Pren tiss Searles Sr. Marketing Issues Associate 1220 L Street, Northwes t Was h ington, DC 20005-4070 Tel 202/682-8227 Fax 202/682-8051 E-mail s earles p @api.org

April 7, 2004

Ms. Lisa Rector Northeast States for Coordinated Air Use Managem e nt 101 Merrim ac Street Boston, Massachusetts 02114

Re: ORVR Compatibility Study

Dear Ms. Rector:

The Am erican Petroleum Institute com m i ssioned a study to determ ine the com p atibility between ORVR system s and a Stage II vapor recovery syst em . The study characterized the em issions of a

vacuum assist system when used with vehicles that have ORVR in place. The study included a test of the system at an operating retail gasolin e dispensing f acility (GDF), a test of ref u eling

em issions inside a SHED (Sealed Housing Evapor ative Determ ination), and a test of em issions from a UST system during several single refueling events. The research exam ined in detail the perform a nce of a specific vac-assist system in two configurations: an A/L set above 1.0 and an A/L set below 1.0 with a m i ni-boot on the nozzle. W e believe that the results of this study provide signif i cant new inf o rm ation on ORVR com p atibility.
There are three key conclusions from the research:

• Em issions during gas cap rem oval (“puf f em issi ons”) and em issions at the f illpipe during refueling are significantly lower for ORVR vehicles than non-ORVR vehicles.

• For the m i ni-booted vac-assist system (A/L <1.0), excess UST em issions are essentially

zero.
• W h en refueling a m i xed population of non-OR VR and ORVR vehicles at a GDF, the installation of m i ni-boots and a decrease in A/L below 1.0 reduced m easured P/V valve

em issions by 98% and reduced total UST em issi ons by at least 64% without significantly inf l uencing f illpipe em issions.

Note that the second conclusion is consistent with the results from ARB’s 1999 study, which showed that a W a yne system (with A/Ls between 0.9 and 1.1) also had negligible UST em issions.

An equal opport unit y employerMs. Lisa Rector April 7, 2004 Page 2
In support of the first conclusion above, the em issions measured in the SHED during gas cap removal (“puff emissions”) and emissions at the fillpipe during refueling are significantly lower for ORVR vehicles than non-ORVR vehicles. These reductions in fillpipe emissions were confirmed for a matrix of in-use vehicles (tested as per ARB test procedure TP-201.2) at an actual service station in San Bernardino where the A/L was set below 1.0. Specifically, both before and after installing mini-boots and reducing the A/L, the average fillpipe emissions from ORVRequipped vehicles were 0.31 lb/1000 gallons lower than those from non-ORVR vehicles. SHED tests showed an even greater reduction of 0.46 lb/1000 gallons at the fillpipe.
The second key conclusion is drawn from the test s done at the UST system during several single refueling events. Direct measurements of fugitive emissions from the tank system showed that, for the mini-booted vac-assist system (A/L <1.0) , UST emissions from ORVR refuelings were essentially zero and were less than UST emissions from non-ORVR refueli ngs. Thus, excess UST emissions (ORVR minus non-ORVR) are essentially zero for the mini-booted vac-assist system. The results also show that excess UST emissions for the standard (A/L >1.0) vac-assist system (0.72 lb/1000gal) are comparable to ARB’s 1999 estimate of 0.86 lb/1000 gal of excess UST emissions. However, depending upon temperature c onditions, these excess UST emissions may be entirely offset by reduction in puff and fillpipe em issions (i.e., see conclusion #1). In addition, the study notes that measured fugitive UST emissions were consistently below those calculated using ARB’s TP-201.2F methodology by 1-2 orders of magnitude.
The third key conclusion comes from the San Bern ardino test data that show, on average, the installation of mini-boots and a decrease in A/ L (A/L<1.0) reduced UST emissions (calculating fugitives as per TP 201.2F) from 1.38 lb/1000 ga l to 0.49 lb/1000 gal (i.e., a reduction of 0.89 lb/1000 gal, 64%) without significantly influenc ing fillpipe emissions. Of the 0.89 lb/1000 gal reduction, 0.82 lb/1000 gal were reductions measured at the P/V valve, rather than calculated as fugitives (see Figure 1 attached). To the extent TP201.2F over predicts fugitive emissions (and the study shows TP-201.2F estimates were biased high by 1-2 orders of magnitude), the reduction in total UST emissions caused by the use of mini-boot nozzles is likely higher than 64% and possibly as high as 98% (if one applies the TP201.2F co rrection factors derived in this study). Consequently, the study’s conclusions are conservative.

Our data lead us to conclude that ARB has significantly overstated the extent to which there are “excess emissions” due to ORVR that were not accounted for in emission inventories prior to the EVR program. Specifically, although ORVR vehi cles can produce higher UST emissions when fueled with a vac-assist VRS with an A/L > 1.0, ORVR vehicles produce lower emissions at the fillpipe, both when the gas cap is removed and during refueling. Finally, as discussed above, the use of the mini-booted vac-assist system eliminates ORVR incompatibility and excess emissions.Ms. Lisa Rector April 7, 2004 Page 3
We look forward to an opportunity to discuss th is new information with you. Should you have any questions or would like to further discuss this study, please do not hesitate to contact me via the information given above.
Sincerely,

c: Michael Block

Attachment EnclosureFigure 1. U S T Emissions D e t e rmined U s ing A R B TP- 201.2, While R e f u eling Vehicles at an Operat ing San B e rnardino GD F ( R VP 7.0 gasoline)

0.00 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80

S t andard Gilbarco V R S (A /L = 1.15) M i ni-booted Gilbarco V R S (A /L = 0.95)Emissions (lb/1000 gal)

M eas ured at P/V Valv e

Calc ulated Fugitiv e s (TP-201.2F)

# ORVR COMPATIBILITY STUDY

O R T H E G I L B A R C O V A P O R V A C V R S F

February 2004

TECH ENVIR ONME N TAL, INC.

# ORVR COMPATIBILITY STUDY

FOR THE GILBARCO VAPORVAC VRS

Prepared for:



### American Petroleum Institute 1220 L Street N.W. Washington, DC 20005

Prepared by:


### Tech Environmental, Inc. 1601 Trapelo Road Waltham, MA 02451 (781) 890-2220

February 5, 2004FORE WORD

The California Air Reso urces Board (CARB) has r ecen tly s t ated that significant em issions occur
when curren tly ins t a lled Stage II system s are used to fuel vehicles with onboard refueling vapor recovery (ORVR) system s. The purpose of this study was to test the accuracy of CARB' s
statem ent by using a com m e rcially av ailab l e Stag e II sys t em to determ ine its com p atib ility with onboard vapor recovery system s. The selection of the Gilbarco VaporVac for this research project should not be interprete d as an endorsem e nt of this eq uipm ent over other comm ercially available eq uipm ent.

2TABLE OF CONTENTS

Section Title Page

1.0 EXECUTIVE SUMMARY............................................................................................ . 1
1.1 Overall Study Conclusions..................................................................................2 1.2 Results for Phase 1 – Fleetwide Tests..................................................................3 1.3 Results for Phase 2 – Laboratory Tests................................................................4

2.0 INTRODUCTION.......................................................................................................... 6

2.1 Overview............................................................................................................ 6 2.2 Phase 1 – Fleetwide Tests ..................................................................................7 2.3 Phase 2 – Laboratory Tests.................................................................................7 2.4 Description of the Refue ling Emissions Process................................................ 8

3.0 SCIENTIFIC PRINCIPLES...........................................................................................11
3.1 Factors Affecting Uncontrolled Refueling Emissions.......................................11 3.2 Onboard Refueling Vapor R ecovery (ORVR) Canisters..................................13 3.3 Vacuum-Assisted Stage II Vapor Recovery Systems (VRS)..............................16 3.4 ORVR / VRS “Incompatibility”....................................................................... 17

4.0 TESTING METHODOLOGIES.................................................................................. 20

4.1 Phase 1 – Fleetwide Tests................................................................................ 20

4.1.1 Overview.............................................................................................. 20 4.1.2 Testing Details..................................................................................... 22

. 4.2 Phase 2 – Laboratory Tests ..............................................................................23

4.2.1 Overview.............................................................................................. 23 4.2.2 Testing Details – Outdoor Tests.......................................................... 27 4.2.3 Testing Details – Indoor SHED Tests................................................. 30

4.3 Ethanol Correction – Phase 1 and 2................................................................. 37

iiiTABLE OF CONTENTS (continued)

Section Title Page

5.0 PHASE 1 – ANALYSIS AND RESULTS................................................................ 40
5.1 Analysis of Factors Affecti ng “Uncontrolled Emissions”............................... 40
5.1.1 Temperatures...................................................................................... 40 5.1.2 ORVR................................................................................................. 42
5.2 Analysis Of Continuous UST Data................................................................. 45

6.0 PHASE 2 OUTDOOR TESTS – ANALYSIS AND RESULTS................................ 58

6.1 Continuous UST Pressure Data...................................................................... 58 6.2 Fugitive Emissions From UST/Piping............................................................ 67 6.3 Performance of the CARB Estimation Method for Fugitive Emissions......... 71 6.4 Fillpipe Emissions and Return Vapor Line Concentrations............................ 74

7.0 PHASE 2 INDOOR SHED TESTS – ANALYSIS AND RESULTS......................... 76
7.1 Nozzle/Fillpipe Refueling Emission............................................................... 76

7.1.1 ORVR................................................................................................. 77 7.1.2 RVP..................................................................................................... 82 7.1.3 A/L Ratio............................................................................................. 82 7.1.4 Temperatures...................................................................................... 83
7.2. Fuel Cap “Puff” Emissions a nd Canister Outlet Emissions............................ 91

8.0 CONCLUSIONS.........................................................................................................99

ivEXECUTIVE SUMMARY

The goal o f the ORVR Com p atibility Study is to investigate refueling em issions and th e

com p atibility of a Gilbarco vacuum -assisted vapor recovery system (VRS) with onboard refueling vapor recovery (ORVR) canisters in stalled on motor vehicles. The California Air Resources Board (CARB) has stated there is a potential for “excess e m issions” of pressurerelated fugitives when the two vapor control sy stem s are used together . To understand this report, the reader needs to be in tro duced to f our key terms, defined below. Pressure-related
f ugitives ( a lso ref e rred to as f ugitive em issions in this repo rt) are HC emissions f r om a gasolin e dispensing f acility due to positive g a uge pressu re in the headspace (ullage) of the Underground Storage Tan k (UST). These occur as leaks in the piping system . These e m issions do not include
transfer em i ssions a t the nozzle / f illp ipe inte rface nor the em issions from the vent pip e P/V valve.
Excess em issions of pre ssure- r elated f

ugitives (also referred to as jus t ex cess em issio n s in this report) a r e the dif f e renc e between p r essur e -r ela t ed f ugitives f o r an ORVR vehicle v e rsus a non
ORVR vehicle when refueled with a Stag e II VRS. Total incom p atibility em issions are the
dif f e rence b e tween a ll r e f u eling em issions (pr e ssure- r elated f

ugitives, P/V valve a nd f illpip e

em issions) for an ORVR vehicle v e rsus a non -ORVR vehicle. Unco ntrolled em issions are

em issions from the nozzle/fillpipe interface that would results if neither a Stage II V R S nor an ORVR system were pres ent.

There were two phases to the study. In Phase 1, fl eetwide tests were done at a California service station using CARB test procedures to quantify the differences in refueling em issions for ORVR
vs. non-ORVR vehicles. The service station di spenser was equipped with a Gilbarco VaporVac Stage II V R S. In Phase 2, labo ratory tests were done at a f acility in Ariz ona to study the

com p atibility between the Gilba r a c o VRS an d ORVR-equipped vehicles. Refueling tests perform e d in a Sealed H ousing for E v aporative De term inations (SHED) quantif ied the controlle d
nozzle / f illp ipe em ission s as a f unction of th e type of ORVR equipm ent, f u el RVP, the

tem p erature of dispense d f u el and vehicle tank , and the air-to

- liquid ( A /L) ra tio. In add ition , “excess em issions” of pressur e -r elated f ugitiv es were dir ectly m e asured during six CARB refueling tests at the laboratory . These tests were not designed to m easure VRS efficiency under

1the CP-201 Vapor Recovery Cert ification Procedure. In the sections below, the overall
conclus i ons from the stu dy are prov ided, followed by the res u lts of each Phase. .

1.1 Overall Stu d y Conclusions
Analysis of the ex tensiv e m easurements of f

illp ipe and pr ess u re-r ela t ed f ugitiv e em issions m a de in this study support the following overall conclu sions, which are applicable to statewide HC

em ission inventories:

• For a standard vapor recovery nozzle (A /L = 1.15) on a Gilbarco VRS, “excess

em issions” do occur when an ORVR vehicle is refueled. T h is study docum e nts the vapor growth process in the UST fo r individual refueling even ts, and m easurem ents reveal “excess em issions” of pressure-related fug itives are 0.72 lb/1,000 gallo ns, slightly less than the level CARB assum e s (0.86 lb/1,000 ga llons). The CARB estim a te is less reliable as it is not derived from actual m eas urem ents of pressure-related fugitives associated w ith refueling ORVR vehicl es, the test m e thod used on this study.

• When a Gilbarco VRS is used, ORVR vehicl es produce substantially lower em issions at the nozzle/fillpipe than non-ORVR vehicles. This is a significant offset to the excess

em issions, which CARB does not account for in analyzing ORVR compatibility. Thus, CARB in practice as su m e s that total in co m p a tibility em issions are equal to excess

em issions (0.86 lb/1,000 gallons).

• Total incompatibility em issions for the standard nozzle (A/L = 1.15) are only 0.42 lb/1,000 gallons, about half of what CARB presum es for all ORVR vehicles (0.86 lb/1,000 gallons).

• Measured fugitiv e em issions from ORVR vehi cles refueled with a m i ni-boot nozzle are near zero (0.003 lb/1,000 gallons) and are less than m e asured non-ORVR fugi tive

em issions (0.011 lb/1,000 gallons). Thus, wh en the m i ni-boot nozzle (A/L = 0.95) is used on a Gilbarco VRS, there is no OR VR incom p atibility and m easured “excess

em issions” are zero (actually –0.008 lb/1,000 gall ons). In addition, with the m i ni-boot nozzle in use the combination of ORVR and Stage II VRS controls produces 0.39 lb/1,000 gallons less em issions at the fillpipe than if just Stag e II controls are used.

• The CARB estim ation m e thod for UST fugitiv e HC e m issions (TP201.2F) over-p redicts actual press u re-related fugitiv e em issions by factors of 13 to 660. These data support an earlier analy s is by Tech Environm ental that po in ted to ove r- predic tion a nd f l aws in the analytica l f o rm of the equation f o r pr essure -re late d f ugitives.

• States and E P A should revise the calculation of refueling em issions for O R VR vehicles in MOBILE6 to reflect the new variable depe ndencies found in this study and to ensure that future em ission inventories are accurate.

2• Puff losses were found to be on the s a m e order of magnitude as fillpip e refueling

em issions for both ORVR and non-ORVR ve hicles. Puff losses are the losses of hydrocarbon vapors that occur when the gas cap is rem o ved and are not captured in

em ission inventories calculated by the EPA MOBILE6 m odel s

.

1.2 Results for Phase 1 – Fleetw i de Tests

In this first phase of the test prog ram, testin g was done in accord ance with test p r ocedures in
CARB m e thod TP201.2 at a Conoc o Service Stati on in San Bernardino, California to provide

som e initial data on ORVR vs. non-ORVR vehicle em ission s for an in -use vehicle fleet. Two sets of tests were perform e d: Test 1 with standard nozzles 1 and Test 2 with m i ni-boot nozzles and a reduced air-to-liq uid ra tio ( A /L). The f u el was Calif ornia s u mm ertim e ref o rm ulated federal gasoline (RVP 7.0 with ethanol). UST pr essure, headspace concentrations, and em issions
from the UST P/V valve were m onitored continuously.

The results support the following conclusions:

• CARB’s calculations of total incom p atib ility em issions are o v erestim a ted because they ignore the decrease in em issions at the nozzl e/fillpipe from ORVR equipm ent. W h en a Gilbarco S t age II VRS is used, ORVR vehicles had 73% lower em issions from the nozzle/fillp ipe than non-ORVR vehicles, a difference of 0.31 lb/1,000 gal, when fuele d with RFG (7.0 RVP). This is a sig n ifican t d i fference that CARB does not accoun t for and it partially offsets the 0.86 lb/1,000 gal excess em issions from the UST that CAR B has assigned to ORVR vehicles. Results we re the sam e for standard vacuum as sist nozzle and m i ni-boot nozzle refuelings.

• Use of a m i ni-boot nozzle w ith the Gilbarco V R S reduced m easured em issions from the P/V valve by 98%, and reduced total UST/pi ping system em issions by 64% to 98%. This reduction is greater th an the 50% reduction CARB cl aim s for the mini-boot.

• Since the s u m of the vapor in the return line plus the fillpipe em issions for ORVR vehicles (roughly 1.2 g/gal) is larger than the m a xi m u m 0.2 g/gal that is allowed for

em issions from an ORVR car refueling at a non-Stage II service station, it appears that the VRS m a y be preferentially capturing vapors o v er the O R VR canister. Alterna tive l y, the vacuum assiste d Stag e II equipm ent m a y be i n creasing the volatization of liquid f u el in th e f illp ipe as it is be ing dispens e d.

1 In this study, t h e term “standard nozzle” refers t o a vap o r r ecove ry nozzl e wi t h a n A/ L o f 1. 15

.

31.3 Results for Phase 2 – Laboratory Tests

The second phase of the study was perform e d at Au tom o tive Testing Laboratories, Inc. in Mesa, AZ and directly ex am ined the issu e of com p atibility be tween the Gilbarco VRS and ORVRequipped vehicles by m easuring pressure-related fugitive em issions. This phase had two separate work tasks: outdoor tests using CARB m e thod TP201.2 at a di spenser drawing product
from a 3,000 gallon UST containing 1,000 gallons of RVP 7.8 summ er grade gasoline, and indoor SHED tests conducted using a procedure sim ilar to the fede ral ORVR certification test to quantify nozzle/fillpipe em issions an d their dependence on independent variab les. T h e effects of three processes were docum ented in the contin uous one-second pressure records of the 3,000 gallon UST: initia l positive or negative pressur i z a tion (dep en ding on A/L) f r om the return vapor line; vapor growth in th e UST headspace from unsat urated return air; and continuo us leaks from the UST/pip i ng system (sim ulated with a leak va lve on an otherwise tigh t system ). The results
of the Phase 2 – outdoor tests s upport the following conclusions:

• Measured fu gitiv e em issions from ORVR vehi cles refueled with a m i ni-boot nozzle are

near zero (0.003 lb/1,0 00 gallons) and ar e less than m e asured non -ORVR fugitive

em issions (0.011 lb/1,000 gallons). Thus, wh e n the m i ni-boot nozzle (A/L = 0.95) is used on a Gilbarco V R S, there is no OR VR incom p atibility and m e asured “ex cess
em issions” are zero (actually –0.008 lb/1,000 ga llons). In addition, with the m i ni-b oot nozzle in use the combination of ORVR and Stage II V R S controls produces 0.39 lb/1,000 gallons less em issions at the fillpipe than if just Stag e II controls are used.

• “Excess em i ssions” from the UST/piping syst em when a standard nozzle (A/L=1.15) is used are 0.7 2 lb/1,000 g a llons. Con s idering th e decrease in f illp ipe em issions produced by the OR VR-VRS c o m b ination of 0.39 lb /1,000 gallons, total incom p atibility

em issions for the standard nozzle are only 0.33 lb/1,000 gallons, or less than half of the figure of 0.86 lb/1,000 gallons that C A RB presum es for all ORVR vehicles.

• In situations where Gilb arco sys t em s are equipp ed with s t an dard nozz l es (A/L = 1.1 5), a correction should be applied for the fact th at the MOBILE6 m odel (the tool used to

crea te sta t e em ission inventor ies) a ssum e s f illp ipe em issions f o r ORVR cars are lo wer than those f o r non-ORVR cars controlled with Stage II. That is, som e of the fillpipe

em issions reduction attributable to ORVR (and discussed in the bullet above) are already credited in the em issions inventory. Thus, when used in statewide em ission inventories developed with MOBILE6, a slig htly higher figure of 0.42 lb/1,000 gallons should be assum e d for total in com p atibility em issions for th e Gilbarco dispenser with a standard nozzle.

4• The CARB estim ation m e thod for UST fug itive em issions (TP201.2F) over-predicted actual pres s u re-related fugitiv e em issions by factors of 13 to 660. These data supp ort an earlier analysis by T ech Environ m ental that pointed to o v erpred ictio n and flaws in the analytical form of the equati on for pressure-related fugitives.

The Phase 2 – indoor SHED tests quantified th e dependence of fillpipe em issions on several independent variables. The result s support the following conclusions:

• The SHED refueling em issions at the fillpipe for ORVR and non-ORVR vehicles fall within the range of values m easured in the Phase 1 and Phase 2-outdoor T P 201.2 tests.

• Com p arison of ORVR and non-ORVR fillpipe em issions in the SHED tests p r o duced results confirm i ng those found in the Phas e 1 TP201.2 tests. In Phase 1, fillpipe

em issions were 73 % le s s for ORVR than for non-ORVR ve hicles usin g a Gilbarco VRS. In the contr o lled ref u eling tes t s in the SH ED, f i llpip e em issions for the ORVR-equipped vehicles were 91% lower than those for th e non-O R VR vehicles using a G ilbarco VRS.

• The dependence of f

illpipe em issions on RVP, A/L ratio an d tem p eratures is dif f e rent f o r ORVR and non-ORVR vehicles.

• For ORVR-equipped ve hicle s , the r e is very little to no cor r e lation of f

illpip e em issions with RVP, no corr ela tion with A/L ra tio, no cor r e c tion with ∆ T (vehic le ta nk tem p erature
m i nus dispensed tem p erature), and positive correlation with T T (vehicle tank tem p erature).

• For the non-ORVR vehicle, there is a positive co rrelation of fillp ipe em issions with RVP, a negative correlation with A/L, and a ne gative correlation of em iss i ons with ∆ T, as

assum e d in the EPA MOBILE6 m o del.

• “Puff” losses of HC va por that occur when the gas cap is rem oved on a vehicle are

com p arable to (50% to 1 00% of ) f illpipe em issions f r om a single ref u elin g event. “Puf f ”

em issions are positively correlated with T T and RVP.

• Since f illp ipe em issions f o r ORVR-equipped vehicle s do not exhibit the s t an dard correlations with RVP and ∆ T assum e d in the MOBILE6 m odel, States and EPA should revise the c a lculation of ref u eling em issions for ORVR vehi cle s in MO BILE6 to re f l ect the new variable dependencies found in this study and to ensure that future em ission invento r ies are accurate.

5INTRODUCTION

2.1 Overview

This repor t docum ents the resu lts f r om a two- phase study of vapor r ecove ry com p atibility associated with refueling em issions when a G ilbarco vacu um -assisted vapor reco very sys t em (VRS) is operated in the presen ce of a vehicle having onboard refu eling vapor recovery (ORVR). The test program has two overall goals:

1. To better quantify refueling em issions for use in em issions inventorie s under a variety of conditions and to address the California Ai r Resources Board (CA RB) claim s of ORVR

excess em issions using scientif ically defendable m e thods; and

2. To quantitatively address the appropriat eness of CARB’s m e thods for determ ining pressure-related fugitive em issions from the gasoline dispensing facility (GDF) underground storage tank (UST) and pi ping when a VRS is in operation.

CARB’s m e thodologies for testing refueling em issi ons are included in A ppendix A and take five

em issions points into account (see Figure 2

- 1) . These locations are: 1 ) em itted at th e nozzle/vehicle in terface, 2) returned through the vapor pas s age of the ho se, 3) em itted from the pressure/vacuum (P/V) v a lve(s ) on th e underg rou nd storage tank (UST) v e nt pip e (s ), 4) em itted
f r om the assist pro cesso r , if applicab le, and 5) em itted as pr es sure re la ted f ugitives.
Em issions from points 1 and 2 are on a per-vehicle basis, for vehicles at the dispenser being tested, whereas em issions for points 3 and 4 are continuous and influenced by other vehicles refueling at the facility s i nce all disp enser v a por return lines are conn ect ed t oget h er at t h e UST

common ma nifold. Em i ssions from point 5 are calculated, using the eq uations in C A RB Test
Procedure T P -201.2F. Location 4 is not appli cable in this study. Se ction 4 discusses these

m e thodologies in m o re detail. A testing program to m easure re f u eling em issions is typica lly
divided into two com ponents: those from spillage during the fu eling process, and those fr om vapor disp lacem ent. Uncontrolled spillage em issions are sm all relative to u n contro lled displacem ent em issions, and were not cons id ered in this tes tin g program

.

6The rem a inder of this section gives a brief ov erview of the test program and describes the refueling em issions process. Scientific principl es are discussed in Section 3, test protocols are
detailed in Section 4, a nd the study’s results and conclusions are su mmarized in Sections 5 through 8. The test reports from VOC Testing, Inc. are included in Appendices B and C of this report, and the test report from Automotive Testi ng Laboratories, Inc. is attached as A ppendix D.

2.2 Phase 1 – Fleetw i de Tests

In the first phase of the test program, a GDF in San Bernardino, CA e quipped with a Gilbarco

vac-ass i st VRS was selected for refueling em i ssions testing of an in -use v e hicle f l e e t in
accordan ce with test p r ocedures in CARB m e thod TP201.2. VOC Testing, Inc. of San Bernardino, CA is the only known contractor with a depth of experience conducting this type of testing, and was subcontracted to perform the testing. Hydrocar bon concentration and pressure data were continuously recorded utilizing a strip chart recorder , and one-m i nute average data

were sto r ed electron ically. The ob jectiv es were to quantify differences in refueling em issions between ORVR and non-ORVR vehicles, both at th e fillpipe and from the UST. (Note that
TP201.2 m easures both vapor displa cem ent losses from refueling and the sm aller component of UST breathing losses.) These test s were not designed to m easure VRS efficiency u nder the CP

201 Vapor Recovery Certification Procedure.

2.3 Phase 2 – Laboratory Tests

In the second phase of the study, laboratory test s were done at Autom o tive Testing Laboratories, Inc. (ATL) of Mesa, AZ using a dispenser equipped with a Gilbarco vacuum

- a ssist VRS (VaporVac). ATL has perform e d ve hicle em issi ons testing for EPA, CARB, and CRC for m a ny years and their Mesa facility is equipped with six SHEDs and two 3,000 gallon USTs. SHEDs are used by vehicle m a nufacturer s to certif y complianc e with EPA ref u eling em ission standards for ORVR vehicles, and are ideal for studying refueling em issions as a function of different variables. In this study, thos e variables were: type of vehi cle ORVR equipm ent (ORVR wit h vapor recirculation to the fi ll neck, ORVR without recircul ation, no ORVR), fuel RVP,

tem p erature conditions, and A/L ratio. A m a trix of 36 SHED t e sts was perfor m ed to quantify the

7dependence of refueling em issions at the nozzle/f illp ipe as a f unction of the above variab les and

to exam ine the com p atibility issue. In add ition, six refueling tests using CARB m e thod TP201.2 were perform e d by VOC Testing, In c. outdoors at a dispenser equi pped with the sa m e Gilbarco
VRS and ne xt to the US T. During those tests and for a period of up to two hours after each test,
ATL collected em issions at the P/V valve and a n eedle le ak valve on the instrum e nted cap of the UST, calibrated to leak at the m a xim u m rate allowed under CARB TP201.3. (The UST and piping were first tested to en sure they were airtight.)

As with the Phase 1 TP201.2 tests, hydrocarbon concentration and pressure data were continuously recorded. The objectives were to quantify differences in refueling em issions and

excess em issions between ORVR and non-ORVR ve hicles, and to compare actual m e asured

excess em issions to those predicted using the equation in C A RB’s m e thod in TP201.2F. These tests were not designed to m easure efficiency under the CP-201 Vapor Recovery Certification
Procedure.

2.4 Description of the Refu eling Emissions Process

Ref u eling em issions occur f r om vapor displa ce m e nt and f r om spillage. This testing program only exam ined vapor d i s p lacem ent e m issions, which result from the addition of liqu i d fuel to a vehicle’s fu el tank. As the tank is filled, v a por p r esent in the headspace of the tank is displaced
from the tank. For a vehicle without ORVR (“non-ORVR ve hicle” ), these vapors are pushed out the vehicle’s fillpipe. The am ount of e m issi ons displaced is known to be depend ent upon th e fuel volatility, the tem p eratu r e of the vehicle’s fuel tank, the tem p erature of th e fuel being dispensed, and the vehicle b e ing refuel ed (e.g., fillpip e geom etry and desig n ). 2 Vehicles equipped with ORVR (“ORVR vehi cles”) cap tu re vapo rs from the tank headspace on a carbon
canis ter within the vehicle; the va po rs are late r d e sorbed in to the engine while the engine is being operated. Som e ORVR vehicles are equipped with a recirculati on loop that returns a portion of the gasoline vapors to the neck of the fill pipe to r e duce the intrusion of outside air into th e system . All ORVR system s without a m echanical seal use a “liquid seal” to prevent vapors from

2 US EP A, “C o m pil a t i on o f A i r P o l l u t a nt Em i ssi on Fact o r s, ” AP -4 2, C h a p t e r 5 , Sect i o n 5

. 2. 2. 3 (re v. 1/ 9 5 )

.

8going out th e fill neck. The eff ectiv eness of this nonm echanical seal dep e nds on m a ny factors,
includ ing th e f illpip e an d ORVR designs, and th e f u el f l ow rate.

A VRS—som e ti m e s referred to as “Stage II” equipm ent 3 —is designed to capture vapors from
the a r ea whe r e th e ref u e l ing nozz l e is inse rted into the veh i c l e f illp ipe. E ach VRS is designed to
direct thes e vapors back to the headspace of th e UST. In theory, if the volume of liquid dispensed from a UST is equal to the volum e of vapor r e turned and the tem p eratures and
concentratio ns in the v a por retu rn line and UST are iden tic al, there is no change in the UST pressure. S o m e VRS models are vacuum -assisted ( “ vac- assi st ”) , meani ng t h at a vacuu m pu mp i s utilized to h e lp cap ture the displaced vapors fro m the dispenser/fillpip e in terface an d direct th em to the UST. W h en an ORVR ve hicle is refueled , however, som e of the displaced vapors are not being r e tu rn ed to the dispenser / f

illp ipe inte rf ace . Ther ef ore , f o r m o st vehicles, 4 if a vac-assis t VRS is utilized on an ORVR vehicle, the VRS m a y draw in am bient air at the no zzle

- f illp ip e interface and return it to the UST. Because this dilutes th e conc entratio n of hydroc arbons in th e UST headspace, there is potential for the gasoline in the UST to evapo r ate, in o r der to equilibrate
the he adspa ce with th e liquid. Th is in turn ra is es th e press u re of th e U S T, and can cause it to

vent m o re often than if no VRS ha d been presen t. This c oncept is co mmonly referred to as
“ORVR inc o m p atibility” and is di scussed further in Section 3.4.

3 “St a ge I” e q ui pm ent refers t o sy st em s t h at r ecove r va po rs du ri n g t h e t r a n sfer o f gas o l i n e fr om t a nker t r

uc ks t o t h e UST at a GDF.
4 A sm al l perce n t a ge o f vehi cl es—t he C a l i f or

ni a Ai r R e s o u r ces B o a r d (C A R B ) est i m a t e s 5% or l e ss—a r e eq ui p p ed with “m ech an i cal seals” b e t w een th e d i sp en ser n o zzle and fillp ip e, redu cing th e opp ortun i ty fo r air t o b e d r awn in t o th e VR S.

9FIGURE 2-1TP-201.2TEST POINTS3.0 SCIENTIFIC PRINCIPLES

This section provides a brief su mmary of relevant existing know ledge on the factors affecting uncontrolled refueling em issions, Onboard Refu eling Vapor Recovery (ORVR) Canisters,

vacuum -assisted Stage II Vapor Recovery Sys t em s (VRS) , and the issue of ORVR / VRS
“Incom patibility”.

3.1 Factors Affecting Uncontro lled Refueling Emissions

Uncontrolle d vapor dis p lacem ent refueling emi ssions (exp ressed in un its of m a ss em itted per
unit volum e of gasoline transferre d) are known to be a functi on of the tem p e r ature of the dispensed fu el (T D ), th e tem p erature of the vehicle fuel tank (T T ), the f u el vola tility ( R VP), and differences in vehicle design (e.g., fillpipe des i gn) that are not readily quantifiable. EPA’s
for m ula for estim ating uncontrolled refueling em i ssions (not including sp illage), in E P A’s AP-42

em issions factor publication, 5 involves the use of an equati on which takes tem p erature and gasolin e volatility (RVP) into accou n t:

E R = (-5.909) – 0.0949 ( ∆ T) + 0.0884 (T D ) + 0.4 85 (RVP) (3-1)

where:

E R = em issions factor in gram s VO C per gallon transferred (g/gal) ∆ T = T T - T D , o F T D = tem p erature of dispensed fuel, o F RVP = Reid vapor pressure, psia

The dependence upon ∆ T results is explained by a hypothesis that “vapor growth” occurs if the fuel being added is w a rm er than the fuel in the tank (i.e., tank temp erature increas e s an d therefore eq uilib rium vapor pressure above the liquid increas e s), while “vapor shrink age” occurs
if

the f u el being added is coole r than the f u el in the tank . Equation (3-1) is ap plied to all gasoline-fueled vehicle types (rang in g from motor cycles to vehicl es with gross vehicle weights of over 60,000 lb) and was developed by EPA i n 1985, based upon tests conducted in a Sealed

5 US EP A, “C o m pil a t i on o f A i r P o l l u t a nt Em i ssi on Fact o r s, ” AP -4 2, C h a p t e r 5 , Sect i o n 5

. 2. 2. 3 (re v. 1/ 9 5 )

. 11Housing for Evaporative Determ inations (SHED) , on eight vehicles for m odel years 1979-1984. Testing was conducted with gaso line RVP’s of 9.0-12.6 psia, disp ensing tem p eratures of 66-95 o F, and ∆ T values ranging from –12 to +32 o F. The equation explains 79 % of the var i ance in the

em pirical d a ta. 6 EPA noted th at d i fferences between vehicles con t ribu te to em issions factor variability (differences of 18% were seen in the resu lts in at leas t one study) and that other factors (fill rate, am ount of resi dual f u el in the tank, total amount of fill, position of the nozzle in
the fill-neck , and am bient tem p eratu r e) also had an effect but that th e m a gnitude of these effects
was rela tive l y low.

EPA’s AP-42 form ula (3-1) is also incorporated in to EPA’s MOBILE 7 m odels (including versions 5ah, 5b, and 6), which calculate ∆ T as follows:

∆ T = 0.418*T D – 16.6 o F ( 3

- 2 )
EPA has not provided any docum entation for E quati on 3-2, and the origin of this equation is
unclear. There are at least two other issues that are not m e n tioned in E P A’s documentation of
the ref u eling em issions c a lculation s

. 7 First, sin ce T D is not easily m easured, the MOBILE m ode l

program code assum e s that T D is eq ual to the a m bient tem p eratu r e T A (an API study by Radian 8
found that T D is som e what higher than T A , and that this offset varies seasonally and regionally).
The second issue is that the m odel program code 9 “cuts off” as pects of the for m ula, as follows:

If T D < 20 o F, MOBILE sets T D = 2 0 o F. If T D > 95 o F, MOBILE sets T D = 9 5 o F. If ∆ T is calc u lated to be > 20 o F, MOBILE sets ∆ T = 20 o F.

6 D. R o t h m a n an d R

. Jo h n so n ( U S E P A ) , “R ef uel i n g Em i ssi ons fr om Unc o n t rol l e d Ve hi cl es,” R e p o r t N o

. EPA

- A A

SD SB

- 8 5

- 6 , Au gu st 19 85

. 7 U S EPA, “U ser ’ s Gu id e to M O BI LE5 ( M obile So ur ce Em issio n Factor M o d e l) , ” EPA-AA -A QA B-94 -01 , May 1 994 an d “User ’ s Gu id e to M O BI LE6 ( M obile So ur ce Em issio n Factor M o d e l ) ,” EPA420

- R

- 0 2

- 00 1, Jan u a r y 2 002

. 8 Radian Corp., “Sum m a ry and A n alysis of D a ta Fr om Ga soline Tem p erature Survey C o nducte d at Se rvice Stations b y API , ” API Pub licatio n N o . 427 8, 1 976

. 9 See th e REFUEL su brou tin e with in t h e M O BILE m o d e ls. 12If inputs are such that E R is calculated to be less than 1.80 g/gal (= 3.97 lb/1000 gal), E R is se t equal to 1.80 g/gal. The origin of these cutoffs is unclear; 10 the original study only m e ntions that
the m a xi m u m fuel tem p eratu r e (T D ) studied was 95 o F and does not m e ntion the other cutoffs. When reformulated gasoline is utilized, MOBILE6 assigns an RVP of 6.7 psia in calendar years 2001-2002 and an RVP of 6.8 psia in calendar years 2003 and later.

3.2 Onboard Refueling Vapor Recovery (ORVR) Canisters

Onboard Refueling Vapor Recovery (ORVR) vehicl es incorporate a carbon canister that adsorbs gasoline vapors displaced during ref u eling and de sorbs them during vehicl e operation, at which
tim e they are burned in the engine

. ORVR canis ters h a ve a f

i nite capacity and are on ly desorb ed during engin e operation; thus, if a car sits for enough days in the hot sun, em issions will ven t off the canister through a release line under the car. A potential pr oblemwhen fueling an ORVRvehicle is th at th e f l ow of f

u el ente r i ng th e na rr ow f illpipe crea tes a ve nturi ef f ect r e sulting in a suction of outside air through the fuel nec k, adversely affecting system perfor mance. 11 T o prevent a i r ingestion a t the f ill neck and to reduc e the vapor load to the c a nister dur in g ref u eling,

m a ny ORVR system s are equipp ed with recircu l ation line to retu rn vap o rs in the ta nk to the to p of

the nozz l e/f illp ipe ar ea. 12 The recircu l ation line also help s isolate the tank from the outside
environm ent and reduce em issions out the fuel n eck. All ORVR system s without a m echanical seal use a “liquid seal” (really a fluid dyna m i cs s eal) in which the liquid colum n of fuel in the
vehicle’s fu el neck and its downward flow mos tly p r even ts disp laced vapors during refueling
f r om escaping out the f ill neck. The ef f ectiven ess of this nonm echanic al seal dep e nds on m a ny f actors, in cluding f illp ip e and ORVR designs, a nd the f u el f l ow rate.

Section 202 (a)(6 ) of the Clean Air Act require s vehicle manufacturers to equip new vehicles nationwide with ORVR system s in accordan ce with the s c h e dule in Table 3-1. O R VR systems

10 Lo is Platte (US EPA), in a telep h o n e co n v er sat i on wi t h R o bert R o ssi (Tec h E n vi ro nm ent a l ) , M a rc h 1 2 , 20 0 2 , stated th at th e cu toffs correspo n d e d to p a rameter rang es fo r wh ich d a ta ex isted , bu t d i d n o t elab orate as to wh y t h ese do n o t m a t c h t h e param e t e r r a nge s i n EP A’ s 1 9 8 5 re fere n ce d o cum e nt

. 11 Belforte G ., C a rello M., E u la G. , Fe rra resi C., I v a n ov A., “Prelimin ary stu d y of th e liqui d seal phenomenon”, FLU C O M E 2 0 0 0 , Sh er br ook e, Can a d a , 13 -17 ag osto 20 00 , I S BN 2- 762 2-0 126 -8

. 12 Pers o n al com m unication wit h Har o ld Has k ew, Ha rol d Ha skew & Ass o ci ates, Inc., M i l f or d, M I , M a rc h 18 , 20 0 2 , an d Stan t Manu fact u r ing , In c., “Stan t OR VR Sy stem Th eo ry o f Op eration , ” Con n e rsv ille, IN, h ttp ://www.g ates.co m /in d e x

. cfm ? lo cation_ id=7 06

. 13are required by federal law to be 95% effective at reducing refueling em issions fr om ordinary GDFs (not equipped with Stage II VRS) and federal test proce dures require that “refueling

em issions” include both vapor displacem ent and spillage during refue ling. EPA regulations require th at ORVR canisters keep refueling em issions at or below 0.20 gram s per gallon of gasoline dispensed throughout the full useful life 13 of the v e hicles, and wh en tes t ed m o st ORVR
vehicles eas ily m eet the lim it, e m itting typ i cally 0.10-0.15 g/gal. EPA’s MOBI LE6 m odel

assum e s ORVR controls ref u eling em issions f r om the f ill pipe by 98%, and ref u elin g spillage b y 50%. EPA’s refueling em issions test proced ures in clud e m easurement of both the vapo r displaced during refueling and the evaporation of any liquid spillag e that o ccur s ; tes ting is conducted in a SHED. Dispensed f u el tem p erature (T D ) is kept at 67 (+/- 1.5) o F, a n d r e fue l i ng is conducted with a standard (non-S t age II VRS) nozzle.

When EPA prom ulgated the ORVR standards in 1994, Stage II VRS were no longer required in
Moderate ozone non-attainm e nt areas (except in the Ozone Transport Re gion, com p rised of the
States from Virginia to Maine pl us the District of Colum b ia), and section 202(a)(6) also states
that the EP A Adm i nistrator “m ay...waive the a pplication of the requirem e nts [for GDF vapor recovery system s in nonattainm e nt areas classif i ed as Serious, Severe, or Extrem e]...after such
tim e as the Adm i nistrator determ ines that [ORV R] systems...are in widespread use throughout
the m o tor vehicle fleet.” Although the term “i n widespread use” has not yet been for m ally defined, EPA has suggested that it will cons ider e ith er “th e percentage of the automobile fleet equipped with ORVR,” or “when O R VR achieve s em issions reductions on a one-to-one basis
when com p ared to Stage II.” 14

13 EPA de fi nes “f ul l use f ul l i f e” i n 4 0 C F R 8 6

. 1 8 0 5

- 0 1 a n d 8 6

. 1 8 0 5

- 0 4; al t h ou g h t h e exact defi ni t i on va ri es f o r
v e h i cle typ e s, t h e m i n i m u m d e fin itio n is 1 0 years or 10 0,00 0 m i les.
14 Let t e r fr om Jason G r um et (N ESC A UM ) t o Tom Helm s and Gre g ory Gre e n (EP A ) , Oct obe r 1 1 , 2 0 0 1

. 14TABLE 3- 1

ORVR IMPLEME N T A TION SCHEDUL E

Model Years (MY) for Which ORVR Mandat e Must Be Met 15 ORVR Mandate

( % of Vehicles

Sold) Light-Duty Vehicles 16 Light LightDuty Truck s 17

(0-6,000 lb) Heavy Ligh tDuty Truck s 17 (6,001-8,500 lb) Medium Duty Passenger Vehicles 18 (8,501-10,000 lb) Complete Heavy Duty Vehicles 19 (8,501-10,000 lb)

4 0 % 1 9 9 8 2 0 0 1 2 0 0 4 2 0 0 4 2004 20

8 0 % 1 9 9 9 2 0 0 2 2 0 0 5 2 0 0 5 2 0 0 5

1 0 0 % 2 0 0 0 + 2 0 0 3 + 2 0 0 6 + 2 0 0 6 + 2 0 0 6 +

15 OR VR p h ase-i n sc he dul e i s i n cl u d ed i n 4 0 C F R 8 6

. 1 8 1 0

- 0 1 ( k) f o r l i g ht

- dut y vehi cl es a n d l i ght -d ut y t r uck s ;
ex tend ed to m e d i u m -d u t y p a ssen g e r v e h i cles in §86 .1 811 -04(e)(3)(iii).
16 Defi ned as “a passe nge r ca r or pass en ger c a r deri vat i ve c a pabl e o f seat i n g 1 2 passe n g e r s or l e ss ” ( 4 0 C F R 8 6 .180 3-0 1 )

. 17 “Light Duty Trucks” (LDT ’s ) are define d as “any m o tor v e h i cle r a ted at 8,50 0 pou nd s GVW R or less wh ich h a s a
cur b wei g ht of 6, 00 0 p o u n d s o r l e ss a n d whi c h has a basi c v e hi cl e fr o n t a l a r ea of 4 5 s q uar e feet or l e ss , whi c h i s : (1 ) desi g n e d pr im ari l y for pu r pos es of t r an sp ort a t i o n of p r o p ert y or i s a de ri vat i v e of s u c h a ve hi cl e; or (2 ) Desi g n e d p r im arily fo r tran sp ortatio n of p e rson s and has a cap acity of m o re t h a n 12 pers o n s; or ( 3 ) Avai l a bl e wi t h speci al feat ure s e n abl i ng o f f

- st reet or o f f

- hi gh way o p erat i o n a n d us e.” L D T ’ s a r e subdi v ide d int o “Li ght Li ght-Duty Truc ks” ( u p t o 6, 00 0 l b GV W R ) an d “ H ea vy Li g h t

- D u t y Tr uck s ” ( 6 , 0 01

- 8 ,5 00 l b G V W R )

. 18 Defi ned as “a n y [ve h i c l e rat e d at m o re t h a n 8, 50 0 l b GV W R or t h at has a vehi cl e c u r b w e i ght of m o re t h an 6 , 0 0 0 lb or t h at has a basic vehicle frontal a r ea in excess of 45 s q

. ft.] with a [ GVW R] or less t h an 1 0 ,000 p oun d s th at is d e sign ed p r im a r ily for th e transp ortatio n of person s.”
19 Defi ned as “a n y Ot t o -cy c l e [ v ehi c l e rat e d m o re t h a n 8, 50 0 l b G V W R or t h at ha s a ve hi cl e cur b wei g ht of m o re t h an 6, 0 0 0 l b o r t h at has a ba s i c vehi cle frontal area in exce s s of 45 sq. ft .]

.. .that ha s the pr im ary load ca rr ying device or c onta i ner attache d at the tim e the vehicle l eaves t h e c ont rol of the m a nufacturer of the engine .”
20 Manufacturers can c h oose a c o m p liance op tio n th at elim in a t es th e refu eling stan d a rds for 20 04 fo r t h is veh i cle typ e [§ 86 .18 16- 05 ( e ) ( 3) ]. 153.3 Vacuum-Assisted Stage II Vapor Recovery Systems (VRS)

Sections 18 2(b)(3 ) and (c)-(e) of th e Clean Air Act requ ire gasolin e dis p ensing f a c i lities (GDFs)
in nonattainm ent areas classified as “Moderate,” “S erious,” “Severe, or “Extrem e” to install and operate vap o r recov e ry system s (VRS) to capture vapor d i splaced fro m vehicles ’ fuel tanks as they are f ille d. These are comm only ref e rred to as “Stage II” s y stem s and are cer tif ied to be 95%
effective on a fleetwide averag e at capturing di splaced vap o rs. His t orically, the 9 5 % control efficiency was determ ined by only considering em i ssions at the fillpipe- nozzle in terface and at
the P/V va lv e on th e UST. There was no cons id er ation pr es sure- r elated f

ugitive em issions f r om the UST and piping. Only GDFs with average m onthly throughputs of less than or equal to 10,000 gallons, “independent sm all business m a rket ers” with average m onthly throughputs of less than or equal to 50,000 gallons, and marina s/m a rine vehicles are exem pt from these requirem e nts.

When fuel is added to a vehicle’s tank, air and gasoline vapor in the tank headspace (which can consist of approxim a tely 30-40% gasoline vapor a nd 60-70% air in the summ er) are displaced.
W ith a vacuum assist Stage II VRS, a vacuum sy stem pulls the gases in through perforations in the nozzle spout to a return hose that connects to the headspace of the underground storage tank (UST). For these sys t em s, the GDF’s stor age tank is required to be equipped with a pressure/vacuum (P/V) valve, which is designed to open o n ly if th e p r essur e in side the tank
increases to m o re than 3” wate r colum n (w.c.) above atm o spheri c pressure or decreases to less
than 8” w.c. below atm o spheric pressure.

The ratio of the volume of air and vapor return ed to th e UST (A) to the vo lu m e of liquid dispensed (L) is the A/L ratio, and air flow m e ters used in CARB m e thod TP201.2 are calibrated with nitrog e n gas. Stage I gasoline transf ers in to the UST from a tanker truck can pressurize the UST and temporarily af fect the A/L. Filter cha nges at the UST can also affect the A/L through the dispen sing rate. In theory, if A/L>1, pressu riza tion of the UST will occur. Vac u um assist
VRS are certified at A/ L ratios from 0.85 to 1.20, with the ex ception that a sm all percentage of such systems are equipp ed with destructive pro c essors (i.e., that therm a lly oxidize the vapors) and have higher A/L ratios in the range of 1.35 to 2.4. Som e vacuum ass i st system s use a “m ini16boot” to enable the system s to r un at slightly lower A/L ratios (sim ilar to the “vapor balance” VRS, which require a boot to m a ke a tight fit during refueling).

3.4 ORVR / VRS “Incompatibility”

The California Air Resources Board (CARB) has stated that there is a potential for “excess

em issions” of pressure-related fugitives when v acuum assist Stage II VRS are used to refuel vehicles equipped with ORVR. Spe c ifically, be cause th e ORVR system s rem ove much of the vapors that vacuum assist Stag e II s y stem s are designed to pull back, the vacuum assist system s

can cre a te n e gativ e pres sure in the f ill p i pe. If this occu rs, am bient air f r om the vic i nity of th e GDF nozzle/fill p i pe in terface will be drawn back in to the UST. Because th is dilu tes th e concentration of gasoline vapor in the headspace of the stor age tank, a portion of the liquid gasolin e in the stor age tank will v o latize and in cre a se the partial pre ssures of th e gasolin e constituents towards the i r equilibr iu m values. Th is causes the total pre ssure in th e storage tank
to rise. In creas ed UST pressu re in the h ead space (ullag e) can in crease fugitiv e em issions through leaks in the piping system , a nd if the gauge pressure increases above the positive setting
of

the P/V valve ( t ypic a lly 3” w.c.), the storag e ta nk will ven t to the a t m o sphere.

To date, the only publicly available test repor t addressing O R VR com p a tibility is a 1999 study conducted by CARB personnel. 21 Two different GDFs were teste d, each with a different vacuum
assist VRS: one in Sacram ento, CA, which utilized a Dresser Industries W a yneVac VRS, and one in El Sobrante, CA, which utiliz ed a Gilbar co VaporVac VRS. At t h e tim e that testing was conducted, few vehicles were equipped with ORVR. To sim u late ORVR vehicles, CARB modified dispensers at the fac ility to sim p ly ingest am bient air (0% va por) to the UST via the VRS vapor return line. Thus, no ORVR vehicles were actually tested in the C A RB study. CARB calculated (bu t did not dire ctly m easure) f ugitive UST em ission increas e s resulting f r om ORVR incompatibility from differences in UST pressures. The CARB st udy did not quantify the
decrea se in em issions at the nozz l e/f illp ipe in terf ace tha t re su lted from ORVR.

21 C a l i f or

ni a E n vi r onm ent a l Pr ot ect i on A g e n c y , Ai r R e so urc e s B o a r d , P r el i m i n ary Dra f t T e st R e po rt , “ T o t al Hy dr oca r b o n E m i ssi ons f r o m Tw o P h ase II Vacu um Assi st Va po r R e c ove ry Sy st em s Du ri n g B a sel i n e Ope r at i o n
an d Sim u lated Refu eling o f On bo ard Refu elin g Vapo r Reco very (OR V R ) Eq ui p p ed Ve hi cles,” Project Num b er ST98 -X X, J une 1 9 9 9

. 17In the CARB ORVR compatibility study, negligible em issions were e m itted from the P/V valve, i.e., all UST em issions were in the for m of pressure-related fugitives from other unknown
locations. These em issions cannot be m easured directly by CARB m e thods and are difficult to quantify. T h eir exis ten ce is assum e dly th e reas on why UST pressure d ecays s l owly with tim e , rather th an holding steady. Thu s , fugitiv e em issions are es tim ated by m u ltiplying the hydrocarbon vapor concentration in the UST he adspace by a fugitive leakage flow rate. Th e volum etric leakage rate is in turn calculated as a function of US T pressure and pressure changes
with tim e. CARB’s equation for calculating volum e tric leakage rate (TP201.2F) has changed significantly over tim e and has several deficiencies. For exam ple, the assum e d dependence of
volum etric leakage on the square root of tank pressure (s ee Section 5.2, equa tion 4-2) is
inconsistent with data in the 1999 CARB report that s how flow rate is a quadratic function of pressure; this error leads to ove r-prediction, especially at low ta nk pressures. In a related study by the Bay Area AQM D, testing was done with bot h standard and m i ni-boot nozzles, and the
results show ed UST pres sures decreased com p ared to s t andard nozzle con f igurations when m i niboots were em ployed. CARB calculated a 50% redu ction in fugitive em issions for m i ni-boot
nozzles from those test data.

CARB found higher em issions for the Gilbar co VaporVac system than for the W a yneVac system , due in par t to the lower A/L ratio f o r the W a yneVac com p ared to the VaporVac. A review of CARB’s work by Tech Environmental, Inc. revealed that the calcu l ated Gilb arco VaporVac “excess em issions” were biased h i gh becau se: (1) som e A/L values were too high; and (2) th e A/L values d r if te d upwards f r o m the tim e of the base line tes ting to the tim e of the ORVR
sim u lations. CARB also acknowledges in their repor t (p.8) that the incom p atibility effect wa s overestim ated by the introduction of am bient air and no return vapors into the UST headspace.
Data for the W a yne system support the conclusion that when considering total em issions from
ref u eling (f r o m both the f ill ne ck an d the UST), ther e ar e n o “exces s e m issions” due to ORVR
incom p atibility f o r the W a yne syste m that was te sted. Other research done by CARB shows that refueling liquid seal ORVR-equipped vehicles wh en a Gilbarco VRS is in oper a tion returns a

18vapor m i xture containing an average of 6.6% h ydrocarbons in the vapor return line to the UST (average of data from 54 tests). 22

22 C a l i f or

ni a Ai r R e sou r ces B o a r d , “ V ap or R e t u r

n P a t h Hy d r ocar b o n C o nce n t r at i o ns i n Va cuum Assi st V a po r R ecove ry Sy st em s Di spe n si n g Gasol i ne t o OR VR E q ui p p e d Vehi cl es,” Pro j ect C

- 9 7

- 0 24 , M a rc h 1 9 9 8 , Tabl es 6

- 8 t h r o u g h 6- 10

. 194.0 TESTING METHODOLOGIES

4.1 Phase 1 – Fleetw i de Tests

4.1.1 Overview

This first phase of the testing program was conduc ted to investigate vehi cle refueling em issions
from gasoline dispensing facil ities (GDFs) and the com p atibili ty of a Gilbarco VaporVac VRS
with ORVR on m o tor vehicles. Tes ting was do ne in accord ance with test pro c edures in CARB

m e thod TP201.2 at the Conoco Service Station located at 3405 Highland Avenue in San Bernardino, California. Mr. Del Powell of VOC Testing, Inc. conducted the testing between
October 31 and Nove mber 7, 2002.

The test procedures in the m o st recent a dopted version of TP201.2, Efficiency and Em ission Factor for Phase II System s, (July 25, 2001) we re used, with CARB’s r ecent 100-vehicle m a trix (March 18, 2002). This m e thod has a quantifiabl e m i ni m u m value of 0.01 lb/1,000 gallons (see Section 4.1 of TP201.2). Two sets of tests were perform e d:

1. Test 1 consisted of a 100-car m a trix. Sta ndard OPW 11VA1 nozzles w e re used with the Gilbarco system , certified to operate at an air/liquid (A/L) ratio of 1.0 to 1.2, and operated in the upper end of the allowable range (1.14-1.19).

2. Test 2 consisted of a 100-car m a trix. OP W 12VW nozzles with “m ini-boots,” certified to operate at an A/L ratio of 0.9 to 1.1, and operated at the lower end of the allowable range (0.92).

The fuel in the USTs during the entire testi ng program (through November 7) was California
summertim e reform ulated federal gasoline (RFG), oxygenated with ethanol, in grades 87 and 91 octane, and having a Reid Vapor Pressure (RVP) of 7.0 psi.

Three CARB test procedures were used: TP20 1.2 (7/25/01 version) for refueling em issions; TP201.3 (3/17/99 versio n) for pressu re decay te sts on the UST; and TP201.2F (8/20/0 2 proposed
revis i on) for pressure measurem ents , fugitiv e e m ission calculations, an d UST headspace vapor

20sam p ling. The CARB test procedur es were used to collect resear ch data and not to certify a GDF, and thus som e details for certification we re not followed. TP201.2 is a fleetw ide average
test and norm a lly a m a t r ix of 200 vehicles is re quired for the certification test at a GDF. This testing program used CARB’s s m alle r 100-car m a trix. A copy of all test procedures is given in Appendix A.

CARB Test Procedure TP-201.2, used in this pha se of the test progr am , was developed to quantify the vapor recovery m a ss efficiency and/ or m a ss em ission factor by directly m easuring
the m a ss of hydrocarbon s at the loca tions shown in Figure 2

- 1

. Thes e locations are: 1) em itted at
the nozzle/v e hicle in terf ace, 2) returned through the vapor p a ssage of th e hose, 3 ) em itted from the pressure/vacuum (P/V) valve(s) on the unde rground storage tank (UST) vent pipe(s), 4)

em itted f r om the assis t processo r, if applic able, and 5) em itted as pres su re re lated f ugitiv es.

Em issions from points 1 and 2 are on a per-vehicle basis, for vehicles at the dispenser being tested, whereas em issions for points 3 and 4 are continuous and influenced by other vehicles refueling at the facility s i nce all disp enser v a por return lines are conn ec ted together at the UST

common ma nifold. Em i ssions from point 5 are calculated, using the eq uations in C A RB Test Procedure TP-201.2F. This first phase of the te st program quantified em issions from locations 1,2, and 3. Location 4 is not applicable. The s econd phase of this tes ting program directly

m easured em issions point 5 for ORVR vehicles.

To quantify the vapor tightness of the VRS syst em, CARB Test Procedure TP-201.3 was used. In this procedure, the VRS is pressurized with nitrog en to 2.0 in. w.c. and then is allowed to decay
over five minutes. This value is com p ared w ith an “allowable value”, which is based on the system ullag e and pres su re decay equ a tions. Th e test was con ducted at th e beginning and end of Tests 1 and 2, and this inf o rm ation was used to calcu late f u gitiv e em issions using the equation s in TP-201.2 F. UST headspace vapo r concen trations were co llected con t inuously fro m(and recircu l ated b ack to) the UST common h eader an d analyzed with an NDIR.

214.1.2 Testing Details

The Conoco Service Station at 3405 Highland Ave nue in San Bernardino, CA, was selected for testing refueling em issions. The s t ation has a fairly low throughput and consists of eight dispensers, all Gilbarco VaporVac s y stem s; two of the nozzles ar e generally equipped with m i niboots and six are not. During Test 1 the two nozzl es equipped with m i ni-boots were covered and identified as not operational. All T P 201.2 test s were done at dispenser #3. Additional m i nibooted nozzles were installed for Test 2, so that all gas was dispensed from a sim ilarly equipped
nozzle durin g each test. To elim inate any variab ility due to different operato rs, VOC Testing, Inc. perform e d all fueling at dispenser #3.

The test procedures in CARB method TP-201.2 were used with CARB’s 100-vehicle m a trix (March 18, 2002), rather than the 200-vehicle m a trix identified in the test procedure. During Test 1, 95% of the vehicles identified in the m a tr ix were o b tained ; during Test 2, 99% were
obtained. V e hicles tested were identified by m a ke , m odel, and whether or not the vehicle has
ORVR. CARB’s m e thodology for determ ining whet her or not a vehicle has ORVR (by the “evaporative fa m ily” sticker under th e hood) was not always successful, since som e vehicles did not have this sticker. Thus, in some instance s the contracto r estim ated ORVR from the age of
the vehicle and other factors.

A f actor af f ecting the nozzle / f illp ipe em ission s was whether or not a ca r pr e-p a id f o r the gasoline. The area where the station is locate d is econom ically depressed, which resulted in

m a ny custom ers opting to pre-pay for the fuel (g enerally $5 or $10 worth), rather th an filling up their vehicle tanks. Since CARB requires a m i nimu m of 6 gallons for refueling tests, custom ers were given an incen tive for fueling at least 6 gall ons of gas. In a pre-pa y refueling, during the last 15-30 seconds the liquid a nd vacuum pumps slow down, executing a slow cutoff; VOC Testing noted a spike in e m issions towards the end of the refueling. During Test 2, there was less of a spike, due to the m i ni-boot.

At dispenser #3, less than 20% of the fuel wa s dispensed to vehicles equipped with ORVR system s. The ORVR portion of tested veh i cles could no t be increased b ecause TP201.2 tests at

22dispenser #3 were targeting vehicl es within a m a ndated m a trix. W e also note that this num ber i s not representative of the percentage of fuel dispensed to ORVR vehicles at the GDF

. Inform ation regarding all other vehicles refue ling at the station was not possible to obtain throughout the course of this study, but a short survey one after noon suggests that approxim a tely
8% of the fuel norm a lly dispensed by the GDF was dispensed to ORVR-equipped vehicles. The
station’s loc a tion in a lo w-incom e area could e xplain the lower percentage of ORVR vehicles than in the general vehicle population.

This phase of the study was not designed to study differences in refueling em issions linked to fuel RVP, a nd over the course of the testing pr ogram , the RVP of the fu el was never varied. However, given that the RVP of fuel should ch ange from summ er-tim e RVP to winter tim e RVP
on Nove m b er 1, vehicles refueling at the stat ion after Novem b er 1 c ould potentially contain higher-RVP fuel, obtained from anot her station. Drivers were ask e d wh en and where they had most recently refueled and this inform ation wa s noted, thoug h drivers often did not recall their last refueling. From this lim ited infor m ation, it was not possible to definitely determ ine the effect of potential ch ang e in RVP of the fuel re m a ining in a vehicle tank before it was refuele d
with the RF G RVP 7.0 fuel, and none of th e Test 2 vehicle data were excluded.

During the testing, Underground Storage Tank (UST) tem p erature data were collected with the Veeder-Root system . Meteorological data, incl uding am bient tem p erature data, were obtained
from the nearest Nation a l W eather Service (NWS) station in Rivers ide , California (and from the Riverside March Air Force Base on one day, N ovem b er 7, when data were m i ssing from the
NW S station).

4.2 Phase 2 – Laboratory Tests

4.2.1 Overview

The second phase of the study was perform e d a t Autom o tive Testing Laboratories in Mesa, AZ
under the direction of Mr. Dennis McClem ent, Vi ce President of Engineering. Mr. Del Powell of VOC Testing, Inc. also conducted refueling test s with CARB m e thods as part of this phase of the program. The se cond phase directly exam in ed the issue of com p atibility between the

23Gilbarco VRS and ORVR-equipped vehicles and “excess em issions ” by m e asuring the pressurerelated fugitive em issio n s at the U S T (leaks ) pl us em issio n s at the P / V valve. T h e work was done between July and October 2003. This phase had two separate work tasks:

1. Task 1 – Outdoor Tests . Data were taken on three vehi cles and two USTs in order to:

a. Com p are f u gitiv e em issions at th e UST, b. Com p are fugitiv e em issions resultin g from ORVR and non-ORVR vehicles, and

c. Com p are fugitiv e em issions predicted by CARB’s m e thod TP 201.2F.

To accom p lish this w o rk six refueli ng tests using CARB m e thod TP201.2 were perform e d outdoors at a dispenser equipped with a Gilbarco vacuum -assist VRS (VaporVac) drawing product from a 3,000 gallon UST containing 1,000 gallons of RVP 7.8 psi sum m e r grade gasoline oxygenated with ethanol (91 octane). This m e thod has a quantifiable m i nim u m value of 0.01 lb/1,000 ga llons. The UST and piping were first tested and tightened to ensure they were esse n t ially a i rtight. During ea ch ref u eling tes t and for up to two hours after, ATL collected em issions at the P/V valve and pressurerelated fugitive em issions at a needle leak va lve on the instru m e nted cap of the UST. The needle valve was calibrated to leak at th e m a ximum rate allowe d under CARB TP201.3. Finally, “ex cess em issions” re late d to ORVR incom p atibility with the VRS were calcu lated.

2. Task 2 – Indoor SHED Tests . Thirty-six refueling test s in a SHED we re conducted f o llowing a test procedu r e s i m ilar to the f e de ral ORVR certif i cation tes t to quan tif y the nozzle / f illp ipe em issions as a f unction of f

our variab les : type of ORVR equipm ent, f u el RVP, te m p e r ature conditions, and A/L ratio for the VRS.

Three CARB test procedures were used: TP20 1.2 (7/25/01 version) for refueling em issions; TP201.3 (3/17/99 versio n) for pressu re decay te sts on the UST; and TP201.2F (8/20/0 2 proposed
revis i on) for pressure measurem ents , fugitiv e e m ission calculations, an d UST headspace vapor

sam p ling.

Test Vehicles

Three vehicles were used in this phase of the pr ogram , and all ORVR vehicles used a liquid seal typical of such vehicles on the road in the U.S. A baseline certification test was done on each of the ORVR vehicles (without the VR S in operation) to verify they complied with the federal 0.2

24g/gallon lim it as a check on the proper operation of their ORVR system s. The t h ree vehicle s

were:

Vehicle 1 ORVR with vapor re -cir culation to the f ill neck. 2003 Toyota Echo (ORVR Certification Test result 0.008 g/gal)

Vehicle 2 ORVR without vapor recirculation 2003 Chevy Blazer (ORVR Certification Test result 0.001 g/gal)

Vehicle 3 No OR VR 1995 Nissan Maxim a

Fuels and Tanks

The two fuels used in this pha se were RVP 7.8 psi summ er gaso line, oxygenated with ethanol (5.5% by volum e), octane 91 and Certified RFG, RVP 7.0 psi , oxygenated with ethanol (8.3% by
volum e), octane 91. ATL perform e d RVP testing throughout this phase of the study and a m i nor

am ount of butane was added as n ecessary. The RVP had to rem a in in the range of +0.2 psi to – 0.3 psi of the target RVP (7.0 or 7.8 psi) at the com p letion of a test for that test to be valid.

Fuel was s t o r ed in a series of ATL’s existi ng USTs, and where tem p erature was a constant 83 o F.
For Task 1 – Outdoor T e sts, 1,000 gallons of th e RVP 7.8 fuel were pum ped into a 3,000 gallon UST, providing 2,000 gallons of ullage (head space) which exceeds the 1,000 gallon m i ni m u m ullage sp ecified in CARB’s pressu re decay te st (TP201-3 , Section 6. 3). ATL continuously monitored pressure in the UST during the outdoor tests. For Task 2 – Indoor SHED Tests, 50 gallons of fuel at a tim e were pum pe d into an instrum e nted fuel delivery cart.

ATL installed a P/V valve on a ri ser pipe from the 3,000-gallon UST that opens only at tank

pressur e s higher than +3 ” w.c. and le ss than –8” w.c. There was a m i nimum waitin g tim e of one hour between the outd oor tests to allow the h ead space concentratio n in the U S T to reach equilibrium , and just prior to each s u ch test, th e UST was set at 0” w.c. (i.e., depres surized ) so
that each test was done with th e same starting tank conditions.

25Three tem p eratu r e con d itions were studied using as independent variables: 1) T D , the

tem p erature of dispensed fuel; and 2) ∆ T = T T - T D , where T T is the vehicle fuel tank

tem p erature. T D was controlled by a heating / chiller co il in th e fuel line and m easured by ATL in a coupling b e tween the fuel line and the nozzle. T T was cont rolled by soaking the vehicle in the SHED for four hours; this ensu re d both the veh i cle fuel tan k and head -space vapo r stabilized at the spec if ied test tem p erature. A national gasoline temperat ure survey done for API 23 reveals that in the summ er m onths the highest dispensed fuel tem p erature for the hottest days (T D ) ranges between 75 o and 90 o F and ranges 0 o to 15 o F abov e the tem p erature of th e U S T, T g , depending on the region of the country.
That research also sho w s that in the summ er , vapor shrinkage condi tions are 5 tim es m o re prevalent than vapor growth conditions and the average ∆ T values are +13 o F (for vapor shrinkage conditions) and –4 o F (for vapor growth conditions). Using this inform ation in our study, reasonable summertim e (ozone season) tem p er atures were selected, m a king sure to vary only one independent variable betw een test cond itions, and to provide si gnificant tem p eratures differences ( ∆ T) so that both vapor shrinkage and vapor growth effects could be studied. T g is

assum e d invariant at 75 o F. The three selec t ed su mmertim e conditions ar e:

Condition T D ∆ T T T

1 75 o -5 o 70 o vapor growth 2 75 o +15 o 90 o vapor shrinkage 3 90 o +15 o 105 o vapor shrinkage

A/L Ratios

A new Enc o re 300 dispenser with a Gilbarco VaporVac VRS was purchased by ATL and equipped to use either a standard OPW 11VA1 nozzle (certified to operate in the range of 1.0 – 1.2 A/L) or an OPW 12VW nozzle with a m i ni-boot (certified to operate in the range of 0.9 – 1.1 A/L). ATL purchased both nozzles new. The G ilba r co sys t e m was set at the f o llowin g ratios:

1) A/L = 1.15 with standard nozzle

23 Radian Corp., “Sum m a ry and A n alysis of D a ta Fr om Ga soline Tem p erature Survey C o nducte d at Se rvice Stations b y API , ” API Pub licatio n N o . 427 8, 1 976

. 262) A/L = 0.95 with m i ni-boot nozzle

The A/L ratio was tested first as part of the pre- te st integr ity v e rif i ca ti on (see below) and several
additional tim e s during the test program , especially when the A/L ratio an d nozzle were changed. All the targe t value s and with in th e c e rtif ication r a nges.

The contractor installing th e Gilba r co VRS perf orm e d the f o llowing integ r ity tests :

CARB TP201.5 Air to Liquid Volu m e Ratio (2/1/01 version) CARB Advi sory No. 179 Ring or Bag Test (11/29/00 version)

4.2.2 Testing Details – Ou tdoor Tests

Perform i ng controlled tests outdoor s at ATL’s facility in Mesa, AZ during the summer presented
a tim ing challeng e to the research team . Pres sure m easurem ents on t h e UST over a diurnal period showed heating effects of the sun influe nced UST s y stem pressures not too long after sunrise, s t ar ting at 8:30 a

. m ., and did not abate u n til sho r tly bef o re sunse t . Thus, it was decided
that all tests would be done at ni ght and end before 8:30 a.m

. in the m o rning. Due to a persistent high-pre ssur e ridge over the western U.S. during the m onth of July, nighttim e tem p eratu r es in
Mesa rem a ined high and in general varied no more than 1 o F per hour. Air tem p eratures during
the m u lti-night tests (as m easured at nearby Ph oeni x Sky Harbor Airp ort) were in the range of
87 o to 99 o F

. The dry air, lack of rain, lack of so lar insula tion and f a irly constan t tem p eratures during the test periods provided fairly consis tent weather conditions for the outdoor tests.

Prior to the tests, the Gilbarco installer (W est Star Contracting) did several TP201.3 pressure decay tests and found t h e system t o be essentially airtight (the m easured decay rate was only
0.01-0.02” w.c. from 2.00” w.c. pr essurization over five m i nutes). A second TP201.3 test at the conclusion of the outdoor tests by the Gilbarco installer co nfirm e d the sam e , al m o st zero leak rate (0.02” decay from 2.00” pressu rization ove r five m i nutes). A TP201.3 test do ne by ATL
toward the end of the tests s howed a loss of 0.05” w. c. over five m i nutes. TP201.3 tests done by VOC Testing, Inc. show ed rates of 0.04” to 0.09” w.c. over five m i nutes, with the higher decay

rates m easured before m i nor leaks were found and fixed in their tubi ng connections to the system

. 27Once the team was confident th e UST and pip i n g sy stem was essen tially air tight, a needle valve
was insta lle d on the in strum e nted cap of the UST and calibrated to produce a leak rate equal to
the m a xi m u m allowed under TP201.3 (for 2,000 gall ons ullage, single dispenser), nam e ly a decay from 2.00” w.c. to 1.56” w.c. (a decay of 0.44” w.c.) in five m i nutes. The orifice of the leak valve was fit with a coupler for a Tedlar sampling bag. The outlet of the P/V valve was also bagged, though pressures in the syst em never rose high enough to cr ack the P/V valve, due to the engineered leak at th e n eedle valve and the f act that only a single re fueling event was being
studied at a tim e

.

The six refueling tes t s u s ed the h i gh er RVP 7.8 fuel and Tem p eratu r e Co ndition 1 (v apor growth scenario). T h e th ree veh i cles were tested at each of the two A/L ratios. P r ior to the tes t s, the full
canis ter certification pro cedure per 4 0 CFR 86.151 was perform ed on each ORVR vehicle once. At the end of the procedure, the canister wa s weighed, purged of all hydrocarbons with 300 bed
volum es, and then reweighed to determ ine the standa rd loading for that canister. Prior to each test on ORVR-equipped vehicles, the ORVR c a ni sters were conditioned by first purging them and then adding an am ount of butane equal to the standard loading level. The vehicles were
soaked in a SHED at 70 o F prior to each test to ensure the v e hicle, its tank and head space vapo r were at the proper tem p erature, and then pushe d outside to the dispenser above the UST just before the refueling test. Before the vehicle temperature s o ak, the fuel tank was drained and refilled to 10% of capacity.

To dispense fuel into the vehicle during the te st at a tem p erature close to the targ et of 75 o F, an
ice water chiller had to be used o n the fuel lin e from the UST to the dispens e r. The actual dispensed f u el tem p erature during the outdoor tests varied from 75.3 o F to 77.8 o F (Mean =
76.8 o F, S.D. = 1.0 o F). The variability in fu el temperature could have introduced a bias of up to
+4% in the em issions, a sm all inaccuracy for the test prog ram

.

By conducting a single refueling test under cont rolled conditions with co ntinuous m easurem ents of

UST pressure an d he adspace con centr ation, a nd actu a l b a gged sam p les of f

ugitive em issions (leak valve) and P/V em i ssions, the outdoor tests in this study were able to docum ent as real the

28UST vapor growth phenom enon that CA RB claim s produces ORVR-Gilbarco VRS
incom p atibility (see the discussion in Section 3.4). Under CARB’s in com p atibility hypothesis, the vapor return line retu rns unsatu r ated air back to the UST, and vapor growth occurs over some period of tim e until the headspace v a por is again fully satu rated. Th at e v ent would be detec t able
as an S-curv e increase in UST pressure (rising rapidly after a period of tim e for m i xi ng to occur and then leveling off as saturation w a s achieved). Overlaid on the vapor-growth process was the

constan t los s in pressur e f r om the needle valv e r e presen ting all le aks of fugitiv e em issions. The two effects together p r o duced a pressure trace th at rises after a tim e period for m i xing to som e

m a xi m u m value and th en decays b ack to zero, at which p o int fugitive em issions cease (see figures and discussion in Section 6.1).

A third effect on UST pressure was the A/L for th e refueling event. W ith the standard nozzle (A/L = 1.15), a higher return vo lum e produced a short spike upw ards in pressure during the refueling test, and with the m i ni-boot nozzle (A/L = 0.95) a lower return volum e produced a short spike downwards in pressure (see Section 6.1 fo r details). Since the goal of this part of the study was to fully captu r e the fugitive em issions associated w ith the s i n g le ref u eling event, each
test was allo wed to run, with continu ous pre ssu re m easure m ent and b a g s a m p ling, until the team decided the pressure bulge from vapor growth and UST hea d space re-saturation had occurred and the UST pressure had declined back to esse ntia lly zero. In som e cas es th is m eant tha t m a ss

sam p ling continued for up to two hours after the refueling event. In cases where the in itial pressure was expected to go negative for a peri od of ti m e (m ini-boot nozzle), the sam p ling ba g was not connected to th e leak valve until pre ssu re retu rned to zero to allow the syste m to leak in

am bient air into the UST, which th en contribu te d to vapor growth, subse quent pressurization of the UST, and f ugitive e m issions lea k ing out in to the sam p ling bag. The pressur e tra ces f r om the six outdoor tests are presented in S ection 6.1. The Tedlar bags of UST leak emissions were “washed” repeated ly with am bient air inside a S H ED to elim inate “hang up” of HC m a ss in the bags, and th e SHED contents were analyzed with an FID to determ ine th e m a ss. The SHED-FID system was calibrated using inject ion of a known m a ss of pr opane a nd certified to be within the
+/- 2% lim it in federal regulations both before and af ter the te sts.

294.2.3 Testing Details – Indoor SHED Te sts

A Sealed Housing for Evaporative Em issions (SHE D) is used by vehicle m a nufacturers to certify

com p liance with EPA refueling em issions standard s for ORVR vehicles, a nd they w e re used in
the 1970’s to determ ine uncontrolled refueling em i ssions as a function of RVP, di spensed fuel

tem p erature, and vehicle tank tem p erature for EP A’s AP- 42 publication. In this part of the study, 36 refueling tests were c onducted in a S H ED following a te st procedure sim ilar to the
f e deral ORVR certif ica tion test in o r der to quan tif y the nozzle/fillpipe em i ssions as a function of four variables (described in Se ction 4.2.1) and to separately qua ntify any initial “puff” from

rem oval of the fuel tank cap:

1. Type of ORVR equipm ent (3 different vehicles)
2. Fuel RVP (2 fuels)
3. Tem p erature conditions (3 com b inations)
4. A/L ratio (2 settings corresponding to standard and m i ni-boot nozzles)

SHED Procedure

The deta iled tes t pro ced ure used in the SHED te sts is d e scr i bed be low within the c ontext of a f e deral ce rtif ication ORVR te st, as described in 40 CFR §86.150 – 154. 24 This m e t hod has a

m i ni m u m quantifiable value of 0.01 g/gallon. Modi fications of the CFR procedure applying to this p r ogram are specified at app r opriate poin t s. Figure B98-12 provides an overview of the CFR test seq u ence. The ”Integ rated Syst em s” path applies to this program.

24 “Refueling T e st Procedures,” 40 CFR C h a p ter I (7 -1

- 0 1 ) , Section 8 6 , s u bpa rt B “Test Procedure s ”, paragraphs 8 6 .150 -98 thr o u g h 86 .1 54- 98

. 3031The steps of a certific a t ion test inclu d e:

1. Fuel dra i n a nd 40% f ill. 2 Soak vehicle 12 – 36 hours 3. Perform 7.5 m ile precondition i ng drive 4. Fuel dra i n a nd 40% f ill 5. Canister preconditioning (l oad to 2 gram breakthrough) 6. Cold and Hot Start exhaust tes t ( “ City ” driv ing cy cle) 7. Additional driving (“running loss” driving cy cle). Disconnect canis ter after com p letion of driving cycle. 8. Fuel dra i n a nd 10% f ill 9. Vehicle Soak. Reconnect can ister immediately before test. 10. Refueling test.

Steps 1 – 4 insures that the vehi cle fuel system is com p letely purged of non-test fuel. S t ep 5

purges any rem a ining fuel vapors, and provides a comm on s t arting point for the test by loading the canister with butane vapors to saturation (2-gram breakthrough) . In steps 6 and 7 canister loading is n o rm alized b y a sp ecific driving cycle under co ntro lled con d itions. While running , engine vacu um purges the charcoal canis ter. Th e canis ter ab sorbs vapors when the key is off or whenever vapor generation exceed s canister purge . At the end of step 7 the canis ter is
disconnected from the vehicle load and purge syst em to “freeze” the lo ading state. The vehicle
fuel tank is then drained, and a 10% fuel charge is added. The vehicle is p l aced in soak a t 80±3°F to stabilize th e v e hicle and fuel tank temperatu r e for the refueling test.

Experim e nts were perform e d to determ ine a me thod of reproducing canister loading between
SHED tests. The canisters of the tw o ORVR ve hicles were we ighed as Steps 1 through 10 were perform e d. Later, steps 1 through 7 were perform e d on all three vehicles. The canisters of the latter tests then received a load to 2 gram breakthrough, followed by a 300 bed volum e purge. The resu lts of this testing dem onstrate that th e driving in steps 6 and 7 com p letely purged the
canis ter.

For th is p r o g ram , before each test the can isters received a load to 2 g r am breakthro ugh, followed by purge until the following weight reductions (th e work ing cap acities of the canisters) are
achieved :

32Vehicle 01 – 90 gram s less than fully loaded weight Vehicle 02 – 184 gram s less than fully loaded weight Vehicle 03 – 36 gram s less than fully loaded weight

The “can ister preconditioning step” in th e certifi cation p r otocol uses th e 50/50 bu tane nitrogen

m i x and 40-gram /hour load rate. Purge was perf orm e d with a vacuum pump.

The test v e h i cle s in th is program we re drained using the onboard fu el rail before each test. The
vehicle tank then receiv ed a 10% fill of fuel for the upcom ing test. Th e vehicle was placed in soak at a target tem p erature ±3° F. Target tank tem p eratures for this program are 70, 90 and
105° F. The vehicles rem a ined in soak for 6 to 24 hours. The vehicles passed briefly from a

contro lled temperature soak space th rough the main soak roo m at a nom i nal tem p erature of 75° F to the refueling Sealed Housing for Evapora tive Determination (SHED) at the specified

tem p erature. During the soak period the vehicle canister rec e ived the lo ad and purge to target weight. Th e canister w a s not recon n ected to th e vehicle until imm e diately before the refueling

test.

For this pro g ram , the outle t of the canis ters wa s connected to a leak tight bag to captur e all canister-venting em issions occurring during the re fueling operation. The em issions captured in the canister vent bag were m easured in a sepa rate SHED by establishi ng a stable background,
includ ing e t hanol levels , m u ltiple bag f ill an d purge cycles to rin s e the b a g a nd m i x the

em issions in the SHED enclosure, and m easurem ent of a stable final reading, including ethanol
level.

The SHED r e fueling tests were perform e d as follows:

1. Transfer the vehicle to th e ref u eling S H ED.
2. Evacuate the canister ou tlet bag (use shop vac or sam p le pump). Connect the bag to the canis ter ou tlet.
3. Connect the canis ter to the vehicle p u rge/load sy stem

. 4. Seal the SH ED enclosure door.
5. Start the data logger and continuously record Flam e Ionization Detector (FID) calibration and SHED re adings.

336. Allow total hydrocarbon (THC) background levels and SHED te m p erature to stabilize. Capture a gas chrom a tography (GC) sam p le ba g for subsequent ethanol analysis when stable background readings are achieved.
7. Re m ove the vehicle gas cap. Mark the data logger stream . Allo w data c o llec tion to continue for 2 m i nutes after fuel cap rem oval. Laboratory equipm ent designed to perform new vehicle certification ORVR tests has been m odifi ed to evaluate refueling em issions with the Gilba r co dispense r

. The f u el delive r y ca rt is ins t rum e nted to con t r o l the tem p e r ature of a fuel reservoir at 67°F (the dispensed fuel tem p erature specified for certi fication tests) and to dispense fuel at 9.8 gallons/m in through a non-Stage II nozzle. Tem p erature and flow m easurem ents are continuous ly transm itted to a data logger durin g an ORVR test. For this program , the fuel cart has been m odifi ed by the addition of a high-pressure fuel pum p ( t o m a intain the 9.8 gallon/m in flow r a te through the G ilbarco dispenser, extended fuel delivery lines, and a Stage II no zzle). Fu el is recalculated from the nozzle back to the fuel cart with a low v o lum e pum p to control v a riation in dispensed tem p erature. 8. During this two- m i nute period, recirculated fuel through the Gilbarco dispenser and stage II nozzle to insure uniform fuel tem p er ature. Pum p into the fuel delivery cart

reservo i r. A f ter recircu l ating, turn o ff booster delivery pum p to avoid unn ecessary fuel heating and Reid Vapor Pressure (RVP) reduction.
9. At the end of the two-m i nute period, insert nozzle into the vehicle, turn on booster pum p, and start the refueling operation. Oper ate refueling app a ratus to insure dispensed tem p erature is m a intained at target temperat ure ±1.5° F and delivery rate is m a intained at 9.8±0.3 gal/m in.
10. The final THC and GC sam p le will be taken 60 seconds after the final n o zzle shu t off. Turn off booster pum p after shut off. Th e change in HC level observed between the background reading prior to cap removal and that observed 120 seconds after rem oval of the cap will b e used to com pute “puff” e m issions. The change observ e d between 120 seconds after cap rem o val and 60 seconds after the end of fuel delivery will be us ed to

com pute refueling em issions. The ethanol spec iation data will be used to correct th e initial and final readings. The m i ddle ethanol reading will b e interpolated in proportio n with the FID readings f o r

the in itial, m i ddle, and final readings.
11. An RVP sa mple will be collected from the fuel rem a ining in the ORVR cart following

com p letion of the test. This RVP must fall within the target range of +0.2 psi to –0.3 psi of the target RVP (7.0 or 7.8 psi). The fuel cart reservo i r will be refilled with fres h fuel as required to m a intain final RVP speci fications. This is expected to be required before each vehicle with the 7.8 psi f u el at th e elevated (90° F ) dispensed tem p erature. 12. All equipm ent and tests must be operated and perform e d to m a intain the specified dispensed fu el tem p eratu r e, dispen sed fuel delivery rate, vehicle am bient tem p erature, and fuel RVP levels.

An ethanol (EtOH) response fact or was established for the refu eling S H ED FID. The response
factor “r” is defined as the ratio of the obser ved FID response with a known ethanol span gas and

34the expected FID response for that concentration. For exa m ple, with a 16 ppm Ethanol standard (32 ppm vC 1 ), the observed FID response was 22.16 ppm vC 1 , yielding r = 22.16/32.0 = 0.69. FID readings were corrected using the following:

Non EtOH ppm = FID ppm – “r” x [independently m easured EtOH ppm 25 ]

The Non EtOH ppm wa s used to compute non- EtOH hydrocarbon m a ss using the standard (40
CFR 86) refueling em ission hydrocarbon density valu es. The ethanol ppm was us ed with the density of pure e t hanol to com pute the ethano l m a ss result. The eth a nol m a ss was multiplied b y a correction factor to remove the non-HC weight of the oxygen m o lecule, to be consistent with evaporative em ission tes t procedu r es used by Ca lifornia and EPA. The t w o m a sses were then
summed to com pute the total HC m a s s of the refueling em issions.

The Canister outlet bags were tr e a ted sim ilar l y. An initia l FID and GC sam p le were taken to establish background levels. Following thorough flus hing of the bag c ontents and m i xing in the SHED, a final FID and GC sam p le m easure m ent were used to establish canister venting em ission
levels.

GC sa m p les were collected from a subset of th e experim e ntal m a trix to perm it calculation of
correction s for ethanol content in the SHED. Sa m p les from one of ea ch of the three vehicles
tested at each tem p erature-fuel RV P-A/L comb ination r e c e ived sp eciation analy s is, nam e ly analysis for 12 of the 36 test conditions. Si m ila rly, the canister outlet bags collected during the “vapor growth” scenario (70° F Tank/75° F Di spensed) receiv ed s e parate SHED and GC analys is.

The resulting ethanol correction factors were found to be approxim ately 1.02, i.e., HC
concentratio ns from the SHED tests were scaled up by 2% o n averag e to correct for the pres ence of ethanol. No significant differences in the ethanol correction factor were found for vehicle/ORVR type, RVP, A/L ratio or fuel te mperature. Thus, for SHED tests where a GC

sam p le was not analyzed, a correction factor of 1.02 was uniform l y applied. This sam e factor was applied to the outdoor test results for the e ngineered leak valve, th e e m issions from which

35were collected in Tedlar bags and washed w ith air inside a SHED to analyze HC m a ss (see Section 4.2.2).

Ethanol GC Method

ATL has developed a hydrocarbon sp eciation m e thod that is functi onally equivalent to the dualGC AQIRP 26 m e thod. Instrum e ntation dem a nds are sim p lified, and overall analysis tim e is shortened, yet high resolution and sensitivity ar e still ach ie ved. In th is single-GC/dual co lum n

m e thod, all com ponents are separated using one colum n type and tem p erature program. Analysis tim e for a cycle is 65 m i nutes. E ach exhaust or evaporative gas sam p le is
sim u ltaneously injected (using a single sam p ling f r om the bag) into two identical colum n s present in the GC. Column A contains a 85 μ l sample loop (splitless inje ction) that provides an injection volum e that is s m all enough to allow resolution of the C 1 through C 4 hydrocarbons while large enough to retain th e highest sensitivity possible. Colum n B receives a 1000 μ l splitless injection, providing higher sensitivity for compone nts eluting after isobutene. Quantitative com p arison of two overlap com ponents (bu t ane and isopen t ane) prov ides a quality

contro l m easure. Data from column A is used to detect and quantify the 12 earliest eluting hydrocarbons with detection lim its of 15-25 ppb v C corresponding to 0.2-0.3 m g / m i hydrocarbon for FTP stages 1 and 3, and 0.3-0.5 mg/ m i for FTP st age 2. Data from c o lum n B gives detection
lim its 0.017-0.04 m g / m i HC for components eluting afte r isopentane (18th in elution order). The

com ponents eluting between the 9th and 18th in elution order have detection limits ranging
between the levels listed above for each colum n.

The advantage of this approach is that, ev en fo r relatively clean vehicles , essentially all of the
first 12 species are typ i cally presen t at levels exceeding th e colum n A detection lim it. Those speciated components that are below the first colu m n detection lim it tend to be in the m o lecular weight range best suited for the 1000 μL inject ion analysis, which provides the lim its 0.017-0.04 mg/ m i HC for com pone nts eluting after isopentane. In previous work that applied this analysis

25 “CAL IFOR NI A NO N-M E T H A N E OR GA NIC G A S T E S T PROCE D U R ES”, am ende d Au g u st 5, 1 9 9 9 , Pa rt B, Sect i on 5. 4. 1 f o r “r” fact o r de t a i l s

. 26 Au to /Oil Air Qu ality Im p r ov em en t Research Pro g ram

. 36approach, detection limits were determ ined to be between 0.02 and 0.06 m g / m i for the toxic s 1,3-butadiene and benzene.

ATL’s hydrocarbon m e thod uses V a rian 3400 GC' s with dual injectors, colum n s, and flam e ionization detectors, allowing two sim ilar anal yses to be run sim u ltaneously, as m e ntioned above. A Varian Star PC-based (using Microsof t W i ndows) data system is us ed for data acquisition. Custom

- m a d e software is used for peak identifica tion and converting data into a
Microsoft E x cel spreadsheet form at. A com p ar ison of the total hydrocarbon determined using
the GC vers us the Cons tant Volum e Sam p ler is used as a quality con t rol m easure, and ATL routinely achieves hydrocarbon speciation "recove ries" ranging from 93% to 105% for lower

em itting vehicles. A 23 hydrocarbon standard m i xture (Scott Specialty Gas e s, Troy, MI) is analyzed at the start of each day on each GC to provide quantifying coe fficients an d a quality control check on daily reproducibility of instrument perform a nce.

For this program , the following m o difications to the basic GC m e thod apply. A certified m i xture of ethanol in nitrogen was processed daily in the GC to provide a standard for that species. Ethanol elutes at approxim atel y 11.1 m i nutes. The base column te m p erature program has been
modified to accelerate colum n pur ge between eth a nol-on l y an alysis, redu cing the to tal cycle tim e to approximately 40 m i nutes. Colum n B area c ount readings are norm a lly used for ethanol.
Colum n A r eadings are used as a confirm a tion/ independent m e asure of the Colum n B results.

A/L Adjustments
A qualified technician perform e d e ach A/L ad justm e nt using an OPW VacuSmart Vacuum Assist Vapor Recover Analyzer (M odel 13000). Multiple readings were recorded prior to each adjustm e nt to docum ent any slip from the prior st ate. Mu ltiple readings were record ed after the adjustm e nt. A m i ni m u m of five readi ngs were recorded in each state.

4.3 Ethanol Correction – Phase 1 and 2

The type of oxygenate in fuels has been shifting from MTBE to Ethanol f o r a num ber of reasons, including reports of ground wate r contam ination by MTBE. Calif ornia banned the use of MTBE
as a fuel add itiv e as of th e end of 2002, and Conn ecticut and New York have bans set for the end 37of 2003. Al l of the fuels used in this study were oxygenated with ethanol. This study utilized both highly prescribed test procedures (CARB TP 201.2) as well as nontraditional test procedures designed to achieve certain research objectives. Both us e FID as a n analytical m e thod for

m easuring total HC in a vapor sam p le.

In Phase 2 of this research program at Au tomotive Testing Laboratories (ATL) in Arizona, experim e nts were done to m easure the potential under-estim ation of hydr ocarbon concentrations by a Flam e Ionization D e tector (FID) when the ga soline vapor contains et hanol as a com ponent. The SHED testing ch ambers use a F I D for sam p le analy s is. Air sam p les f r om the SHEDs were analyzed both by FID and a GC to determ ine the response factor “r” for the FID. Then, to be
consistent w ith evapo r ative em issio n test p r oc edures used by Californi a and EPA, a correction

was m a de to rem ove the non-HC weight of oxygen in the ethanol fraction. The resulting ethanol
correction f actor was f ound to be approxim a tely 1.02, i.e. HC concentrations from the SHED tests were scaled up by 2% on average to correct for the presence of ethan o l.

In Phase 1 of this program , testing followed Ca lifornia Air Resources Board’s Test Procedures TP201.2 and TP201.2F, used California RFG oxygenated with ethanol with an RVP of 7.0 psi, and were perform e d by VOC Testing, Inc. of San Bernardino, California. ARB has m a de no changes to their Tes t Procedures to accoun t for the possible effect of ethanol on HC

m easure m ents, and discussions with ARB staff r e veal they are not concerned about the issue and have no plans to m odify their Test Procedures. 27 Both FI D and NDIR i n strum e nts are used in the TP201.2 procedure. To quantif y the potential bias in the HC m easurem ents and results for Phase 1, known sam p le s of etha nol and gasoline headspace vapors from the UST used in the second phase of testing were coll ected in Tedlar bags, driven fr om ATL to VOC Testing, Inc. in San Bernardino and run through their FID and NDIR analyzers. The F I D response factor for VOC Testing, Inc. was found to be alm o st identical to that for the FID at ATL, and the response
factor for the NDIR a s calibrated for the TP201.2 procedure was found to be higher. The resulting ethanol correction factors for the inst rum e nts used in Phase 1 of the program are 1.02
for all FID m easure m ents (no zzle/fillpipe em issions) and 1.01 for all NDIR measurem ents (vapor return line of the Stage II Gilbarco sy stem, the P/V valve on the UST and UST headspace

27 Per s on al co m m u n i catio n , M s . Cind y Castro nov o, Calif orn i a A RB, Sep t e m b e r 1 2 , 2 003

. 38concentratio ns). These sm all adjustm e nts of 1- 2% have no effect on the conclusions in Section 5.0, Phase 1 – Analysis and Results. The results for Phase 1 are presen ted in Section 5.0 with
ethanol co rrection and the m i nor effects of including ethanol correct ion are discussed in
footnotes in that secti on of this report.

395.0 PHASE 1 – ANALYSIS AND RESULTS

This section details the results of Phase 1 of the ORVR com p atibility test program , which was conducted using the CARB TP201.2/201.3 test m e thodol ogy to provide som e initial data o n O R V R
vs. non-ORVR vehicle em issions for an in-use vehicle fleet. The analysis is broken into two parts.
Section 5.1 focuses on the factors that affect “unc ontrolled em issions”, i.e., em issions that would result if the Stage II VRS were not present. Section 5.2 focuses on continuously recorded data related to the UST, including calculations of pressure-related f ugitive em issions.

5.1 Analysis Of Factors Affecting “Uncontrolled Emissions”

This first phase of the test program was desi gned to provide som e initial data on ORVR vs. nonORVR em issions for an in-use vehicle fleet a nd could not fully address all factors affecting
uncontrolled em issions (particularly RVP, which wa s not investigated). As stated previously,
uncontrolled em issions (expressed in units of m a ss em itted per unit volum e of gasoline transf erred)
are known to be a function of the tem p erature of the dispensed fuel (T D ), the tem p erature of the vehicle fuel tank (T T ), the fuel volatility (RVP), and diffe rences in vehicle design (e.g., fillpipe design) that are not readily quantif iable. The presence or absence of ORVR is an additional variable

a ffe c t i ng unc ontrolled em issions. “Uncontrolled em issi ons” in this section are defined as the sum of

m a ss em issions m easured at the nozzle/fillpipe interface (M 1 ) and those m e asured in the vapor return line (M 2 ) and exclude em issions f r om the UST includi ng f ugitive em issions which are discussed in Section 5.2. Section 4.1 provides an overview of the f i ve potential em ission points. L o cations 1 and 2 in Figure 4-1 correspond to m a ss em issions M 1 and M 2 discussed in this section.

5.1.1 Temperatures

Uncontrolled em issions are known to be a f unction of the tem p erature of the dispensed f u el (T D ) and
the tem p erature of the vehicle fuel tank (T T )

. Vehi cl e fuel tank tem p eratures were m easured directly
in Phase 1 and are correlated to the am bient tem p erature (T A ), see Figure 5-1. T D , which was not directly m easured in Phase 1, is assum e d to be equal to T A , as in EPA’s MOBILE6 m odel.

40For both ORVR and non-ORVR ve hicles, it was noted that M 1 +M 2 , the sum of the m a ss of hydrocarbons collected at the nozzle/fillpipe interface (M 1 ) and the m a ss of hydrocarbons returned by the VRS to the UST (M 2 ), shows a slight positive correlation to the am bient tem p erature T A , see Figure 5-2. As discussed in Section 3.1, EPA’s form ula for refueling em issions (which is incorporated into EPA’s MO B I L E 6 em is s i o n s m o d e l) predicts that uncontrolled em issions exhibit a positive correlation with the tem p er ature of the dispensed f u el (T D ) and a negative correlation with
the difference between the vehicle tank tem p erature (T T ) and T D , the logic being that if T T > T D , refueling with the cooler gasolin e will result in vapor shrinkage in the gasoline tank. As m e ntioned previously, T D was not m easured directly. In the field, both T T and T D have been found to exhibit
correlations with T A , although there is som e discrepancy in how best to approxim a te T D . A t echnical report by EPA contends that “vehicle tank tem p erat ures follow am bient tem p eratures m o re closely [than dispensed tem p eratures].” 28 An API study by Radian investig ated tem p erature trends m o re closely by region, and found that for th e region which includes California, T D was actually m o re closely corrected to T g , the tem p erature of the underground storage tank (UST). 29

Figure 5-3 shows the variation in the tem p erature of the fuel in the USTs, the tem p erature of the fuel in the vehicle tank, and the am bient tem p erature over tim e. It is clear that over the tim e period studied, there are significant dif f e re nces between these tem p erature data sets. As expected, the UST

tem p eratures are m u ch less variable, and they ar e also significantly higher than the daily m e an

am bient tem p eratures. The UST tem p eratures ro se during the course of the study period, possibly reflecting warm ing trends (with respect to daily highs) between Oct. 31- Nov. 3 and Nov. 4-Nov. 6 (though decreases on Nov. 4 and Nov. 7 are not appare nt), but possibly reflecting other variables (e.g., if the tem p erature of the fuel delivered to the USTs before the test program began was significantly lower than the tem p erature of the gr ound, the tem p erature rise m i ght be the result of a long-term tem p erature equilibration). Therefore, se parating the effects of various tem p eratures is subject to large uncertainties due to their code pendency. As anticipated, it was not possible to
isolate the effects of the various tem p eratures in this phase of the study, and this issue will be m o re adequately studied in Phase 2.

28 D. Rothm a n and R. Johnson (US EPA), “Refueling Em i ssions fromUncontrolled Vehicles,” Report No. EPA-AASDSB-85-6, August 1985.
29 Radian Corp., “Sum m a ry and Analysis of Data From Ga soline Tem p erature Survey Conducted at Service Stations by API,” API Publication No. 4278, 1976.

415.1.2 ORVR

Uncontrolled em issions are affected by whether the vehicle being refueled is equipped with ORVR or not. As described in Section 3.4, CARB has stated that there is a potentia l f o r “excess em issions”
when a vacuum assist Stage II VRS is used to refuel vehicles equipped with ORVR. The results obtained in this phase of testing support earlier theoretical work by Tech Environm ental that suggested CARB’s calculations of total incom p atib ility em issions are over-estim ated because they ignore the decrease in nozzle/fillpip e em issions from ORVR equipm ent. 30 The test results

summa r i zed in Figure 5-4 reveal that, on averag e, ORVR vehicles em itted 0.05 g/gal (0.0001 to 0.13 g/gal for individual refueling events) whereas non-ORVR vehicles em itted on average 0.19 g/gal (0.003 to 0.71 g/gal for individual refueling even ts); the difference is 0.14 g/gal or 0.31 lb/1,000

ga l l ons. The r e wa s no di sc e r na bl e di fference in average fillpipe em issions for the second set of tests (with the m i ni-boot nozzle) com p ared to the first set, for either ORVR or non-ORVR vehicles (see
Fi gur e 5- 5) . This confir m s that the m i ni-boot, in conjunction with a lower A/L setting, perform s just

a s we l l a s t h e s t a nda r d noz z l e a nd the higher A/L in capturing vapor. (The effect of the m i ni-boot on
UST em issions is described in Section 5.2.) These results show that for the Gilbarco VRS studied (with and without the m i ni-boot), ORVR vehicles when fueled with refo rm ulated ga soline had 0.31 lb/1,000 gallons fewer em issions. Stated differently, these system s had 73% lower em issions from the nozzle/fill pipe than non-ORVR vehicles. Th is is a significant difference that CARB does not account for and it partially offsets the 0.86 lb/1,000 gal excess em issions from the UST that CARB has assigned to ORVR vehicles fueling with a Gilbarco VRS (assum i ng RVP 7.8 fuel and high A/L settings on the VRS). 31

It was confirm e d that lowering the A/L increased hydrocarbon concentrations in the vapor returned to the UST (M 2 ), and that em issions at the f illpipe did not increase as a result of lowering A/L.
Fi gur e 5- 6 pr e s e n t s t h e ma ss e m i ssi ons, pe r volum e of gas dispensed, at the fillpipe along with those

30 Tech Environm ental, “Com m e nts on ARB’s August 20, 2002 Proposed Revision to TP201.2F and Other Issues Related to EVR Em ission Calculations for Underground Stor age Tanks,” com m e nts sent to CARB by API, Septem ber, 2002.
31 C a l i f o r

n i a A i r R e s o u r c e s B o a r d , “R e v i s ed EVR Em issions Reduction Calculations, Module 3: ORVR Com p atibility,” in letter from Mr. W illiam Loscutoff, Chief, Monitoring and Laboratory Division, CARB to Mr. Prentiss Searles, API, August 5, 2002.

42in the vapor return line to the UST. As expected, the vapor concentration in the return line is lower (about half) for ORVR vehicles confirm i ng that som e am bient air is being pulled in at the nozzle/fillpipe interface and being sent to the UST. Si nce the sum of th e v a p o r in th e re tu rn lin e p l u s the f illpipe em issions (M 1 +M 2 ) for ORVR vehicles (roughly 1.2 g/ga l) is larger than the m a xim u m 0.2 g/gal that is allowed f o r em i ssions f r om an ORVR car ref u eling at a non-Stage II GDF, it appears
that the VRS m a y be preferentially capturing vapor s over the ORVR canister. Alternatively, the

vacuum assisted Stage II equipm ent m a y be increasi ng the volatilization of liqui d f u el in the f illpipe as it is being dispensed.

Figure 5-6 illustrates another interesting point. CAR B ’ s claim of O R V R incom p atibility rests on an

assum p tion that alm o st no hydrocarbon vapors are re turned to the UST in the VRS return flow, causing UST pressurization from s ubsequent vapor growth. For Test 1, the test data show the
ORVR return flow em issions to the UST are a pproxim a tely one-third of the non-ORVR em issions, revealing that the return flow is not devoid of hydrocarbon vapor. In fact, the average vapor concentration when using the system with the A/L set to 1.15 in the return flow for ORVR vehicles
was 11.3% 32 and ranged from 3 to 20% for individual test s, see Figure 5-7. For Test 2 with a m i niboot in place (and A/L set to 0.95), ORVR return flow em issions are even higher, approxim a tely h a lf
of the non-ORVR em issions. W ith the m i ni-boot, the average vapor concentration in the return f l ow to the UST for ORVR vehicles was 17.4% 33 a nd ranged from 3 to 25% for individual tests, as shown in Figure 5-8. Thus, the return flow is closer to saturation than expected, hi gher t h an the 0% used in the 1999 CARB ORVR study, and 2 to 2.5 tim es the average of 6.6% that CARB found in earlier tests (see Section 3.4).

Calculations of the sum of M 1 +M 2 for both ORVR and non-ORVR vehicles were com p ared to
uncontrolled em issions calculations using EPA’s AP -42 form ula and the form ula in MOBILE6 for each refueling in the study, as shown in Figure 5-9. As stated previously, T D was not m e asured directly in this study so T D was assum e d to be equal t o am bient tem p erature (T A ). By com p aring the

su m o f M 1 +M 2 to uncontrolled em issions predicted by the EPA form ulas, we are assum i ng that all of the hydrocarbons in the vapor return line are em itted directly to the atm o sphere and not vented to the

32 W ith the correction for ethanol (Section 4.3) , average HC vapor concentration is 11.4%.

43UST. A com p arison of the data for the non-ORVR ve hicles shows the actual test data (average of 2.75 g/gal) are close in value and bracketed by the uncontrolled em issions predicted by MOBILE6 (average of 2.23 g/gal) and AP-42 (average of 2.98 g/gal). The average uncontrolled em issions

pr e d i c t e d by AP-42 are higher than those predicted by MOBILE6 due to differences in the definition
of ∆ T. Differences between the actual test data and MOBILE6 could be due to m a ny factors, including the error in estim ating T D using T A and possibly volatilization of fuel in the f illpipe by the VRS, which is not considered in the MOBILE6 calculations of uncontrolle d em issions. The ORVR
actual test data are less than half the value of the non-ORVR test data because the ORVR system is collecting som e level of refueling vapors and less va por m a ss is present in the VRS retu r n

lin e f l o w

. Uncontrolled em issions from non-ORVR vehicles are lower than what has been seen with CARB

m e thods in the past: i.e., CARB predicts em issi ons of 7.6 lb/1000 gal = 3.4 g/gal for vehicles being
refueled with RFG. 34 There are several potential reasons for the discrepancy, nam e ly there are
differences in test m e thodology validity (e.g., betw een CARB’s test m e thod and EPA’s SHED test

m e thod) and there are differences in test conditions (e.g., the tem p erature range for the SHED tes t s is significantly different from the tem p erature range used here).

33 W ith the correction for ethanol (Section 4.3) , average HC vapor concentration is 17.6%.
34 California ARB, “Staff Report – Enhance Vapor R ecovery Technology Review,” October, 2002, p. 6.

445.2 Analysis Of Continuous UST Data The UST pressure, UST headspace concentrations, and concentrations at the UST P/V valve ex h a u s t (diluted with sweep air at a constant flowrate for safety) were m onitored continuously. UST pressurization and venting (through the P/V va lve) were found to depend strongly upon the “tightness” of the UST, VRS, and sam p ling system . At the beginning of the first set of tests, pressure decay tests showed pressure decays from 2.00” water colum n to 1.75” water colum n in 5

m i nutes. This com p lied with TP201.3, which set an allowable m i nim u m pressu re af ter 5 m i nutes of 1.68” w.c. (ullage of 3,000 gallons and 8 nozzles). During this tim e period, continuously recorded UST pr essur e s cl ear l y showed t h e effect s of vehi cl e r e fuel i ngs, and the decay in pressure after those refuelings. The P/V valve rarely opened during these first few days. Then, in the m i ddle of the first set of tests, the contractor located and fixed a l eak. Im m e diately afterwards, the character of the UST pressures changed dram atically: decays were not seen, the UST pressures were frequently at +3” w.c. (the cracking pressure of the P/V valve), and the P/V valve vented frequently. The system was kept tight for the second set of tests with th e m i ni-booted nozzles. Three leak decay tests done
after the leak was fixed revealed alm o st no pressu re decay, i.e. decays of only <0.01” to 0.03” w.c.
in 5 m i nutes. Unfortunately, interferences from othe r vehicles sim u ltaneously ref u eling at the GDF’s four other operational dispensers (as well as the ti ghtening of the system ) prevented an analysis of
the effects of ORVR vs. non-ORVR vehicles on UST pressures and UST venting. However, these
effects were m easured in the outdoor portion of Phase 2 of the study (see Section 6).

Using data for the second half of Test 1 and all of Test 2 when the system was tight (Table 5-1),

e m i s s i ons out t h e P/ V va l v e we r e me a s ur e d to be approxim a tely 0.374 g/gal during Test 1 and 0.004 g/gal during Test 2. Thus, there is approxim a tely a 0.37 g/gal benefit, a 98% reduction in P/V valve

em issions that resulted from using the m i ni-boot nozzles. UST fugitive em issions were calculated using the CARB TP201.2F m e thod (proposed August 20, 2002 version, but with actual ullage and final pressure values used in CARB equati on 9.1.1) in conjunction with 1-m i nute average

m easurem ents of pressure and headspace vapor con centration. These calculati ons w e re m a d e f o r th e second half of Test 1 and all of Test 2 when the system was tight. Equation 9.1.1 of TP201.2F calculates the pressure-related fugitive flowrate (Q) in cubic feet per hour, as:

45 

### ( ) ( ) ( ) ⎢ ⎣ ⎢ ⎢ ⎢ ⎢ ⎢ ⎡

V P
⎥ ⎦ ⎥ ⎥ ⎥ ⎥ ⎥ ⎤

/ 2 0

. 0 f P

− ) 60 (

5 9 406

. 7 ( ) 4

. 8 1 2 ⎢ ⎣ ⎢ ⎡ 2 / 1
0 0 ⎟ ⎞ ⎠ 2 f

. P 0

. 0 ⎜ ⎛ ⎝ 1 ⎥ ⎦ ⎥ ⎤ 2 = / 1 2 Q (4-2)where:

Q = Pressure-related fugitive flowrate, cubic feet per hour, ft 3 /hr V = Total ullage affected by the test, gallons P f = Final pressure of the leak decay test. P = Actual pressure m easured in UST containm ent space, inches H 2 O

Once Q is calculated, this is used to calculate the m a ss em ission rate of pressure-related f ugitive

em issions:

(386.9) * (100) ⎢ ⎣ ⎢ ⎢ ⎢ ⎢ ⎢ ⎡

⎥ ⎦ ⎥ ⎥ ⎥ ⎥ ⎥ ⎤

Q * C * M W Μ= (4-3)

M = Mass rate of fugitive em issions, lb/hour C = Hydrocarbon concentration, percent (C 3 or C 4 ) MW = Molecular weight, lb/lb-m ole [44.096 for C 3 or 58.123 for C 4 ]
These data are shown along with the m easured P/V va lve em issions in T a ble 5-1. T h e total of actual
P/V valve and calculated f ugitive em issions equal the total UST/piping system em issions. Total
UST em issions for Test 1 (the standard nozzle) were 0.627 g/gal, and for Test 2 (the m i ni-boot nozzle) were 0.224. Thus, use of a m i ni-boot nozzle on the Gilbarco VaporVac VRS reduced
estim ated total UST em issions at the UST by 64%. 35 To the extent TP201.2F overpredicts fugitive

e m i s s i ons (and test data in Section 6.3 show it greatly overpredicts these em issions), the reduction in
UST em issions attributable to use of the m i ni-boot nozzle is higher than 64%. If the UST system
had been com p letely leak tight, the reduction in pressure-related em issions would equal 98%, the reduction at the P/V valve. Thus, the true reduction value in total UST em issions is som e where in

35 W ith the correction for ethanol (Section 4.3), Test 1 tota l em issions increase to 0.633 g/gal and Test 2 em issions are 0.226 g/gal. The reduction in em issions due to the m i ni-boot nozzle is unchanged at 64%.

46the range of 64% to 98%. This reduction is greater than the 50% reduction CARB claim s 36 for t h e

m i ni-boot on vacuum -assist system s.

36 The 50% reduction figure is calculated from the reduction in A/L on CARB spreadsheet “tosco em red 120501.”

47TABLE 5-1

DEMONSTRATION OF UST EMISSIONS REDUCTION PROVIDED BY THE USE OF A MINI-BOOT NOZ Z LE ON A GILBARCO VAPORVAC VRS

Date Test Measured P/V Valve Emissions

(g/gal) Calculated TP-201.2F

Fugitive Emissions

(g/gal) Total UST/ Piping System Emissions

(g/gal)

1 1 / 2 / 0 2 1 0

. 2 8 1 0

. 2 3 2 0

. 5 1 3

1 1 / 3 / 0 2 1 0

. 5 6 0 0

. 2 9 4 0.855

Test 1 Standard

N o zzl e A v e r a g e 0

. 3 7 4 0

. 2 5 3 0

. 6 2 7

1 1 / 5 / 0 2 2 0

. 0 0 8 0

. 1 4 6 0

. 1 5 3

1 1 / 7 / 0 2 2 0

. 0 0 1 0

. 2 8 3 0

. 2 8 4

Test 2 Mini-boot

N o zzl e A v e r a g e 0

. 0 0 4 0

. 2 2 0 0

. 2 2 4

48FIGURE 5-1. COMPARISON OF AMBIENT AND FUEL TANK TEMPERATURES5055606570758085909510050 55 60 65 70 75 80 85 90Ambient Temperature (TA), Deg. F

Temperature of fuel in tank (T T ), Deg. FFIGURE 5-2. EMISSIONS AS A FUNCTION OF AMBIENT TEMPERATURE00.511.522.533.544.550 55 60 65 70 75 80 85Ambient Temperature, deg. F

Mass Emissions divided by Gas Dispensed (g/gal)Non ORVR(M1+M2)ORVR (M1+M2)Linear (ORVR(M1+M2))Linear (Non ORVR(M1+M2))FIGURE 5-3. TEMPERATURE VARIATIONS DURING THE TEST PROGRAM3040506070809010011010/31 0:00 11/1 0:00 11/2 0:00 11/3 0:00 11/4 0:00 11/5 0:00 11/6 0:00 11/7 0:00 11/8 0:00Date and Time

Temperature, Deg. FUST 1 TemperatureUST 2 TemperatureAmbient TemperatureVehicle Fuel Tank TemperatureFIGURE 5-4. FILLPIPE EMISSIONS AND AMBIENT TEMPERATURE00.10.20.30.40.50.60.70.850 55 60 65 70 75 80 85Ambient Temperature, Deg. F

Mass Emissions divided by Gas Dispensed (g/gal)Emissions at Fillpipe(M1), Non ORVREmissions at Fillpipe(M1), ORVRPoly. (Emissions atFillpipe (M1), NonORVR)Poly. (Emissions atFillpipe (M1), ORVR)FIGURE 5-5. FILLPIPE EMISSIONS BY TEST00.10.20.30.40.50.60.70.810/31/020:0011/1/02 0:00 11/2/02 0:00 11/3/02 0:00 11/4/02 0:00 11/5/02 0:00 11/6/02 0:00 11/7/02 0:00 11/8/02 0:00Date and Time

Mass Emissions divided by Gas Dispensed (g/gal)Test 1 Emissions atFillpipe (M1), Non ORVRTest 1 Emissions atFillpipe (M1), ORVRTest 2 Emissions atFillpipe (M1), Non ORVRTest 2 Emissions atFillpipe (M1), ORVRFIGURE 5-6. EMISSION COMPONENTS M1 AND M200.511.522.533.5410/31/020:0011/1/02 0:00 11/2/02 0:00 11/3/02 0:00 11/4/02 0:00 11/5/02 0:00 11/6/02 0:00 11/7/02 0:00 11/8/02 0:00Date and Time

Mass Emissions divided by Gas Dispensed (g/gal)Emissions at Fillpipe(M1), Non ORVREmissions at Fillpipe(M1), ORVREmissions Returned toUST (M2), Non ORVREmissions Returned toUST (M2), ORVRFIGURE 5-7. TEST 1, VAPOR RETURN LINE CONCENTRATION05101520253035404510/31/02 0:00 11/1/02 0:00 11/2/02 0:00 11/3/02 0:00 11/4/02 0:00Date and Time

VRL conc (% HC)Non ORVRORVRFIGURE 5-8. TEST 2, VAPOR RETURN LINE CONCENTRATION010203040506011/4/02 0:00 11/5/02 0:00 11/6/02 0:00 11/7/02 0:00 11/8/02 0:00Date and Time

VRL Conc (% HC)Non ORVRORVRFIGURE 5-9. COMPARISON OF UNCONTROLLED EMISSIONS012345610/31/020:0011/1/02 0:00 11/2/02 0:00 11/3/02 0:00 11/4/02 0:00 11/5/02 0:00 11/6/02 0:00 11/7/02 0:00 11/8/02 0:00Date and Time

Uncontrolled Emissions (g/gal)EPA AP-42 formulaMOBILE6 prediction (NonORVR)Non ORVR, Actual TestData (M1+M2)ORVR, Actual Test Data(M1+M2)6.0 PHASE 2 OUTDOOR TESTS – ANALYSIS AND RESULTS

This section presents the results of the six out door TP201.2 refueling tests, perform e d to carefully

m easure the UST vapor growth phenom enon and a ssociated “excess em issions” that CARB claim s are caused by ORVR-Gilbarco VRS incom p atibility. Section 6.1 presents the continuous UST pressure data, while Section 6.2 discusses the m eas ured em issions at the leak valve and P/V valve
and exam ines the ORVR com p atibility issue. S ection 6.3 exam ines the perform a nce of the CARB
estim ation m e thod for fugitive em issions, and TP201.2 da ta from the tests are discussed in Section
6.4.

6.1 Continuous UST Pressure Data

The pressure in the UST was m easured continuously for the duration of each test and for up to two
hours after to allow the full effect s of any vapor growth in the UST to occur (see Section 4.2.2 for details). In general, three effects are consistently found in the pressure graphs:

(1) If the standard nozzle (A/L = 1.15) was used, then a higher return volum e of air pr oduc e d a s hor t s p i k e upwa r ds i n pr e s s u r e dur i ng r e fueling, conversely if the m i ni-boot nozzle (A/L = 0.95) was used, a lower volum e of return air produced a short spike downwards in pressure during refueling;
(2) The vapor growth process begins af ter an initial period of tim e f o r

m i x i n g to o c c u r in th e UST headspace, pressure rises and then levels off as vapor saturation is achieved;
(3) Overlaid on the other two processes is th e constant loss in pressure through the leak valve, representing all leaks of f

ugitive em issions at a gasoline dispensing f acility.
The six tests covered the following conditions:

Test Vehicle Noz z le A/V

1 01 – ORVR with recirculation Standard 1.15 2 01 – ORVR with recirculation Mini-boot 0.95 3 02 – ORVR no recirculation Standard 1.15 4 02 – ORVR no recirculation Mini-boot 0.95 5 03 –ORVR Standard 1.15 6 03 –ORVR Mini-boot 0.95

58The pressure graphs are shown in Figures 6-1 th rough 6-6, respectively for Tests 1 through 6. Note that the pressures are quite low, none exceeded 0.50” w.c., and for that reason the P/V valve never cracked. A description of each test is given below. High frequency variations in the pres s u re tra ces are due to light winds at night in the desert that affected the am bient side of the pressure transducer.

In Figure 6-1 for Test 1 (ORVR w i th recirculation / standard noz z l e) , there is an initial spike upwards due to the fact 115% of the fuel volum e in the form of air/vapor is being returned to the UST. The pressure then begins to drop due to l eaks through the engineered orifice. The 12 gallons
of return air start m i xing into the 2,000 gallon h eadspace of the UST and as the headspace vapor

concent r at i on decl i n es near t h e vapor /liquid interf ace, gasoline vaporizes into the headspace and we see the pressure begin to rise in the UST from vapor growth. Since leaks and vapor growth are going on sim u ltaneously, vapor growth is first seen by a lessening of the slope in the pressure decline and then an increase in tank pressure around 2,500 seconds after the refueling. By 3,000 seconds, vapor growth seem s to have ended and pressure leaks seem to again dom inate. Around 7,200 seconds, the pressure stabilized at 0.06” w.c. and would go no lower. This suggests the pressure differential was so sm all that no furthe r em issions were leaking into the bag through the orifice. (Atm ospheric pressure is 406.9” w.c., so a positive pressure differential of 0.06” to

atm o spheric represents a differential of only 1/100 of 1%). The dip down at the end of the pressure graph represents what happened when ATL disc onnected the bag at 7,271 seconds and opened the
f itting on the top of the UST cap; pressure declined but not f u lly to zero.

Test 2 (ORVR w i th recirculation / mini-boot noz z l e) had to be done twice. During the first

attem p t, the sam p le bag was not disconnected from th e leak orifice during the early part of the test when the pressure went negative, and it prevented am bient air from leaking into the UST. Fig u r e 6

- 2 shows the pressure trace for the second, successful try. There is an initial spike down due to the fact only 95% of the fuel volum e in the f o rm of air/vapor is being returned to the UST. The

sam p ling bag was attached to the leak orifice when the pressure returned to zero at 3,055 seconds. Pressure continued to rise and peaked ar ound 5,000 seconds. (The dip around 4,200 seconds is unexplained). The bag was disconnected at 7,029 seconds.

59In Test 3 (ORVR no recirculation / standard noz z l e) , there is an initia l s p ik e u p a s e x p e c t e d a n d a steady decline toward a stable level of 0.04” w. c. A slight pressure bulge upwards around 1,000
seconds m a y reflect vapor growth in the UST. The test was ended at 5,685 seconds when the pressure reached zero.

The pressure trace for Test 4 (ORVR no recirculation / mini-boot noz z le) is shown in Figure 6-4. There is an initial spike down as expected and the l eak orif ice was lef t open during the early part of the test when the pressure went negative to a llow am bient air to flow into the UST. At 2,387 seconds when it was judged that the pressure had ri sen to zero, the sam p ling ba g was attached to the orifice. Vapor growth is evident just after 1,000 seconds by a bulge in the curve, and the pressure peak is reached around 3,500 seconds before it declined to zero and sam p ling was ended at 4,272
seconds.

Test 5 (no ORVR / standard noz z l e) had to be done twice. During the first attem p t, the bag was left on the leak valve orifice for 2,000 seconds after the pressure level had dropped below zero,
which m eans sam p le m a ss was sucked back out of the bag. In the second, successful try, two

sam p ling bags were used, and the m a ss in each sum m e d to obtain the leak em issions for the test. Figure 6-5 shows there is an initial spike upwards and then pressure declines as air leaks out of the orifice. The first bag collected em issions from 0 to 904 seconds, a point in tim e where the pressure was hovering around zero. A second sam p le bag, connected from 904 to 4,187 seconds, collected
additional m a ss. The peak in pressure, possibly due to vapor growth in the UST, occurred around 1,500 seconds.

In Figure 6-6 for Test 6 (no ORVR / mini-boot noz z l e) , there is an initial spike down as expected, and then the pressure rises due to air leaking in through the orifice. A possible bulge due to vapor growth occurs around 3,500 seconds and then the pr essure settles back to zero. The sam p ling bag was connected at 2,500 seconds when the pressure was judged to have risen to zero and sam p ling continued until the end of the test at 3,989 seconds.

60FIGURE 6-1. TIME VARIATION OF UST PRESSURE FOR OUTDOOR TEST 1 -ORVR WITH RECIRCULATION / STANDARD NOZZLE-0.050.000.050.100.150.200.250.300.350.400 1000 2000 3000 4000 5000 6000 7000 8000Time From Start of TP201.2 Refueling Test, seconds

UST Pressure, inches w.c.Bag Connected 0 - 7,271 secondsFIGURE 6-2. TIME VARIATION OF UST PRESSURE FOR OUTDOOR TEST 2 -ORVR WITH RECIRCULATION / MINIBOOT NOZZLE-0.40-0.30-0.20-0.100.000.100.200.300 1000 2000 3000 4000 5000 6000 7000 8000Time From Start of TP201.2 Refueling Test, seconds

UST Pressure, inches w.c.Bag Connected 3,055 - 7,029 secondsFIGURE 6-3. TIME VARIATION OF UST PRESSURE FOR OUTDOOR TEST 3 -ORVR NO RECIRCULATION / STANDARD NOZZLE-0.050.000.050.100.150.200.250.300.350.400.450 1000 2000 3000 4000 5000 6000Time From Start of TP201.2 Refueling Test, seconds

UST Pressure, inches w.c.Bag Connected 0 - 5,686 secondsFIGURE 6-4. TIME VARIATION OF UST PRESSURE FOR OUTDOOR TEST 4 -ORVR NO RECIRCULATION / MINIBOOT NOZZLE-0.50-0.40-0.30-0.20-0.100.000.100 500 1000 1500 2000 2500 3000 3500 4000 4500Time From Start of TP201.2 Refueling Test, seconds

UST Pressure, inches w.c.Bag Connected 2,387 - 4,272 secondsFIGURE 6-5. TIME VARIATION OF UST PRESSURE FOR OUTDOOR TEST 5 -NO ORVR / STANDARD NOZZLE-0.30-0.20-0.100.000.100.200.300 500 1000 1500 2000 2500 3000 3500 4000 4500Time From Start of TP201.2 Refueling Test, seconds

UST Pressure, inches w.c.Bag 1 Connected 0 - 904 secondsBag 2 Connected 904 - 4,187 secondsFIGURE 6-6. TIME VARIATION OF UST PRESSURE FOR OUTDOOR TEST 6 -NO ORVR / MINIBOOT NOZZLE-0.60-0.50-0.40-0.30-0.20-0.100.000.100 500 1000 1500 2000 2500 3000 3500 4000 4500Time From Start of TP201.2 Refueling Test, seconds

UST Pressure, inches w.c.Bag Connected 2,500 - 3,989 seconds6.2 Fugitive Emissions From UST/Piping

The six outdoor refueling tests were designed to fully capture the pressure-related fugitive em issio n s f r om vapor growth in the UST associated with ORVR-Gilbarco VRS inco m p atibility. All f ugitive

em issions were captured in 1-2 Tedlar bags ove r periods of tim e up to two hours in length during and after a single refueling and then rinsed in a SHED and analyzed for m a ss. The results are
conservative for the m i ni-boot nozzle test since the leak valve orif ice w a s le f t open during the initial negative pressure spike (caused by an A/L of 0.95) , allowing am bient air to flow into the UST headspace and potentially create m o re vapor growth. At a gasoline station equipped w ith m i ni-boot nozzles, the rapid succession of ref u eling events m i ght tend to keep the UST pressure positive (assum i ng each refueling generates a sm all am ount of vapor growth as shown in Table 6-1 f o r T e sts 2,4, and 6), and thus inflow of am bient air through system leaks, like that allowed in this study,

m i ght not occur. As discussed below, fugitive em issions from m i ni-boot refuelings are near zero.

The total fugitive HC em issions m easured of each test are sum m a rized in Table 6-1. An ethanol correction factor of 1.02 has been applied to a ll m easurem ents (see Section 4.3). As m e ntioned

pr e v i ous l y, t h e r e we r e no e m i s s i ons out the P/V valv e due to the fact UST pressure never rose above 0.5” w.c. Table 6-1 shows that the fugitive em issi ons for all the m i ni-boot refuelings are near zero (about 0.003 lb/1,000 gallons for the ORVR vehicles and 0.011 lb/1,000 gallons for the non-OR V R vehicle) and below the m i nim u m quantifiable lim it of the SHED of 0.01 g/gal. The “excess

em issions” of pressure-related f ugitives f r om OR VR incom p atibility with the Gilbarco VRS are
defined as the difference between the m easured ORVR and non-ORVR em issions for each type of

noz z l e , a nd t h e s e r e s u l t s a r e s u mma r i z e d i n Ta bl e 6-2. For a standard nozzle and an A/L of 1.15, the

m easured “excess em issions” from ORVR inco m p atibility are 0.72 lb/1,000 gallons. For the

m i niboot nozzle and an A/L of 0.95, the m easured “excess em issions” are –0.008 lb/1,000 gallons, i.e., zero. By com p arison, CARB’s presum ed figure for “excess em issions” for all O R V R vehicles is 0.86 lb/1,000 gallons. The CARB estim ate is less re liable as it is not derived from actual

m easurem ents of pressure-related f ugitives associ ated with ref u eling ORVR vehicles, the test

m e thod used in this study. Not considered in th ese figures is the very im portant decrease in

em issions at the nozzle/f illpipe f r om the use of ORVR in addition to the Stage II VRS. The fleetwide tests in Phase 1 of this study docum en ted an em issions decreas e at the fillpipe of 0.31

67lb/1,000 gallons (see Section 5.1.2) while the SHED tests in Phase 2 have established a fillpipe

em issions decrease of 0.46 lb/1,000 gallons (see Sec tion 7.1.1). The average of these two estim ates is 0.39 lb/1,000 gallons. From these results, the following conclusions are drawn:

• Measured fugitive em issions from ORVR vehicles ref u eled w ith a m i ni-boot nozzle are near zero (0.003 lb/1,000 gallons) and are less than m easured non-ORVR fugitive em issions (0.011 lb/1,000 gallons). Thus, when the m i ni-boot nozzle (A/L = 0.95) is used on a Gilbarco VRS, there is no ORVR incom p atib ility and m easur e d “ e x c e s s e m is s i o n s ” a r e z e r o (actually –0.008 lb/1,000 gallons). In additi on, with the m i ni-boot nozzle in use the

com b ination of ORVR and Stage II VRS controls produces 0.39 lb/1,000 gallons less

em issions at the f illpipe than if just Stage II controls are used.

• “Excess em issions” f r om the UST/piping syst em , due to ORVR incom p atibility with a Gilbarco VRS, when a standard nozzle (A /L = 1.15) is used are 0.72 lb/1,000 gallons. Considering the decrease in fillpipe em issions produced by the ORVR-VRS com b in atio n o f 0.39 lb/1,000 gallons, total incom p atibility em issions for standard nozzle (A/L = 1.15) refueling are only 0.72 – 0.39 = 0.33 lb/1,000 gallons, or less than half of the figure of 0.86 lb/1,000 gallons that CARB presum es for all ORVR vehicles.

The application of this inf o rm ation to statewide em ission inventories in the case where all Gilbarco VRS are equipped with m i ni-boot nozzles is sim p le: there are no “excess em issions” and no O R V R
incom p atibility. In situations where Gilbarco system s are equipped with standard nozzles (A/L=1.15), a correction should be applied for the f act that the E P A MO B I L E 6 m odel (the tool used

to create state em ission inventories) assum e s f illp ipe em issions f o r ORVR cars are lo w e r th a n th o s e for non-ORVR cars controlled with Stage II (98% vs. 95% control). That is, som e of the fillpipe

em issions reduction attributable to ORVR and disc ussed above is already credited in the em ission
inventories. W h ile uncontrolled em issions will var y, in this study those em i ssions were f ound to be approxim a tely 3 g/gal for non-ORVR vehicles fu eled with RFG 7.0 RVP fuel (see Figure 5-9).
Assum i ng MOBILE6 has already credited 3% of 3 g/gal = 0.09 g/gal, that m eans total
incom p atibility em issions for a standard nozzle refueling is 0.33 lb/1,000 gallons (bullet item above) + 0.09 lb/1,000 gallons (adjustm ent) = 0.42 lb/ 1,000 gallons, when assem b ling an areawide

em issions inventory with MOBILE 6, or about half of what CARB assum e s (0.86 lb/1,000 gallons).

68TABLE 6-1

TOTAL UST/PIPING SYSTEM FUGITIVE EMISSIONS FOR THE SIX OUTDOOR TESTS

Test No. Vehicle Type Noz z le Type A/L Ratio Fuel (gal) HC (g) Emissions (g/gal)

1 ORVR w / r e c i r c

. s t a n d a r d 1

. 1 5 1 0

. 2 0 4

. 2 5 0

. 4 1 7

2 ORVR w / r e c i r c

. m i n i b o o t 0

. 9 5 1 0

. 0 7 0

. 0 2 0

. 0 0 2

3 ORVR n o r e c i r c

. s t a n d a r d 1

. 1 5 1 5

. 0 4 1

. 5 7 0

. 1 0 4

4 ORVR n o r e c i r c

. m i n i b o o t 0

. 9 5 1 5

. 1 4 0

. 0 1 0

. 0 0 1

5 no O RV R s t a n d a r d 1

. 1 5 1 4

. 1 4 0

. 1 4 * 0

. 0 1 0

6 n o O R V R m i n i b o o t 0

. 9 5 1 4

. 0 8 0

. 0 7 0

. 0 0 5

* Bag 1 contained 0.06 gram s. Bag 2 contained 0.08 gram s.

69TABLE 6-2

“EXCESS EMISSIONS” OF PRESSURE-RELATED FUGITIVE HC EMISSIONS FOR ORVR VEHICLES REFUELED USING A GILBARCO VAPORVAC VRS

“Excess Emissions” of Fugitives Type of Vehicle N o zzl e T y p e (A/L Ratio) (g/gal) (lb/1,000 gal)
ORVR with recirculation Standard (1.15) 0

. 4 0 7 0

. 9 0

ORVR no recirculation Standard (1.15) 0

. 0 9 4 0

. 2 1

W e ighted Average* Standard (1.15) 0

. 3 2 9 0

. 7 2

ORVR with recirculation Miniboot (0.95) - 0

. 0 0 3

- 0

. 0 0 7

ORVR no recirculation Miniboot (0.95) - 0

. 0 0 4

- 0

. 0 0 9

W e ighted Average* Miniboot (0.95) - 0

. 0 0 3

- 0

. 0 0 8

* Assum e s 75% of ORVR-equipped vehicles in the population are equipped with a recirculation line to the top of the fillpipe. See footnote 37 in Section 7.1.1.

706.3 Performance of the CARB Estimation Method for Fugitive Emissions

UST fugitive em issions were calculated for the Ph ase 2 outdoor tests in the sam e way calculations

were m a de for Phase 1 (see Section 5.2), using the TP201.2F m e thod with actual ullage (2,000

ga l l ons ) a nd fi na l pr e s s u r e for the leak decay test (1.56” w.c.). Table 6-3 com p ares actual, m easured fugitive em issions to those predicted by the CARB m e thod for the six outdoor tests and the data are plotted in Figure 6-7. The results reveal that the CARB m e thod consistently and substantially overpredicts pressure-related fugitive em issions, by f actors of 13 to 660, nam e ly on e to tw o o r d e rs o f

m a gnitude. Tech Environm ental has previously pointed out overprediction problem s with the TP201.2F equation to CARB in com m e nts on proposed ch anges to the EVR Test and Certification Procedures. That earlier analysis showed that th e estim ation m e thod could ove rpredict the leak rate (and theref ore f ugitive em issions) by m o re than a f actor of 10 f o r low positive pressures in the UST due to an incorrect analytical form of the e quation, with the greatest overprediction occurring for very low UST pressures (very low f ugitive em issions), and the data in Figure 6-7 conf irm this very

sam e behavior: f o r the actual f ugitives associated with the standard nozzle the overprediction is in the range of 13 to 36 (roughly a factor of 20) w ith the greatest overprediction occurring for the
lowest actual f ugitive em issions. W h ile there app ears to be a statistically signif i cant correlation
between m easured and calculated f ugitives f o r the standard nozzle, such is not the case f o r the

m i niboot nozzle data where there is no correlati on. W h ereas actual fugitive em issions are m u ch
lower for the m i niboot nozzle, again we see th at the CARB estim ation m e thod produces larger overpredictions in the range of 31 to 660 (roughly a factor of 300).

W h ile the objective here was not to develop a be tter m e thod for calculating fugitive em issions, the consistent overprediction of fugitives by the CARB TP-201.2F estim ation m e thod could be roughly corrected by dividing predictions for standard no zzles (A/L>1) by 20 and dividing predictions for

m i niboot nozzles (A/L<1) by 300.

71TABLE 6-3

PERFORMANCE OF CARB TP201.2F METHOD IN PREDICTING ACTUAL PRESSURE-RELATED FUGITIVE EMISSIONS

Phase 2 Outdoor Test N o zzl e T y p e Total Measured Fugitive HC (grams) Calculated TP201.2F Fugitive HC (grams)

1 S t a n d a r d 4

. 2 5 5 5

. 0
2 M i n i b o o t 0

. 0 2 1 3

. 2
3 S t a n d a r d 1

. 5 7 3 4

. 3
4 M i n i b o o t 0

. 0 1 1

. 6 5
5 S t a n d a r d 0

. 1 4 5

. 0 8
6 M i n i b o o t 0

. 0 7 2

. 2 0

72FIGURE 6-7. PERFORMANCE OF CARB TP201.2F METHOD IN PREDICTING ACTUALPRESSURE-RELATED FUGITIVE EMISSIONS0510152025303540455055600 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5Measured Pressure-Related Fugitives (g)

TP201.2F Calculated Pressu re-Related Fugitives (g)Standard NozzleMiniboot NozzleLinear (StandardNozzle)6.4 Fillpipe Emissions and Return Vapor Line Concentrations

The CARB TP201.2 test procedure was followed for th e Phase 2 outdoor tests to provide a rigorous protocol f o r the ref u eling tests, the f o cus of wh ich were UST pressurization and f ugitive em issions.
The m easurem ents of nozzle/f illpipe em issions and return vapor line HC concentrations f r om the
TP201-2 tests are sum m a rized in Table 6-4. (These data have been corrected for ethanol, see Section 4.3). Excluding one data point invalidated by an apparent splash-back at nozzle cut-of f

, the
ORVR vehicles em itted 0.001 to 0.012 g/gal, which is in the sam e range as TP201.2 m easurem ents

m a de in Phase 1. The non-ORVR vehicle em itted 0.697 to 0.959 g/gal, levels som e what higher than
the TP201.2 m easurem ents m a de in Phase 1, which ranged up to 0.710 g/gal.

Vapor return line concentrations for the non-ORVR vehicle were close to saturation at 33% to 39% HC. The return line concentrations for the ORVR vehicles, which ranged from 0.6% to 7.6%, are
lower than the levels m easured in the Phase 1 TP201.2 tests (3% to 25%). This m eans that the
Gi l b a r c o r e t u r n e d l o we r t h a n expected HC concen trations to the UST during the outdoor tests on the ORVR vehicles, producing possibly higher than norm a l levels of vapor grow th and pressure-related fugitive em issions. Thus, the m easur em ents of f

ugitive em issions presented in the previous sections are conservative, and actual f ugitives at a service station will likely be less. Also, since the P/V valve at a station cracks occasionally from the eff ects of m u ltiple refuelings and releases headspace air, som e of which is below-saturation vapor retu rn line air, the f u ll potential f o r vapor growth as

m easured in this study is not realized at a servi ce station. (The Phase 2 m easurem ents of pressurerelated fugitives considered the full potential for vapor growth over a 1 to 2 hour period following a refueling event.) Thus, the results of this study likely overpredict actual fugitive em issions as they
occur at a service station.

74TABLE 6-4

FILLPIPE EMISSIONS AND RETURN VAPOR LINE HC CONCENTRATIONS FOR THE TP201.2 PHASE 2 OUTDOOR TESTS

Test No. ORVR ? Noz z l e/Fillpipe Emissions

(g/gal) Return Vapor Line HC Concentration (% )

1

2

3

4

5

6 Yes

Yes

No

Yes

Yes

No 0.011

0.001

0.697

0.267*

0.012

0.959 3.0

5.4

33.2

7.6

0.6

38.8

* Splash back of fuel into the sam p ling sleeve (placed over the nozzle) likely occurred as evid en ced by a single concentration spike at the end of th e refueling test, invalidating this data point.

757.0 PHASE 2 INDOOR SHED TESTS – ANALYSIS AND RESULTS

This section presents the results of the indoor SH ED tests to quantify the dependence of refueling

e m i s s i ons on the following independent variables: t ype of vehicle ORVR equipm ent, A/L ratio, fuel RVP, a nd t e mpe r ature conditions. Section 7.1 discusses refueling em issions at the nozzle/fillpipe as
a function of these variables and exam ines the OR VR com p atibility issue. Section 7.2 discusses the separate and initial “puf f ” em issions f r om rem oval of the f u el cap bef o re ref u eling begins.

7.1 Noz z l e/Fillpipe Refueling Emissions

The results from the 36 refueling tests in the SH ED are sum m a rized in Ta bles 7-1 through 7-3 for vehicles 01 through 03, and are graphed in Figure 7-1. It can be readily seen that nozzle/fillpipe

em issions are substantially less for the two OR VR-equipped vehicles (01,02) com p ared to the nonORVR vehicle (03), generally confirm i ng results f ound in the Phase 1 f l eetw i de tests that em issions
are 73% less for ORVR than non-ORVR vehicles (see Figure 5-5). The m easured refueling

em issions of 0.001 to 0.041 g/gal for ORVR vehi cles, and 0.031 to 0.693 g/gal for the non-ORVR vehicle, fall within the range of values m easured in the Phase 1 fleetwide tests.

The dif f e rences in Phase 1 test results attributable to individual vehicle and fuel system designs are represented by the scatter of data points in Figur es 5-4 and 5.5. Sim ilarly, there is a difference between average refueling em issions for the two ORVR vehicles used in the Phase 2 SHED tests. Vehicle 01 (the 2003 Toyota Echo, ORVR with vapor r ecirculation) had averag e ref u eling em issions of 0.026 g/gal, a value that is quite low. By com p arison, vehicle 02 (t he 2003 Chevy B l azer, O R V R without recirculation) had em i ssions of only 0.003 g/gal. Considering the fact that uncontrolled

em issions are in the range of 3 to 5 g/gal (see Fi gure 5-9) and that 95% c ontrol by either ORVR or Stage II controls brings those em issions down to no mor e t h an 0.2 g/gal, the m easured em issions for vehicle 02 of 0.003 g/gal are essentially zero and repr esent 99.93% control. Given the fact all test results for vehicle 02 were essentially zero and sca tter in the data m a y just represent m e asurem ent
im precision, no data analysis was perform e d for vehicle 02. W h ile the Phase 2 tests cannot identif y exactly why vehicle 02 had such low em issions, the possibilities include: 1) the Chevy Blazer h a s a larger carbon canister than the Honda Echo in its ORVR system with double the “working capacity,”

76while its fuel tank is only 50% la rger (18 gallons for the Blazer versus 12 gallons for the Echo); and 2) the Blazer’s fuel tank, fillpipe and ORVR system design, including the absence of a recircu l atio n loop, is superior to that of the Echo’s in term s of vapor capture during refueling.

7.1.1 ORVR

As described in Section 3.4, CARB has stated that there is a potential f o r “excess em issions” w h en a

vacuum assist Stage II VRS is used to refuel vehi c l e s equipped with ORVR. The results from Phase
2 confirm findings from Phase 1 (Section 5.1.2) that CARB’s calculations of total incom p atibility

em issions are over-estim ated because they ignore the decrease in nozzle/fillpipe em issions from
ORVR e qui pme n t

. The t e s t r e s u lts in Tables 7-1 through 7-3 reveal that, on average, the two ORVR
vehicles em itted 0.015 g/gal (0.001 to 0.041 g/gal for individual refueling tests), whereas the nonORVR vehicle em itted on average 0.23 g/gal (0.031 to 0.693 g/gal for individual refueling test). Since approxim a tely 75% of new car ORVR system s are equipped with recirculation, 37 for t h e purposes of this com p arison a weighted average is used, nam e ly 0.020 g/gal (see Table 7-1). Thus, the difference in fillpipe em issions between ORVR and non-ORVR vehicles when a Gilbarco VRS is operating is 0.21 g/gal or 0.46 lb/1,000 gal. This is a significant differe nce that CARB does not account for and it partially offsets the 0.86 lb/1,000 gal excess em issions from the UST that CARB has assigned to ORVR vehicles refueling with a Gilbarco VRS (assum i ng RVP 7.8 fuel and high A/L settings on the VRS). 38 The ORVR vehicles had 91% lower HC em issions from the nozzle/fillpipe than the non-ORVR vehicle.

37 Auto industry consultant, Mr. Harold Haskew (Milford, MI) estim ates 75% of all new passenger vehicles have a recirculation loop in their ORVR system . Personal com m unication, Novem b er 7, 2003.
38 C a l i f o r

n i a A i r R e s o u r c e s B o a r d , “R e v i s ed EVR Em issions Reduction Calculations, Module 3: ORVR Com p atibility,” in letter from Mr. W illiam Loscutoff, Chief, Monitoring and Laboratory Division, CARB to Mr. Prentiss Searles, API, August 5, 2002.

77TABLE 7-1

SUMMARY OF INDOOR SHED REFUELING TEST RESULTS FOR VEHICLE 01-ORVR WITH RECIRCULATION (FORD ECHO)

RVP (psi) A/L Target Actual Dispensed Temp. o F ∆ T

o F Noz z le/Fillpipe Emissions

(g/gal)

1.15 1.15 1.15 1.15 1.15 1.15 7.8 7.8 7.8 7.0 7.0 7.0 7.79 7.78 7.67 7.12 6.97 7.04 75 75 90 75 75 90 -5 15 15 -5 15 15 0.033 0.028 0.024 0.015 0.018 0.028

Average For A/L 1.15 0.024

0.95 0.95 0.95 0.95 0.95 0.95 7.8 7.8 7.8 7.0 7.0 7.0 7.84 7.93 7.68 7.03 7.16 7.16 75 75 90 75 75 90 -5 15 15 -5 15 15 0.020 0.041 0.039 0.012 0.022 0.028

Average for A/L 0.95 0.027

Average for Vehicle 01 0.026

78TABLE 7-2

SUMMARY OF INDOOR SHED REFUELING TEST RESULTS FOR VEHICLE 02-ORVR NO RECI RCULATION (CHEVROLET BLAZ E R)

RVP (psi) A/L Target Actual Dispensed Temp. o F ∆ T

o F Noz z le/Fillpipe Emissions

(g/gal)

1.15 1.15 1.15 1.15 1.15 1.15 7.8 7.8 7.8 7.0 7.0 7.0 7.76 7.73 7.63 7.03 6.91 6.96 75 75 90 75 75 90 -5 15 15 -5 15 15 0.002 0.001 0.002 0.003 0.005 0.005

Average For A/L 1.15 0.003

0.95 0.95 0.95 0.95 0.95 0.95 7.8 7.8 7.8 7.0 7.0 7.0 7.88 7.94 7.66 7.07 7.15 7.10 75 75 90 75 75 90 -5 15 15 -5 15 15 0.002 0.002 0.003 0.004 0.003 0.003

Average for A/L 0.95 0.003

Average for Vehicle 02 0.003

79TABLE 7-3

SUMMARY OF INDOOR SHED REFUELING TEST RESULTS FOR VEHICLE 03 - NO ORVR (NISSAN MAXIMA)

RVP (psi) A/L Target Actual Dispensed Temp. o F ∆ T

o F Noz z le/Fillpipe Emissions

(g/gal)

1.15 1.15 1.15 1.15 1.15 1.15 7.8 7.8 7.8 7.0 7.0 7.0 7.77 7.83 7.56 7.03 7.20 7.03 75 75 90 75 75 90 -5 15 15 -5 15 15 0.311 0.093 0.117 0.224 0.031 0.099

Average For A/L 1.15 0.146

0.95 0.95 0.95 0.95 0.95 0.95 7.8 7.8 7.8 7.0 7.0 7.0 7.88 7.85 7.62 7.14 7.17 7.23 75 75 90 75 75 90 -5 15 15 -5 15 15 0.693 0.261 0.157 0.430 0.170 0.170

Average for A/L 0.95 0.314

Average for Vehicle 03 0.230

80FIGURE 7-1. FILLPIPE EMISSIONS AND FUEL RVP0.0000.1000.2000.3000.4000.5000.6000.7006.80 7.00 7.20 7.40 7.60 7.80 8.00Reid Vapor Pressure (RVP), psi

Mass Emissions divided by Gas Dispensed (Q), g/galVeh01 ORVR w/ recirc.Veh02 ORVR no recirc.Veh03 No ORVRLinear (Veh01 ORVRw/ recirc.)Linear (Veh02 ORVRno recirc.)Linear (Veh03 NoORVR)7.1.2 RVP

The dependence of refueling em issions on fuel RV P is sum m a rized in Figure 7-1 and reveals that

em issions are:

• Positively correlated with fuel RVP, as a ssum e d in the EPA MOBILE6 m odel, for the nonORVR vehicle (vehicle 03) with a slope of 0.2 g/gal per psi.

• Very slightly positively correlated with f u el RVP f o r the ORVR vehicle with recirculation (vehicle 01) with a slope of 0.02 g/gal per psi.

• Uncorrelated with RVP for the ORVR vehicle without recirculation (vehicle 02) as all values are essentially zero.

The em pirical f o rm ula f o r f illpipe em issions in EPA’s Publication AP-42 and MOBILE6 m odel

assum e s a positive correlation with f u el R V P w ith a slope of 0.5 g/gal per psi (see Section 3.1). That equation was developed using SHED tests for conditi ons quite different from those in the present study: all vehicles (1979-1985) were non-ORVR a nd did not have tank/fuel system s designed to

m i nim i ze evaporative em issions, the fuel used had a m u ch higher RVP a nd RVP range (9.0 to 12.6 psi), and no Stage II VRS was in operation duri ng EPA’s “uncontrolled em issions” tests.

The results from Phase 2 of the present study suggest that as m o re refueling em ission controls are
im plem ented (just Stage II control for vehicle 03, a nd both ORVR and Stage II controls f o r vehicles 01and 02), the dependence of f

illpipe em issions on f u el RVP declines.

7.1.3 A/L Ratio

Looking at the data grouped by A/L ratio in Tabl es 7-1 through 7-3, refueling em issions at the fillpipe for the ORVR vehicle (01) are the sam e whether the standard nozzl e w ith a high A / L of 1.15
is used or a m i ni-boot nozzle with a low A/L of 0.95 is em ployed. (A t-test on the six-sam p le subsets shows no statistically significant difference at the 95% confidence level.) Thus, the 12 data points for vehicle 01 can be analyzed as a com p lete s e t t o determ ine the dependence of em issions on

tem p erature conditions.

82For the non-ORVR vehicle (03), there is a negative correlation of fillpipe refueling em issions with A/L ratio, showing the m i niboot in com b ination w ith a low A/L setting did not perform as well as the standard nozzle and a high A/L setting for this particular vehicle (a 1995 Nissan Maxim a ). The fleetwide test results in Phase 1, however, dem onstrate that for a broa d population of non-ORVR
vehicles there is no discernable di ffe r e nce in refueling em issions for the two com b inations of nozzle and A/L ratios (see Figure 5-5).

7.1.4 Temperatures

As discussed in Section 3.1, EPA’s form ula for refu eling em issions (which is incorporated into
EPA’s MOBILE6 em issions m odel) predicts that uncontrolled em issions exhibit a positive
correlation with the tem p erature of the dispensed fuel (T D ) and a negative correlation with ∆ T the
vehicle tank tem p erature (T T ) m i nus T D , the logic being that if T T > T D , refueling with cooler gasoline will cause vapor shrinkage in the gasoline tank. Conversely if T D > T T , then vapor growth
in the vehicle tank is assum e d to produce higher re fueling em issions. Thes e hypothesized effects are
for unc ont r o l l e d em issions from an autom obile wit hout evaporative em ission controls or ORVR and

assum e no Stage II controls on the dispenser. The Phase 2 SHED test was designed to test whether these relationships still apply for today’s vehicles, fuels and refueling conditions.

Two tem p erature variables were treated as independent variables: 1) T D ; and 2) ∆ T. As shown in Section 4.2.1, the three sum m e rtim e tem p erature conditions included in the test m a trix were:

Condition T D ∆ T T T

1 75 o -5 o 70 o vapor growth 2 75 o +15 o 90 o vapor shrinkage 3 90 o +15 o 105 o vapor shrinkage

Figure 7-2 presents refueling em issions for the OR VR vehicle with recirculation (vehicle 01) vs. RVP, with data partitioned by tem p erature conditions. By com p aring tem p erature conditions 1 and 2, T D is held constant and only ∆ T is varied. The results are the opposite from that assum e d in the

83EPA form ula, nam e ly em issions for the vapor grow th case (condition 1) are lo wer than those f o r the vapor shrinkage case (condition 2). Since that is im plausible, the difference in em issions m u st be
related to the tank tem p erature (T T ), which is lowest for tem p erature condition 1, and not to ∆ T.

By com p aring tem p erature conditions 2 and 3 in Figure 7-2, ∆ T is held constant and T D is varied,
but it turns out T T is also varied and since the first com p arison suggests T T is an im portant independent variable (a situation not anticipated in t h e e xpe rim e nt design) the increase in em issions between condition 2 to condition 3 can only be said to be due to som e com b ination of the variables
T D and T T . The average of T D and T T is graphed vs. refueling em issions in Figure 7-3. The graph reveals that (T D +T T )/2 is positively correlated with em issions , with the relationship being stronger
f o r the lower RVP f u el.

For the ORVR vehicle with recirculation (veh icle 01), the following conclusions are drawn regarding refueling em issions and tem p erature conditions:

• Em issions are not correlated with ∆ T as in the EPA form ula for refueling em issions, and the vapor growth and shrinkage scenarios whic h affect refueling em issions in non-ORVR vehicles do not appear to influence em issions in ORVR vehicles. This is likely due to the rapid and continuous rem oval of headspace vapors from the tank by the ORVR canister.

• Em issions are positively correlated with the tank tem p erature (T T ), although the rate of change is fairly low: 0.003 g/gal per 10 o F. Em issions m a y also be positively correlated with dispensed tem p erature (T D ), but any separate effect could not be quantified.

Figure 7-4 presents refueling em issions for the non- ORVR vehicle (vehicle 03) vs. RVP, with data partitioned by tem p erature conditions. A com p arison of tem p erature conditions 1 and 2 reveals that

em issions are negatively correlated to ∆ T and that the vapor growth/shrinkage hypothesis in the
EPA form ula for refueling em issions applies to the non-ORVR vehicle. A com p arison of

tem p erature conditions 2 and 3 in Figure 7-4 shows no relationship between em issions and dispensed tem p erature (T D ) or tank tem p erature (T T ). The correlation between em issions and ∆ T is shown clearly in Figures 7-5 and 7-6, with the re lationship being stronger for the higher RVP fuel
and the lower A/L ratio.

84For the non-ORVR vehicle (03), th e follow i ng conclusions are draw n regarding ref u eling em issions
and tem p erature conditions:

• Em issions are negatively correlated with ∆ T a s i n t h e EPA form ula for refueling em issions. The rate of change is an increase of 0.125 g/gal per –10 o F ∆ T.

• Em issions are not correlated with dispensed tem p erature (T D ) or tank tem p erature (T T ).

85FIGURE 7-2. FILLPIPE EMISSIONS, RVP AND TEMPERATUREFOR VEHICLE 01 - ORVR WITH RECIRCULATION0.0100.0150.0200.0250.0300.0350.0400.0456.80 7.00 7.20 7.40 7.60 7.80 8.00Reid Vapor Pressure (RVP), psi

Mass Emissions divided by Gas Dispensed (Q), g/galTemp. Condition 1Temp. Condition 2Temp. Condition 3Linear (Temp. Condition 1)Linear (Temp. Condition 2)Linear (Temp. Condition 3)FIGURE 7-3. FILLPIPE EMISSIONS AND AVERAGE FUEL/TANK TEMPERATUREFOR VEHICLE 01 - ORVR WITH RECIRCULATION0.0100.0150.0200.0250.0300.0350.0400.04570 75 80 85 90 95 100Average of Dispensed Temperature (TD) and Vehicle Tank Temperature (TT),oF

Mass Emissions divided by Gas Dispensed (Q), g/galRVP 7.8RVP 7.0Expon. (RVP7.8)Expon. (RVP7.0)FIGURE 7-4. FILLPIPE EMISSIONS, RVP AND TEMPERATUREFOR VEHICLE 03 - NO ORVR0.0000.1000.2000.3000.4000.5000.6000.7006.90 7.00 7.10 7.20 7.30 7.40 7.50 7.60 7.70 7.80 7.90 8.00Reid Vapor Pressure (RVP), psi

Mass Emissions divided by Gas Dispensed (Q), g/galTemp. Condition 1Temp. Condition 2Temp. Condition 3Linear (Temp. Condition 1)Linear (Temp. Condition 2)Linear (Temp. Condition 3)FIGURE 7-5. FILLPIPE EMISSIONS ANDT (TANK-FUEL) TEMPERATUREFOR VEHICLE 03 - NO ORVR0.0000.1000.2000.3000.4000.5000.6000.700-10 -5 0 5 10 15 20T = Vehicle Tank Temperature (TT) - Fuel Temperature (TD),oF

Mass Emissions divided by Gas Dispensed (Q), g/galRVP 7.8RVP 7.0Expon. (RVP7.8)Expon. (RVP7.0)FIGURE 7-6. FILLPIPE EMISSIONS ANDT (TANK-FUEL) TEMPERATUREFOR VEHICLE 03 - NO ORVR0.0000.1000.2000.3000.4000.5000.6000.700-10 -5 0 5 10 15 20T = Vehicle Tank Temperature (TT) - Fuel Temperature (TD),oF

Mass Emissions divided by Gas Dispensed (Q), g/galA/L 0.95A/L 1.15Expon. (A/L0.95)Expon. (A/L1.15)7.2 Fuel Cap “Puff” Emissions and Canister Outlet Emissions

“Puff” losses of HC vapor that occur when the ga s cap is rem oved on a vehicle are not counted as
ref u eling em issions in the EPA OR VR certif ication test (see 40 CFR 86.154-98). One of the goals of Phase 2 of this study was to quantify these em i ssions and the SHED test protocol w a s designed to

s e pa r a t e l y me a s ur e “ puff” em issions, defined as those occurring in a two-m i nute period after the gas cap is rem oved and bef o re the nozzle is inserted into the f illpipe. The m easured levels are

sum m a rized in Tables 7-4 through 7-6 and in Figures 7-7 through 7-9. These em issions are presented as gram s of HC per refueling event sin ce the am ount in the “puff” is unrelated to the gallons of fuel dispensed. Average fuel cap “ puff” em issions for the two ORVR-equipped vehicles (01, 02) of 0.05 to 0.14 gram s are one to two orders of m a gnitude less than com p arable em issions f o r the non-ORVR vehicle of 2.26 gram s.

Using data on the average am ount of fuel dispensed in each of the 36 SHED tests and the average refueling em issions, Table 7-7 com p ares the “pu f f ” em issions to the total ref u eling em issions averaged over the 12 tests on each vehicle. The resu lts show that the fuel cap “puff” em issions are correlated with refueling em issions. The total HC “puff” m a ss is about half that of the refueling

em issions m a ss for vehicles 01 and 03, and equal to the refueling em issions m a ss for vehicle 02.
Carbon canister outlet em issions during ref u eling (b agged during each SH ED test) are also show n in Table 7-7 and the levels are very lo w as one would expect. The fact that “puff” em issions are alm o st equal to and correlated with refueling em issions raises an interesting point regarding EPA’s
MOBILE m odels that only count vapor displacem ent and spillage from refueling activities, one

com ponent of m o tor vehicle HC em issions. The data in Table 7-7 suggest that by not counting fuel cap puff em issions, the MOBILE m odels m a y underes tim ate the effect of reductions in refueling

e m i s s i ons on t o tal m o tor vehicle HC em issions in com i ng years as the vehicle population shifts from being predom inantly non-ORVR to ORVR-equipped. Figures 7-7 through 7-9 reveal that “puff”

em issions are positively correlated with tank tem p er ature for vehicles 01 a nd 03, and only slightly
for vehicle 02. The vehicle 02 resu lts in Figure 7-8 are difficult to interpret since the em issions are near zero. A positive correlation between “puf f ” em issions and f u el RVP exists.

91TABLE 7-4

SUMMARY OF INDOOR SHED PUFF EMISSIONS FOR VEHICLE 01 – ORVR WITH RECIRCULATION

Fuel RVP (psi) Vehicle Tank Temperature ( o F) Puff Emissions (g/refueling event)

7.8 7.8 7.8 7.0 7.0 7.0 70 90 105 70 90 105 0.133 , 0.119 0.143 , 0.125 0.178 , 0.167 0.102 , 0.099 0.162 , 0.156 0.146 , 0.136

Average for Vehicle 01 0.139

Note: Two refueling tests were done for each RVP/T T com b ination.

92TABLE 7-5

SUMMARY OF INDOOR SHED PUFF EMISSIONS FOR VEHICLE 02– ORVR NO RECIRCULATION

Fuel RVP (psi) Vehicle Tank Temperature ( o F) Puff Emissions (g/refueling event)

7.8 7.8 7.8 7.0 7.0 7.0 70 90 105 70 90 105 0.059 , 0.042 0.053 , 0.056 0.053 , 0.052 0.051 , 0.035 0.046 , 0.041 0.071 , 0.045

Average for Vehicle 02 0.050

Note: Two refueling tests were done for each RVP/T T com b ination.

93TABLE 7-6

SUMMARY OF INDOOR SHED PUFF EMISSIONS FOR VEHICLE 03 – NO ORVR

Fuel RVP (psi) Vehicle Tank Temperature ( o F) Puff Emissions (g/refueling event)

7.8 7.8 7.8 7.0 7.0 7.0 70 90 105 70 90 105 0.571 , 0.031 2.771 , 3.351 4.340 , 5.147 0.092 , 0.031 0.080 , 3.219 4.334 , 3.127

Average for Vehicle 03 2.258

Note: Two refueling tests were done for each RVP/T T com b ination.

94TABLE 7-7

COMPARISON OF FUEL CAP “PUFF” EMISSIONS AND CANISTER OUTLET EMISSIONS TO SINGLE REFUELING EVENT EMISSIONS

Vehicle Fuel Cap Puff Emissions

(g/gal) Canister Outlet Emissions

(g/gal) Refueling Emissions

(g/gal) Puff/Refueling Ratio

01 – ORVR with recirculation

02 – ORVR without recirculation

03 – no ORVR 0.014

0.003

0.146 0.001

0.002

0.001 0.026

0.003

0.230 0.5

1.0

0.6

95FIGURE 7-7. FUEL CAP "PUFF" EMISSIONS, VEHICLE TANK TEMPERATURE AND RVPFOR VEHICLE 01 - ORVR WITH RECIRCULATION0.0900.1000.1100.1200.1300.1400.1500.1600.1700.18065 70 75 80 85 90 95 100 105 110Tank Temperature (TT),oF

Mass Emissions from Releases of Fuel Cap, gRVP 7.8RVP 7.0Expon. (RVP7.8)Expon. (RVP7.0)FIGURE 7-8. FUEL CAP "PUFF" EMISSIONS, VEHICLE TANK TEMPERATURE AND RVPFOR VEHICLE 02 - ORVR NO RECIRCULATION0.0350.0400.0450.0500.0550.0600.0650.0700.07565 70 75 80 85 90 95 100 105 110Tank Temperature (TT),oF

Mass Emissions from Releases of Fuel Cap, gRVP 7.8RVP 7.0Expon. (RVP7.8)Expon. (RVP7.0)FIGURE 7-9. FUEL CAP "PUFF" EMISSIONS, VEHICLE TANK TEMPERATURE AND RVPFOR VEHICLE 03 - NO ORVR0.0001.0002.0003.0004.0005.0006.0007.0008.00065 70 75 80 85 90 95 100 105 110Tank Temperature (TT),oF

Mass Emissions from Releases of Fuel Cap, gRVP 7.8RVP 7.0Expon. (RVP7.8)Expon. (RVP7.0)8.0 CONCLUSIONS

Fr om t h e fi r s t pha s e of t h e t e s t pr ogr a m , Pha s e 1 – fl e e t wi de t e s t s us i ng CARB m e thod TP201.2 at a Conoco Service Station in San Bernardino, Califor nia, the following conclusions can be drawn:

• CARB’s calculations of total incom p atibility em issions are overestim ated because they ignore the decrease in em issions at the nozzl e/fillpipe from ORVR equipm ent. W h en a Gilbarco Stage II VRS is used, ORVR vehi cles had 73% lower em issions from the nozzle/fillpipe than non-ORVR vehicles, a di fference of 0.31 lb/1,000 gal, when fueled with RFG (7.0 RVP). This is a significant difference that CARB doe s not account for and it partially offsets the 0.86 lb/1,000 gal exce ss em issions from the UST that CARB has assigned to ORVR vehicles. Results were the sam e for standard vac uum assist nozzle and

m i ni-boot nozzle refuelings.

• Use of a m i ni-boot nozzle with the Gilbarco VRS reduced m easured em issions from the P/V valve by 98%, and reduced total UST/piping system pressure-related em issions by 64% to 98%. This reduction is greater than the 50% reduction CARB claim s for the m i niboot.

• Since the sum of the vapor in the return line plus the f illpipe em issions f o r ORVR vehicles (roughly 1.2 g/gal) is larger than the m a xim u m 0.2 g/gal that is allowed f o r em issions f r om an ORVR car refueling at a non-Stage II service station, it appears that the VRS m a y be preferentially capturing vapors over the ORVR canister. Alternatively, the vacuum assisted Stage II equipm ent m a y be increasi ng the volatilization of liquid f u el in the f illpipe as it is being dispensed.

The Phase 2 – outdoor tests done at Autom o tive Testing Laboratories (ATL) in Mesa, Arizona provided direct m easurem ents of the f ugitive em i ssions f r o m th e U S T / p i p i n g s y s t e m a

n d th e c h a n g e s in pressure in the UST caused by the sim u ltaneous use of ORVR and Gilb arco VRS vapor control system s. The effects of three processes were docum ented in the continuous one-second pressure records of the 3,000 gallon UST: initial positive or negative pressurization (depending on A/L) f r o m the return vapor line; vapor growth in the US T headspace from unsaturated return air; and
continuous leaks from the UST/piping system (sim ul ated with a leak valve on an otherwise tight system ).

The following conclusions were m a de:

99• Measured fugitive em issions from ORVR vehi cles refueled with a m i ni-boot nozzle are near zero (0.003 lb/1,000 gallons) and are less than m easured non-ORVR fugitive

em issions (0.011 lb/1,000 gallons). Thus, when the m i ni-boot nozzle (A /L = 0.95) is used on a Gilbarco VRS, there is no ORVR incom p atibility and m easured “excess em issions” are zero (actually –0.008 lb/1,000 gallons). In addition, with the m i ni-boot nozzle in use the com b ination of ORVR and Stage II VR S controls produces 0.39 lb/1,000 gallons less

em issions at the f illpipe than if just Stage II controls are used.

• “Excess em issions” from the UST/piping syst em when a standard nozzle (A/L=1.15) is

use d a r e 0.72 lb/1,000 gallons. Considering th e decrease in fillpipe em issions produced by the ORVR-VRS com b ination of 0.39 lb/1,000 ga llons, total incom p atibility em issions for the standard nozzle (A/L = 1.15) are only 0.33 lb/1,000 gallons, or less than half of the figure of 0.86 lb/1,000 gallons that CARB presum es for all ORVR vehicles

• In situations where Gilbarco system s are e quipped with standard nozzles (A/L = 1.15), a correction should be applied for the fact that the MOBILE6 m odel (the tool used to create state emission inventories) a ssumes f illpipe em issions f o r ORVR cars are lower than those for non-ORVR cars controlled with Stage II. That is, som e of the fillpipe em issions reduction attributable to ORVR (and discussed in the bullet above) are already credited in the em issions inventory. Thus, when used in statewide em ission inventories developed with MOBILE6, a slightly higher figure of 0.42 lb/1,000 gallons should be assum e d for total incom p atibility em issions f o r the Gilb arco dispenser with a standard nozzle.

• The CARB e s t i m a t i on me thod for UST fugitive em issions (TP201.2F) overpredicted actual pressure-related fugitive em issions by factors of 13 to 660. These data support an earlier analysis by Tech Environm ental that pointed to overprediction and flaws in the analytical f o rm of the equation f o r pressure-related f ugitives.

The Phase 2 – Indoor SHED tests done at ATL quan tified the dependence of refueling em issions on several independent variables. The following conclusions were reached:

• The SHED refueling em issions at the fillpipe for ORVR and non-ORVR vehicles f a ll w ith in the range of values m easured in the Phase 1 and Phase 2-outdoor TP201.2 tests.

• Com p arison of ORVR and non-ORVR fillpipe em issions in the SHED tests produced results confirm i ng those found in the Phase 1 TP201.2 tests. In Phase 1, fillpipe em issions were 73% less for ORVR than for non-ORVR ve hicles using a Gilbarco VRS. In the controlled ref u eling tests in the SHED, f illpipe em issions f o r the ORVR-equipped vehicles were 91% lower than those for the non-ORVR vehicles using a Gilbarco VRS.

• The dependence of f

illpipe em issions on RVP, A/ L ratio and tem p eratures is dif f e rent f o r ORVR and non-ORVR vehicles.

• For ORVR-equipped vehicles, ther e is very little to no correlation of f

illpipe em issions with RVP, no correlation with A/L ratio, no correction with ∆ T (vehicle tank tem p er a t u r e m i nu s dispensed tem p erature), and positive correlation with T T (vehicle tank tem p erature).

100• For the non-ORVR vehicle, there is a positive co rrelation of fillpipe em issions with R V P , a negative correlation with A/L, and a ne gative correlation of em issio n s w ith ∆ T, as assum e d in the EPA MOBILE6 m odel.

• “Puff” losses of HC vapor that occur when the gas cap is rem oved on a vehicle are

com p arable to (50% to 100% of) fillpipe em issi ons from a single refueling event. “Puff”

em issions are positively correlated with T T and RVP.

• Since f illpipe em issions f o r ORVR-equipped vehicles do not exhibit the standard correlations with RVP and ∆ T assum e d in the MOBILE6 m odel, States and EPA should revise the calculation of refueling em issions fo r ORVR vehicles in MO BILE6 to ref l ect the new variable dependencies found in this study and to ensure that future em ission inventories are accurate.

Analysis of the extensive m easurem ents of f

illpip e and pressure-related f ugitive em issions m a de in this study support the following overall conclusions, w h ich are applicable to statew ide H C em ission
inventories:

• For a standard vapor recovery nozzle (A/L = 1.15) on a Gilbarco VRS, “excess em issions” do occur when an ORVR vehicle is refueled. This study docum ents the vapor growth process in the UST for individual refueling events, and m easurem ents reveal “excess

em issions” of pressure-related fugitives are 0.72 lb/1,000 gallons, slightly less than the level CARB assum e s (0.86 lb/1,000 gallons). The CARB estim ate is less reliable as it is not derived f r om actual m easurem ents of pressure-related f ugitives associated with ref u eling ORVR vehicles, the test m e thod used on this study.

• Since the P/V valve at a station cracks occasiona lly from the effects of m u ltiple refuelings and releases headspace air, som e of which is below-saturation vapor return line air, the full pot e n t i a l for va por gr owt h a s me a s ur e d i n t h i s st udy is not realized at a service station. (This study’s Phase 2 m easurem ents of pressure-relate d fugitives considered the full potential for vapor growth over a 1 to 2 hour period following a refueling event.) Thus, the results given in this report likely overpredict actual fugitive em issions as they occur at a service station.

• W h en a Gilbarco VRS is used, ORVR vehicles produce substantially lower em issions at the nozzle/fillpipe than non-OR V R v e h i cles

. T h is is a s i g n i f i can t o f f

s et to th e ex ces s em is s i o n s , which CARB does not account for in analyz ing ORVR com p atibility. Thus, CARB in practice assum e s that total incom p atibility em issions are equal to excess em issions (0.86 lb/1,000 gallons).

• Total incom p atibility em issions for the sta ndard nozzle (A/L = 1.15) are only 0.42 lb/1,000 gallons, about half of what CARB presum es for all ORVR vehicles (0.86 lb/1,000 gallons).

• Measured fugitive em issions from O R V R vehicles ref u eled w ith a m i ni-boot nozzle are near zero (0.003 lb/1,000 gallons) and are less than m easured non-ORVR fugitive em issions

101(0.011 lb/1,000 gallons). Thus, when the m i ni-boot nozzle (A/L = 0.95) is used on a Gilbarco VRS, there is no ORVR incom p atib ility a n d m e a s u r e d “ e x c e s s e m is s i o n s ” a r e z e r o (actually –0.008 lb/1,000 gallons). In additi on, with the m i ni-boot nozzle in use the

com b ination of ORVR and Stage II VRS controls produces 0.39 lb/1,000 gallons less

em issions at the f illpipe than if just Stage II controls are used.

• The CARB estim ation m e thod for UST fugitiv e HC em issions (TP201.2F) over-predicts actual pressure-related fugitive em issions by f actors of 13 to 660. These data support an earlier analysis by Tech Environm ental that pointed to over-prediction and flaws in the analytical f o rm of the equation f o r pressure-related f ugitives.

• States and EPA should revise th e calculation of refueling em issions for ORVR vehicles in MOBILE6 to reflect the new variable dependenc ies found in this study and to ensure that future em ission inventories are accurate.

• Puff losses were found to be on the sam e order of m a gnitude as fillpipe refueling em issions for both ORVR and non-ORVR vehicles. Pu ff losses are the losses of hydrocarbon vapors that occur when the gas cap is rem oved a nd are not captured in em ission inventories calculated by the EPA MOBILE6 m odels.

102

# APPENDIX A

CARB TEST PROCEDURES

# APPENDIX B

PHASE 1 TEST REPORT FROM

VOC TESTING, INC.

# APPENDIX C

PHASE 2 TEST REPORT FROM

VOC TESTING, INC.

# APPENDIX D

PHASE 2 TEST REPORT FROM AUTOMOTIVE TESTING LABORATORIES, INC.