**UNITED STATES ENVIRONMENTAL PROTECTION AGENCY** NATIONAL VEHICLE AND FUEL EMISSIONS LABORATORY

2000 TRAVERWOOD DRIVE ANN ARBOR, MI 48105

- 2498

OFFICE OF AIR AND RADIATION
March 1, 2013
MEMORANDUM
SUBJECT: Test Program to establish L DV Full Useful L ife PM Performance
FROM: Rafal Sobotowski

– USEPA/OTAQ/ASD
TO: EPA Docket # EPA

- HQ

- OAR

- 2011

- 0135

**Description of the Full Useful Life Program**
In order to establish the feasibility of the particulate matter ( PM ) emission standards proposed in the Tier 3 rule, the U.S. EPA conducted a test program to measure PM emissions from Tier 2 light

- duty vehicles. The test program was designed to measure PM emissions from late model y ear vehicles that represented a significant volum e of annual light duty sales and included vehicles that ranged from small cars through trucks , including a cross section of technologies from port fuel injected (PFI) engines to g asoline d irect i njection (GDI) engines. In addition, one PFI vehicle was inc luded with known high oil consumption. Seventeen model ye ar 2005

- 2010 Tier 2 Bin 4, 5, and 8 vehicles were tested at the U.S. EPA National Vehicle and Fuel Emissions Laboratory (NVFEL) facility

. A summary of their characteristics is provided i n Table 1

. They included ten cars and seven trucks. Fifteen of these vehicles had accumulated 102,000

- 124,000 miles prior to the launch of the test program. One vehicle had accumulated 37,000 miles and another accumulated 21,000 miles . Three cars and one truck were equipped with Gasoline Direct Injection ( GDI ) engines. Twelve of the seventeen test vehicles had previously been used in the Department of Energy ( DOE ) V4 Program. The remaining five vehicles were recruited in southeastern Michigan. The twelve vehicles acquired from the DOE V4 Program were selected to represent a broad cross section of some of the highest sales vehicles in the U.S. market for model years 2005

- 2009. These vehicles had originall y been purchased by DOE with odometer rea dings ranging from 10,000

- 60,000 miles, placed in a mileage accumulationprogram and operated over the EPA Standard Road Cy cle on a test track or on mileage

accumulation d ynamometers to 110,000

- 120,000 miles. i Im mediatel y prior to inclusion in the EPA PM Test Program, the test vehicles were serviced per the manufacturer’s published service schedule and maintenance procedures and underwent engine oil aging over a distance of 1,000 miles accumulated over the EPA Standard Road Cycle to stabilize engine oil co ntribution to PM emissions ii

. One vehicle (vehicle K) tested from the DOE V4 program was suspected of having aty

picall y high oil consumption and had only 37,000 miles of mileage accumulation

. Vehicle K was a duplicate of Vehicle C and was determined to con sume two and one half times the average oil consumption of vehicle C and three vehicles of the same make, model and model y ear which were tested within the DOE V4 program. 1 Vehicle K did not accumulate 120,000 miles because it was removed from the mileage accumulation program after the at ypical oil consumption was confirmed. Vehicle K was tested in this program to investigate the potential impact of high oil consumption on PM emissions. Three recruited test vehicles were selected because they used GDI tec hnolo gy and one GDI equipped vehicle was obtained from the DOE V4 Program

. Vehicle Q was recruited for another test program but was included in this program because it was a GDI technology

vehicle. Otherwise, an attempt w a s made to only recruit vehicles approaching the 120,000 mile useful life level. All of the recruited test vehicles were thoroughl y inspected, but otherwise tested as received. All vehicles were tested on an E15 fuel with RVP, aromatic content, sulfur content, T50 and T90 of 9.1 psi, 23 .8 vol%, 7 ppm, 160F and 311F, respectively . The properties of this fuel approximated those of a projected E15 market fuel. The test program included three cold start and three hot start UDDS tests and three US06 tests conducted on each vehicle. FTP res ults were calculated for gaseous and PM emissions by

appl yi ng the cold

- start and hot

- start weighting factors to the complete cold and hot UDDS results, respectivel y. This eliminated separate anal ys is of the ty picall y ver y low concentration FTP phase

- 2 gas eous and PM emissions samples and represented one method proposed within 40 CFR 1066 for increasing sample integration of measured gaseous and PM mass. During these tests, triplicate PM samples were collected in parallel on PTFE membranes and single (comp osite) PM samples were collected on primary

and secondary

quartz filters for Thermol Optical Reflectance (TOR) Organic Carbon (OC) and Elemental Carbon (EC) PM speciation anal ys is. Additional quartz filters were collected to determine the contribution o f gas

- phase artifact to the OC collected on the quartz filter samples. The compositing of quartz filters over three repeats of each test was done to enhance the precision of subsequent OC/EC thermogravimetric measurements. Single background (dilution air ) PM samples were also taken during each emissions test. Weekly tunnel blank and field blank PM samples were also collected.

1 Vehicle K consumed approximately 1 quart per 3,000 miles vs. an average of approximately 1 quart per 8,000 miles for the other four vehicles of this make, model and year tested within the DOE V4 program.The following parameters were measured: NO X , NMHC, NMOG, alcohols,

carbon yl s, CO, CH **4** , CO 2 and fuel consumption and PM mass as per the 40 CFR 1065 and the proposed 40 CFR part 1066 test procedures. L imited exhaust HC speciation was also performed. PM composition was determined from filter samples taken on both quartz filters and PTFE membrane s. PM compositional analy ses include determination of the contribution of elemental and organic carbon to PM mass, iii elemental anal ysis via energy dispersive x

- ray

fluorescence ( EDXRF ) , and sulfate anal ys is via ion chromatography

. **Table 1.**  **Vehicles teste d as part of EPA’s Light** 
**- Duty Vehicle PM Test Program**  Vehicle Make, Model and Designation Model Year Certified to

Emissions Standard Odometer at

Start of Program, miles Fuel

Delivery a Used in

DOE V4 Program? Honda Civic A 2009 Tier 2/Bin 5 121,329 PFI Yes Toy ota Corolla B 2009 Tier 2/Bin 5 120,929 PFI Yes Honda Accord C 2007 Tier 2/Bin 5 123,695 PFI Yes Dodge Caliber D 2007 Tier 2/Bin 5 114,706 PFI Yes Chevrolet I mpala E 2006 Tier 2/Bin 5 114,284 PFI Yes Ford Taurus F 2008 Tier 2/Bin 5 115,444 PFI Yes Toy ota Tundra G 2005 Tier 2/Bin 5 121,243 PFI Yes Chry sler Caravan H 2007 Tier 2/Bin 5 116,742 PFI Yes Jeep L ibert y I 2009 Tier 2/Bin 5 121,590 PFI Yes Ford Explorer J 2009 Tier 2/Bin 4 121,901 PFI Yes Honda Accord K 2007 Tier 2/Bin 5 36,958 PFI Yes Ford F150 L 2005 Tier 2/Bin 8 111,962 PFI No VW Passat M 2006 Tier 2/Bin 5 102,886 TGDI No Chevrolet Silverado P 2006 Tier 2/Bin 8 110,898 PFI No Manufacturer’s Development Vehicle b N PC None (Tier 2/L EV II Prototy pe) * 120,011 TGDI No
Saturn Outlook O 2009 Tier 2/Bin 5 123,337 GDI Yes Cadillac STS4 Q 2010 Tier 2/Bin 5 21,266 GDI No Notes:
a PFI is Naturally

aspirated, port fuel injected; GDI is Naturall y aspirated, gasoline direct injection; TGDI is Turbocharged, gasoline direct injection b Manufacturer’s developmental vehicle. Vehicle used a spray

- guided GDI fuel sy stem with a centrall y - mounted injector and turbocharging . Emissions were targeted at Tier 2 Bin 5 or better.**Original Particulate Matter**  **Results (Fall 2011)** The original particulate matter test results measured i n this program are plotted in Figure 1 and Figure 2 , for the FTP and US06 test cy cles, respectivel y. In the figures, the vehicles are divided into two groups: PFI and GDI. Within each group they are list ed in the sequence of increasing CO 2 emissions on the FTP test cy cle

. The colored bars shown in the figures represent the means by test cy cle and vehicle, and include accompany ing standard deviations. The data points indicate the average emissions for ea ch individual vehicle test

. The number of tests, mean PM emission rates, and standard deviations by vehicle are tabulated in Tables 2 and 3. All reported tests passed the Federal Register proportionality

requirements for particulate sampling light

- dut y g asoline exhaust iv

. Vehicles I and M are not included in Figure 3 because the tests did not meet the proportionality

requirements on the FTP cy cle. As shown, the original PM emission rates for PFI vehicles were quite low on the FTP cy cle , but were very high on the US06 for several PFI vehicles. The original results on the US06 showed that several of the PFI vehicles had very high PM emission rates, which tended to be the higher

- weight trucks.

**Figure 1. Original c**  **omposite FTP PM emission results.** In dividual test results are marked with data points, average test results b y vehicle ± 1 standard deviation are display ed with the bar graphs.FTPPM(mg/mile)

0 2 4 6 8 10 PF I (P C) PC

A B C K D E F PFI ( LDT 1/ 2) LDT 1/ 2

G H PFI ( LDT 3/ 4) LDT 3/ 4

P J L GDI

PC PC LDT

3/ 4

N Q O**Figure 2. Original**  **US06 PM emission results.** In dividual test results are marked with

data points, average tes t results by vehicle ± 1 standard deviation are display ed with the bar graphs.
**PM Sampling Contamination Issue**  Upon review of the elemental anal ys is results, high concentrations of silicon (Si) were discovered on some of the PTFE filters. Corresponding Si emission rates in mg/mile are reported in Tables 2 and 3, and display ed in Figure 3 a nd 4 for the FTP and US06 cy cle s . The highest Si emission rate s were all measured on the US06 cy cle, and were more than an order of magnitude hi gher than the highest Si emission rate reported on the FTP cy cle. The Si emission rates on the US06 exhibit ed substantial variability , spanning four orders of magnitude among the different vehicles. The highest Si emission rates occurred predominately

on t he trucks. Each of the vehicles with high Si emission rates also had high PM emission rates on the US06.US06PM(mg/mile)

0 10 20 30 40 50 PFI ( PC ) PC

A B C K D E F PFI ( LDT 1/ 2) LDT 1/ 2

G H I PFI ( LDT 3/ 4) LDT 3/ 4

P J L GDI

PC PC LDT

3/ 4

N Q O**Table 2. Original FUL FTP c**  **om posite PM and Si results by**  **v ehicle** 
Vehicle Tests PM mean

(mg/mi) PM sd

(mg/mi) Si mean

(ug/mi) Si sd

(ug/mi) A 3 0.27 0.11 9.5 2.8 B 3 0.22 0.09 5.1 3.5 C 3 0.18 0.07 5.6 1.4 K 3 0.93 0.23 3.6 0.7 D 3 0.45 0.10 11.4 0.8 E 3 0.14 0.03 2.9 1.3 F 3 0.11 0.06 4.8 1.3 G 3 0.36 0.05 11.6 3.6 H 3 0.40 0.22 13.8 4.9 I

- - - - - P 3 1.22 0.12 22.0 2.5 J 3 0.11 0.10 10.2 5.8 L 3 0.81 0.14 16.8 5.6 N 3 2.55 0.74 47.9 4.2 M

- - - - - O 2 4.72 0.30 84.6 3.5 Q 1 7.15

- 73.0

- **Table 3. Original FUL US06 Composit e PM and Si results by v**  **ehicle**
Vehicle Tests PM mean

(mg/mi) PM sd

(mg/mi) Si mean

(ug/mi) Si sd

(ug/mi) A 2 0.76 0.35 18.4 0.2 B 3 2.05 0.41 225.6 61.9 C 3 1.05 0.36 101.5 36.4 K 3 2.84 1.08 257.5 128.7 D 3 7.39 3.16 1447.5 605.0 E 3 0.46 0.36 10.1 7.4 F 3 1.61 0.09 243.6 5.8 G 2 5.84 1.10 866.7 350.2 H 3 2.04 0.64 295.0 84.6 I 2 24.44 19.26 4349.7 3939.1 P 3 29.46 2.10 4777.3 1119.4 J 3 41.93 5.97 7441.1 1038.2 L 3 8.82 1.21 1298.3 18.5 N 3 2.37 0.25 133.1 19.1 M 3 37.42 18.59 516.8 250.3 O 3 4.75 1.03 858.4 247.7 Q 3 11.13 5.98 629.9 374.2**Figure 3. Original c**  **omposite FTP s**  **ilicon e**  **mission r**  **esults.** In dividual test results are

marked with data points, average test results b y vehicle ± 1 standard deviation are display ed with the bar graphs.

**Figure 4. Original c**  **omposite US06 s**  **ilicon e**  **mission r**  **esults**

. In dividual test results are marked with data points, average test results b y vehicle ± 1 standard deviation are display ed with the bar graphs. Sources of contamination were investigated in the test cell used for this program at the NVFEL facility

. The investigation discovered that silicone elastomer transfer tubes (pictured in Figure 5) were used to transfer the tailpipe exhaust from the vehicle to the constant volume sampler ( CVS ) sy stem. Silicone is a poly mer that contains Si, C, H, and O atoms, whic h can break down at high temperature and exposure to lubricating oil v . The silicone tubes were suspected as the source of the high measured Si and PM rates on the US06. Maricq et al. ( 1999 ) con firmed that silicone couplers can contribute to high concentra tions of ultrafine particles measured under high exhaust temperatures vi

.FTPSiliconEmissions(mg/mile)

0. 00 0. 02 0. 04 0. 06 0. 08 0. 10 PFI ( PC ) PC

A B C K D E F PF I (LDT 1/ 2) LDT 1/ 2

G H PFI ( LDT 3/ 4) LDT 3/ 4

P J L GDI

PC PC LDT

3/ 4

N Q OUS06SiliconEmissions(mg/mile)

0 2 4 6 8 10 PFI ( PC ) PC

A B C K D E F PFI ( LDT 1/ 2) LDT 1/ 2

G H I PFI ( LDT 3/ 4) LDT 3/ 4

P J L GDI

PC PC LDT

3/ 4

N Q O**Figure 5. Silicone exhaust transfer tubes used in**  **initial NVFEL**  **testing** A follow

- up investigation program was conducted to verify the effect of silicone sampling lines on PM emi ssions and to assess its magnitude on the PM emission rates. Vehicle J (Ford Explorer) was selected for the investigation follow

- up test program because it was the vehicle with the highest recorded PM and Si emission rates on the US06 test cy cle. Three US0 6 tests were conducted with the silicone rubber transfer lines, and three tests with stainless steel transfer lines. Figure 6 graphs the PM emission rates recorded from the 2009 Ford Explorer. The average PM emission rates were 10.28 mg/mile with the silic one transfer tube and 0.92 mg/mi with the stainless steel transfer line. The Si emission rates with the silicone transfer tube were on average 0.91 mg/mile, but were onl y 0.003 mg/mile with the stainless steel transfer line. Using the results from the foll ow - up Ford Explorer US06 tests, almost all the PM measured on the US06 was coming from the silicone transfer tube. As suspected, the measured elemental silicon was only a portion of the silicone break down products that contribute d to the particulate mass on the PTFE filter samples . In the case of the follow

- up investigation, the elemental Si only contributed ~ 10% of the increase in measured PM. The follow

- up study confirmed that silicone elastomer exhaust connections exposed as wetted surface area to hot engine exhaust can contribute substantially to particulate matter filter sample mass from CVS samples

.**Figure 6. US06 PM results from follow**
**- up investigation on silicone**  **elastomer transfer tubes** 
**Criteri a for Test Removal**  The follow

- up investigation demonstrated that samples contaminated excessively by silicone transfer lines were no longer valid and need to be excluded

. The elemental Si emission rates were used to identify tests with excessive silicone contamination. The follow

- up test program estimated that silicone lines can contribute up to 10 times as much PM as measured elemental Si, y ielding a PM:Si ratio of 10. The PM:Si ratio likely varies test

- to

- test and vehicle

- to

- vehicle, and the PM:Si rat io for most tests appears to be smaller than 10. By

apply ing a 10:1 PM:Si ratio to the US06 Si data in Table 3 , the silicone transfer tube would contribute more PM than was measured for nine of the sixteen vehicles, including Vehicle J (Ford Explorer). All vehicles that had elemental Si emission rates greater than 300 μg/ mi (0.3 mg/mi) were excluded

. This limit was selected to assure that none of the high PM emission rates on the US06 were caused b y silicone contamination

. This criteria excluded eight vehicle tests on the US06: one PFI car (Vehicle D), five PFI trucks (Vehicle G, I, P, J, L) and two of the GDI vehicles (Vehicle Q, O). Using this criterion, the silicone transfer tube cannot contribute more than 2.84 mg/mile in the any of the rem aining US06 PM averages, because all the remaining US06 PM values are less than 2.84 mg/mi (Vehicle K), notwithstanding the remaining Si rates are below 300 μg/ mi. The FTP tests had minor contributions of silicone contamination compared to the US06 cy cle

. This is expected due to the smaller engine loads and lower exhausts 0 2 4 6 8 10 12 14**P M** **( m** **g /** **m i** **) US**  **06 P M E**  **mission Rat**  **es from**  **2009 Ford**  **Explorer**

Silicone T ra ns fe r Tu be Stainles s St eeltemperatures experienced on the FTP cy cle. None of the FTP composite emission rates

had Si emission rates above 1 00 μg/ mile. Assuming the 10:1 PM to Si ratio is an upper bound, the m aximum silicone PM contribution on the final FTP results were 0. 84 mg/mile, using the maximum FTP Si emissions recorded from Vehicle O

. **Supplemental Test Program (Summer 2012)**  The light

- dut y trucks with the four highest US06 PM and Si rates (J, I , L, a nd P) were retested at the NVFEL laboratory with stainless steel exhaust transfer lines on the same test fuel as the original test program. The results for both the FTP and US06 from the stainless steel tests were used to replace the original data. The final set of PM results (which includes all the retests) is graphed in Figure 7 and Figure 8 for the FTP and US06 test cy cles, respectivel y. The final average PM emission rates, number of tests and standard deviations are presented in Table 4. The quality control criteri a of 300 μg/ mile appears to be a reasonable cutoff for excluding vehicle tests from the sample for demonstrating compliance. Vehicle I had the highest PM emission rates in the fi nal US06 data set which was tested with the sta inl ess steel transfer line

. The US06 cy cle PM emission rates from four v ehicles ( D, G, M and O ) were removed due to silicone contamination and were not retested

. T he FTP results from th ree of these vehicles are reported

. The FTP results from Vehicle M were removed due to proportionality

requirements as discussed earlier.

**Figure 7. Final c om**  **posite FTP PM e mission**  **r esult**  **s .**  In dividual test results are marked with data points, average test results by vehicle ± 1 standard deviation are display ed with the bar g raphs.FTPPM(mg/mile)

0 2 4 6 8 PFI ( PC ) PC

A B C K D E F PFI ( LDT 2) LDT 2

G H I PFI ( LDT 3/ 4) LDT 3/ 4

P J L GD I

PC PC LDT

3

N Q O**Figure 8. Final US06 PM e**  **mission r**  **esults** . Individual test results are marked with data

points, average test results by vehicle ± 1 standard deviation are display ed with the bar

graphs.
**Table 4. Final PM r**  **esults for the composite FTP and the**  **US06**

Composite FTP US06 Vehicle n Mean (mg/mi) SD (mg/mi) n Mean (mg/mi) SD (mg/mi) A 3 0.27 0.11 2 0.76 0.35 B 3 0.22 0.09 3 2.05 0.41 C 3 0.18 0.07 3 1.05 0.36 K 3 0.93 0.23 3 2.84 1.08 D 3 0.45 0.10 Removed E 3 0.14 0.03 3 0.46 0.36 F 3 0.11 0.06 3 1.61 0.09 G 3 0.36 0.05 Removed H 3 0.40 0.22 3 2.04 0.64 I 1 2 1.36 0.08 2 3.31 0.81 P 1 3 0.18 0.06 3 1.83 0.81 J 1 3 0.10 0.04 3 0.27 0.01 L 1 3 0.39 0.13 3 2.13 1.76 N 3 2.55 0.74 3 2.37 0.25 O 2 4.72 0.30 Removed Q 1 7.15

- Removed Notes: 1 Retested vehicles at NVFEL laboratory with stainless steelUS06PM(mg/mile)

0 2 4 6 8 PFI ( PC ) PC

A B C K E F PFI ( LDT 2) LDT 2

H I PFI ( LDT 3/ 4) LDT 3/ 4

P J L GD I PC

N**Discussion** The silicone contamination issue had a very significant impact on the results of the US06 cy cle, illustrated most dramatically with Vehicle J, which reduced the US06 PM emissions from over 40 mg/mile with the silicone contamination to under 1 mg/mile with the stainless steel transfer line. T he silicone contamination on the FTP cy cle was minor and no tests were removed or replaced due to silicone contamination

. In the final data set, all but one of the PFI vehicles had FTP PM emission rates under 1 mg/mile , and all PFI vehicles had emissions below the proposed 3 mg/mi FTP standard

. On the US06 cy cle all of the PFI vehicles were well in compliance of the proposed US06 standards, and all tests were below 4 mg/mile. The GDI vehicles all had higher FTP emissions than the highest tested PFI vehicle. In comparison to the proposed 3 mg/mi standard, onl y Vehicle N, the spray

guided OEM vehicle, had average FTP emissions below the standard. More testing on GDI vehicles is needed to evaluate their PM emis sions on the US06 cy cle, but the current testing shows that GDI technology (Vehicle N) can perform comparable to PFI engine technology on the US06 cy cle

.

i U.S. Code of Federal Regulations, Title 40, § 86.1823

– 08 Durability demonstration procedures for exhaust emissions.

ii Christianson, Michael G. “Impact of Lubricating Oil Condition on Exhaust Particulate Matter Emissions from Light Duty Vehicles” SAE Technical Paper No. 2010

- 01

- 1560

iii Chow, J.C.; Watson, J.G.; Crow , D.; Lowenthal, D.H.; Merrifield, T. Comparison of IMPROVE and NIOSH Carbon Measurements. Aerosol Sci.Technol., 2001, 34, 23

- 34.1.

iv U.S. Code of Federal Regulations, Title 40, § 86.1310

- 2007 Exhaust gas sampling and anal ytical system for gaseous emissions from heavy

- duty diesel

- fueled engines and particulate emissions from all engines.

v Keller, R. W.; Effects of Engine Oils on Silicone Oil Seal Material. SAE Technical Paper Series 860494. 1986.

vi Maricq, M. M atti., Chas e, Richard E. Podsiadlik , Diane H. ; Vehicle exhaust particle size distributions: A comparison of tailpipe and dilution tunnel measurements. SAE Paper 1999

- 01

- 1461