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OAR Box 1830 

Prepped by Ollie Stewart 

Document Number: 

172)IV-C-139 

Docket Number: 

A-87-11 

Printed 11/13/2008 7:21:00 AM Sheet 172 of 232 
^° SUr„ 

WS&. # 

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

e C<cP WASHINGTON. D.C. 20450 

OCT 2 7 1988 

T H E ADMINISTRATOR 

Honorable John D. Dingell 

Chairman, Subcommittee on 

Oversight and Investigations 

Committee on Energy and Commerce 

House of Representatives 

Washington, DC 20515 

Dear Mr. Chairman: 

Thank you for your August 9, 1988 letter concerning onboard 

refueling vapor control systems and EPA's proposed test 

procedures for both refueling and evaporative emissions 

measurement. Your letter contained many comments made by the 

Motor Vehicle Manufacturers Association (MVMA) in an August 4, 

1988 letter and questions of your own regarding these matters 

along with a June 28, 1988 letter to EPA from Toyota Motor 

Corporation concerning EPA's prototype onboard system. All of 

these concerns will be addressed in this letter. 

In addition, as you may recall, our August 19, 1988 

response to your June 13, 1988 letter responded to all but one 

set of questions. On page four of that letter, you raised 

questions regarding NHTSA comments to EPA in a letter dated 

April 12, 1988 from George L. Parker of NHTSA. In his letter, 

Mr. Parker raised concerns about potential vehicle operating 

and safety problems which may be created as a result of onboard 

controls or other regulatory factors related to fuel economy, 

emissions, and safety. Our August 19, 1988 letter promised a 

response to your questions upon completion of the safety 

analyses being prepared for the onboard reproposal. Our 

response with regard to these issues is at the end of this 

letter. 

In your letter you identify 10 contentions raised by MVMA 

about the new test procedures for refueling and evaporative 

emissions control presented by EPA at a June 30, 1988 

workshop. In order to address these contentions and the intent 

of the changes, the history and background of the test 

procedures, the need for changes and the methodology used in 

developing the procedures will be explained. 

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EPA's reasons for proposing changes to the test procedures 

are to ensure the control of refueling emissions and 

evaporative emissions, which includes what is now referred to 

as excess evaporative emissions and running losses. In 

addition, we have attempted to develop procedures which 

minimize the testing burden to the extent possible. Thus, in 

response to MVMA Contentions #1 and #2, these changes are not 

meant to force a particular design and in fact manufacturers 

would have design choices. 

In the past, EPA expected that manufacturers would choose 

integrated rather than separate refueling and evaporative 

control system designs because the engineering and production 

of integrated systems seems to be simpler and less costly. 

Because under most in-use conditions the integrated canister 

has extra capacity, EPA expected that integrated onboard 

systems would control a large portion of non-Federal Test 

Procedure (FTP) evaporative emissions (based on our 

understanding of the scope of the problem at that time) without 

additional regulatory action. At the time of the August 1987 

proposal, EPA had not quantified the exact percentage of 

non-FTP evaporative emissions that integrated onboard systems 

would control but assumed that each vehicle model would provide 

control roughly equivalent to its refueling load. 

The comments received and new information obtained since 

August 1987 convinced EPA that three major changes had to be 

made to the test procedures in order to represent actual in-use 

emissions in a laboratory test. First, there was a need to 

simplify the test procedure for integrated systems in order to 

make it less resource intensive. Second, manufacturers' 

comments indicated that many would use separate rather than 

integrated system designs. This necessitated a review of the 

test procedure for separate systems to ensure that they would 

provide the same level of emission control as integrated 

systems. Finally, EPA generated new information on the 

magnitude of running loss and non-FTP emissions and their 

relationship to the ozone problem. Since these constitute a 

much larger environmental impact than was previously presumed, 

there was a clear need to revise the evaporative test procedure 

regardless of whether refueling controls are adopted. 

Specific changes were made to the test procedures in order 

to address each of these needs. First, we were able to 

simplify the canister conditioning sequence of the integrated 

refueling test procedure without forfeiting any evaporative or 

refueling control. Second, a vapor containment requirement and 

a fuel cap removal step were incorporated into the integrated 

test procedure to provide control of running losses. Third, 
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since the comments indicated many manufacturers would use 

separate systems, the non-integrated and/or evaporative system 

only test procedure was revised to ensure in-use emission 

control equivalent to integrated systems. This was done by 

incorporating the same running loss procedure and by adding two 

extra diurnals to the evaporative test sequence to provide 

control capacity for non-FTP emissions equivalent to that 

provided by an integrated system canister. Therefore, contrary 

to MVMA Contention #3 that EPA is forcing integrated systems, 

the test procedures for integrated and separate system designs 

were carefully developed so that vehicles tested on either 

procedure would provide the same evaporative emission control 

performance in-use. 

The methodology used in developing these revised test 

procedures included modeling of real world conditions. Thus, 

Contentions #5 and #6, that real world conditions were not 

adequately examined and that EPA's methodology was predicated 

on achieving equivalent canister sizes with both procedures, 

are not true. Our goal was to assure equivalent in-use 

performance for all certified systems. This does not always 

require the same canister size, given the relationship between 

size and purge rate. Contention #4 is correct -- EPA had not 

conducted any testing using the new procedures prior to the 

workshop. However, our modeling results appear sufficiently 

reliable so that we believe that the revised procedures will 

result in equivalent control from any type of control system 

used. Additionally, in early September we sent copies of the 

revised procedures, in regulatory format, to vehicle 

manufacturers for comment. Of course, any interested party 

will have an opportunity to comment on the procedures since 

they will be included in our reproposal. 

In conclusion, the test procedures are driven by 

conditions encountered by vehicles in actual use, not by an 

attempt by EPA to force a particular design. We are proposing 

performance standards which permit manufacturers to retain 

design choices. 

Another MVMA comment concerns the test procedure 

requirement that the canister begin the preconditioning in a 

loaded-to-breakthrough state. It is important to note that 

this is not a change to the test procedure as it was also 

required in both the volatility and refueling 1987 proposals. 

MVMA's contention #8 argues a lack of field data demonstrating 

canister saturation in-use. We disagree. Based upon data for 

in-use fuel RVP's, tank temperatures and driving patterns, it 

seems clear to EPA that canisters are regularly reaching 
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saturated states in-use. The fact that nearly 20 percent of 

the vehicle fleet experiences 2 or more consecutive diurnal 

loadings without being driven provides some evidence. Also, 

the 1985 API report #4393 "Survey of Evaporative Emission 

Systems Condition of In-Use, High Mileage Automobiles" found 

that 4 of 20 (20%) of the randomly chosen, in-use, carbureted 

vehicles tested had canister loads between 75 to 100 percent of 

capacity. For fuel-injected vehicles, 4 of 32 (12.5%) had the 

canister loaded in that range. 

The remaining MVMA Contentions (#7, #9 and #10) concern 

the suggestions that a large canister will emit more vapor than 

a small canister when both are loaded to a certain percentage 

of capacity, purged at the same rate for a given amount of time 

and then reloaded with a given quantity of hydrocarbon vapors. 

Some manufacturers have raised the idea that because EPA's test 

sequence begins with a canister loaded to breakthrough, the 

purge and loading phenomena requirements may be unintentionally 

encouraging the use of canisters just large enough to pass the 

test. Based upon our understanding of canister performance 

characteristics, we believe that the best performing systems 

in-use will have the smallest canister sizes which are able to 

meet the proposed requirements. This is because smaller 

canisters will have increased purge rates compared to larger 

canisters and will recover their control capacity more quickly 

following a highly loaded condition. Therefore, we find it 

desirable to encourage use of smaller canisters. 

Overall, the importance of the canister loading step 

deserves to be emphasized since it is this requirement which 

ensures that certified systems will have adequate purge to 

control generated vapors and to recover from highly loaded 

states. In-use conditions often cause canister loading beyond 

breakthrough and the proposed test procedures will ensure that 

control systems will recover from such loading quickly when 

driven. 

The remainder of your letter contains many questions on 

the characteristics and effects of running losses. The source 

of the article which appeared in the August 5, 1988 edition of 

Inside EPA is unknown. EPA does not agree with all of the 

information contained in the article. There is no EPA "staff 

paper* as referred to in the article. We are enclosing all 

documents related to running losses that are currently in (or 

being processed to be entered in) the public dockets for the 

volatility (A-85-21) or refueling (A-87-11) rulemakings. EPA 

is still gathering information on this topic and will submit 

additional relevant papers to these dockets as they become 

available. Such information is now being compiled in support 

of our upcoming reproposal and will be available by the time 

the reproposal is published. 
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A quantification of the running loss problem was made by 

EPA using data obtained from vehicle testing based on various 

RVPs, temperatures and trip lengths representative of in-use 

conditions. The data were weighted to reflect the percentage 

of vehicles which experience the various in-use conditions. 

The weighted average of these data is 1.7 grams per mile. 

(Under certain conditions, vehicles with running losses as high 

as 10 grams per mile were measured in our testing.) If 

uncontrolled, this translates to 1.85 million tons per year of 

volatile organic compounds (VOCs) due to running losses in the 

year 2010 assuming 11.7 RVP fuel. This amounts to 17.5 percent 

of the total nationwide VOC inventory of 10.55 million tons per 

year in 2010 which includes both excess evaporative and running 

loss emissions. Running losses are exacerbated by conditions 

typical of ozone violation days (such as high fuel tank 

temperatures) when control is needed the most. Fewer running 

losses occur at lower volatility levels but even with 9.0 RVP 

fuel a vapor containment requirement is necessary to control 

these emissions. 

Running losses are best controlled by a combination of 

vehicle improvements and volatility controls. Integrated 

onboard systems help to provide the necessary control or it can 

also be attained separately from improvements to evaporative 

control systems. However, once sufficient capacity is added to 

evaporative systems to handle these emissions, only small 

enhancements are needed to also control refueling emissions. 

In summary, although available data are limited, running 

losses appear to be a substantial source of VOCs. We have been 

studying them for some time and were therefore able to take 

direct action once the scope of the problem became clear. 

However, running losses are not the "smoking gun" of the ozone 

problem as claimed in the Inside EPA article. 

Your letter contains several more questions concerning 

running losses. First, the Automotive/Oil industry proposal to 

limit in-use gasoline to 10.5 RVP and then later increase 

certification test fuel to 10.5 RVP would only address a 

portion of the running loss and non-FTP evaporative emissions 

problem. If this proposal &Ss^ implemented, there would still 

be a significant amount of uncontrolled emissions which would "*TlK"jtv( 

likely necessitate a further eventual reduction of in-use fuel 

RVP. Furthermore, the necessary vehicle changes needed to 

certify on 10.5 RVP fuel and effectively control remaining 

excess evaporation and running loss emissions would be 

considerably more costly and technically challenging than at 9 

RVP. 

CM.'< ^ t'tr7' 
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Next, you inquire about the safety and fuel economy 

ramifications of controlling running losses and excess 

evaporative emissions. We see no significant safety issues 

related to the control of these emissions. However, if one 

accepts the premise that venting these vapors into the engine 

compartment or under the vehicle as occurs in vehicles today 

constitutes a safety problem, then there is some safety benefit 

to the proposed control since the vapors would be completely 

contained and routed only to the engine. As for the fuel 

economy ramifications of running losses and excess evaporative 

emission controls, our preliminary estimate is that an average 

$8.00 lifetime fuel recovery credit will be attained by 

light-duty vehicles. A complete accounting of these benefits 

will be contained in the reproposal. 

Your final question concerning running losses is whether 

or not this information has been shared with the National 

Highway Traffic Safety Administration (NHTSA) as part of the 

new procedures under the Memorandum of Understanding (MOU). On 

August 25,1988 NHTSA was briefed on our reproposal and safety 

study. This briefing included a presentation on running 

losses. Our draft reproposal has also been forwarded to them 

for review as part of the MOU. 

EPA has received and reviewed the June 28, 1988 letter 

from Toyota Motor Corporation containing their comments on 

EPA's prototype onboard refueling control system. The purpose 

of this system was to demonstrate the concept of a simple 

refueling control design. EPA has asked for any suggestions 

for improvements which could be made in the effectiveness and 

safety of this system. Although EPA did not attempt to 

anticipate every potential problem with its prototype design, 

it seems that all of the problems raised by Toyota are 

addressable. It is difficult to accept all of Toyota's 

criticisms as valid since they have not actually built and 

tested the prototype system, but simply just critiqued the 

design "on paper". In any case, Toyota's comments and others 

like them will be addressed as we proceed with this rulemaking. 

Finally, I would like to respond to your June 13, 1988 

questions concerning NHTSA's comments on potential vehicle 

operating or safety problems related to emission controls or 

other vehicular regulatory factors. To begin with, it should 

be noted that the concerns raised by NHTSA are design 

considerations that must be taken into account anytime a design 

change is to be made regardless of whether the change is 

imposed by regulation or self-initiated by a manufacturer. 

These concerns are not unique to emission controls or other 

regulatory requirements. Manufacturers must routinely consider 
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the potential effects of design modifications made from one 

model year to another, even if the change is introduced for 

performance or safety improvements. All design changes 

introduce the risk of potential unforeseen problems, but this 

does not (nor should it) prohibit any design changes from ever 

being implemented. 

As a general rule, EPA always attempts to consider the 

potential effects of a new control device on the performance of 

other vehicle systems or functions, especially any specific 

concerns raised by commenters. In the case of the onboard 

rulemaking, we have analyzed this issue in great detail. Our 

analysis shows that emission control systems like onboard 

(i.e., evaporative systems) have created only a minimal number 

of problems in the past, and of the few problems that did 

occur, only minor consequences resulted. Overall, it is 

reasonable to expect that onboard systems will demonstrate a 

similar level of performance. 

It is true that test procedures and leadtime do have some 

effect on the degree to which onboard systems interact with 

other vehicle systems or functions. We will thoroughly 

evaluate all comments we receive on these issues. 

As far as the role of automotive part suppliers, we rarely 

have direct contact with them. While we occasionally discuss 

component design/function with suppliers, the role and 

responsibility of a supplier to provide an acceptable product 

is dictated by the business relationship developed between a 

manufacturer and the supplier. EPA is independent from this 

relationship. 

Your June 13 letter also asked to what extent the MOU will 

help to address the issues discussed above. As a matter of 

past practice, NHTSA has always had the opportunity to comment 

on actions which have the potential to affect motor vehicle 

safety. The MOU will provide a more formal process to ensure 

that all important safety-related issues are taken into 

consideration by NHTSA and EPA. 

Finally, we would like to emphasize that safety is a key 

factor in any system or component design and development. This 

issue is not limited to emission control systems; nor are the 

potential problems that can result. NHTSA's records indicate 

that a large variety of problems with numerous vehicle systems 

result in recalls. NHTSA would be in the best position 
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to discuss the types of problems associated with various 

recalls. Our experience with emission control systems has 

shown that these systems do not create unique or unusual 

problems. If anything, the consequences of an emission control 

system failure are relatively minor in comparison to other 

system failures. Further, NHTSA's records indicate that 

emission control systems account for only a very small fraction 

of the number of problems that do occur. Overall, emission 

control systems appear to have been implemented safely. 

Sincerely, 

lee M. Thomas 

Lee M. Thomas 

Enclosures 

cc: The Honorable Diane K. Steed 

Administrator, NHTSA