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OAR Box 1850 

Prepped by Ollie Stewart 

Document Number: 

7DIV-B-1 

Docket Number: 

A-90-07 

Printed 11/18/2008 11:09:28 AM Sheet 71 of 161 
IV- 6-0 1 

^ * °

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WJ 

\ UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

ANN ARBOR. MICHIGAN 48105 

*t mf* 

APR . 3 1392 

MEMORANDUM 

:!? APR I Ti992 PJ 

EPA AIR DOCKET J 

OFFICE OF 

AIR ANO RADIATION 

SUBJECT: 

FROM: 

TO: 

THRU: 

Revised Base Diesel Fuel Determination Procedures 

for the Fuels and Fuel Additives Rulemaking 

James Greaves, Mechanical Engineer 

Regulation Development and Support Division 

Docket No. A-90-07 

Judith Gray, Project Manager 

Regulation Development and 

Glenn W. Passavant, Senior Project Manager 

Regulation Development and Support Division 

/ / Chester J. France, Directory , iM 

Regulation Development and Suppo Division 

Summary 

This memorandum presents a set of diesel fuel parameter values 

intended to replace the parameter values presented in the 

memorandum "Base Fuel Determination Procedures for the Fuels and 

Fuel Additives Rulemaking". The diesel parameter values have been 

revised due to the availability of diesel fuel survey data 

unavailable at the time the previous memorandum was being prepared. 

Background 

The Fuels and Fuel Additives Notice of Proposed Rulemaking 

(NPRM) proposes the use of "base fuels" to generate emissions for 

testing purposes in certain instances, and to serve as the fuel 

component of additive/fuel mixtures used in the testing of fuel 

additives. The NPRM should be consulted for a detailed description 

of the intended use of base fuels. 

J 
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Base fuels were proposed to be determined by performing a 

sales-weighted average of the fuels sold in the U.S. The previous 

memorandum on base fuel determination illustrated this procedure 

for gasoline and diesel fuels. However, only one source of diesel 

fuel surveys was available at that time to determine the diesel 

fuel parameter values. Since then, additional diesel fuel survey 

data have been acquired and merged with existing diesel fuel data 

to form a revised set of diesel fuel parameter values which are 

presented in this memorandum. 

Sources of Diesel Fuel Data 

The diesel fuel specifications presented in this memorandum 

are based on analyses of 1990 diesel fuel surveys performed by the 

Motor Vehicle Manufacturers Association (MVMA) and on 1990 diesel 

fuel surveys recently acquired from Southwest Research Institute 

(SwRI). Both the MVMA and SwRI surveys were performed two times 

per year, once in January and once in July. These surveys present 

fuel parameter values by city, along with the number of samples 

analyzed per city. 

As in the previous base fuel analysis, 1990 diesel fuel sales 

are taken from a Department of Energy, Energy Information 

Administration publication. However, instead of using the 

Petroleum Marketing Monthly (PMM) report as was done in the 

previous memorandum, the Petroleum Marketing Annual (PMA) report 

was used. As with the PMM report, the PMA report presents fuel 

sales by fuel type, month, and state. The sales data are listed 

under "Volumes of First Sales of Distillate Fuel Oils" and reflect 

first delivered sales of diesel fuels into the states where they 

are expected to be consumed. 

Calculation Methodology 

The following discussion explains the methodology used to 

combine the diesel fuel surveys to obtain a single value for each 

of the identified parameters (see Figure 1 for a summary) . The 

method used here is similar to that used to combine the gasoline 

fuel surveys in the previously referenced memorandum. The MVMA 

diesel surveys present diesel fuel parameters for 17 U.S. cities 

for all of the identified diesel fuel parameters. The SwRI surveys 

present diesel fuel parameters for 38 U.S. cities for all of the 

identified diesel fuel parameters except filterability plugging 

index, flash point, kinematic viscosity, olefins, and saturates. 

Fifteen U.S. cities are included in both surveys. Only those 

parameters which were reported in both the MVMA and SwRI surveys 

have been revised in this new analysis (i.e. excluding 

filterability plugging index, flash point, kinematic viscosity, 

olefins, and saturates). 

For those 15 cities sampled both by MVMA and SwRI, the data 

from MVMA and SwRI were averaged together on a sample-weighted 

basis for each fuel parameter and city. That is, each sample from 

each survey was treated equally and independently. For cities 
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included in only one of the two surveys, the samples from the one 

available survey were averaged in the same way. 

Next, one parameter value was determined for each state based 

on city data, as follows. If a state did not contain any cities in 

the survey, it was not assigned a parameter value and was not 

represented in the averaging procedure. If a state contained only 

one city in the survey, the parameter value determined for that 

city was assigned to the state. If the state contained more than 

one city in the survey, the state parameter value was determined by 

weighing parameter values determined for each city by the 

population in that city (1980 census). The parameter value from 

each of the cities was multiplied by its population and the sum of 

these factors was divided by the population sum to find the 

aggregate parameter value. The result is one parameter value for 

each state and time period. Thirty states plus the District of 

Columbia were represented in the diesel surveys. 

Finally, each state's sales of Number 2 diesel fuel (as 

reported in PMA for January and July 1990) was multiplied by that 

state's parameter value for the month. This resulted in a weighted 

fuel parameter value for each surveyed state for each month. The 

sum of these weighted fuel parameter values over all surveyed 

states and both months was divided by the total Number 2 diesel 

fuel consumption of all surveyed states from both months, to yield 

the final, nationwide base fuel parameter. 

Results 

Using the methodology described above, the following revised 

annualized sales-weighted average characteristics for diesel fuels 

were determined. 

Aromatics, volume percent 38.4 

Sulfur, weight percent 0.24 

Initial Boiling Point, °F 351 

TIO, OF 433 

T50, °F 516 

T90, O F 606 

End Point, O F 651 

Cetane Number 45.2 

Cetane Index 45.7 

Cloud Point, O F 5.2 

Pour Point, O F -9.1 

Specific Gravity 0.86 

A comparison of the original and revised industry average diesel 

fuel parameter values is found in Figure 2. As shown in this 

figure, the recently acquired diesel fuel survey data caused the 

aromatics parameter value to change from 42.2 to 38.4 volume 

percent, a reduction of 3.8 volume percent. Since the sum of 

aromatics, olefins and saturates must equal approximately 100 
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percent of the fuel content1, the decrease in aromatics content 

necessitates an increase in saturates, olefins, or both. It is 

proposed that saturates be increased by the amount aromatics were 

reduced for the purpose of determining an industry average diesel 

fuel. This proposal is based on two reasons. First, light cycle 

oil, the fuel fraction from which most of the diesel fuel aromatics 

are obtained, is also responsible for most of the olefins. 

Therefore, if aromatics are reduced it seems likely that olefins 

would be reduced in the process as well. Secondly, if saturates 

and olefins were both increased proportionally to make up for the 

3.8 volume percent reduction, the olefins value would be changed by 

only 0.1 volume percent, a change which would probably be within 

the blending tolerances of a fuel made to these specifications. 

Comment is requested on this proposed change. 

Statistics that describe the mean, maximum, minimum, and 

standard deviation of the parameter values from the surveyed cities 

are presented in Figure 3. These statistics are expected to be 

useful when base fuel blending tolerances are determined during 

development of the final rule. The mean parameter values reported 

in Figure 3 differ from the results listed above because the mean 

parameter values (and the maximum and minimum values) have not been 

weighted by fuel sales. 

xThe sum of aromatics, olefins, and saturates content would 

equal exactly 100 percent if the were no additives or impurities in 

the fuel. 
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Figure 1: Fuel Averaging Method Used to Determine 

Base Diesel Fuel Parameter Values 

1. Acquire fuel parameter data (monthly or bi-monthly if 

possible, otherwise twice per year) for each city for a one year 

period. These data should include the number of samples taken at 

each city. More than one survey should be acquired, if possible. 

2. Combine the data from the different surveys by weighing 

the average parameter values determined for each survey by the 

number of samples taken in each survey. The result is one 

parameter value for each city and time period. 

3. Determine one parameter value for each state for each 

time period: 

A. If the state does not contain any cities in the 

survey, it is not assigned a parameter value and is 

not represented in the parameter averaging 

procedure. 

B. If the state contains only one city in the survey, 

the parameter value determined for that city in 

step #2 is assigned to the state. 

C. If the state contains more than one city in the 

survey, the state parameter value is determined by 

weighing parameter values determined for each city 

in step #2 by the relative amount of fuel sold in 

that city. Relative city fuel sales are estimated 

by the fraction of population in each of the cities 

surveyed in that state in relation to the sum from 

all of the surveyed cities in that state. 

4. Acquire Number 2 diesel fuel sales for each state and 

each time period for which a parameter value was determined in #3. 

Sum these fuel sales from all represented states and all time 

periods surveyed. This is referred to as "Total Sales". 

5. Multiply the parameter values determined in step #3 by 

the state fuel sales values of step #4, and divide each by the 

Total Sales of step #4. Sum up all of the weighted values to 

determine the average value for the parameter. 
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Figure 2: Comparison of Original and Revised 

Diesel Fuel Parameter Values 

Aromatics, vol% 

Olefins, vol% 

Saturates, vol% 

Sulfur, wt% 

IBP, O F 

TIO, O F 

T50, O F 

T90, O F 

End Point, op 

Cetane Number 

Cetane Index 

Cloud Point, O F 

Flash Point, °F 

Pour Point, O F 

Specific Gravity 

Kin. Viscosity, cs4 

Filterability Plugging 

Index 

Original1 Revised2 

42.2 

1.5 

56.1 

0.26 

368 

441 

519 

609 

655 

45.6 

46.0 

2.82 

145 

-6.15 

0.86 

2.87 

35.1 

38.4 

NA 

59.93 

0.24 

351 

433 

516 

606 

651 

45.2 

45.7 

5.18 

NA 

-9.13 

0.86 

NA 

NA 

^'Original" diesel fuel parameter values refers to the diesel 

fuel parameter values presented in the memorandum "Base Fuel 

Determination Procedures for the Proposed Fuels and Fuel Additives 

Rulemaking" found in the Fuels and Fuel Additives rulemaking 

docket. 

2NA indicates that the parameter values have not been revised. 

3see the text for an explanation 

4centistokes at 40 oc 
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Figure 3: Parameter Statistics From Surveyed 

Cities for 1990 Diesel Fuels1 

Mean Maximum Minimum Standard 

Aromatics, vol% 

Olefins, vol% 

Saturates, vol% 

Sulfur, wt% 

IBP, O F 

TIO, O F 

T50, O F 

T90, O F 

End Point, O F 

Cetane Number 

Cetane Index 

Cloud Point, O F 

Flash Point, OF 

Pour Point, °F 

Specific Gravity 

Kin. Viscosity, cs2 

Filterability 

37.5 

1.4 

59.4 

0.26 

348 

426 

508 

601 

647 

45.2 

45.5 

2.5 

140 

-12.8 

0.854 

2.59 

33.7 

54.3 

3.3 

75.0 

0.46 

393 

485 

543 

639 

671 

51.2 

49.9 

25 

168 

6 

0.869 

3.28 

78.6 

23.7 

0.6 

45.9 

0.024 

295 

382 

464 

559 

606 

40.8 

43.3 

-17 

118 

-40 

0.835 

2.11 

1.4 

Deviation 

6.68 

0.6 

6.6 

0.10 

18.5 

17.0 

17.0 

14.7 

13.9 

1.6 

1.3 

7.2 

10.9 

10.4 

0.007 

0.32 

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xThe diesel fuel statistics for all parameters except olefins, 

saturates, filterability plugging index, flash point, and kinematic 

viscosity have been derived from 1990 diesel fuel surveys performed 

by the Motor Vehicle Manufacturer Association and Southwest 

Research Institute. Statistics for olefins, saturates, 

filterability plugging index, flash point, and kinematic viscosity 

have been derived from Motor Vehicle Manufacturer Association 

surveys only and have been taken from the memorandum "Base Fuel 

Determination Procedures for the Proposed Fuels and Fuel Additives 

Rulemaking". 

2centistokes at 40 °C 

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