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R Incorporated Providing Environmental Technical Support Since 1989

501 Eastowne Drive, Suite 325 y Chapel Hill, North Carolina 27514 Telephone: (919) 484-0222 y Fax: (919) 484-0122 MEMORANDUM

DATE: February 4, 2010

SUBJECT: Draft MACT Floor and MACT De termination for Existing Stationary NonEmergency CI RICE Greater Than or Equa l to 100 HP Located at Major Sources

FROM: Bradley Nelson and Tanya Parise, EC/R, Inc.

TO: Melanie King, EPA OAQPS/SPPD/ESG

1.0 PURPOSE

The purpose of this memorandum is to document the analysis of the maximum achievable control technology (MACT) floor a nd MACT for existing stationary non-emergency compression ignition (CI) reciprocating internal combustion engines (RIC E) greater than or equal to 100 horsepower (HP) located at major s ources that are subject to the National Emission Standards for Hazardous Air Pollutants (NESHAP).

The MACT analysis for existing stationary non-emergency CI engines less than 100 HP and existing stationary emergency and black start CI engines at major sources, and the Generally Achievable Control Technology analysis for exis ting stationary CI e ngines located at area sources of hazardous air pollutants (HAP) emissi ons are presented in a separate memorandum titled “MACT Floor Determination for Existing St ationary Non-Emergency CI RICE Less Than 100 HP and Existing Stationary Emergency CI RI CE Located at Major Sources and GACT for Existing Stationary CI RICE Located at Area So urces,” which is available in the rulemaking docket (Docket No. EPA-HQ-OAR-2008-0708). A “major source” means generally any stationary source or group of stationary sources located with in a contiguous area and under

common control that emits or has the potential to emit considering controls, in the aggregate, 10 tons per year or more of any hazardous air po llutant or 25 tons per year or more of any

combination of HAP.

2.0 INTRODUCTION

The EPA has developed a regulation affecting existing stationary CI RICE located at major sources that will address toxic air emissi ons from these engines. The regulation was developed following criteria set forth under se ction 112 of the Clean Air Act (CAA). The MACT floor for existing sources must be no less stringent than the average emission limitation achieved by the best performing 12 percent of ex isting sources for which the Administrator has2 emissions information. 1 The MACT standards must be no le ss stringent than the MACT floor.

EPA must also determine whether to control emi ssions “beyond-the-floor, ” after considering the costs, non-air quality health and environmental im pacts, and energy requirements of such more stringent control. The EPA has previously issu ed a similar regulation affecting existing and new stationary RICE greater than 500 HP at major sources, which was promulgated in 2004 and for new stationary RICE less than or equal to 500 HP at major sources, which was promulgated in

2008.

Section 112 of the CAA allows the EPA to establish subcategories among a group of sources. A complete discussion of the subcat egory selection is presented in a separate

memorandum 2 which can also be found in the rulemaking docket.

3.0 MACT FLOOR AND MACT DETERMINATION

General Approach

The MACT floor for existing stationary RICE must be no less stringent than the average emission limitation achieved by the best performi ng 12 percent of existing sources for which the

Administrator has emissions information. In the proposed rule, EPA established the MACT floor for each subcategory of stationary existing CI engines using the emissions data that EPA had for stationary CI engines, which consiste d of testing conducted by EPA and industry at Colorado State University (CSU) on a 1,000 HP CI engine. During the comment period, EPA

received five additional test re ports that included emission results for 13 existing stationary CI engines ranging from 160 HP to 3,570 HP. These ne w test data along with the test data from the CSU testing were used to determine the MACT fl oor for each of the subcategories. A summary of the average test results for each of the engine s is presented in Appendix A. The test reports

for the test data used to determine the MACT fl oor are provided in the Docket as Document ID Nos. EPA-HQ-OAR-2002-0059-0018 a nd EPA-HQ-OAR-2008-0708-0272 through 0275.

EPA has previously conducted an analysis for the RICE NESHAP for engines greater than 500 HP at major sources, which investigated whether carbon monoxide (CO) could be used as a surrogate for HAP from stationary engines. The conclusion of the anal ysis was that CO is a reasonable surrogate for formaldehyde for CI engi nes, and that formaldehyde is a reasonable surrogate for HAP for CI engines. 3 To determine the MACT floor for each of the subcategories, EPA used the following methodology: (1) we ra nked the average emissions from each engine from lowest to highest; (2) we determined th e units in the MACT floor; (3) we assessed variability. The MACT floor a nd MACT determination for each subcategory is described below and is summarized in Table 1. A summary of the te st data that was used to set the MACT floor is presented in Appendix B.

1 Note there are more than 30 engines in each subcategory

2 Memorandum from Bradley Nelson and Tanya Parise, EC/R Inc. to Melanie King, EPA OAQPS/SPPD/ESG, Subcategorization of Existing Stationary CI RICE, January 29, 2010.

3 Memorandum from Melanie Taylor and Jennifer Snyder, Alpha-Gamma Technologies to Sims Roy, EPA OAQPS ESD Combustion Group, CO Removal Efficiency as a Surr ogate for HAP Removal Effi ciency, January 7, 2004 (EPA-HQ-OAR-2002-0059-0665.)3 Table 1. Summary of Determination for Existing Stationary Non-Emergency CI RICE ≥ 100 HP Located at Major Sources

Subcategory MACT Floor MACT

Non-Emergency CI

100 ≤ HP ≤ 300 230 ppmvd CO @15% O 2 230 ppmvd CO @15% O 2

Non-Emergency CI

300<HP ≤ 500 137 ppmvd CO @15% O 2 49 ppmvd CO @15% O 2

or 70% CO reduction

Non-Emergency CI

>500 HP 38 ppmvd CO @15% O 2 23 ppmvd CO @15% O 2

or 70% CO reduction

Non-Emergency CI 100 ≤ HP ≤ 300

EPA has test data for two engines in this s ubcategory; therefore, the best performing 12 percent of sources in this subcategory is repres ented by a single engine. The MACT floor engine

was tested for three runs. To account for variab ility, EPA used the highest individual run to

establish the MACT floor. As shown in Appendix B, the resulting MACT floor for nonemergency CI engines between 100 and 300 HP is 230 parts per million by volume, dry basis (ppmvd) of CO at 15 percent oxygen (O 2 ).

We also evaluated whether to go beyond-th e-floor. Specifically, EPA considered

additional emission controls that would furthe r reduce HAP emissions. One control that we considered for reducing HAP is a diesel oxida tion catalyst (DOC). The DOC technology is capable of reducing HAP emissions by 70 percen t or more. The DOC technology also reduces emissions of CO by 70 percent or more, as we ll as particulate matter (PM) emissions.

Achievable reductions of PM are on th e order of 30 percent for the DOC.

EPA also considered the use of open crankc ase ventilation (OCV) or closed crankcase ventilation (CCV) systems to further reduc e emissions of metallic HAP under section 112(d)(2)(B) and (C), as a measure that encloses systems to eliminate emissions or collects, captures or treats such pollutants. EPA also notes that it does not believe it would be feasible at this time to prescribe an emission standard for metallic HAP. It is believed that combustion gases and oil mist that are vented from the e ngine crankcase are a subs tantial source of any metallic HAP emissions from stationary CI engines. Most existing stationary CI engines have open crankcases that vent the crankcase emissions directly to the atmosphere. It would not be practicable to measure the metallic HAP emissions since the crankcase is open directly to the atmosphere rather than vented to the engine exhaust. Capturing these emissions using EPA

Method 29 would be difficult due to the sporadic flowrate of the blow-by gases, making isokinetic sampling of the crankcas e exhaust difficult. In addition, testing for metallic HAP is at least $15,000-$20,000 per engine, and the emission leve ls from stationary CI engines are likely4 to be below method detection limits, so current test methods may not be able to accurately measure such emissions. Consequently, it would be infeasible to prescr ibe a numerical emission standard for metallic HAP for existing stationary CI engines. Therefore, the use of OCV or CCV systems would also be justified under secti on 112(d)(2)(D) as a design, equipment or work practice. EPA believes that a st andard that requires the use of OCV or CCV systems would be the most appropriate method for further reducing metallic HAP emissions for existing stationary CI engines. For the purpose of this analysis, EPA used OCV, rather than CCV as the emission control we would expect sour ces to use; while CCV system s that prevent the crankcase emissions from being emitted to the atmosphere are also an option for reducing crankcase emissions, EPA does not believe that it is feasible to retrofit all existing stationary CI engines with CCV systems due to feasibility concerns. This was discussed in a meeting between EPA and the Engine Manufacturers Association on No vember 19, 2009 and in a letter from EMA to EPA dated December 4, 2009. A summary of th at meeting and the letter from EMA are

available in the docket as Document ID Numbers EPA-HQ-OAR-2008-0708-XXXX and

YYYY.

EPA evaluated the cost of DOC/OCV contro l compared to the HAP reductions that would be achieved. Going above-the-floor and requiring DOC/OCV on all non-emergency CI engines would require significant total capital inve stment and total annual control costs, which EPA does not believe are justified for these engi nes. For example, the cost per ton of HAP reduced for non-emergency CI engines between 100 HP and 175 HP is more than $265,000. The cost per ton is based on reduci ng HAP emissions by 70 percent from uncontrolled levels or an emission reduction of approximately 15 pounds per year (lb/yr) for a 200 HP engine. Capital costs for a 200 HP for installing DOC/OCV is es timated at close to $6,000. For information on the cost per ton of HAP reduced, please refer to the memorandum entitled “Cost per Ton of HAP Reduced for Existing Stationary CI RICE ” in the rulemaking docket (EPA-HQ-OAR-2008- 0708). MACT is therefore equivalent to the MACT floor for th is subcategory.

Non-Emergency CI 300<HP ≤ 500

EPA has test data for two engines in this s ubcategory. The average of the top 12 percent of existing sources is therefore based on data from one engine. In order to account for emissions variability, the highest test run for the engine wa s determined to be the MACT floor. As shown in Appendix B, the MACT floor for CI non-emer gency stationary RICE between 300 HP and 500 HP is 137 ppmvd of CO at 15 percent O 2

.

We also evaluated whether to go beyond-the-fl oor for this subcategory. Specifically,

EPA considered additional emission controls to further reduce HAP emissions. EPA considered the use of DOC systems in conjunc tion with OCV systems. Stationary existing CI engines were largely uncontrolled at the Fede ral level prior to the promulga tion of EPA’s emission standards for stationary CI engines in 2004, which affect ed engines constructed beginning in 2002. Nonemergency CI engines are estimated to emit 90 percent of total combined PM and nitrogen oxides (NO X ) emissions from all existing stationary CI engines, with emergency engines emitting the remaining 10 percent. Of th e non-emergency CI engines, about 50,000 nonemergency engines rated 300 HP or higher were built prior to 2002, which is about 29 percent of the existing population of non-emergency stationa ry CI engines. These 50,000 non-emergency5 CI engines emit approximately 72 percent of the total HAP emissions, 66 percent of the total PM emissions, and 62 percent of the total NO X emissions from existing non-emergency stationary CI engines. This information is based on data from the Power Systems Research Database that was presented in Tables 1-4 of EPA’s January 24, 2008 ANPRM for stationary CI engines emission standards (73 FR 4136). For thes e reasons, EPA concluded that it can achieve the highest level of emission reduction relative to cost, while requ iring controls where a ppropriate, by requiring more stringent emission standards on non-emergenc y stationary CI engine s with a power rating greater than 300 HP.

EPA evaluated the cost of these systems compared to the emission reductions that would be achieved by the use of DOC/OCV for engines in this subcategory and determined that the costs were reasonable when compared to the amount of emission reductions that would be achieved through the use of these controls. For example, the cost per ton of HAP reduced for non-emergency CI engines between 300 HP and 500 HP is about $170,000. Again, the cost per ton is based on reducing HAP emissions by 70 percent from uncontrolled levels. For a nonemergency 400 HP CI engine this would equate to an emission reduction of approximately 30 lb/yr; twice that of a 200 HP engine. For info rmation on the cost per ton of HAP reduced, please refer to the memorandum entitled “Cost per Ton of HAP Reduced for Existing Stationary CI RICE” in the rulemaking docket (EPA-HQ-OAR-2008-0708).

To determine MACT for non-emergency CI engi nes greater than 300 HP and less than or equal to 500 HP, EPA reviewed the test data for CI engines greater than 300 HP and less than or equal to 500 HP and selected the highest CO test run for the two engines in that range. Then, EPA applied a control efficiency of 70 percent to that CO concentration level. The 70 percent reduction efficiency for DOC represents the lo west reduction in CO from a DOC that was measured during EPA’s testing of a stationary di esel engine at CSU; the CO reduction measured during the CSU testing ranged from 70 to 84 per cent. By selecting th e lowest reduction, EPA has accounted for emissions variability in the su bcategory while ensuring that emission levels will be below the MACT floor level after accounting for emission controls. Consequently, EPA determined that MACT for HAP for non-emerge ncy CI engines greater than 300 HP and less than or equal to 500 HP is 49 ppmvd of CO at 15 percent O 2 , or 70 percent CO efficiency. EPA

has also determined that it woul d be appropriate to require the use of ultra low sulfur diesel (ULSD) fuel for these engines. The use of ULSD is necessary due to concerns about DOCs simultaneously oxidizing SO 2 to form sulfate particulate. A lim it on the diesel fuel sulfur level of 15 ppm will reduce the potential for increased sulfate emissions from diesel engines equipped

with DOCs. The limit on fuel sulfur will also improve the efficiency of the DOC.

In order to further reduce metallic HAP emissions, EPA believes it is appropriate establish a separate requirement for metallic HAP emissions from the crankcase. As discussed above, it is not possible to set a numerical em ission standard for metallic HAP. To reduce emissions of metallic HAP, an OCV filtration sy stem was considered. The OCV system captures blow-by emissions from the pistons, which incl ude both oil mist and worn metal from the combustion cylinders, and reduces metallic HAP em issions from the engine. Closed crankcase ventilation (CCV) systems that prevent the cr ankcase emissions from being emitted to the atmosphere are also an option for reducing cran kcase emissions; however EPA believes that it may not be feasible for some existing stationary CI engines to retrofit with CCV systems (see6 EPA-HQ-OAR-2008-0708-XXXX and YYYY). Therefore, EPA believes it is appropriate to provide sources the option to choose either OC V or CCV systems and has specified that nonemergency CI engines between 300 HP and 500 HP located at major sources must either: 1) install a closed crankcase ventilation system that prevents crankcase emissions from being emitted to the atmosphere, or 2) install an open crankcase filtration emission control system that reduces the crankcase emissions by filtering the exha ust stream to remove oil mist, particulates,

and metals.

Of further consideration are the co-benefits that would be achieved by requiring the use of the DOC/OCV option. The control technology will reduce other pollutants such as CO and PM, which are of significant health concern. In addition, the requireme nt will also reduce the emissions of sulfur dioxide (SO 2 ), because this cont rol option requires the use of ULSD fuel. Taking into account the reductions in CO, SO 2 and PM associated with applying DOC/OCV to non-emergency CI engines, the cost per ton of po llutants reduced decreases. For instance, the cost per ton of PM reduced for non-emergenc y CI engines between 300 HP and 500 HP is around $61,000 and the cost per ton for SO 2 is about $32,000. The cost per ton for PM is based on reducing PM emissions by 30 percent from uncontrolled levels, which would mean an emission reduction of more than 80 lb/yr of PM fr om a 400 HP engine. It is estimated that the benefits per ton are $210,000 (Pope, 7%) a nd $500,000 (Laden, 7%) for PM for existing stationary CI engines at major s ources. The benefits per ton of SO 2 for existing stationary CI engines at major sources are estimated at $27,000 (Pope, 7%) and $65,000 (Laden, 7%). It is clear that the overall benefits significantly ou tweigh the costs. Furt her information on the

monetized benefits can be found in the memo randum titled “Cost per Ton of HAP Reduced for Existing Stationary CI RICE,” available fromthe docket as Document ID Number EPA-HQOAR-2008-0708-XXXX. The total co-benefits of this regulation are presented in the memorandum titled “Impacts Associated with NE SHAP for Existing Stationary CI RICE,” available from the rulemaking docket.

Non-Emergency CI >500 HP

EPA has test data for eight engines in this subcategory. The average of the top 12 percent is therefore based on data for one engine. To determine the MACT floor for this subcategory, EPA selected the highest test run for the MACT floor engine in order to account for emissions variability. As shown in Appendix B, the MACT floor for CI non-emergency stationary RICE greater than 500 HP is 38 pp mvd of CO at 15 percent O 2

.

We also evaluated whether to go beyond-the-fl oor for this subcategory. Specifically, EPA considered DOC/OCV. After evaluating th e cost of these controls and the emission

reductions that can be achieved for engines in this subcategor y, EPA believes that requiring

above-the-floor levels that ar e based on DOC/OCV control is a ppropriate for non-emergency CI engines greater than 500 HP. Fo r example, the cost per ton of HAP reduced for non-emergency CI engines above 500 HP is about $162,000 or less. Based on reducing HAP emissions by 70 percent from uncontrolled levels, annual emission reduction would be approximately 45 lb/yr per engine for a 600 HP engine.7 To determine the above-the-floor emissi on limitation for non-emergency CI engines greater than 500 HP, EPA reviewed the test data for CI engi nes greater than 500 HP. EPA applied a control efficiency of 70 percent to the CO concentra tion level that represented the highest CO concentration value taken from th e CSU-Engines & Energy Conservation Laboratory data, which tested over a wide range of operati ng loads. The CO reduc tion measured during the CSU testing ranged from 70 to 84 percent; EPA se lected the lowest percent reduction that was measured during the testing in order to account for emissions variabilit y. As a result, EPA

determined that MACT for HAP emissions for no n-emergency CI engines greater than 500 HP is 23 ppmvd of CO at 15 percent O 2 or 70 percent CO efficiency.

To further address metallic HAP emissions from stationary non-emergency CI engines greater than 500 HP, EPA is requiri ng that these sources either: 1) install a closed crankcase ventilation system that prevents crankcase emissi ons from being emitted to the atmosphere, or 2) install an open crankcase filtration emission control system that reduces the crankcase emissions by filtering the exhaust stream to remove oil mist, particulates, and metals.

Of further consideration are the co-benefits that would be achieved by requiring the use of the DOC/OCV option. The control technology will reduce other pollutants such as CO and PM, which are of significant health concern. In addition, the requireme nt will also reduce the

emissions of SO 2 , because this control option requires the use of ULSD fuel. Taking into account the reductions in CO, SO 2 and PM associated with applying DOC/OCV to nonemergency CI engines, the cost per ton of polluta nts reduced decreases. The cost per ton of PM reduced for non-emergency CI engines above 500 HP is less than $58,000 and the cost per ton

for SO 2 is $31,000 or less. The cost per ton of VOC is $7,000 or below for non-emergency engines above 500 HP. Again, the cost per ton for PM is based on reducing PM emissions by 30 percent from uncontrolled levels, which would mean an emission reduction of more than 120 lb/yr of PM from a 600 HP engine. Again, the to tal benefits per ton for existing stationary CI engines at major sources, which for PM are $210,000 (Pope, 7%) and $500,000 (Laden, 7%) and

for SO 2 are $27,000 (Pope, 7%) and $65,000 (Laden, 7%) show that overall benefits significantly outweigh the costs. Further information on the monetized benefits can be found in the memorandum titled “Cost per Ton of HAP Reduced fo r Existing Stationary CI RICE,” available

from the docket as Document ID Numb er EPA-HQ-OAR-2008-0708-XXXX. The total cobenefits of this regulation are presented in the memorandum titled “Impacts Associated with NESHAP for Existing Stationa ry CI RICE,” available from the rulemaking docket.8 Appendix A

Existing Stationary CI Engine Test Data Summary9Test Date Engine NumberEngineSize(HP)Test MethodUsedCO Concentration (ppmvd @ 15% O2)CommentsAverageRun1Run2Run31/22/2009 East Crane 3 160 CARB 100 479.8 496.4 497.5 445.41/22/2009 West Crane 1 160 CARB 100 222.9 221.3 217.5 229.91/20/2009 East Crane 1 450 CARB 100 129.6 124.2 127.5 137.21/21/2009 East Crane 2 450 CARB 100 154.4 140.3 160.2 162.77/27/2005 Engine 1 550 EPA Method 10 45.6 46.6 45.0 45.1 100% load7/29/2005 Engine 2 550 EPA Method 10 90.9 93.5 90.4 88.8 25% load7/29/2005 Engine 2 550 EPA Method 10 57.7 56.6 58.8 57.5 50% load7/29/2005 Engine 2 550 EPA Method 10 41.6 42.5 41.0 41.4 75% load7/27/2005 Engine 2 550 EPA Method 10 23.5 23.7 23.7 23.0 100% load7/28/2005 Engine 3 550 EPA Method 10 82.8 62.0 93.5 92.9 25% load, Arctic fuel7/28/2005 Engine 3 550 EPA Method 10 59.9 59.3 58.3 62.3 50% load, Arctic fuel7/28/2005 Engine 3 550 EPA Method 10 39.5 40.8 39.7 37.8 75% load, Arctic fuel7/28/2005 Engine 3 550 EPA Method 10 42.8 41.6 44.3 42.4 100% load, Arctic fuel7/26/2005 Engine 3 550 EPA Method 10 42.3 41.9 43.7 41.2 100% load7/26/2005 Engine 4 550 EPA Method 10 28.9 25.6 23.2 38.0 100% load9/2/1999 Caterpillar 3508 1000 EPA Method 10 76.8 76.8 70% load9/1/1999 Caterpillar 3508 1000 EPA Method 10 44.1 44.1 70% load8/31/1999 Caterpillar 3508 1000 EPA Method 10 43.5 43.5 100% load8/31/1999 Caterpillar 3508 1000 EPA Method 10 41.6 41.6 100% load9/1/1999 Caterpillar 3508 1000 EPA Method 10 42.7 42.7 100% load8/31/1999 Caterpillar 3508 1000 EPA Method 10 45.2 45.2 100% load8/31/1999 Caterpillar 3508 1000 EPA Method 10 44.1 44.1 100% load9/1/1999 Caterpillar 3508 1000 EPA Method 10 41.6 41.6 100% load9/1/1999 Caterpillar 3508 1000 EPA Method 10 76.2 76.2 70% load8/31/1999 Caterpillar 3508 1000 EPA Method 10 39.8 39.8 100% load6/26/2003 Generator 2 1680 EPA Method10 327.1 330.3 330.1 320.8 75% load6/26/2003 Generator 2 1680 EPA Method10 265.4 267.2 263.7 265.1 100% load6/26/2003 Generator 2 1680 EPA Method 10 196.9 182 200 209 50% load6/25/2003 Generator 2 1680 EPA Method 10 77.7 77.8 74.9 80.3 25% load7/8/2004 Engine 6 3570 EPA Method 10 69.4 69.2 69.2 69.9 Low load7/8/2004 Engine 6 3570 EPA Method 10 54.9 55.8 54.2 54.6 High load7/9/2004 Engine 6 3570 EPA Method 10 55.5 56.7 54.9 54.8 Mid load7/9/2004 Engine 7 3570 EPA Method 10 142.9 142.9 Mid load7/9/2004 Engine 7 3570 EPA Method10 131.1 126.5 132.1 134.8 High load7/9/2004 Engine 7 3570 EPA Method 10 127.8 127.8 Low load10 Appendix B

MACT Floor Summary11Test Facility Test Date Engine NumberEngine Size(HP)Test MethodUsedHighest CO run (ppmvd@ 15% O2)Average COConcentration(ppmvd @15% O2) CommentsSanta Barbara County Air Pollution Control District1/22/2009West Crane 1160CARB 100229.9222.9Santa Barbara County Air Pollution Control District 1/22/2009 East Crane 3 160 CARB 100 479.8Santa Barbara County Air Pollution Control District1/20/2009East Crane 1450CARB 100137.2129.6Santa Barbara County Air Pollution Control District 1/21/2009 East Crane 2 450 CARB 100 162.7 154.4Precision Power7/26/2005Engine 4550EPA Method1038.028.9100% loadPrecision Power 7/27/2005 Engine 1 550EPA Method10 45.6 100% loadPrecision Power 7/28/2005 Engine 3 550EPA Method10 82.825% load, ArcticfuelPrecision Power 7/29/2005 Engine 2 550EPA Method10 90.9 25% loadCSU-Engines & Energy Conversion Laboratory 9/2/1999Caterpillar3508 1000EPA Method10 76.8 76.8 70% loadBadami Development Facility 6/26/2003 Generator 2 1680EPA Method10 327.1 75% loadNorthstar Development Project - BP 7/8/2004 Engine 6 3570EPA Method10 69.4 Low loadNorthstar Development Project - BP 7/9/2004 Engine 7 3570EPA Method10 142.9 Mid loadDraft Floor (< 300 HP)Count2Top 12%1Ave of Top 12%230ppm @15 %O2Draft Floor (300-500 HP)Count2Top 12%1Ave of Top 12%137ppm @15 %O2Draft Floor (> 500 HP)Count8Top 12%1Ave of Top 12%38ppm @15 %O2Above the Floor (300-500 HP)Data Point Used162.7 ppm @15 %O2CO reduction70 %Above the FloorStandard49 ppm @15 %O212Above the Floor (> 500 HP)Data Point Used76.8 ppm @15 %O2CO reduction70 %Above the FloorStandard23 ppm @15 %O2