy is presently used to conduct short-term fluorinated GHG emission 

measurements from processes. In recent discussions with FTIR CEMS vendors, they noted that 

the units can operate continuously. Some units require liquid nitrogen cooling and the liquid 

nitrogen vessel (dewar) has a limited capacity. These nitrogen cooled units can operate for up to 

12 hours on a single charge (nitrogen), and continuous operation of the unit could be achieved 

through the use of an extended dewar with an automated fill cycle. With the extended dewar, the 

unit can operate for approximately 3 days. (The detector is nitrogen cooled, and a dewar, which 

is an insulated container with a vacuum between its inner and outer layers, is used to hold the 

liquid nitrogen.) FTIR CEMS vendors noted that the sample cell can be adjusted to 

accommodate concentration levels, where a shorter cell length can be used for higher 

concentrations and longer cell lengths can be used for lower concentrations. Another option for 

high concentrations might include use of dilution and a standard cell. The vendor typically sets 

up a software package based on the compounds expected in the measured vent, and the software 

is revised for other compounds as needed. 

However, potential drawbacks to requiring CEMS are that they would be relatively 

expensive to install and they may not tolerate the acidic and reactive environments (e.g., high HF 

concentration) found in vents at many fluorinated gas production facilities. Some FTIR CEMS 

vendors utilize specially configured gas cells that run hot and utilize mirror coatings to protect 

the cell from high HF concentrations and use special types of unit seals (o-rings) that are inert to 

corrosive compounds. In any case, vendors noted that HF in the vent streams is a common 

problem, and that HF concentrations in the percent range are a difficult issue to deal with. The 

latter concern might be mitigated by installing CEMS after a scrubber, if this is practicable. 

Given these potential concerns, it may be appropriate to require CEMS for particularly large 

emission streams, e.g., those resulting in emissions of more than 50,000 mtCO2e annually. 

9. Equipment Leak Emissions Estimates. 

Process vents are only one of several sources of fluorinated GHG emissions at fluorinated 

gas production facilities. Another potentially significant source is equipment leaks, whose 

emissions do not occur through process vents. Emissions from equipment leaks may be 

estimated using EPA Method 21 and the Protocol for Equipment Leak Estimates (EPA-453/R-
40 

95-017). Leak monitoring could be performed periodically, which typically would be quarterly, 

semi-annually, or annually. Due to the nature and scope of the reporting rule, which is focused 

on monitoring and emission estimation rather than on leak repair (control), equipment leak 

monitoring on an annual basis should be sufficient.

The Protocol includes four methods for estimating equipment leaks. These are, from 

least to most accurate, the Average Emission Factor Approach, the Screening Ranges Approach, 

EPA Correlation Approach, and the Unit-Specific Correlation Approach. The Average Emission 

Factor Approach relies on emission factors and equipment counts, the service of each 

component, the composition of the stream, and the length of time the equipment was in service to 

estimate emissions, and does not require any real-world data be collected from the processes. 

The remaining three methods, The Screening Ranges Approach, EPA Correlation Approach and 

the Unit-Specific Correlation Approach all depend on the collection and use of facility-specific 

and process-specific screening data to estimate emissions. The greater accuracy of these three 

methods compared to the Average Emission Factor Approach will provide a more realistic 

estimation of the actual fluorinated GHG emissions at a facility. 

To use these three screening data methods, the facility would need to have (or develop) 

Response Factors relating concentrations of the target fluorinated GHG (or surrogate gas cooccurring in the stream) to concentrations of the gas with which the leak detector is calibrated. 

Our understanding is that flame ionization detectors (FIDs) are generally insensitive to 

fluorinated GHGs, and that they are therefore not likely to be effective for detecting and 

quantifying fluorinated GHG leaks. An exception to this would be a situation in which the 

fluorinated GHG occurred in a stream along with a substance (e.g, a hydrocarbon) to which the 

FID was sensitive; in this case, the other substance could be used as a surrogate to quantify leaks 

from the stream. We understand that at least two fluorocarbon producers currently use methods 

in the Protocol to quantify their emissions of fluorinated GHGs with different levels of accuracy 

and precision. Other analytical techniques that are sensitive to fluorinated compounds may be 

available to monitor concentrations of equipment leaks, including photoionization, ultraviolet, 

infrared, and others. 

A preliminary review revealed a handful of detectors capable of detecting fluorinated 

GHGs. These detectors use various operating principles, including, infrared, photoionization and 

ultraviolet detection. One issue that arose with these detectors was their high sensitivity. For 

some of the equipment, maximum readings were well below the 10,000 ppm leak/no-leak 

threshold of the Screening Ranges Approach, meaning that the Screening Ranges Approach 

could not be used with these detectors. Those capable of reading the 10,000 ppm concentration 

had sampling rates that exceeded the rates established by Method 21. However, the EPA 

Correlation Approach and the Unit-Specific Correlation Approach could be used with these 

detectors, assuming that the detectors do not hit their maximum readings (peg) in the facility. 

Another approach for monitoring leaks from pieces of equipment may include use of the 

Alternative Work Practice (AWP) for EPA Method 21 (similar to monitoring requirements under 

40 CFR part 60, subpart A, §40 CFR part 60.18; 40 CFR part 63, subpart A, §40 CFR part 63.11; 

or 40 CFR part 65, subpart A, §40 CFR part 65.7). This approach would include monitoring 

leaking equipment with an optical gas imaging instrument. Emissions from those pieces of 

equipment found to be leaking could be estimated based on emission factors. Under this 
41 

approach, facilities could image each piece of equipment in fluorinated GHG service, and all 

emissions imaged by the optical gas imaging instrument would be considered leaks and would be 

subject to emissions estimation. 

10. Destruction Efficiency Testing 

EPA is considering a requirement that fluorinated gas producers that destroy F-GHGs 

conduct emissions testing periodically, for example every five years, to determine the destruction 

efficiency (DE) of the destruction device. The testing for determining the DE would be similar 

to the emissions testing that could be conducted to develop process-specific emission factors. 

Facilities would need to conduct testing that shows the destruction device can successfully 

destroy emissions at worse-case operating conditions, for example when operating at high loads 

reasonably expected to occur and when destroying the most-difficult-to-destroy fluorinated GHG 

fed into the device (or when destroying a surrogate that was more difficult to destroy than that 

fluorinated GHG). The last point is particularly important because some fluorinated GHGs (e.g., 

CF4 and SF6

10) are extremely difficult to destroy; DEs determined for other fluorinated GHGs 

would overestimate the destruction of these fluorinated GHGs. 

For destruction of fluorinated GHG compounds to occur, temperatures must be quite 

high, fuel must be provided, flow rates of fuels and air (or oxygen) must be kept above certain 

limits, flow rates of fluorinated GHG must be kept below others, and for some particularly 

difficult-to-destroy chemicals such as CF4, pure oxygen must sometimes be fed into the process. 

If one or more of these process requirements is not met, destruction efficiencies can drop sharply 

(in some cases, by an order of magnitude or more), and fluorinated GHGs will simply be 

exhausted from the device. For more discussion of this issue, see the Technical Support 

Document for Industrial Gas Supply: Production, Transformation, and Destruction of Fluorinated 

GHGs and N2O, Docket number EPA-HQ-OAR-2008-0508-041. 

EPA is considering use of emissions test data on the destruction device that has been 

conducted within the five years prior to the effective date of the rule. Facilities that have 

conducted an emissions test on their destruction device within the five years prior to the effective 

date of the rule may be allowed to use the DE determined during that test if the test was 

conducted in accordance with the proposed test requirements. Facilities could also potentially 

use the DREs determined during principal organic hazardous constituent testing and hazardous 

waste combustor testing, provided those tests determined the DRE based on the most-difficultto-destroy fluorinated GHG fed into the device (or based on a surrogate that was more difficult to 

destroy than the most-difficult-to-destroy fluorinated GHG). 

C. Other Potentially Significant Emission Points 

In addition to the fluorinated GHG emissions captured via the Mass Balance method or 

either of the Process Vent methods, other potentially significant emission points exist both 

upstream and downstream of the production measurement. These other emission points under 

this source category may include fluorinated GHG emissions from equipment leaks, storage 

tanks, wastewater, container filling (loading), refrigerant blending, reclamation and recycling 

 

10 For example, SF6 ranks 4th in the Class 1 incinerability rankings of the Office of Research and Development and 

Office of Solid Waste and Emergency Response of U.S. Environmental Protection Agency’s Guidance on Setting 

Permit Conditions and Reporting Trial Burn Results Handbook, Volume II. 
42 

processes, and heel evacuation, particularly where these emissions occur before the production 

measurement at fluorinated GHG production facilities. (Equipment leak emissions are discussed 

above in a separate section.) 

Fluorinated GHG emissions from wastewater will depend directly on the concentration 

and volume of the contaminants that are present in the wastewater. Based on an evaluation using 

EPA’s Estimation Program Interface (EPI) Suite, approximately 90 percent or more of all 

fluorinated GHG compounds present in wastewater will be emitted to the atmosphere. The 

operating permits for some facilities referred to wastewater treatment activities for fluorinated 

compounds, although it is unclear what level of emissions might occur from wastewater and 

whether there would be wastewater emissions at all facilities. 

Emissions from returned containers and from recycling depend heavily on the practices 

of individual facilities. If the facility recovers container heels or simply refills containers on top 

of heels, then emissions from returned containers will be small. However, if the facility vents 

heels, then emissions can be significant, even dominating overall facility emission rates. 

According to the 2006 IPCC Guidelines 11, SF6 production operations in Germany whose 

customers did not require highly purified gas had emission rates in the range of 0.2 percent of the 

total quantity of SF6 produced. On the other hand, SF6 production operations in Japan whose 

customers required highly purified gas had emission rates of 8 percent due to the venting of heels 

whose purity was in doubt. 

The situation is similar for recycling. Emissions during recycling include emissions 

during transfer of gas from containers to process equipment, but they also include emissions 

associated with ridding the gas of contaminants, such as noncondensables (air, nitrogen, etc.) and 

oil. (Since lubricants are chosen to be miscible with refrigerants, a significant quantity of 

refrigerant can remain mixed into the oil when the oil is removed from the system or container.) 

If facilities carefully recover and purify gas that is returned for recycling, emissions are likely to

be in the neighborhood of one percent or less of the quantities returned.12 However, if facilities 

use crude methods to purge noncondensables from containers, e.g., venting from the headspace 

of the cylinder, or if they don’t attempt to minimize fluorinated GHG emissions from lubricants, 

then emissions can be closer to five or ten percent of the quantities returned. (Early standards for 

recycling equipment allowed emissions from purging as high as five percent;13 these limits have 

been lowered considerably since.) In the worst case, facilities could simply vent returned 

fluorinated GHGs, e.g., in cases where they are irretrievably contaminated. 

The fluorinated GHG emissions from storage tanks are anticipated to be small to 

insignificant due to the use of pressurized tanks for storage. Emissions from blending activities 

are also likely to be relatively small. In both cases, however, emissions can be more significant 

if leaks or catastrophic failures occur. 

 

11 From IPCC 2006, 2006 IPCC Guidelines for National Greenhouse Gas Inventories, Prepared by the National 

Greenhouse Gas Inventories Programme, Eggleston H.S., Buendia L., Miwa K., Ngara T. and Tanabe K. (eds). 

Published: IGES, Japan., page 3,104 of Volume 3, Industrial Processes and Product Use. 

12 From IPCC Volume 3, Chapter 8. http://www.ipccnggip.iges.or.jp/public/2006gl/pdf/3_Volume3/V3_8_Ch8_Other_Product.pdf 

13 SAE J1990, 1989 Extraction and Recycle Equipment for Mobile Automotive Air-Conditioning Systems; ARI 

Standard 740-1993, For Performance of Refrigerant Recovery and/or Recycling Equipment. 
43 

Currently, it is EPA’s understanding that most fluorinated GHG production facilities 

measure their production before container filling (loading), e.g., by using flowmeters just 

upstream of the container connection to measure the mass flowing into the containers. If this is 

the case, emissions that occur during or after filling (e.g., from hoses and connections) would 

have been included in the production (supply) measurement. However, if production is 

measured by weighing containers before and after filling, then emissions during container filling 

would not have been included in the production measurement. In these cases, facilities using the 

emission factor approach would need to quantify container filling emissions for completeness. 

The IPCC Guidelines (Volume 3, Chapter 7) estimate that emissions related to container 

management (including refrigerant transfers between containers and handling of returned 

containers) range between 2 and 10 percent of the refrigerant market. 

In the event that the other potentially significant emission points were included under the 

rule, possible methods for tracking these emissions include engineering estimates (e.g., for 

container filling), equipment leak testing (e.g., for storage tanks and blending activities), default 

or site-specific emission factors (all sources), and mass balances (e.g., weighing returned 

container heels). For example, site-specific, gas-specific default factors could be developed for 

container heels based on measurements of these heels over some period of time. This approach 

could be similar to the approach for quantifying container heels in proposed subpart I (the 

proposed rule for monitoring emissions of fluorinated GHG emissions from electronics 

manufacturing). 

4. Procedures for Estimating Missing Data 

In the event that a scale or flowmeter normally used to measure reactants, products, byproducts, or wastes fails to meet a test to verify its accuracy or precision, malfunctions, or is 

rendered inoperable, facilities may estimate these quantities using other measurements where 

these data are available. For example, facilities that ordinarily measure production by metering 

the flow into the day tank could use the weight of product charged into shipping containers for 

sale and distribution as a substitute. It is our understanding that the types of flowmeters and 

scales used to measure fluorocarbon production (e.g., Coriolis meters) are generally quite 

reliable, and therefore that it should rarely be necessary to rely solely on secondary production 

measurements. In general, production facilities rely on accurate monitoring and reporting of the 

inputs and outputs of the production process. In the event that a secondary mass measurement 

for the stream is not available, producers can use a related parameter and the historical 

relationship between the related parameter and the missing parameter to estimate the flow. 

If concentration measurements are unavailable for some period, we are proposing that the 

facility use the average of the concentration measurements from just before and just after the 

period of missing data. 

5. QA/QC Requirements 

Typical QA/QC requirements for measuring devices include initial and periodic 

verification and calibration. (For example, see the requirements of EPA’s Acid Rain regulations 

at 40 CFR Part 75.) In this case, it may be appropriate to require an initial verification of 

flowmeters and weigh scales and periodic calibration in accordance with the applicable industry 
44 

standards or manufacturer directions. If the flowmeter manufacturer performed this verification 

at the flowmeter factory and did not recommend a second verification upon installation, the 

factory verification should suffice. Calibration of flowmeters and scales could be performed 

prior to the reporting year; after the initial calibration, recalibration could be performed as 

frequently as specified by the manufacturer. Under this approach, producers could perform the 

verification and calibration of their weigh scales during routine product line maintenance. 

For the gas chromatography analytical method described under the monitoring section of 

this document, monthly calibration, using known certified standards should be used. The 

calibration involves validating accurate measurement of these fluorocarbon standards across a 

range of possible concentrations, depending on which process streams are being measured. 

For development of process-vent-specific emission factors, facilities would need to 

conduct and meet the QA/QC procedures specified in the test methods used. 

6. Reporting and Recordkeeping Procedures 

To verify and document their emissions estimates, owners and operators of facilities 

producing fluorinated gases would be required to report the following information, depending on 

their activities and on the estimation approach that they used. All facilities would be required to 

report both their fluorinated GHG emissions and the quantities used to estimate them on a 

process-specific basis. They would also be required to report the results of each scoping test, 

specifically, the chemical identities of the contents of potentially emitted streams. Facilities 

using the mass-balance approach would report the masses of the reactants, products, by-products, 

and wastes, and, if applicable, the quantities of any product in the by-products and/or wastes (if 

that product is emitted at the facility). They would also report the chemical identities of 

reactants, products, and by-products, along with the chemical equations used to estimate 

emissions. Facilities using the emission factor approach would report the activity data used to 

calculate emissions (e.g., the quantity produced, transformed, or destroyed) and the emission 

factors used to estimate them. Owners and operators would be required to report annual totals of 

these quantities by process and facility. 

Where fluorinated GHG production facilities have estimated missing data, the facility 

would be required to report the reason the data were missing, the length of time the data were 

missing, the method used to estimate the missing data, and the estimates of those data. 

Maintaining records of the information used to determine the reported GHG emissions 

would enable us to verify that the GHG emissions monitoring and calculations were performed 

correctly. Owners and operators of facilities producing fluorinated GHGs would be required to 

retain records documenting the data reported, including records of monthly emission estimation 

calculations, all data that went in to the calculations, calibration records for flowmeters, scales, 

and gas chromatographs, and documentation of emission factor development activities. 

7. References 

3M 2009. Meeting Documentation for Telephone Calls on October 9 and November 12, 2009 

with 3M Representatives Regarding Fluorinated Gas Production. U.S. Environmental Protection 

Agency. 
45 

Air Products 2009. Meeting Documentation for 17 November 2009 Telephone Call with Air 

Products Representatives Regarding Fluorinated Gas Production. RTI International. 

Arkema 2009. Meeting Documentation for Various Telephone Calls During Week of 7 October 

2009 with Arkema Representatives Regarding Fluorinated Gas Production. U.S. Environmental 

Protection Agency. 

DuPont 2009. Meeting Documentation for 13 November 2009 Telephone Call with DuPont 

Fluoropolymer Representatives Regarding Fluorinated Gas Production. RTI International. 

INEOS Fluor 2009. Meeting Documentation for October 2009 Telephone Calls with INEOS 

Fluor Representatives Regarding Fluorinated Gas Production. RTI International. 

3M Site Visit 2009. Documentation for October 2009 Site Visit to 3M Cordova, Illinois 

Regarding Fluorinated Gas Production. RTI International. 

DuPont Site Visit 2009. Documentation for October 2009 Site Visit to DuPont Corpus Christi, 

Texas Regarding Fluorinated Gas Production. RTI International. 

Centre Interprofessionnel Technique d’Etudes de la Pollution Atmospherique. Inventaire Des 

Emissions De Gaz A Effect De Serre En France Au Titre de la Convention Cadre Des Nations 

Unies Dur Les Changements Climatiques. Mars 2009. 

http://unfccc.int/files/national_reports/annex_i_ghg_inventories/national_inventories_submission

s/application/zip/fra_2009_nir_7apr.zip 

Daniela Romano, Chiara Arcarese, Antonella Bernetti, Antonio Caputo, Rocío D. Cóndor, Mario 

Contaldi, Riccardo De Lauretis, Eleonora Di Cristofaro, Sandro Federici, Andrea Gagna, Barbara 

Gonella, Riccardo Liburdi, Ernesto Taurino, Marina Vitullo. ISPRA - Institute for 

Environmental Protection and Research. Italian Greenhouse Gas Inventory 1990-2007. National 

Inventory Report, 2009. 

http://unfccc.int/files/national_reports/annex_i_ghg_inventories/national_inventories_submission

s/application/zip/ita_2009_nir_15apr.zip

EPA Office of Research and Development and Office of Solid Waste and Emergency Response 

of U.S. Environmental Protection Agency. Guidance on Setting Permit Conditions and Reporting 

Trial Burn Results Handbook, Volume II. January 1989. 

http://www.epa.gov/nrmrl/pubs/625689019/625689019.pdf

EPA Office of Pollution Prevention Toxics and Syracuse Research Corporation (SRC). EPI Suite 

Version 4.00 January 2009. http://www.epa.gov/oppt/exposure/pubs/episuite.htm

Flemish Environment Agency, Flemish Institute for Technological Research, Walloon Public 

Service, Brussels Institute for the Management of the Environment, Interregional Cell for the 

Environment, ECONOTEC. Belgium’s Greenhouse Gas Inventory (1990-2007). April 2009. 

http://unfccc.int/files/national_reports/annex_i_ghg_inventories/national_inventories_submission

s/application/zip/bel_2009_nir_15apr.zip
46 

IPCC 2006, 2006 IPCC Guidelines for National Greenhouse Gas Inventories, Prepared by the 

National Greenhouse Gas Inventories Programme, Eggleston H.S., Buendia L., Miwa K., Ngara 

T. and Tanabe K. (eds). Published: IGES, Japan. Chapters 3, 6, 7 and 8. http://www.ipccnggip.iges.or.jp/public/2006gl/vol3.html 

IPCC 2006, 2006 IPCC Guidelines for National Greenhouse Gas Inventories, Prepared by the 

National Greenhouse Gas Inventories Programme, Eggleston H.S., Buendia L., Miwa K., Ngara 

T. and Tanabe K. (eds). Published: IGES, Japan. http://www.ipccnggip.iges.or.jp/public/2006gl/index.html

U.S. Environmental Protection Agency (EPA). Emission Inventory Improvement Program 

Volume II: Chapter 16. Methods for Estimating Air Emissions From Chemical Manufacturing 

Facilities. August 2007. www.epa.gov/ttn/chief/eiip/techreport/volume02/ii16_aug2007final.pdf

U.S. Environmental Protection Agency (EPA) Office of Air and Radiation and Office of 

Atmospheric Programs, Climate Change Division. Protocol for Measuring Destruction or 

Removal Efficiency (DRE) of Fluorinated Greenhouse Gas Abatement Equipment in Electronics 

Manufacturing. March 2010. 

U.S. Environmental Protection Agency (EPA) Office of Air Quality Planning and Standards. 

Protocol for Equipment Leak Emission Estimates. EPA-453/R-95-017. November 1995. 

www.epa.gov/ttnchie1/efdocs/equiplks.pdf

U.S. Environmental Protection Agency (EPA). Eli Lilly and Company, Airtech Environmental 

Services Inc.. Tracer Gas Protocol for the Determination of Volumetric Flow Rate Through the 

Ring Pipe of the Xact Multi-Metals Monitoring System. September 2006. 

www.epa.gov/ttnemc01/prelim/otm24.pdf

U.S. Environmental Protection Agency (EPA). Emission Measurement Center Approved 

Alternate Method (ALT-012)- An Alternate Procedure for Stack Gas Volumetric Flow Rate 

Determination (Tracer Gas). http://www.epa.gov/ttn/emc/approalt/alt-012.pdf

U.S. Environmental Protection Agency (EPA). Method 1- Sample and Velocity Traverses for 

Stationary Sources. http://www.epa.gov/ttnemc01/promgate/m-01.pdf

U.S. Environmental Protection Agency (EPA). Method 18 – Measurement of Gaseous Organic 

Compound Emissions by Gas Chromatography. http://www.epa.gov/ttnemc01/promgate/m18.pdf

U.S. Environmental Protection Agency (EPA). Method 205 - Verification of Gas Dilution 

Systems for Field Instrument Calibrations http://www.epa.gov/ttnemc01/promgate/m-205.pdf

U.S. Environmental Protection Agency (EPA). Method 21 – Determination of Volatile Organic 

Compound Leaks. http://www.epa.gov/ttnemc01/promgate/m-21.pdf

U.S. Environmental Protection Agency (EPA). Method 2A – Direct Measurement of Gas 

Volume Through Pipes and Small Ducts. http://www.epa.gov/ttnemc01/promgate/m-02a.pdf
47 

U.S. Environmental Protection Agency (EPA). Method 2B- Determination of Exhaust Gas 

Volume Flow Rate from Gasoline Vapor Incinerators. 

http://www.epa.gov/ttnemc01/promgate/m-02b.pdf

U.S. Environmental Protection Agency (EPA). Method 2C- Determination of Gas Velocity and 

Volumetric Flow Rate in Small Stacks or Ducts (Standard Pitot Tube) 

http://www.epa.gov/ttnemc01/promgate/m-02c.pdf

U.S. Environmental Protection Agency (EPA). Method 2D – Measurement of Gas Volume Flow 

Rates in Small Pipes and Ducts. http://www.epa.gov/ttnemc01/promgate/m-02d.pdf

U.S. Environmental Protection Agency (EPA). Method 2F- Determination of Stack Gas 

Velocity and Volumetric Flow Rate With Three-Dimensional Probes. 

http://www.epa.gov/ttnemc01/promgate/Methd2F.pdf

U.S. Environmental Protection Agency (EPA). Method 2G- Determination of Stack Gas Velocity 

and Volumetric Flow Rate With Two-Dimensional Probes. 

http://www.epa.gov/ttnemc01/promgate/Methd2G.pdf

U.S. Environmental Protection Agency (EPA). Method 301--Field Validation of Pollutant 

Measurement Methods from Various Waste Media. http://www.epa.gov/ttnemc01/promgate/m301.pdf

U.S. Environmental Protection Agency (EPA). Method 3B- Gas Analysis for the Determination 

of Emission Rate Correction Factor or Excess Air. http://www.epa.gov/ttnemc01/promgate/m03b.pdf

U.S. Environmental Protection Agency (EPA). Method 3-Gas Analysis for the Determination of 

Dry Molecular Weight. http://www.epa.gov/ttnemc01/promgate/m-03.pdf 

U.S. Environmental Protection Agency (EPA). Method 4 – Determination of Moisture Content 

in Stack Gases. http://www.epa.gov/ttnemc01/promgate/m-04.pdf

U.S. Environmental Protection Agency (EPA). Test Method 320- Measurement of Vapor Phase 

Organic and Inorganic Emissions by Extractive Fourier Transform Infrared (FTIR) 

Spectroscopy. http://www.epa.gov/ttnemc01/promgate/m-320.pdf

U.S. Environmental Protection Agency Center for Environmental Research Information, Office 

of Research and Development. Compendium Method TO-15- Determination Of Volatile 

Organic Compounds (VOCs) In Air Collected In Specially-Prepared Canisters and Analyzed By 

Gas Chromatography/ Mass Spectrometry (GC/MS). January 1999. 

www.epa.gov/ttnamti1/files/ambient/airtox/to-15r.pdf

U.S. Environmental Protection Agency Office of Air and Radiation. Technical Support 

Document for Emissions From Production of Fluorinated GHGs: Proposed Rule for Mandatory 

Reporting of Greenhouse Gas. February 2, 2009.