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OAR Box 1846 

Prepped by Ollie Stewart 

Document Number: 

11) ll-B-8 

Docket Number: 

A-90-07 

Printed 11/18/2008 7:30:14 AM Sheet 11 of 93 
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'*'* ^ *T, UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

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MAR 2 4 1992 

MEMORANDUM 

ANN ARBO.S—MJ£,fcHlGAN-.4S4^S 

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IV[ APR- I 

EPA AIR DOCKET 

#-90 -07 

OFFICE OF 

AIR ANO RADIATION 

SUBJECT: 

FROM: 

TO: 

THRU: 

A Preconditioning Cycle for Potential Use 

Fuels and Fuel Additives Registration Program 

in the 

James D. Greaves,, Mechanical Engineer 

Standards Development and Support Branch 

Docket Number A-90-07 

Judith Gray, Project Manager 

Standards Development and S 

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Glenn W. Passavant, Senior Projec t Manager . 

Standards Development and Support Branchrr/l^^t/M 

Cheste r J. France, Chief I^/l/l^ 

Standards Development andiMupj/ort Branch 

Summary 

This memorandum contains a description of a vehicle operation 

cycle intended to significantly reduce short-term emission 

carryover effects from fuels and fuel additives. The cycle could 

be used during emissions generation for health and emission effects 

testing under the proposed changes to EPA's Fuels and Fuel 

Additives Registration program. In addition, long-term emission 

carryover effects from fuels and additives previously used in test 

vehicles are also examined. 

Background 

As part of the proposed Fuels and Fuel Additives Registration 

program implementing Section 211(b)(2) of the Clean Air Act, 

combustion and evaporative emissions from motor vehicle fuels and 

fuel additives would be generated and tested to determine their 

composition and effects on human health. EPA is initially 

proposing that only new vehicles would be eligible for generating 

emissions for testing and that a given test vehicle would only be 

operated on the particular fuel/additive under evaluation. 

However, other alternative proposals are under consideration. 

One alternative would allow used vehicles acquired from the in-use 

U.S. fleet to be eligible as test vehicles. Another alternative 

would permit test vehicles to be used to generate emissions for 
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more than one test fuel or additive. These methods would have the 

advantage of requiring less resources than if new vehicles are 

required for each product tested. However, unrelated emissions may 

potentially be introduced due to "carryover effects" from products 

previously used in the vehicle. This memorandum describes 

potential emission carryover effects and presents a vehicle 

operation cycle intended to minimize carryover emissions in the 

event that in-use vehicles are permitted to generate emissions, or 

that test vehicles are permitted to be used to generate emissions 

for more than one product, or both. 

Emission Carryover Effects 

A fuel's or additive's emission carryover effects can be 

"short-term" or "long-term". Short-term carryover effects result 

from the presence of the previously used raw product or combustion 

emissions in the fuel system (i.e., fuel tank, fuel pump, transfer 

lines, filters, injectors, 8tc.)r evaporative emission control 

system (i.e., canister, transfer lines, purge valves, etc.), and/or 

engine/exhaust system (i.e., engine, exhaust manifold, exhaust 

pipes, oxygen sensor, catalytic converter, muffler, etc.). For 

most fuels or fuel additives, it is postulated that raw or 

combusted product that remains in the systems would not permanently 

affect the emissions of the vehicle. Therefore, removal of shortterm carryover effects essentially requires "rinsing out" these 

systems by operating them for a sufficient amount of time on the 

new product. 

Long-term carryover effects are related to modifications or 

damage to a vehicle's components caused by the product or its 

emissions. Long-term carryover effects include product deposits on 

fuel injectors and intake valves and combustion emission deposits 

on the combustion chamber, oxygen sensor, and catalytic converter. 

Also, a canister's performance can be degraded by the introduction 

of large amounts of difficult-to-purge evaporation products into 

the activated carbon. Long-term carryover effects typically occur 

over extended periods of time and can have large affects on the 

emission characteristics of the vehicle, even after the product 

used in the vehicle is changed. 

Short-Term Carryover Effects 

The preconditioning sequence that has been identified to 

address short-term carryover effects is entitled the "Intermediate 

Preconditioning Cycle". The Intermediate Preconditioning Cycle is 

intended to remove previously used fuel and emissions from a 

vehicle's fuel, exhaust, and combustion and evaporative emission 

control systems. A test vehicle that has used a fuel or additive 

other than the intended test product would need to perform this 

cycle before usable emissions could be generated from the new test 

product. The cycle could be performed anytime before emissions are 

generated using the new test product. However, once the 

Intermediate Preconditioning Cycle has been performed, the vehicle 

would need to use the test fuel or additive/fuel combination 
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exclusively, or else the Intermediate Preconditioning Cycle would 

need to be repeated. 

The Intermediate Preconditioning Cycle, shown in Figure 1, is 

based on a preconditioning sequence proposed by EPA's Office of 

Research and Development, Mobile Source Emissions Research Branch. 

Their cycle was developed for use in a vehicle emissions and fuel 

economy study for the U.S. Department of Energy, where it serves a 

similar purpose. The Intermediate Preconditioning Cycle contains 

one fuel drain and complete fuel fill and a minimum of one fuel 

drain and 40 percent fuel fill, which, when accompanied with the 

fuel drain and 40 percent fuel fill required in the preconditioning 

sequence of the Federal Test Procedure (FTP), brings to three the 

minimum number of times the fuel tank would be rinsed with the new 

test product before emission generation could begin. The need for 

additional fuel drains and fills, due to evaporative emission 

canister loading performance, is explained in a succeeding section 

of this memorandum. 

During the Intermediate Preconditioning Cycle the test vehicle 

is operated until 95 percent of a tank of fuel has been consumed. 

A light-duty gasoline fueled vehicle would accumulate approximately 

350 miles of driving from this amount of fuel. A limited amount of 

additional vehicle operation would also be encountered during the 

preconditioning phase of the FTP prior to emission generation. The 

fuel changes and vehicle operation requirements of the Intermediate 

Preconditioning Cycle are expected to remove short-term carryover 

effects from the fuel delivery system and from the engine/exhaust 

system. 

Evaporative Emission Canister Conditioning 

The effects of previously used fuels and/or additives on a 

vehicle's evaporative emission control system are expected to be 

thoroughly removed by the vehicle operation and bench purge 

sequences of the Intermediate Preconditioning Cycle. The bench 

purge sequence would be performed only on vehicles equipped with 

evaporative emission control canisters. During the bench purge 

sequence, the canister is removed from the vehicle and purged with 

300 F nitrogen at 20 liters/minute until the canister loses less 

than one gram of weight in 30 minutes. The purge process requires 

approximately 3-4 hours for a late model light-duty gasoline fueled 

vehicle and removes approximately 100-120 grams of adsorbed 

material. This amount of purge is expected to remove the vast 

majority of organic material adsorbed onto the canister material 

and thereby return the canister to much the same state it was in 

when it was new. Any fuel' or additive-related material remaining 

in the canister at completion of the bench purge sequence would be 

unlikely to be removed during vehicle operation. 

The purged canister is later installed on the test vehicle and 

reloaded with vapors produced by the new test fuel or additive/fuel 

mixture. Canister loading is performed in a Sealed Housing for 

Emission Determination (SHED) through the performance of 72-120 F, 
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Figure 1 - The Intermediate Preconditioning 

Cycle 

* Remove the canister from the vehicle and purge it with 300° F 

nitrogen at 20 1/min until the incremental weight loss of the 

canister is less than 1 gram in 30 minutes (this typically takes 3-

4 hours and removes 100 to 120 grams of adsorbed gasoline vapors). 

* Drain the fuel tank and fill it to capacity with the test fuel 

or additive/fuel mixture. 

* Operate the vehicle until at least 95% of the fuel tank 

capacity is consumed. 

* Return the "purged" canister to the vehicle. 

* Drain the fuel tank and fill it to 40% capacity with test 

fuel. 

* Perform 72« to 120° F, 2-hour fuel tank heat builds repeatedly 

as necessary to achieve canister breakthrough (drain and fill prior 

to each heat build). 
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two hour heat builds until "breakthrough" occurs. If breakthrough 

does not occur during the first heat build, additional heat builds 

are performed using fresh fuel each time until breakthrough occurs. 

Another option for canister preconditioning is to replace the 

vehicle's canister with a new canister. In this way one could be 

assured that there would be no carryover effects from previously 

used fuels and additives. The new canister would be purged and 

loaded as described above prior to installation in the test 

vehicle. EPA requests comment on the use of new canisters for this 

purpose. 

If adopted for use in the program, the Intermediate 

Preconditioning Cycle would be performed on a test vehicle anytime 

after the test product in the vehicle has been changed and before 

emissions are generated using the new test product. Of course, 

additional vehicle operation could be performed after the 

Intermediate Preconditioning Cycle has been completed to further 

condition the vehicle with the new test product, if so desired. 

Additional vehicle operation, as with all use of the test vehicle 

other than that specifically prescribed, would be done with the 

vehicle unmodified (e.g., the canister could not be removed for 

further bench conditioning). 

Long-Term Carryover Effects - Used Vehicles Acquired from the InUse Fleet 

Assessing long-term carryover effects from a vehicle generally 

requires a significant amount of effort. First it must be 

determined if and where a problem has occurred, and then a means 

must be developed to address the problem. Replacing damaged 

components may alter a vehicle's emission characteristics so that 

"correct" emissions (i.e., emissions that would have been generated 

if the long-term carryover effect was not present) may never be 

properly recovered. Thus, avoiding the need to address long-term 

carryover effects would be preferable. 

In order to assure that vehicles acquired from the in-use 

fleet and intended to generate emissions for the Fuels and Fuel 

Additives program are free from long-term carryover effects, 

comprehensive records concerning the candidate vehicle may be 

required. These might include complete and accurate records of 

fuel use, aftermarket fuel additive use, and vehicle maintenance. 

Eligible vehicles could be limited to those with a history of 

consistent use of deposit control additives and which were used 

only with products unlikely to cause long-term carryover effects 

from emissions (e.g., contain no atypical elements). A history of 

vehicle maintenance according to the owner's manual would be 

required. Also, preliminary characterization of the emissions 

generated from candidate vehicles might be required to verify that 

they are reasonably within expectation and are stable with time. 

Even with these precautions, the manufacturers must assume the risk 

that long-term carryover effects, which were undetected when the 

vehicle was screened and tested, might affect the emissions in a 
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negative way. 

With all of these requirements, added to the fact that the 

vehicle must be of the proper model, model year, and vehicle 

configuration, it may be easier to purchase new vehicles and 

accumulate mileage than to find and verify suitable in-use vehicles 

for the program. 

Long-Term Carryover Effects - Vehicles Used to Test More Than One 

Product 

Another alternative being considered for the Fuels and Fuel 

Additives Registration program would allow vehicles to generate 

emissions for more than one test product. Under this alternative, 

if a test vehicle was used to generate emissions for test products 

composed of only carbon, hydrogen, nitrogen, oxygen, and/or sulfur, 

concerns regarding long-term effects should be minimal and it would 

be reasonable to allow the vehicle to generate emissions for other 

test products after performing the Intermediate Preconditioning 

Cycle. If the test vehicle was used to generate emissions for a 

product that contained any element other than the five listed above 

(i.e., contained an "atypical element"), concerns regarding longterm effects would have to be addressed. In this case it would 

appear to be less prudent to allow these vehicles to generate 

emissions for other products for the Fuels and Fuel Additives 

Registration program. 

As with vehicles acquired from the in-use fleet, vehicles 

which were previously used for testing in this program should be 

free from long-term carryover effects if they are to be used for 

further emission generation. In this case, the question becomes 

whether long-term carryover effects can occur while a vehicle is 

used to generate emissions for emission characterization and 

biological testing purposes. To generate emissions for emission 

characterization purposes would probably require less than 50 miles 

of driving. Emissions for biological testing would require at 

least 6,300 miles for light-duty vehicle driving and over 330 hours 

of heavy-duty engine operation. 

The primary long-term carryover effects identified have been 

fuel deposits on the fuel injectors and intake valves, and 

combustion deposits in the engine and on exhaust emission control 

systems. However, the formation of fuel injector and intake valve 

deposits during emission generation would be unlikely, since the 

base fuel with which additives are mixed is required to contain a 

deposit control additive (for gasoline fuels). Also, almost all of 

the gasoline fuels sold in this country contain deposit control 

additives. Much of the risk of long-term carryover effects from 

exhaust emission deposits can be avoided if vehicles which generate 

emissions for fuels and additives that contain atypical elements 

are not permitted to generate emissions for other test products. 

Thus, the program can be structured so that it is unlikely 

that long-term emission carryover effects would occur while a 
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vehicle is being used to generate emissions for this program. 

However, with the large number of products and the wide range of 

potential effects they can have on a vehicle, it cannot be assured 

that there would be no short' or long-term carryover effects 

created during emission generation. Any risk of emission carryover 

effects involved with using vehicles previously used to test other 

products would have to be assumed by the fuel or additive 

manufacturer.