United States

Environmental Protection

Agency

Air and Radiation EPA420-P-98-012

November 1998

Modeling Diurnal and

Resting Loss Emissions

from Vehicles Certified

to the Enhanced

Evaporative Standards

 Printed on Recycled Paper
EPA420-P-98-012

- Draft -

Modeling Diurnal and Resting Loss Emissions from

Vehicles Certified to the Enhanced Evaporative

Standards

Larry C. Landman

Report Number M6.EVP.005

November 23, 1998

U.S. EPA

Assessment and Modeling Division

National Vehicle Fuel and Emissions Laboratory

2000 Traverwood Drive

Ann Arbor, Michigan 48105-2425

734-214-4939 (fax)

mobile@epa.gov

NOTICE

These reports do not necessarily represent final EPA decisions

or positions. They are intended to present technical analysis

of issues using data which are currently available. The

purpose in release of these reports is to facilitate the

exchange of technical information and to inform the public of

technical developments which may form the basis for a final

EPA decision, position or regulatory action.
ABSTRACT

This document reports on EPA's proposed methods of

estimating the resting loss and diurnal emissions from vehicles

certified to the enhanced evaporative standards (i.e., some 1996

through 1998 and all 1999 and newer vehicles). Since this draft

report is a proposal, its analyses and conclusions may change to

reflect comments, suggestions, and new data.

Please note that EPA is seeking comments that might aid us

in modeling any aspect of resting loss or diurnal evaporative

emissions.

Comments on this report and its proposed use in MOBILE6

should be sent to the attention of Larry Landman. Comments may

be submitted electronically to mobile@epa.gov, or by fax to (734)

214-4939, or by mail to "MOBILE6 Review Comments", US EPA

Assessment and Modeling Division, 2000 Traverwood Drive, Ann

Arbor, MI 48105. Electronic submission of comments is

preferred. In your comments, please note clearly the document

that you are commenting on, including the report title and the

code number listed. Please be sure to include your name,

address, affiliation, and any other pertinent information.

This document is being released and posted. Comments will be

accepted for sixty (60) days from the posting date. EPA will

then review and consider all comments received and will provide a

summary of those comments, and how we are responding to them.
***DRAFT***

Modeling Diurnal and Resting Loss Emission from Vehicles Certified

to the Enhanced Evaporative Standards

Report Number M6.EVP.005

Larry C. Landman

U.S. EPA Assessment and Modeling Division

1.0 Introduction

Evaporative emissions of hydrocarbons (HC) are a significant

portion of the emissions estimated in the MOBILE model. In

recently released draft reports (M6.EVP.001 and M6.EVP.002), the

US Environmental Protection Agency (EPA) proposed methods of

estimating resting loss and diurnal emissions from 1995 and older

model year vehicles. These estimates were based on the results

of real-time diurnal (RTD) tests of in-use vehicles in which the

ambient temperature cycled over a 24-degree Fahrenheit range to

simulate in real-time the daily heating and cooling that parked

vehicles experience over a 24-hour period.

Beginning with the 1996 model year, manufacturers were

required to certify twenty percent of their vehicles using a new

"enhanced" evaporative testing procedure; that percentage is

scheduled to increase to one hundred percent by the 1999 model

year. The phase-in percentages are given below in Table 1

(copied from 40 CFR 86.096-8).

Table 1

Phase-In of Vehicles with

Enhanced Evaporative Controls

Model Year Percentage

1995 0%

1996 20%

1997 40%

1998 90%

1999 100%

In order to meet the enhanced evaporative standards,

manufacturers have implemented a number of changes, including

(but not limited to):

• "quick connects" that reduce the possibility of

improper assembly when the vehicle is serviced,
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• advanced materials that are less permeable, less

susceptible to puncture, and more durable (i.e.,

elastomeric materials used in hoses and connectors),

• improvements made to the purge system (to enable the

vehicles to pass both the running loss test and the

multi-day diurnal test),

• tethered gas caps, and

• improved fractional-turn gas caps.

Since these changes are expected to result in improved control of

evaporative emissions, EPA proposes to use a separate set of

estimates of both resting loss and diurnal emissions for these

vehicles.

Unlike the analyses for older vehicles that were based on

results of tests of in-use vehicles, the analyses in this report

generally are not based on testing of these in-use 1996 and newer

vehicles because EPA has very few test results on that segment of

the in-use fleet. In this report, EPA proposes methods of

estimating the resting loss and diurnal emissions from these inuse 1996 and newer vehicles based on RTD testing of older but

similar vehicles.

2.0 Data Sources

EPA proposes to base its estimates of resting loss and

diurnal emissions on the results of real-time diurnal (RTD)

tests. At the time of this analysis, EPA had two available

sources of RTD test data on vehicles that were certified to the

new evaporative standards:

1) a summary of RTD testing used by the ARB and by the EPA

to certify new (1996-97 model year) vehicles (30 and 35

vehicles, respectively) and

2) results of RTD testing performed by Mercedes-Benz on six

of its 1996 model year vehicles (at two years of age) as

part of the proposed Compliance Assurance Program (CAP

2000).

However, the test data (from these two sources) on the 1996

and newer vehicles have two serious limitations:

 • First, all of the 1996 and newer vehicles from these two

sources had properly functioning evaporative control

systems. Since it is likely that some similar in-use

vehicles during the course of their useful life would
-3- DRAFT

develop malfunctions in their evaporative control

systems, EPA's analysis is limited by not having test

results on such malfunctioning in-use vehicles.

 • Secondly, all of these RTD tests were performed using a

single test fuel with a Reid vapor pressure (RVP) of 9.0

psi and using a single temperature cycle (72 to 96

degrees Fahrenheit). Since, all the RTD testing

performed on these 1996 and newer vehicles had been run

at a single combination of temperature cycle and fuel

volatility, EPA is limited in using those data to predict

evaporative emissions at other combinations of

temperature cycle and fuel volatility.

To compensate for those significant limitations, EPA

proposes to supplement those data with the results of RTD testing

of older vehicles that were not certified to the enhanced

evaporative standards. Two sources of those test results were:

3) RTD testing performed on 119 in-use 1971-95 model year

vehicles for EPA by its testing contractor and

4) RTD testing performed on 151 in-use 1971-91 model year

vehicles for the Coordinating Research Council (CRC).

Although none of the 270 in-use vehicles tested in the EPA

or CRC programs (sources 3 and 4) had been certified to the new

evaporative standards, the combined sample does include both:

 • in-use vehicles with malfunctions in their evaporative

control systems

as well as

 • vehicles for which the RTD test were performed over three

different temperature cycles and using fuels with

different RVPs.

A fifth source of information on these vehicles certified to

the enhanced evaporative standards was:

5) an analysis of evaporative emissions (not explicitly

based on RTD testing) of vehicles certified to the

enhanced evaporative standard presented to the California

Air Resources Board (ARB) (in December 1997) by the

American Automobile Manufacturers Association (AAMA) and

the Association of International Automobile Manufacturers

(AIAM).

In Section 3.0, EPA proposes how to use RTD test results

from some of the older (i.e., 1990-95) vehicles (i.e., from
-4- DRAFT

sources 3 and 4) to compensate for the limitations of the test

results on the 1996 and later vehicles.

3.0 Simulating Test Data from In-Use 1996 and Newer Vehicles

The MOBILE model must be able to estimate the resting loss

and diurnal evaporative emissions from the 1996 and newer

vehicles over a variety of daily temperature cycles and with a

variety of fuel RVPs. However, as noted in the preceding

section, the only test data on those vehicles available at this

time are with a single combination of fuel volatility (RVP of 9.0

psi) and daily temperature profile (i.e., ambient temperatures

cycling between 72 and 96 degrees Fahrenheit). EPA, therefore,

proposes to use results of RTD tests on older vehicles (i.e.,

model years 1990 through 1995) to estimate the effects on the

actual "base line" emissions (from source 1) of different fuel

volatility and different temperature cycles on the resting loss

and diurnal evaporative emissions of the 1996 and newer vehicles.

For the purpose of characterizing the effects of varying the

fuel RVP and/or the temperature cycle, EPA proposes to continue

(from the previous analyses) the approach of dividing the in-use

fleet into four strata. The first of these strata consists of

vehicles having substantial leaks of liquid gasoline (as opposed

to simply vapor leaks); these vehicles were labeled "gross liquid

leakers." EPA proposed (in M6.EVP.001) using as a definition for

such vehicles the requirement that the hourly resting loss (at 72

degrees Fahrenheit) be at least 1.0 grams per hour of HC. EPA

realizes that such a definition could result in potentially

ignoring a vehicle having a substantial leak that is apparent

only when the engine is operating (e.g., some fuel line leaks).

While neither the purge test nor the pressure test measures

evaporative emissions, a vehicle’s failure on either test is

indicative of potential malfunctions of the vehicle's evaporative

control system. Additionally, the recruitment of the vehicles in

the third data source was intentionally skewed to recruit a

larger proportion of vehicles with potentially malfunctioning

evaporative control systems (i.e., a stratified random

recruitment). Therefore, the results of any analysis must be

weighted to correctly represent the entire in-use fleet. Thus,

the analyses will be stratified to match the recruitment process.

EPA proposes to use the results on the purge and pressure tests

to define the remaining three strata. This approach produces the

following three additional strata each containing:

1) vehicles that pass both the purge and pressure tests,

2) vehicles that fail the pressure test (regardless of their

performance on the purge test), and
-5- DRAFT

3) vehicles that fail only the purge test.

As discussed previously, it is necessary to make use of the

RTD tests performed on older vehicles to predict the effects on

the evaporative emissions of changes to the temperature cycle or

the fuel RVP. In order to make use of those RTD tests on some of

those 270 vehicles, EPA made the following assumptions:

1) The 1996 and newer vehicles are expected to be port fuel

injected (PFI); therefore, EPA chose the 1990 to 1995

model year vehicles that were equipped with PFI as

appropriate surrogates. (RTD tests on a total of 25

vehicles were found and appear in Appendix A.)

2) RTD tests were performed on 65 1996-97 model year

(enhanced evaporative procedure certified) vehicles using

a daily temperature profile in which the ambient

temperatures cycled between 72 and 96 degrees with a fuel

having an RVP of 9.0 psi (data source number 1). EPA

proposes to use those test results to obtain baseline

evaporative emissions for these "properly functioning"

vehicles for that specific temperature cycle and for that

test fuel. To "correct" those baseline values for

temperature and RVP changes, EPA identified, in its RTD

data base (data source 3), ten 1990-95 model year PFI

vehicles that:

 • passed both the purge and pressure tests,

 • had a RTD test performed using a daily temperature

cycle ranging between 72 and 96 degrees with a fuel

having an RVP of 9.0 psi (i.e., at the baseline

conditions used for the vehicles in data source 1),

and

 • had one or more additional RTD tests performed using

a fuel with an RVP of 6.8 psi.

3) EPA believes that the RTD emissions from malfunctioning

enhanced evaporative control vehicles (i.e., vehicles

that developed problems with their evaporative control

systems) will be similar to the RTD emissions from the

1990 to 1995 model year vehicles that also develop

problems with their evaporative control systems. That

is, those 1996 and newer model year vehicles that had

failed either EPA's purge or pressure tests are expected

to have evaporative emissions similar to those 1990 to

1995 model year PFI vehicles that also failed the same

test.
-6- DRAFT

Thirteen such vehicles were identified in the combined

EPA/CRC sample (eight of the 13 failing only the purge

test and the remaining five failing the pressure test).

(See Appendices B and C, respectively.) EPA proposes to

use these 13 vehicles to estimate the effects on both the

resting loss and diurnal emissions for the malfunctioning

enhanced evaporative control vehicles of changes to the

temperature cycle and/or to the RVP of the fuel.

4.0 Analysis

As noted in two previous reports (M6.EVP.001 and

M6.EVP.002), EPA proposes to use the results of the RTD test to

model two distinct mechanisms of evaporative emissions:

1) "Resting loss" emissions are always present, regardless

of vehicle activity, and are relatively weakly related to

the ambient temperature as opposed to diurnal emissions

which are related to the rise in temperature.

The earlier reports calculated the hourly resting loss

emissions to be the mean of the RTD emissions from hours

19 through 24 at the nominal temperature for hour 24.

This method permitted EPA to estimate the hourly resting

loss emissions at three distinct temperatures (60, 72,

and 82 degrees Fahrenheit). In those analyses, resting

loss emissions were determined to be independent of the

RVP of the test fuel.

2) "Diurnal" emissions are the pressure-driven emissions

resulting from the daily increase in temperature.

The diurnal emissions were calculated by first estimating

the resting loss value for the ambient temperature at

each hour of the 24-hour cycle, and then subtracting that

temperature-adjusted resting loss estimate from the RTD

hourly test results.

This approach permitted EPA to analyze separately the relatively

constant resting loss emissions and the (pressure driven) diurnal

emissions.
-7- DRAFT

4.1 Resting Loss Emissions

4.1.1 Resting Loss Emissions of Properly Functioning Vehicles

In Section 3.0, EPA proposed using data from 10 of the older

(1990-95) model year vehicles to characterize the effects on the

baseline evaporative emissions of altering either the temperature

cycle or the fuel RVP for the 1996 and newer model year vehicles

with properly functioning evaporative control systems. Since the

resting loss emissions were calculated as the average hourly

emissions during hours 19 through 24 of the RTD test, to

calculate the baseline resting loss emissions (from the RTD tests

of the 65 vehicles in data source 1) we need the emissions to be

measured and reported hourly (or at least in six hour intervals).

Unfortunately, the test results in data source 1 were reported

for each 24-hour period; therefore, EPA does not currently have

the necessary baseline resting loss data for that stratum. Thus,

EPA must determine not only the correction factors but also the

baseline resting loss values.

EPA believes that, while that sample of 10 vehicles

(proposed in Section 3.0) is appropriate for estimating the

effects of varying either the temperature cycle or fuel RVP, the

actual emission values are not necessarily representative of

actual 1996 and newer vehicles. Hence, those vehicles might not

be appropriate for estimating the baseline resting loss

emissions. To find an appropriate subset of the 10-vehicle

sample composed of vehicles whose emissions are representative of

the 1996 and newer vehicles, we examined the data from the 65

certification vehicles (from data source 1). Those vehicles had

a mean RTD emission for the first 24-hours of a 72-hour RTD test

of 0.745 grams (for a temperature cycle from 72 to 96 degrees and

with a 9.0 RVP fuel). The corresponding median RTD for those 65

tests was 0.635 grams. In the 10-vehicle sample, the five

vehicles that had RTD emissions of at most 1.0 grams (over the

same temperature cycle and using the same test fuel) had mean and

median RTD emissions of 0.726 and 0.653 grams, respectively.

This sample of five vehicles consisted of four light-duty

vehicles and one light-duty truck. Based on the similarity of

RTD emissions as indicated by both the means and medians of the

65-vehicle sample and this five-vehicle sample, EPA proposes to

use the smaller sample to estimate both the baseline and the

temperature corrections of the hourly resting loss emissions of

the properly functioning 1996 and newer vehicles.

We then estimated the hourly resting loss associated with

60, 72 and 82 degrees Fahrenheit for each of those five vehicles

(see Appendices A and D) and regressed the resting loss emissions

against the ambient temperatures to obtain Table 2. A linear

(rather than exponential or polynomial) regression was used for
-8- DRAFT

consistency with the modeling of resting loss emissions of the

pre-1996 vehicles (see reports M6.EVP.001 or M6.EVP.002).

Table 2

Linear Regression of Hourly Resting Loss Emissions

(Vehicles Passing Both Purge and Pressure Tests)

Dependent variable is: Resting Loss

No Selector

R squared = 40.2% R squared (adjusted) = 35.6%

s = 0.0061 with 15 - 2 = 13 degrees of freedom

Source Sum of Squares df Mean Square F-ratio

Regression 0.000320 1 0.000320 8.72

Residual 0.000477 13 0.000037

Variable Coefficient s.e. of Coeff t-ratio prob

Constant -0.027859 0.0125 -2.23 0.0441

Temperature 0.000514 0.0002 2.95 0.0112

Converting that linear regression analysis into an equation

produces equation (1) below:

Hourly Resting Loss (grams/hr) = -0.027859 + [0.000514 * Temperature (°F)] (1)

EPA proposes to use equation (1) to estimate the hourly resting

loss emissions (in grams per hour) of that portion of the fleet

of 1996 and newer model year vehicles with properly functioning

evaporative control systems.

Equation (1) predicts that the mean hourly resting loss

emissions (for the fleet of 1996 and newer model year vehicles

with properly functioning evaporative control systems) would be

negative for all ambient temperatures below or equal to 54.2

degrees Fahrenheit. EPA will assume that the resting loss

emissions at those temperatures will be zero grams per hour.

Equation (1) also predicts that the mean hourly resting loss

emissions (for the fleet of 1996 and newer model year vehicles

with properly functioning evaporative control systems) at 72

degrees Fahrenheit would be 0.009149 grams per hour. Repeating

that calculation for each hour of the full 24 hours of the RTD

test, and then adding the 24 "temperature corrected" hourly
-9- DRAFT

resting loss emissions produces the full day's total resting loss

for the fleet of 0.3596 grams per vehicle. Subtracting that

value from the mean RTD test results (0.745 grams per day) yields

total diurnal emissions of 0.385 grams per vehicle per day (which

will be used as the baseline diurnal emission in Section 4.2.1).

4.1.2 Resting Loss Emissions of Malfunctioning Vehicles

In Section 3.0, EPA proposed using five 1990-95 model year

vehicles to represent the 1996 and newer model year vehicles that

failed the pressure test (four of which were tested over all

three temperature cycles) and using eight vehicles to represent

the 1996 and newer model year vehicles that failed the purge test

(see Appendix D). Repeating the approach used with the vehicles

passing both the purge and pressure tests, we estimated the

hourly resting loss associated with ambient temperatures of 60,

72 and 82 degrees Fahrenheit for each of those 12 vehicles that

were tested over all three temperature cycles. We then regressed

the resting loss emissions against the ambient temperatures

within each of these two strata:

• the stratum represented by the four vehicles failing

the pressure test (see Appendices C and D) and

• the stratum represented by the eight vehicles failing

the purge test (see Appendices B and D).

Additionally, we combined the test results on all 12 vehicles to

create the single stratum of vehicles failing either the purge or

the pressure test, and we again regressed the resting loss

emissions against the ambient temperatures within that third

stratum.

In each of those three strata, the differences in resting

loss emissions from vehicle-to-vehicle exceeded the differences

in emissions resulting from changes in ambient temperature. This

resulted in each regression analysis producing both low R-squared

values and indicated that temperature was not a statistically

significant variable (an unlikely situation). In order to obtain

a model for hourly resting loss emissions based on temperature,

we attempted to reduce the effect of the vehicle-to-vehicle

variability by averaging the resting loss emissions for all 12

vehicles at each of the three temperatures (i.e., producing only

three temperature / resting loss pairs) and then regressing those

three data points. This regression produced an R-squared of

100.0 percent. Since MOBILE6 is designed to predict only the

mean emissions, EPA proposes to use this regression to estimate

the means of the hourly resting loss emissions (in grams per

hour) of the 1996 and newer model year vehicles with
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malfunctioning evaporative control systems. Converting that

linear regression analysis into an equation yields:

Hourly Resting Loss (grams/hr) = -0.076535 + [0.001603 * Temperature (°F)] (2)

Equation (2) predicts that the mean hourly resting loss

emissions (for the fleet of 1996 and newer model year vehicles

with malfunctioning evaporative control systems) will be negative

for all ambient temperatures below 47.8 degrees Fahrenheit. EPA

will assume that the resting loss emissions at those temperatures

will be zero grams per hour.

4.1.3 Resting Loss Emissions of "Gross Liquid Leakers"

In a previous report (M6.EVP.001), EPA proposed that, for

the pre-1996 vehicles classified as gross liquid leakers, the

resting loss emissions are virtually independent of temperature,

averaging a constant 8.84 grams per hour. EPA proposes to

continue that assumption for the 1996 and newer vehicles that

were certified to the enhanced evaporative standard.

4.2 Diurnal Emissions

In Section 4.1, equation (1) indicates that for each one

degree (Fahrenheit) increase in ambient temperature, there is a

corresponding increase of 0.000514 grams per hour in the hourly

resting loss emissions. Applying that temperature correction to

each hour of the full 24 hours of the RTD test, and then adding

the 24 "temperature corrected" hourly resting loss emissions

produces the full day's total resting loss (in grams). This

approach predicts that the full day's resting loss emissions (in

grams) would be 24 times the hourly resting loss (calculated at

the day's low temperature) plus 0.140 grams. Subtracting that

quantity from each of the RTD test scores of the ten properly

functioning vehicles yields the estimated diurnal emissions on

each of the 48 RTD tests on those 10 vehicles.

Repeating this procedure for the 13 malfunctioning vehicles

but using the coefficient (0.001603) from equation (2), predicts

that the full day's resting loss emissions (in grams) would be 24

times the hourly resting loss (calculated at the day's low

temperature) plus 0.437 grams. Subtracting that quantity from

each of the RTD result score of the 13 malfunctioning vehicles

yields the estimated diurnal emissions.

Two factors that significantly affect a vehicle's diurnal

emissions (see M6.EVP.001 and M6.EVP.002) are:

• the Reid vapor pressure (RVP) of the test fuel and
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• the temperature cycle, as represented by the

combination of the cycle's midpoint temperature and

temperature range.

In previous reports (M6.EVP.001 and M6.EVP.002), we created a

single parameter that incorporated all of those factors. That

new parameter is based on the fuel's vapor pressure (VP). In

those reports, we used both the RVP of the fuel and the ambient

temperature to estimate the vapor pressure curve. (The RVP is

the VP measured at 100 degrees Fahrenheit.) The VP was then used

to create that new parameter which was used as the variable on

which diurnal emissions were calculated. That new parameter is

defined by the following formula, equation (3).

VP_Product_Term = (VPHIGH - VPLOW) * (VPHIGH + VPLOW) / 2 (3)

Where

VPHIGH is the VP (in kiloPascals) associated with the

day's high temperature.

VPLOW is the VP (in kiloPascals) associated with the

day's low temperature.

The analyses in those earlier reports modeled the diurnal

emissions as functions of both that VP product term and the RVP

of the test fuel.

4.2.1 Diurnal Emissions of Properly Functioning Vehicles

In Section 3.0, EPA proposed using the 25 1990-95 model year

vehicles listed in Appendix A to model the diurnal emissions from

the 1996 and newer model year vehicles with properly functioning

evaporative control systems. However, only five of those 25

vehicles were tested at each of the six possible temperature and

RVP combinations. (While a sample of five vehicles is relatively

small, the disadvantages of that small size are offset by having

the identical sample of vehicles at each of those six testing

combinations which eliminates some of the problems caused by

having test results on a different group of vehicles at each of

those combinations.)

The approach used in the earlier reports was to first

regress the mean diurnal emission emissions against the RVP of

the test fuel combined with either the VP product term (in

kiloPascals squared) or the square of that product term. Those

six mean values (for the five vehicles) are given in the

following table.
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Temperature Fuel VP_Product Mean

 Cycle RVP Term Diurnal

 60 to 84 6.8 375 0.616

 72 to 96 6.8 567 0.768

 82 to 106 6.8 789 1.781

 60 to 84 9.0 655 0.535

 72 to 96 9.0 969 1.084

 82 to 106 9.0 1,324 4.008

These means do confirm two reasonable patterns:

• For each temperature cycle, as the fuel volatility

increases, so do the diurnal emissions.

• For a given fuel, as the temperature cycle increases,

so do the diurnal emissions.

This confirms that the diurnal emissions, rather than being a

function of the VP product term alone, might be a function of

that term in combination with the fuel RVP or temperature cycle.

A number of different combinations were tested, and the one that

proved most successful in predicting the diurnal emissions was a

regression of the logarithm diurnal emissions against:

• the RVP of the test fuel (in psi) and

• the vapor pressure product term (in kiloPascals

squared).

The results of that regression analysis are given in Table 3.
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Table 3

Linear Regression of Mean Diurnal Emissions

(Vehicles Passing Both Purge and Pressure Tests)

Dependent variable is: Ln_Diurnal

No Selector

R squared = 96.6% R squared (adjusted) = 94.3%

s = 0.1810 with 6 - 3 = 3 degrees of freedom

Source Sum of Squares df Mean Square F-ratio

Regression 2.78802 2 1.39401 42.5

Residual 0.098293 3 0.32764

Variable Coefficient s.e. of Coeff t-ratio prob

Constant 0.860614 0.5792 1.49 0.2340

VP_Product 0.002905 0.0003 8.94 0.0030

RVP -0.381496 0.0900 -4.24 0.0241

In the analyses performed in the previous reports, after we

completed the regression analysis, we then modified the constant

term (produced by the regression) so that the resulting curve

would pass through the mean of all the relevant data (i.e., in

this case, through the mean of the 65 certification RTD tests at

the single temperature / RVP combination). In Section 4.1.1, we

estimated that 0.385 grams per vehicle per day was the baseline

value of the diurnal emissions of the properly functioning 1996

and newer vehicles. Modifying the constant term in the preceding

regression equation so that curve passes through that baseline

value (over the 72 to 96 degree cycle using 9.0 RVP fuel)

produces the equation:

24-Hour Diurnal (grams) = exp [ -0.33599 + (0.002905 * VP_Product_Term )

 - (0.381496 * RVP) ] (4)

EPA proposes to use equation (4) to estimate the 24-hour

diurnal emissions of all 1996 and newer model year vehicles with

properly functioning evaporative control systems with the

following two modifications:

1) Regardless of the increase in ambient temperatures, there

are no diurnal emissions until the ambient temperature
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exceeds 40°F. (This assumption was used consistently for

all evaporative emissions in MOBILE5.)

For a temperature cycle in which the daily low temperature

is below 40°F, EPA proposes to calculate the diurnal

emissions for that day as an interrupted diurnal (see

M6.EVP.002) that begins once the ambient temperature reaches

40 °F.

2) The 24-hour diurnal emissions will be zero grams for any

temperature cycle in which the diurnal temperature range is

zero degrees Fahrenheit (i.e., a constant temperature

throughout the entire day).

For temperature cycles in which the diurnal temperature

range is between zero and ten degrees Fahrenheit, the 24-

hour diurnal emissions will be a linear interpolation

between the predicted value for the ten-degree cycle (with

the appropriate RVP) and zero grams.

4.2.2 Diurnal Emissions of Vehicles Failing the Pressure Test

In Section 3.0, EPA proposed using five 1990-95 model year

vehicles to model the diurnal emissions from the 1996 and newer

model year vehicles that failed the pressure test (Appendix C).

Only four of those five vehicles were each tested using the same

two fuels (i.e., the 6.8 and 9.0 psi RVP fuels) over each of the

three temperature cycles (i.e., the 60 to 84, the 72 to 96, and

the 82 to 106 degree cycles). Thus, at the six different

combinations of temperature cycle and fuel RVP there were a total

24 measurements of diurnal emissions. In Section 4.2.1, we noted

that the diurnal emissions for the vehicles with properly

functioning evaporative control systems were not a strictly

increasing function of the VP product term. However, for the

vehicles that failed the pressure test, the diurnal emissions

increased as the VP product term increased. We, therefore,

repeated the approach used in the earlier analyses of regressing

the diurnal emission emissions against the cube of the VP product

term (in kiloPascals squared), producing the Table 4. (As a

check, we ran other regressions that included RVP as one of the

variables along with the vapor pressure product term. In none of

them was RVP identified as being statistically significant.)
-15- DRAFT

Table 4

Linear Regression of Diurnal Emissions

(Vehicles Failing the Pressure Test)

Dependent variable is: Diurnal

No Selector

R squared = 41.1% R squared (adjusted = 38.4%

s = 12.56 with 24 - 2 = 22 degrees of freedom

Source Sum of Squares df Mean Square F-ratio

Regression 2417.79 1 2417.79 15.3

Residual 3470.15 22 157.734

Variable Coefficient s.e. of Coeff t-ratio prob

Constant 7.94455 3.475 2.29 0.0322

Cube of VP_Product /

1,000,000

0.013004 0.0033 3.92 0.0007

We then modified the constant term (produced by the

regression) so that the resulting curve would pass through the

mean of all the relevant data (i.e., all 28 tests on the five

vehicles at nine temperature / RVP combinations). This

produced the following equation:

24-Hour Diurnal (grams) = 7.804751 + [0.012985 * Cube of VP_Product] / M (5)

Where M = 1,000,000

EPA proposes to use equation (5) to estimate the mean 24-hour

diurnal emissions of all 1996 and newer model year vehicles that

failed the pressure test with the following two modifications

(repeated from Section 4.2.1):

1) Regardless of the increase in ambient temperatures, there

are no diurnal emissions until the temperature exceeds 40°F.

(This assumption was used consistently for all evaporative

emissions in MOBILE5.)

For a temperature cycle in which the daily low temperature

is below 40°F, EPA proposes to calculate the diurnal

emissions for that day as an interrupted diurnal (see

M6.EVP.002) that begins once the ambient temperature reaches

40 °F.
-16- DRAFT

2) The 24-hour diurnal emissions will be zero grams for any

temperature cycle in which the diurnal temperature range is

zero degrees Fahrenheit (i.e., a constant temperature

throughout the entire day).

For temperature cycles in which the diurnal temperature

range is between zero and ten degrees Fahrenheit, the 24-

hour diurnal emissions will be a linear interpolation

between the predicted value for the ten-degree cycle (with

the appropriate RVP) and zero grams.

4.2.3 Diurnal Emissions of Vehicles Failing Only the Purge Test

In Section 3.0, EPA proposed using eight 1990-95 model year

vehicles to model the diurnal emissions from the 1996 and newer

model year vehicles that failed only the purge test. Only five

of those eight vehicles were each tested over the six different

combinations of temperature cycle and fuel RVP. Thus, at the six

different combinations of temperature cycle and fuel RVP there

were a total 30 measurements of diurnal emissions. Repeating the

approach used in Sections 4.2.1 and 4.2.2, we regressed the

diurnal emission emissions against the cube of the VP product

term (in kiloPascals), producing the resulting table:

Table 5

Linear Regression of Diurnal Emissions

(Vehicles Failing Only the Purge Test)

Dependent variable is: Diurnal

No Selector

R squared = 45.0% R squared (adjusted) = 43.0%

s = 6.140 with 30 - 2 = 28 degrees of freedom

Source Sum of Squares df Mean Square F-ratio

Regression 862.12 1 862.12 22.9

Residual 1055.57 28 37.6989

Variable Coefficient s.e. of Coeff t-ratio prob

Constant 2.00177 1.519 1.32 0.1983

Cube of VP_Product /

1,000,000

0.006945 0.0015 4.78 # 0.0001
-17- DRAFT

We then modified the constant term (produced by the

regression) so that the resulting curve would pass through the

mean of all the relevant data (i.e., all 48 tests on the eight

vehicles at nine temperature / RVP combinations). This produced

the following equation:

24-Hour Diurnal (grams) = 1.134838 + [0.006945 * Cube of VP_Product] / M (6)

Where M = 1,000,000

EPA proposes to use equation (6) to estimate the mean 24-hour

diurnal emissions of all 1996 and newer model year vehicles that

failed only the purge test with the following two

modifications (repeated from Sections 4.2.1 and 4.2.2):

1) Regardless of the increase in ambient temperatures, there

are no diurnal emissions until the temperature exceeds 40°F.

(This assumption was used consistently for all evaporative

emissions in MOBILE5.)

For a temperature cycle in which the daily low temperature

is below 40°F, EPA proposes to calculate the diurnal

emissions for that day as an interrupted diurnal (see

M6.EVP.002) that begins once the ambient temperature reaches

40 °F.

2) The 24-hour diurnal emissions will be zero grams for any

temperature cycle in which the diurnal temperature range is

zero degrees Fahrenheit (i.e., a constant temperature

throughout the entire day).

For temperature cycles in which the diurnal temperature

range is between zero and ten degrees Fahrenheit, the 24-

hour diurnal emissions will be a linear interpolation of the

predicted value for the ten-degree cycle (with the

appropriate RVP) and zero grams.

4.2.4 Diurnal Emissions of "Gross Liquid Leakers"

In a previous report (Section 5 of report number

M6.EVP.002), EPA proposed estimating the mean of the diurnal

emissions for each temperature cycle of the vehicles classified

as "gross liquid leakers" using equation (7), below. That

equation predicts diurnal emissions as a function of a single

variable, the diurnal temperature range (i.e., the daily high

temperature minus the daily low temperature):

24-Hour Diurnal (grams) = 20.058 + [ 3.343 * Diurnal_Temperature_Range ] (7)
-18- DRAFT

EPA proposes to continue using equation (7) to estimate the

mean 24-hour diurnal emissions of all gross liquid leakers

regardless of model year whenever the diurnal temperature range

is at least 10 degrees Fahrenheit. The 24-hour diurnal emissions

will be zero grams for any temperature cycle in which the diurnal

temperature range is zero degrees Fahrenheit (i.e., a constant

temperature throughout the entire day). For temperature cycles

in which the diurnal temperature range is between zero and ten

degrees Fahrenheit, the 24-hour diurnal emissions will be a

linear interpolation of the predicted value for the ten-degree

cycle (i.e., 53.49 grams) and zero grams.

5.0 Summary

For the 1996 and newer model year vehicles that were

certified to the enhanced evaporative testing procedure, EPA

proposes to model the resting loss and diurnal emissions

separately for those vehicles having substantial leaks of liquid

gasoline. For the non-leakers, EPA proposes to model the resting

loss and diurnal emissions separately based on the functional

status of the vehicle's evaporative control system.

EPA proposes to model the hourly resting loss emissions (in

grams per hour) using the following three formulae:

 • For vehicles with substantial leaks of liquid gasoline

("Gross Liquid Leakers"):

 Hourly Resting Loss = 8.84

 • For vehicles with properly functioning evaporative control

systems:

 Hourly Resting Loss = -0.02786 + [0.000514 * Temperature (°F)] (1)

 • For vehicles with malfunctioning evaporative control systems:

 Hourly Resting Loss = -0.07654 + [0.001603 * Temperature (°F)] (2)

Additionally, any predicted resting loss emission that is

negative will be replaced with zero.

EPA proposes to model the full (24-hour) day's diurnal

emissions (in grams per day) using the following four formulae:

 • For vehicles with substantial leaks of liquid gasoline

("Gross Liquid Leakers"):

 Diurnal = 20.058 + [3.343 * Diurnal_Temperature_Range (°F)] (7)
-19- DRAFT

 • For vehicles with properly functioning evaporative control

systems:

 Diurnal = exp [ -0.33599 + (0.002905 * VP_Product_Term )

 - (0.381496 * RVP) ] (4)

 • For vehicles failing the pressure test:

 Diurnal = 7.80475 + [ 0.012985 * Cube of VP_Product_Term ] / M (5)

Where M = 1,000,000

 • For vehicles failing the purge test:

 Diurnal = 1.13484 + [ 0.006945 * Cube of VP_Product_Term ] / M (6)

Where M = 1,000,000

Additionally, the following two modifications apply to the

diurnal emission that are predicted by any of the four preceding

formulae:

1) Regardless of the increase in ambient temperatures, there

are no diurnal emissions until the temperature exceeds 40°F.

For a temperature cycle in which the daily low temperature

is below 40°F, EPA proposes to calculate the diurnal

emissions for that day as an interrupted diurnal (see

M6.EVP.002) that begins once the ambient temperature reaches

40 °F.

2) The 24-hour diurnal emissions will be zero grams for any

temperature cycle in which the diurnal temperature range is

zero degrees Fahrenheit (i.e., a constant temperature

throughout the entire day).

For temperature cycles in which the diurnal temperature

range is between zero and ten degrees Fahrenheit, the 24-

hour diurnal emissions will be a linear interpolation of the

predicted value for the ten-degree cycle (with the

appropriate RVP) and zero grams.
-20- DRAFT

Appendix A

Twenty-Five 1990-1995 Model Year Vehicles

Passing Both the Purge and Pressure Tests

Vehicle

No.

Fuel

RVP

Temp Cycle VP Product

Term

RTD

(grams)

Hrly Rst

Loss*

Daily Rst

Loss

Diurnal

(grams)

4912 6.8 72 - 96 567 0.980 0.012 0.428 0.552

6.8 82 - 106 789 5.120 0.102 2.588 2.532

9.0 60 - 84 655 1.930 -0.005 0.020 1.910

9.0 72 - 96 969 3.350 0.045 1.220 2.130

4923 6.8 72 - 96 567 0.670 0.000 0.140 0.530

6.8 82 - 106 789 4.480 0.048 1.292 3.188

9.0 60 - 84 655 1.710 0.018 0.572 1.138

9.0 72 - 96 969 2.550 0.032 0.908 1.642

4928 6.8 72 - 96 567 4.830 0.065 1.700 3.130

6.8 82 - 106 789 8.230 0.142 3.548 4.682

9.0 60 - 84 655 4.170 0.045 1.220 2.950

9.0 72 - 96 969 4.370 0.058 1.532 2.838

4932 6.8 72 - 96 567 1.700 0.017 0.548 1.152

6.8 82 - 106 789 2.850 0.037 1.028 1.822

9.0 60 - 84 655 1.490 0.023 0.692 0.798

9.0 72 - 96 969 2.080 0.017 0.548 1.532

5032 6.8 60 - 84 375 0.374 0.004 0.236 0.138

6.8 72 - 96 567 0.772 0.006 0.284 0.488

6.8 82 - 106 789 1.231 0.012 0.428 0.803

9.0 60 - 84 655 0.473 0.005 0.260 0.213

9.0 72 - 96 969 0.741 0.008 0.332 0.409

9.0 82 - 106 1,324 2.433 0.018 0.572 1.861

5038 6.8 72 - 96 567 0.615 0.005 0.260 0.355

6.8 82 - 106 789 1.011 0.007 0.308 0.703

9.0 60 - 84 655 0.441 0.002 0.188 0.253

9.0 72 - 96 969 1.302 0.004 0.236 1.066

9.0 82 - 106 1,324 4.366 0.006 0.284 4.082

 * “Hourly Resting Loss” emissions are calculated at the lowest temperature

of each cycle.
-21- DRAFT

Appendix A (Continued)

Vehicle

No.

Fuel RVP Temp Cycle VP Product

Term

RTD

(grams)

Hrly Rst

Loss*

Daily Rst

Loss

Diurnal

(grams)

5046 6.8 60 - 84 375 0.439 0.011 0.404 0.035

6.8 72 - 96 567 0.565 0.007 0.308 0.257

6.8 82 - 106 789 1.498 0.020 0.620 0.878

9.0 60 - 84 655 0.360 0.004 0.236 0.124

9.0 72 - 96 969 0.971 0.013 0.452 0.519

9.0 82 - 106 1,324 9.716 0.041 1.124 8.592

5047 9.0 60 - 84 655 0.366 0.005 0.260 0.106

9.0 72 - 96 969 0.653 0.012 0.428 0.225

9.0 82 - 106 1,324 0.906 0.015 0.500 0.406

5052 6.8 60 - 84 375 3.502 0.032 0.908 2.594

6.8 72 - 96 567 4.273 0.071 1.844 2.429

6.8 82 - 106 789 8.937 0.114 2.876 6.061

9.0 60 - 84 655 2.966 0.039 1.076 1.890

9.0 72 - 96 969 5.853 0.106 2.684 3.169

9.0 82 - 106 1,324 11.820 0.205 5.060 6.760

5066 6.3 60 - 84 322 0.390 -0.007 -0.028 0.418

6.3 72 - 96 489 0.351 0.001 0.164 0.187

6.3 82 - 106 684 0.605 0.006 0.284 0.321

6.8 60 - 84 375 0.295 0.000 0.140 0.155

6.8 72 - 96 567 0.397 0.003 0.212 0.185

6.8 82 - 106 789 0.581 0.004 0.236 0.345

9.0 60 - 84 655 0.281 -0.001 0.116 0.165

9.0 72 - 96 969 0.626 0.007 0.308 0.318

9.0 82 - 106 1,324 1.936 0.011 0.404 1.532

5068 6.3 60 - 84 322 0.814 0.006 0.284 0.530

6.3 72 - 96 489 0.580 0.006 0.284 0.296

6.3 82 - 106 684 1.150 0.009 0.356 0.794

6.8 60 - 84 375 0.368 0.003 0.212 0.156

6.8 72 - 96 567 0.839 0.009 0.356 0.483

6.8 82 - 106 789 1.391 0.018 0.572 0.819

9.0 60 - 84 655 0.638 0.009 0.356 0.282

9.0 72 - 96 969 1.385 0.010 0.380 1.005

9.0 82 - 106 1,324 2.132 0.029 0.836 1.296
-22- DRAFT

Appendix A (Continued)

Vehicle

No.

Fuel RVP Temp Cycle VP Product

Term

RTD

(grams)

Hrly Rst

Loss*

Daily Rst

Loss

Diurnal

(grams)

5081 6.3 72 - 96 489 0.647 0.001 0.164 0.483

6.3 82 - 106 684 1.187 0.009 0.356 0.831

9.0 60 - 84 655 0.326 0.005 0.260 0.066

9.0 72 - 96 969 0.639 0.007 0.308 0.331

9009 6.8 72 - 96 567 35.565 0.095 2.420 33.145

9026 6.8 72 - 96 567 1.755 0.031 0.884 0.871

9028 6.8 72 - 96 567 16.984 0.024 0.716 16.268

9033 6.8 72 - 96 567 0.879 0.003 0.212 0.667

9038 6.8 72 - 96 567 5.818 0.106 2.684 3.134

9040 6.8 72 - 96 567 0.810 0.006 0.284 0.526

9048 6.8 72 - 96 567 9.443 0.228 5.612 3.831

9056 6.8 72 - 96 567 3.095 0.046 1.244 1.851

9059 6.8 72 - 96 567 1.009 0.013 0.452 0.557

9088 6.8 72 - 96 567 2.750 0.023 0.692 2.058

9135 6.8 72 - 96 567 1.591 0.012 0.428 1.163

9141 6.8 72 - 96 567 10.328 0.209 5.156 5.172

9143 6.8 72 - 96 567 7.904 0.070 1.820 6.084
-23- DRAFT

Appendix B

Eight 1990-1995 Model Year Vehicles

Failing (Only) the Purge Test

Vehicle

No.

Fuel

RVP

Temp Cycle VP Product

Term

RTD

(grams)

Hrly Rst

Loss*

Daily Rst

Loss

Diurnal

(grams)

4925 6.8 72 - 96 567 4.170 0.063 1.949 2.221

6.8 82 - 106 789 4.450 0.080 2.357 2.093

9.0 60 - 84 655 2.170 0.035 1.277 0.893

9.0 72 - 96 969 3.830 0.058 1.829 2.001

4933 6.8 72 - 96 567 10.750 0.145 3.917 6.833

6.8 82 - 106 789 18.670 0.352 8.885 9.785

9.0 60 - 84 655 7.170 0.137 3.725 3.445

9.0 72 - 96 969 12.120 0.228 5.909 6.211

5004 6.8 60 - 84 375 0.989 0.003 0.509 0.480

6.8 72 - 96 567 1.673 0.023 0.989 0.684

6.8 82 - 106 789 2.924 0.031 1.181 1.743

9.0 60 - 84 655 1.025 0.015 0.797 0.228

9.0 72 - 96 969 5.440 0.018 0.869 4.571

9.0 82 - 106 1,324 20.391 0.047 1.565 18.826

5035 6.8 60 - 84 375 5.593 -0.016 0.053 5.540

6.8 72 - 96 567 5.869 0.016 0.821 5.048

6.8 82 - 106 789 22.973 -0.033 -0.355 23.328

9.0 60 - 84 655 14.493 0.015 0.797 13.696

9.0 72 - 96 969 24.068 0.032 1.205 22.863

9.0 82 - 106 1,324 24.872 0.040 1.397 23.475

5040 6.8 60 - 84 375 0.667 0.003 0.509 0.158

6.8 72 - 96 567 1.143 0.010 0.677 0.466

6.8 82 - 106 789 6.961 -0.013 0.125 6.836

9.0 60 - 84 655 1.065 -0.003 0.365 0.700

9.0 72 - 96 969 2.930 0.012 0.725 2.205

9.0 82 - 106 1,324 20.658 -0.008 0.245 20.413
-24- DRAFT

Appendix B (Continued)

Vehicle

No.

Fuel

RVP

Temp Cycle VP Product

Term

RTD

(grams)

Hrly Rst

Loss*

Daily Rst

Loss

Diurnal

(grams)

5069 6.3 60 - 84 322 1.774 0.001 0.461 1.313

6.3 72 - 96 489 3.593 0.012 0.725 2.868

6.3 82 - 106 684 6.810 0.003 0.509 6.301

6.8 60 - 84 375 1.322 0.004 0.533 0.789

6.8 72 - 96 567 1.953 0.011 0.701 1.252

6.8 82 - 106 789 9.565 0.039 1.373 8.192

9.0 60 - 84 655 7.082 -0.017 0.029 7.053

9.0 72 - 96 969 12.372 0.007 0.605 11.767

9.0 82 - 106 1,324 20.430 0.080 2.357 18.073

5070 6.3 60 - 84 322 0.351 0.002 0.485 0.000

6.3 72 - 96 489 0.690 0.001 0.461 0.229

6.3 82 - 106 684 1.209 0.016 0.821 0.388

6.8 60 - 84 375 0.375 0.002 0.485 0.000

6.8 72 - 96 567 0.745 -0.004 0.341 0.404

6.8 82 - 106 789 1.176 0.007 0.605 0.571

9.0 60 - 84 655 0.416 0.003 0.509 0.000

9.0 72 - 96 969 1.381 0.019 0.893 0.488

9.0 82 - 106 1,324 9.141 0.057 1.805 7.336

5087 6.3 72 - 96 489 1.830 0.042 1.445 0.385

6.3 82 - 106 684 2.435 0.048 1.589 0.846

9.0 60 - 84 655 1.478 0.029 1.133 0.345

9.0 72 - 96 969 2.533 0.043 1.469 1.064
-25- DRAFT

Appendix C

Five 1990-1995 Model Year Vehicles

Failing the Pressure Test

Vehicle

No.

Fuel

RVP

Temp Cycle VP Product

Term

RTD

(grams)

Hrly Rst

Loss*

Daily Rst

Loss

Diurnal

(grams)

4937 6.8 72 - 96 567 3.330 0.028 1.109 2.221

5008 6.8 60 - 84 375 12.853 -0.018 0.005 12.848

6.8 72 - 96 567 17.632 0.013 0.749 16.883

6.8 82 - 106 789 29.663 0.054 1.733 27.930

9.0 60 - 84 655 19.811 -0.002 0.389 19.422

9.0 72 - 96 969 35.202 0.038 1.349 33.853

9.0 82 - 106 1,324 57.174 0.014 0.773 56.401

5021 6.8 60 - 84 375 7.789 0.004 0.533 7.256

6.8 72 - 96 567 15.477 0.029 1.133 14.344

6.8 82 - 106 789 23.810 0.065 1.997 21.813

9.0 60 - 84 655 17.246 -0.003 0.365 16.881

9.0 72 - 96 969 24.840 0.038 1.349 23.491

9.0 82 - 106 1,324 41.963 -0.034 -0.379 42.342

5044 6.8 60 - 84 375 0.286 0.004 0.533 0.000

6.8 72 - 96 567 0.523 0.011 0.701 0.000

6.8 82 - 106 789 0.706 0.014 0.773 0.000

9.0 60 - 84 655 0.467 0.011 0.701 0.000

9.0 72 - 96 969 0.494 0.007 0.605 0.000

9.0 82 - 106 1,324 1.914 0.005 0.557 1.357

5067 6.3 60 - 84 322 5.206 0.037 1.325 3.881

6.3 72 - 96 489 13.206 0.056 1.781 11.425

6.3 82 - 106 684 21.981 0.113 3.149 18.832

6.8 60 - 84 375 12.128 0.025 1.037 11.091

6.8 72 - 96 567 8.644 0.070 2.117 6.527

6.8 82 - 106 789 18.697 0.062 1.925 16.772

9.0 60 - 84 655 7.106 0.036 1.301 5.805

9.0 72 - 96 969 29.697 0.107 3.005 26.692

9.0 82 - 106 1,324 50.741 0.040 1.397 49.344
-26- DRAFT

Appendix D

Resting Loss Data Used in Regression Analyses

1990-1995 Model Year Vehicles

(By Ambient Temperature)

Category Veh. No. 60• F 72• F 82• F

Pass Both 5032 0.0043 0.0069 0.0150

Pass Both 5046 0.0075 0.0097 0.0306

Pass Both 5047 0.0047 0.0117 0.0150

Pass Both 5066 -0.0024 0.0036 0.0071

Pass Both 5081 0.0052 0.0038 0.0090

Means: 0.0039 0.0071 0.0153

Fail Only Purge 4925 0.0350 0.0608 0.0800

Fail Only Purge 4933 0.1367 0.1867 0.3517

Fail Only Purge 5004 0.0088 0.0203 0.0392

Fail Only Purge 5035 -0.0007 0.0236 0.0031

Fail Only Purge 5040 0.0001 0.0108 -0.0106

Fail Only Purge 5069 -0.0042 0.0101 0.0407

Fail Only Purge 5070 0.0024 0.0052 0.0266

Fail Only Purge 5087 0.0290 0.0000 0.0000

Means: 0.0259 0.0397 0.0663

Fail Pressure 5008 -0.0102 0.0253 0.0341

Fail Pressure 5021 0.0006 0.0332 0.0155

Fail Pressure 5044 0.0073 0.0088 0.0096

Fail Pressure 5067 0.0324 0.0778 0.0714

Means: 0.0075 0.0363 0.0327

Fail Either: 0.0198 0.0386 0.0551