# EPA-460/3-76-014 June

# 1976



# INVESTIGATION ANDASSESSMENT OFLIGHT-DUTY-VEHICLE EVAPORATIVE EMISSIONSOURCES ANDCONTROL

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### U.S.ENVIRONMENTALPROTECTIONAGENCY OfficeofAirandWasteManagement OfficeofMobileSourceAirPollutionControl EmissionControlTechnologyDivision AnnArbor,Michigan48105ThisreportisissuedbytheEnvironmentalProtectionAgencytoreporttechnical dataofinteresttoalimitednumberofreaders. Copiesareavailablefreeof chargetoFederalemployees, currentcontractorsandgrantees, andnonprofit organizations

- assuppliespermit

- fromtheAirPollutionTechnicalInformation Center,EnvironmentalProtectionAgency,ResearchTrianglePark,North Carolina27711; or,forafee,fromtheNationalTechnicalInformationService, 5285PortRoyalRoad,Springfield,Virginia22161.

ThisreportwasfurnishedtotheEnvironmentalProtectionAgencybyExxon ResearchandEngineeringCompany,Linden,NewJersey07036,infulfillment ofContractNo. 68-03-2172.Thecontentsofthis.reportarereproducedherein asreceivedfromExxonResearchandEngineeringCompany. Theopinions, findings, andconclusionsexpressedarethoseoftheauthorandnotnecessarily thoseoftheEnvironmentalProtectionAgency. Mentionofcompanyorproduct namesisnottobeconsideredasanendorsementbytheEnvironmentalProtection Agency.

PublicationNo.EPA-460/3-76-014

ii

### EPA-460/3-76-014~



# INVESTIGATION ANDASSESSMENT OFLIGHT-DUTY-VEHICLE EVAPORATIVE EMISSIONSOURCES ANDCONTROL

by P
..J. Clark.t• Exxon Researt"hand**EnJ!;inecrin~**Company P.O. Hox8 Linden,NewJersey07036

ContraetNo.68-03-2172

EPA Projcet**Offin~r:** R.E. Kruse
Pn·paredfor ENVIRONMENTALPROTECTIONAGENCY OffiN·ofAirandWastc**Mana~emcnt** Offic·eofMobileSoun·t•AirPollutionControl EmissionControl**Teehnolo~y** Division AnnArhor,MiehiJ?;all48105 .lurw IIJ7b 

### U.S. Envirohmental ProtectionAgency Region5,Library (PL-12J) 77WestJacksonBoulevard, 12th

## Floor Chicago, IL 60604-3590 ,TABLE OF CONTENTS

I. INTRODUCTION
.. II. SUMMARY
. . III. EVAPORATIVE CONTROL APPROACHES IN CURRENT USE A. 

### B. Sources of Evaporative Emissions. Current Automotive Practice for Control of Evaporative Emissions. 1. Carburetor Evaporative Emission Control 2. Fuel Tank Evaporative Emission Control. 3. Charcoal Canisters
.. 4. Purge Systems
... 5. Summary of Techniques for Evaporative Emission Control..• C. Classification of Systems
.. 

### D. Survey of Evaporative Control Systems IV. MAGNITUDE AND SOURCE OF EVAPORATIVE EMISSIONS FROM CURRENT VEHICLES A. Test Fleet and Test Method
.. 1. Vehicles
.... 2. Vehicle Preparation • 3. SHED Procedure. 4. Test Sequence
. B. Evaporative Emissions from 1973-75 Cars 1. Total Evaporative Losses from Vehicles. 2. Background Data
. 3. Evaporative Losses by Mode of Operation

i Page No. 1 1 3 3

6 6 6 6 9

9 10 10
13 13 13 l3 16 17 17 17 20 20

## v. TABLE OF CONTENTS (CONTINUED)
Page No. 4. Evaporative Losses by Individual Sources. • . . . 20

a. Overflow from the Carburetor Storage System b. Carburetor Leaks.

c. Overflow from the Charcoal Canister
. d. Other Losses. MODIFICATION OF VEHICLES FOR LOWER EVAPORATIVE EMISSIONS • . A. Hardware for Better Control of Evaporative Emissions. 1. Air Cleaner Overflow. 

### 2. Carbon Canister Overflow•. 3. Carburetor Leaks. 

### B. Vehicle Selection and Modification. 1. Selection
.. 2. Current Emissions 3. Individual Vehicle Modifications for Improved Emission Control C. Emissions fromModified Vehicles
.. 1. Evaporative Emissions
a. Total Evaporative Emissions b. Adjustment for Background Levels.
c. Loss byMode of Operation •• 2. Exhaust Emissions
. D. Conclusions from Vehicle Modification Work 

### E. Estimated Costs, Effectiveness and Durability of Modifications

ii 20 25 25 25
25
26 26 28 29 

### 31 31 31
32 

## so so 50 53 53 54 55
55TABLE OF CONTENTS (CONTINUED)

VI. EMISSION LEVELS OF MODIFIED VEHICLES UNDIO:R SEVERE TEST CONDITIONS. • • • • • VI f. 1!1\Ll)CENATED IIYDROCARBONS IN EVAPORATIVE EMISSIONS

iii Page No.

57 58I. INTRODUCTION This report describes a study carried out by the Exxon Research and Engineering Company for the EPA to assess the effectiveness of light duty vehicle evaporative emission control systems. EvaporatLve emissions from light duty vehicles have been controlled nationwide beginning with the 1971 model year vehicle. The emissions can be divided into two main categories: (1) carburetor emissions, and (2) fuel tank emissions. A control level has been set by El'i\ at 2.0 grams per test as measured by the "carbon trap" method. However, an improved measurement technique, the SHED method, has been developed recently. (SHED test, Sealed Housing for Evaporative Determinations, is 

### SAE Recommended Practice Jl7la.) The new method has shown that the "carbon trap" method underestimates vehicular evaporative emissions. Because of this 

### EPA has sought to conduct a study to determine the performance of in-use evaporative control systems with the more accurate SHED method. In addition, there is a considerable incentive to improve the performance of current evaporative control systems. This is because the exhaust hydrocarbon emissions have been reduced considerably in recent years and consequently the evaporative hydrocarbons represent an appreciable portion of total hydrocarbon emissions of a vehicle. This program,undertaken by Exxon Research and Engineering Company,is a study which addresses itself to the following facets of the vehicular evaporative loss problem: 1. A survey and analysis of evaporative control systems on current vehicles. 2. Astudy of the magnitude and source of evaporative emissions from current vehicles using the SHED measurement technique. 

### 3. Modification of vehicles to demonstrate that performance of evaporative control systems can be improved. 

### 4. The effect of severe operating conditions on evaporative losses from modified cars. 

### II. SUMMARY In 1971, evaporative emission controls were imposed by EPA on light duty vehicles. This was to limit the loss of hydrocarbons evaporating from the fuel tank and carburetor of a vehicle. Recently, EPA determined that the test compliance method, known as the "carbon trap" method, underestimated evaporative emissions and a new test method has- 2 -

been proposed by EPA(l). The new testmethod, known as the SHED method, has shown that the evaporative emission controls in the field are less effective than originally estimated and in the case of some critical latemodel vehicles, evaporative emissions are of the same magnitude as the exhaust hydrocarbon emission. To define and deal with the problem at hand, a programhas been initiated at ExxonResearch and Engineering Company with EPA sponsorship. This programhas assessed the effectiveness of current Evaporative Control Systems (ECS) and has shown the feasibility of various hardware approaches which control evaporative emissions to a very low level. The performance of ECS's in current use was evaluated using a cross section of 1973-75 cars with representative control techniques. For this, the Sealed Housing Method for Evaporative Determinations (SHED), SAE Jl7la procedure was used. (This involves enclosing the vehicles in a shed and monitoring the hydrocarbon level in the shed.). The average evaporative loss for a 20 car groupwas 8.7 grams/SHED test. The lowest losswas 0.5 gram and the highestwas 30.6 grams. The results of this study indicate that the bulk of the evaporative losses occur during the hot soakphase of the SHED test, and the source of emissions is the carburetor bowl. Current ECS's appear effective inhandling the diurnal loss from the fuel tank for most vehicles. The major source of loss was overflow from the air cleanersnorkel,indicating inadequate storagevolume for carburetor hot soak vapors reaching the air cleaner. Hydrocarbons also escaped from poorly fitting seals and other leak sources. In some cases therewas significant overflow from the carbon canister. Hardware was developed to improve ECS performance. Six vehicleswere modified to demonstrate the feasibility of improving current systems. The modifications involved: (1) the venting of the carburetor bowl to the canister to alleviate air cleaner overflow, (2) utilization of larger carbonbeds, (3) adaptation of increased purge rates, and (4) sealing and capping of leak sources. Thesemodifications were successful in lowering the evaporative emissions to 2.0 grams/SHED test or lower for each of the sixmodified vehicles. The costs of the hardware**us~d** to accomplish this has been estimated to vary from $2.00 to $25.00. We have concluded from this work that it is feasible to markedly improve the performance of current evaporative control systems. (1) 41FR2022- 3 -

III. EVAPORATIVE CONTROL APPROACHES IN CURRENT USE A. Sources of Evaporative Emissions The evaporative emissions from a vehicle's fuel system can be divided into two main categories, (1) carburetor emissions and (2) fuel tank emissions. The evaporative emissions from the carburetor occur primarily because of fuel boiling in the carburetor bowl and, to a lesser extent, by diffusion across the hydrocarbon concentration gradients at the carburetor vents. The first process occurs during the "hot soak" period, that is when the heat from the engine is being dissipated to the surroundings after shutdown. This causes the temperature of the fuel in the carburetor bowl to rise over a period of about 30 minutes during which time fuel boils in the carburetor bowl. Beyond this point the carburetor slowly cools, the fuel stops boiling and the subsequent losses are primarily due to a diffusion process. Most of the carburetor losses occur during the rising temperature portion of the soak period. The magnitude of carburetor hot soak losses is a function of the increase in bowl gasoline temperature during the hot soak, the volume of the bowl, and the fuel's volatility. Figure 1 is representative of operation on a gasoline with Reid Vapor Pressure (RVP) of 9 psi (62.1 kPa). Typical losses are in the neighborhood of 10-15 grams for a carburetor bowl gasoline temperature increase of 10 to 16°C (maximum temperature of 82 to 88°C). The band in Figure 1 spans the normal size range of carburetor bowl volumes from 50 cc (lower curve) to 100 cc. The range of carburetor bowl sizes found in the field is much larger than 50-100 cc's, and the fuel volatility can vary significantly, thus the range of possible carburetor hot soak losses is much larger. Evaporative emissions from the fuel tank are primarily due to two concurrent processes which cause an increase in the temperature of the fuel in the tank. This rise in tank temperature can occur, (1) while the vehicle is standing still due to variation in the ambient temperature and the evaporation losses are then referred to as "diurnal losses", (2) while the vehicle is operating, due to heat transfer from the exhaust system to the fuel tank and the losses are then referred to as "running losses". The magnitude of fuel tank diurnal losses is shown in Figure 2. The abscissa is the maximum temperature reached during the diurnal, normally 27.7°C in evaporative emission testing. Againwe are using the standard test fuel with a Reid Vapor Pressure of 9 psi (62.1 kPa). For the normal range of fuel tankvolumes, using the prescribed 40% fuel fill, diurnal fuel tank losses vary from 10 to 25 grams or roughly 0.3 gram per litre of fuel tank capacity. Diurnal cycles to higher temperatures increase evaporative losses as shown.FIGL.'Rf 1 CARBURETOR HOT SOAK EVAPORATIVE**EMISSIO~-.s** ARE STRONGLY AFFECTED BY MAXU1UM BOWL TEMPERATURE DURING SOAK 30

__________ _,_ __

25

20

### ~**~ ~**  z c**~** u:. u:.**~** 

### 15

### ~

5**ST~~ARD** 9 RVP GASOLINE

65 

### 75 85 I"IAXD1UH CARBURETOR BOWL TEMPERATURE DURING HOT SOAK,°C 95

### e oc



# .. u:: z 0 1-1 u:: tJ:l 

### 50

40**~** 30

### ~



### 10 FIGCRE 2**Dil:L~AL** 

### CYCLE EVAPORATIVE**~ISSIO~S** ARE 

### STRONGLY AFFECTED BY A."!BIE:iT Tu1PERATURE RISE
. .'0-""J 

### ITEL :'A
... \"'K VOLU:ffi**ST~~ARD** 9 RVP**GASOLI~c** 

### INITAL**GASOLI~~ TEMPER~TGRE,**  

### l5.5°c**VOU~E** OF 

### TA11< 95 Litres



### 75

55



### 35

_j

_______________ l

__________________________

### l

______ . __________ - 20 ?S 30**MAXI~ DIU~~AL**  

### CYCLE TEMPERATURE, °C- 6 -
Running losses frommost ECS equippedvehicles are not significant. If fuel tanks have non-vented caps and are vented to the intake system, the vapors leaving the tankwill beburned in the engine. Carburetor bowls arevented to the carburetor air intake, allowing vapors to be burned in the engine. B. Current AutomotivePractice for Control of Evaporative Emissions In this section, the types of Evaporative Control Systems (ECS) usedby the automotive**indu~try·are** reviewed. 1. Carburetor Evaporative Emission Control The two types of carburetor losses are running losses andhot soak losses. The running losses are controlled internally in the carburetor by venting from the carburetor bowl to the air intake of the carburetorvia thebalance tube (Figures 3 and 4), allowing carburetor running vapors to beburned inthe engine. This is the casebecause the pressure in the intake is lower than that in the carburetorbowl when the vehicle is running. To controlhot soak losses during engine shutdown, two basic systems are used. The first is storage of the vapors in the induction system during shutdown followed by eventual consumption in the engine after start-up. The hydrocarbonvapors move from the bowl into the carburetor intake through the balance tube and then into the carburetor throat and air cleaner. Because hydrocarbons are denser than air, they displace the air. Figure 3 shows a system of this type. The second control system for hot soak losses uses both the induction system and a charcoal canister to store vapors. Aline from the bowl to the canister diverts a portionof thevapors to this alternate storage. This is illustrated in Figure 4. Acarburetor vent valve opens the line to the canister at idle and while shut down. At other times, the line is closed. Vapors stored in the carbon canister are ultimately purged by a portion of engine combustion air which is drawn through the canister during operatingmodes. 2. Fuel TankEvaporative Emission Control Fuel tanks are designed as "closed" systems (non-vented fill caps) which are connected to a vapor storage system through a vapor-liquid separator. The vapor-liquid separator reduces system load by returning condensed and entrained liquid to the tank. Three types of vapor storage techniques areused: (1) charcoal canister, (2) engine crankcase, and (3) an auxiliary tank. 3. Charcoal Canisters The majority of ECS's use a charcoal canister to store the hydrocarbonvapors emitted from the fuel tank. Inmost of these systems, the- 7 -
FIGURE 3 EVAl'ORATlVE**E~liSSIO:~ CO~TROL**  SYSTEH

Carburetor

Liquid/Vapor

Separator**.----~I**

I'**re~;:;**ure/Vacuum FJll.er Gas**Cap~**

Fuel Tank Air Cleaner

Orifice 

# + Carburetor

### ~~~~~ Bowl

Tank Vent Line

Canister---+- 0 0 0 0 0 0

0 0 0 0 0 0 Purge Line

0

## ~t0? 0 0**,//2f~0...,.** Filter Activated

# ~l'urg<! Charcoal Air- 8

- 

### FIGURE 

### 4 EVAPORATIVE EMISSION CONTROL SYSTEM

Liquid/Vapor Separator Pressure/Vacuum Filler Cap Carburetor

Fuel Tank Air Cleaner

Orifice

Tank Vent Line

Canister Valve Bowl Vent

- · Line to Bed

To PCV Valve

Purge Valve

Charcoal Purge Air- 9 -
fuel tank vapors from both hot soak and running losses pass into the canister. Afew systems, however, use a control valve which allows running loss vapors to bypass the charcoal bed and move directly to the engine. The charcoal canister system functions via an adsorptionregeneration process. Hydrocarbon vapors are adsorbed on the surface of the activated carbon for storage purposes. Later the vapors are desorbed from the surface by passing a portion of engine combustion air through tht.• charcoal bed. This regeneration, or purging process, is necessary to restore the capacity of the bed for further hydrocarbon storage. There are several types of carbon canisters inuse. They may be classified by the method of introducing purge air to the bed and by the technique for the handling of running vapors. Inmost cases, purge**~ir** enters the bed through the open bottom of the canister as illustrated in Figure 3. A replaceable filter is used to prevent dust contamination. A**~wcond** type of canister in use has a sealed bottom with an air inlet on top. ln some canisters, running vapors as well as hot soak emissions pass into the carbon bed. In others, a purge valve is used which allows running vapors to bypass the carbon bed. An example of this type of canister is illustrated in Figure 

### 4. 4. Purge Systems There are three general types of purge systems for regeneration of carbonbeds. These systems can purge to: (1) the air cleaner, (2) the carburetor, and (3) the Positive Crankcase Ventilation valve (PCV). Units purging to the air cleaner generally utilize the pressure drop through the air cleaner and inlet system to draw purge air through the canister. One system utilizes the velocity of the air in the air cleaner snorkel to pull air through d1e carbon bed. Purging to the carburetor is the most popular technique. An example of this is shown in Figure 3. Aport at the idle position is most often used so that at idle the purge rate will be very low but \vill increase as the thrott]e is opened. The third type of purge is to the l'CV system. An example of this is shown in Figure 

### 4. With this system, a purge valve is used which pennits only tank running vapors to reach the engine at idle. As the throttle is opened from idle, engine vacuum opens the purge valve on the canister so that both tank running vapors and stored vapors in the bed are drawn into the engine via the purge air stream. 

### 5. Summary of Techniques for Evaporative Emission ControJ

a. Carburetor Bowl Emissions**'T'o~ ~** Induction system only

# ~Both induction system and charcoal bed canister

### - 10

-
b. Fuel Tank. 

### Emissions To:**~**

### Charcoalbed

- Auxiliary Tank

## ~Engine crankcase

c. Carbon Canister: / Open or closedbottom

--Allvapors enter thebed

## ~Running vapors bypass bed

d, CarbonCanister Purges To:

e. Other
C. Classificationof Systems /Air cleaner

- Carburetor

## ~PCV

Evaporative Control Systems have beendivided into two general categories: (1) those using a charcoal canister, and (2) those using a systemother thana charcoal canister for storage of fuel tankvapors. Over 98% of the 1973-1975vehicle populationutilize a charcoal canister. These systems havebeenfurther typed according to carburetor storage and type of canisterpurge. This is shown inFigure 5. Systems not using a charcoal canistermay use the engine crankcase or a small auxiliary tank for storage. Afurther subdivisionis by the style of canister. Adescriptionof'the charcoal canisters used by eachU.S. manufacturer is given inTable I. 

### D. Survey of ECS's inUse Across sectionof about 120vehicles from the 1973-1975 car populationhas beenused in this survey of evaporative control systems incurrentuse. Inaddition to describing theECS, the fuel system components which affect their function suchas proximity of fuel tank to a heat source such as muffler, anduse of a fuelvapor returnline to the tankhave alsobeensurveyed. This survey covered allfamilies of engines from eachU.S. manufacturer and the leading foreign-manufactured cars. All told, this group is representative of at least 99% of thevehicles in the 1973-1975 carpopulation. The results from this survey are shown inAppendix I.

### FIGURE 5 CLASSIFICATION OF EVAPORATIVE**D1ISSIO~** 

### CONTROL SYSTENS



### A. Systems Using Charcoal Canisters**~** 

### Carburetor Storage Type of Canister Purge I

# ·---- 

# ---- Carburetor Induction II System PCV 

# --- Only 

# ---- III Air Cleaner

IV

# ---- ------ Carburetor Induction 1-' 1-' \. 

### System and PCV 

## ri

# --- Canister 

# ---- Air Cleaner



### B. Systems l.';'ot Using Charcoal Canisters VII

# ---- Induction ----Tankfor Fuel Tank Vapor Storage VIII System for Crankcase for Fuel Tank Vapor Storage Carburetor IX

# ---- Vapors

------ Other Than Above

### TABLE I CHARCOAL CANISTERS ON U.S. CARS
Tube Designation Manufacturer No. No. of Tubes Inlet Outlet Other Remarks GeneralMotors 1 2 

### Tank Purge 2 3 

### Tank Purge Carburetor Bowl 3 3 

### Tank Purge Vacuum for (purgevalve) Purge Valve 4 4 Tank Purge Vacuum for (purgevalve) Carburetor Bowl PurgeValve 1-' N 

### Chrysler 1 3 

### Tank Purge Carburetor Bowl sometimes not used Carburetor Bowl 2 

### 4 Tank Purge Vacuum for (purgevalve) Carburetor Bowl PurgeValve
Ford 1 2 

### Tank Purge 300 

### gtns 2 2 

### Tank Purge 500 

### gms 3 3 

### Tank Purge 700 

### gms Carburetor Bowl AmericanMotors 1 2 

### Tank Purge 2 3 

### Tank Purge Carburetor Bowl- 13

-

JIJ. 11N.;IJ'IIIIJI< /\rJIJ**~;(J(Jf(CJ<** IJI'**l~V_fi_!_'_(~~/\~!J**VJ·; JoJ1JSSJ0!'4S FHOM CURRENT VEH1CLES This part of the program evaluated the effectiveness of the evaporative control systems in current use on U.S. and imported cars. A. Test fleet and Test Method 1. Vehicles The twenty vehicles selected for testing are described in Table II. The criteria for their selectionwere: (1) to be representative of the control techniques in use, (2) to represent carburetor designs and fuel tank volumes in the field, and (3) be a cross section of the nation's 1973-1975 car population. All vehicles were at**l~ast** 90 days old prior to the test date. The source of each vehicle is shown in Table III. As far as possible, non-undercoated vehicles were used. Prior to completion of the last phase of this program, it was necessary to return Car No. 3 and replace itwith Car No. 21 which was similar in make, model and engine to its predecessor. 2. Vehicle Preparation Each vehicle underwent a mechanical inspection and was tuned to factory specifications in cases where the ignition system and exhaust emissions were abnormal. For this, the ignition systemwas checked by an electronic analyzer and the exhaust emissions by the diagnostic procedure(l) developed by ExxonResearch for tail pipe CO and HC emissions at idle and 2500 rpm. Other preparation involved thermocouple installations in the carburetor bowl, the underhood area, and the fuel tank. The thermocouple for underhood temperatures was located about four inches in front of the carburetor bowl. In addition to the in-tank thermocouple required by the SAE Jl7la test method, a skin typewas attached to the outside of the tank at the fuel-air interface. Anew fuel tankwas used for each vehicle. 1wo lines were welded into the tank, a drain line and a line from the vapor space in top of the tank. This latter line is for a transducer connection to monitor fuel tank pressure during the diurnal and hot soak cycles. The integrity of the fuel tank systemwas checked prior to the initiation of the test. (1) J. Panzer, "Idle Emissions Testing

- Part II," SAE Paper 740133TABLE II VEHICLES FOR SHED TESTS (AllAutomatic TransMission Except 1119)
Car DisEl· No. No. Make Model Yr. Litres Cu. In. _3_L_-



### --- 1 Ford LTD 75 5.75 351 8 2 Pontiac G.P. 75 6.56 400 8 3 Chrysler NYer 75 7.21 '•40 8 4 Ford Pinto 74 2.00 122 4 5 Chevrolet Nova 74 4.10 250 6 6 Chevrolet Impala 74 5.74 350 8 7 Plymouth Duster 73 3.69 225 6 8 Buick Le Sabre 75 5.74 350 8 9 Chevrolet Vega 75 2.29 140 4 10 Oldsmobile 98 74 7.46 455 8 11 AMC Hornet 74 3.80 232 6 12 Plymouth Fury III 73 5.90 360 8 13 Dodge Dart 74 5.21 318 8 14 Datsun 610 74 1.95 119 4 15 Hazda RX-4 74 1.31 80 Rotary J6 Mercury Cornet 74 4.10 250 6 17 Volvo 144 74 1.98 121 4 1'3 Ford Squire 75 7.54 l!60 8 19 

### vw Beetle 75 1.60 97 4 20 Mercury Monarch 75 '•·95 302 8

(1) Type of Evaporative Control System (ECS) described inFi8ure 5. (2) Canisterhas a purge controlvalve. (3) Also uses a carbon canister for fuel tankvapor storage. (4) Fuel injection. (5) Carbon canister for fuel tankvapor storage. (6) Condensor tank for fuel tankvapor storage. No. Fuel Tank Venturis Litres Gals.


### -·---- 2 92 24 4 95 25 l: 100 26.5 2 49 13 1 79 21 2 93 26 1 60 16 4 98 26 2 60 16 {! 93 26 1 6b 17 2 98 26 2 60 16 2 52 14 4 64 17 1 60 l(j F.I.(4) 60 16 !I 79 21 F.r.(4) 

### t,o 10.5 2 73 19 Air Vapor Return ECS(l) C0nd. Line? Undercoated**~** 

### ------ y tT N VI y y N I y y y IV IJ**~: ~~**  III y N N II(2) y }! y I y ;r y IV y y y I ,, }.' y v(2) ·' y y y I 1-' y N y III .1:- y }) y IV y N y I y y y VIII y y y VII(3) y N N III N y N IX(5) y y y VI N y N IX(6) y v y Il'ICar No. 1 2 3 4 5 6 7 8 9 10 11 12 13 

### 14 15 16 17 18 19 20 21 - 15

-

TABLE III SOURCE OF VEHICLES

Hake LTD Pontiac Chrysler Pinto Nova Chevrolet Duster Buick Vega Olds Hornet Plymouth Dart Datsun Hazda Comet Volvo Ford 

## vw Monarch Chrysler Source Leased Leased Leased Leased PrivateOwner PrivateOwner PrivateOwner Private Owner PrivateOwner Private Owner PrivateOwner PrivateOwner PrivateOwner Private Owner ERE Car Private Owner Private Owner PrivateOT11ner Leased Leased Private Owner- 16

-

3. SHED Procedure Evaporative losses weremeasured using the Sealed Housing for Evaporative Determinations (SHED) procedure as described in SAE Recommended Practice Jl7la. This method employs an enclosure inwhich the vehicle is placed during diurnal and hot soakphases of the test. Vapors escaping from the vehicle are retained in the enclosure and the increase in the hydrocarbon concentration of the atmosphere in the enclosure represents the evaporative emissions. Details for the SHED test are outlined in SAE Jl7la. These were followed in this workwith one or two exceptions such as for preconditioning. Some of the operational steps for the test are covered below: Preconditioning: The preconditioning procedure for this test was as follows: (1) three consecutive LA-4(1) cycles [7.5 mile (12.1 krn) trips), (2) shut down for 10minutes, and (3) a fourth LA-4 cycle. This was followed by an 11-16hour soak at about 24°C. Diurnal Cycle: Aone hour soak in the SHED during which the temperature of the fuel in the tank is raised from 60 to**84°~** (15.6 to 28.9°C). A pressure transducer was used to monitor fuel tank pressure during the diurnal cycle and the hot soak. Federal Test Cycle: The vehiclewas quickly placed on the chassis dynamometer after the diurnal cycle for an exhaust Federal Test Procedure. The dynamometer had previously beenwarmed up with a different vehicle and the load set. Hot Soak: Aone hour hot soak in the shed followed immediately after the Federal cycle to complete the test. The fuel for the SHED test was Indolene of 9.0 psi (62.1 kPa) RVP. Inspections for this fuel are shown inAppendix II.
(1) 1972 Federal Test Procedure- 17

-

4. Test Sequence The sequence of testing for each vehicle is outlined in the diagram in Figure 

### 6. Those vehicles which emitted less than 

### 2 grams/ test were tested a second time by the SHED procedure to complete their test cycle. All vehicles failing the 2 gram limit underwent a source test to determine the location of the leaks. This was followed by two tests to quantify the emissions from individual leak sources using the technique described inAppendix III. Athird quantifying test was made in cases where there was an abnormal variance between the first two tests. This was followed by a second SHED test to complete the testing Hchedule. (Hot and cold background tests were also carried out on each vehicle as per SAE Jl7la.) 

### B. Evaporative Emissions from 1973-75 Cars 1. Total Evaporative Losses from Vehicles Total losses, as measured by the SHED procedure, varied from a low 0.5 gram to a high of 30.6 grams for the 20 car group. The average for the group was 8.7 grams. The range for the 20 cars is shown graphically below:

20

Grams 

### 15

Per Test 10

5

0**,.~ ~** 
f1-



## -

-
1-**~** I 

# I TOTAL EVAPORATIVE LOSSES 20 Cars

Vehicles ....!:.""'



### -



# -



# -

-

-

-

### - 18

- 

### FIGURE 6 

### FLOWDIAGRAM OF TESTING PROCEDURE


# ( START 

# )



# -
BACKGROUND TESTS

SHED TEST



# 0 IF SHED Em.**~** 2 

### Gr. TEST IF Em. > 2 

### Gr.**~** 

### SOURCE 

# - IF j 

### LOCATION TEST Em. > 2 

### Gr. 

## \

INDIVIDUAL SOURCE TEST(l) IF 

# , Em. :;;: 2 

### Gr. INDIVIDUAL SOURCE TEST(Z)
IF 

# 0 (1) :/: (2) 

### IF (1) = (2) 

### INDIVIDUAL**~** 

### SHED SOURCE TEST()) TEST

# ~ ( END \_ 

### J



# -- 19

-

In tllis program, the data arr· for tlH• most part an ;lv•·r;l)'.'' ul two SilEO tests. The initial test may be slightly higher than the HPcond SHEU test because leaks in the air cleanerwere sealed prior to the second test (as part of the quantifying procedure). In cases where there was a substantial difference between the two SHED tests, a third was run and the three averaged for the vehicle. The total evaporative loss was adjusted for vehicle background hydrocarbon levels. The results for individual runs on each car are summarized inAppendix IV. The tablebelow shows total evaporative losses by make and model in descending order from worst to best. No particular U.S. manufacturer appears to stand out from a good performance standpoint. A PlymouthDusterwas the best U.S. car, however, the Chrysler NYer is one of the poorest for high evaporative losses. Some models from both G.M. and Ford also are comparatively good and others fall in the poor category. The best vehiclewas a fuel injected VW Beetlewith only 0.5 gram total evaporative loss. The other fuel injected vehicle in the group, the Volvo, falls in the poorest half of the 20 car group. Table IV Total Evaporative Losses By Make and Model
TotalLoss Car ECz Grams Make Model Yr. No. Type l) 30.6 Ford Country Squire 75 18 VI 17.3 Mercury Comet 74 16 III 17.1 Chrysler NYer 75 3 IV 10.9 Chevrolet Nova 74 5 II 10.7 AMC Hornet 74 11 III 10.6 Mazda 

### RX-4 74 15 VII

9.5 Olds 98 74 10 I 9.3 Mercury Monarch 75 20 Ill 7.5 Volvo 144 74 17 IX 7.5 Pontiac G.P. 75 2 I 6.7 Ford LTD 75 1 VI 6.6 Buick Le Sabre 75 8 I 6.0 Ford Pinto 74 4 III 5.8 Plymouth Fury III 73 12 IV 5.3 Chevrolet Impala 74 6 I 4.1 Chevrolet Vega 75 9 

## v 2.8 Dodge Dart 74 13 I 2.8 Datsun 610 74 14 VIII 1.5 Plymouth Duster 73 7 IV 0.5 

## vw Beetle 75 19 IX
(1)-ECS type described in Figure 5.- 20

-

No single type of ECS systemappears to be superior to the others in the above table. There are, however, desirable features from individual ECS**~ystems** whichwill be discussed later. 2. Background Data Evaporative losses from sources other than the fuel system are generally small. Coldbackground data for U.S. vehicles fall in the range of 0.0 to 0.2 grams per test. Hot backgrounds were higher ranging for 0.0 to 0.7 grams per test. TableVand Appendix IV show individual vehiclebackground data. The only car to have a high background from a non-fuel oriented sourcewas the 1975VW, Car No. 19. The background levels of this vehiclewere 0.7 and 0.8 grams cold and hot respectively. These do not appear to be the result of gasoline absorption from previous spillage on the vehicle as was the case for several test cars. Both the hot and the coldbackground tests were continued for 24 hours. The rate of hydrocarbon.emissiondid not diminish significantly during the 24 hour periods. Comprehensiveprobing for the source of hydrocarbon emission did not reveal any sources. Additional testing showed that essentially all of the hydrocarbonwas coming from the outside of the vehicle and only a small fraction from the interior. This vehicle is at least 5-6months old. It appears that the paint may be the source of the emission. 3. Evaporative Losses byMode of Operation (Test Cycle) The bulkof the evaporative losses occur during the hot soak mode of operation. Evaporative losses by mode of operationare shown in Table VI. For the U.S. cars in this group, 83% of the evaporative loss was experienced during thehot soak. This means that most U.S. cars handle fuel tankvapors from the diurnal cycle satisfactorily in their carbon canister storage system. The loss during the diurnal cycle for 70% of theU.S. cars was 10% or less of the total loss. For the remainingU.S. cars, diurnal losses were as high as 65% of the total loss. Imported vehicles follow the same patternas the U.S. car population. 4. EvaporativeLosses by Individual Sources
a. Overflow from the Carburetor Storage System Hydrocarbonvapors escaping from the air cleaner during the hot soak areby far the largest contributor to evaporative losses. One half of thehydrocarbon loss is by this routewithvapors escaping from the air cleaner snorkel. This indicates that the air cleaner and inductionsystemdo not have sufficient capacity to store all of the vapors emitted from the carburetor bowl during shut down. Asummary of the contributionfrom each source to the total emission for the cars is shown in Table VII along with the mode of operation during which the loss occurs. The source of losses for individual vehicles is summarized inTable VIII.

### - 21

-
TABLE V EVAPORATIVE LOSSES ADJUSTED FOR BACKGROUND
Total Loss Before Total Loss Car Background Adjustment, Background, Grams Adjusted for No. Grams Cold Hot Background, Grams



### ------------ ---- 1 6.7 __(1)

__(1) 6.7 2 7.5 __(1)

__(1) 7.5 3 17.2 0.0 0.1 17.1 4 6.2 o.o 0.2 6.0 5 11.0 0.0 0.1 10.9 6 5.3 __(1)

--(1) 5.3 7 1.5 __(1)

--(1) 1.5 8 

### 7.0 0.1 0.3 6.6 9 4.7 0.0 0.6 4.1 10 10.0 0.2 0.3 9.5 11 

### 10.8 0.0 0.1 10.7 12 6.6 0.1 0.7 5.8 13 

### 2.9 0.0 0.1 2.8 14 3.1 0.1 0.2 ( ) 2.8 15 12.2 o.s(2) 1.1 2 

### 10.6 16 17.4 0.0 0.1 17.3 17 7.7 0.1 0.1 7.5 18 30.7 0.0 0.1 30.6 19 2.0 0.7(3) o.s<3) 0.5 20 9.3 0.0 0.0 9.3**~No** background data for these cars. The results from the background tests for Cars No. 1, 2, 6 and 7, whichwere the first four to be tested for background, were very high due to gasoline spillage on the front carpet. Afuel canhad beenused as an auxiliary fuel tank. This took place after the SHED testing. Procedure changed after these four cars. (2) Evidence of gasoline spillage in the trunk prior to the SHED tests, whichwould account for the highbackground. (3) Appears to be coming from external enamel paint.- 22

-



### TABLE VI EVAPORATIVE LOSS BY MODE OF OPERATION
TotalLoss, 

### %of Loss Car No. Grams Diurnal Cycle Hot Soak 1 6.7 50 50 2 

### 7.5 5 95 3 17.1 45 55 4 6.0 30 70 5 10.9 2 

### 98 6 5.3 10 90 7 1.5 8 6.6 10 90 9 4.1 5 95 10 9.5 5 95 11 

### 10.7 5 95 12 5.8 65 35 13 2.8 5 95 

### 14 2.8 35 65 15 10.6 0 100 16 17.3 0 100 17 7.5 60 40 18 30.6 5 95 19 0.5 20 9.3 20 80Location 1 - Air Cleaner(l) - 23

-

TABLE VII SUMMARY OF SOURCES OF EVAPORATIVE LOSSES FROM 20 CAR GROUP

Mode Hot Soak 2 - CarburetorLeaks(2) Hot Soak 3 - Carbon Canister Diurnal 

### 4 - CarbonCanister Hot Soak 5

- Other Diurnal

### &H.S.

(1) Snorkel

- other leaks sealed before tests. %of Total Losses 50 25 10 10

5

(2) Primarily from around accelerator pump shaft. Some smaller leaks elsewhere.

### - 24

-

TABLE VIII SOURCES OF EVAPORATIVE LOSSES
%

### of Total EvaEorativeLoss Air Cleaner CarbonCanister Car Total Loss, Diurnal Hot Diurnal Hot Carb. SHED(l) No. Grams Cycle Soak Cycle Soak Leakage



### ---

1 6.7 0.0 0.0 45 45 0.0 10 2 7.5 0.0 60 5 5 25 5 3 

### 17.1 0.0 2o<2> 45(2) 20(2) 10 5 4 6.0 0.0 65 30 0.0 0.0 5 5 10.9 0.0 45 0.0 0.0 5oO> 5 6 

### 5.3 0.0 95 0.0 o.o 0.0 5 7 1.5 8 6.6 o.o 70 0.0 0.0 25 5 9 4.1 o.o 90 0.0 0.0 0.0 10 10 9.5 o.o 75 0.0 0.0 20 5 11 10.7 o.o 40 0.0 0.0 60 0.0 12 5.8 0.0 0.0 35 35 30 0.0 13 

### 2.8 0.0 60 0.0 o.o 35 5 14 2.8 ls(2) 0.0 45 4o(5) 15 10.6 0.0 100 0.0 0.0 16 17.3 0.0 85 0.0 0.0 15 0.0 17 7.5 5 50 0.0 0.0 35(4) 10 18 30.6 0.0 20 0.0 10 65 5 19 0.5 

### 20 9.3 o.o 25 20 o.o 50 5

(1) Hydrocarbonvapors not collected in quantifying test or otherwise accounted for. (2) Estimated. (3) This carburetor also externally vented upon slight pressure inbowl. (4) Leakage from gas cap. (5) Crankcase storage.- 25

-

The vehicles with the lowest loss from the air cleanerwere those utilizingboth canister and air cleaner storage for vapors from the carburetor bowl. These are Type IV-VI systems. Using the canister to handle part of the hot soak load alleviates the overloading of the air cleaner. However, unless the canisterhas sufficientworking capacity to adsorb the added load, it in turnwill overflow. b. CarburetorLeaks This is the second largest contributor to evaporative losses and accounts for 25% of the total loss. For themost part, these leaks occur 1ncarburetors which do not utilize a diaphragm type of accelerator pump (used inFord Motor Company and some other carburetors). Sixty percent of the cars tested had problems withhydrocarbon leakage around the accelerator pump shaftwhere it passes through the air horn or body of the carburetor. Car No. 5, in addition to leakage around the accelerator pump linkages, vented to the atmospherewith a slight pressure buildup in the carburetorbowl.

c. Overflow from the Charcoal Canister This is the third largest source of evaporative emissions with 

### 10% occurring during the diurnal cycle and an additional 

### 10% during the hot soak. This indicates insufficientworking capacity in the canister of five of the twenty cars in the group. Vehicles with overflow during the hot soakutilized the carbonbed to store carburetorbowl vaporsas well as fuel tankvapors. d. Other Losses Some hydrocarbon is lost from small leaks such as from the ends of the throttle shaft as it passes through the carburetor body and other places. Running losses during the Federal Cyclewere not measured. The most likely source of running vapors is venting through the gas cap due to pressure build-up in the tank. Car No. 17was the only vehicle to have a significant pressure build-up in the fuel tank. It vented hydrocarbon vapors through the gas cap during the diurnal cycle and hot soak and probably during the Federal Cycle.
V. MODIFICATION OF VEHICLES FOR LOWER EVAPORATIVE EMISSIONS The purpose of this phase of the program is to develop hardware to give better control of emissions, select vehicles with typical or representative sources of evaporative emissions, and then to modify the vehicles to demonstrate the effectiveness of the new hardware.- 26

-

A. Hardware for BetterControl of Evaporative Emissions 1. Air Cleaner Overflow Five techniques to control air cleaner overflow during the hot soak are shown as Controls No. 1 through 5 in Table IX and discussed below: Control No. 1 - Vent the Carburetor Bowl to the Canister Aportion of the hot soak emissions is directed to the carbon canister for storage in lieu of the air cleaner. Avalve in the carburetor opens to vent the bowl to the canister during idle and shutdown. At other times, the vent line is closed. Venting of the bowl to the canister is now used in the ECS's of Vehicles No. 1, 3, 9, and 12. This modification requires minimum flow resistance in the line to the canister, viz.**lin~** should slope toward the canister and be of adequate size to handle the vapor load. Undue resistance to flow results in excessive hydrocarbon vapors entering the air cleaner via the carburetor bowl balance tubes. This modification requires a larger storage capacity in the carbon canister than ECS's with air cleaner storage only for hot soak emissions. The canistermust now accommodate both the hot soak and the diurnal emissions at the same time. Control No. 2 - Ventilating Engine Compartment with a Fan Afan is used to provide cool air to the engine compartment to lower the temperature increase of the bowl during the hot soak. The lower bowl temperature contributes to a decrease inhot soak emissions and lessens the load on the storage system. The fan can be actuated by a thermal switch through the ignition system. This will cool the engine compartment until its temperature is lowered to the control point at which time the fan is shut off. Control No. 3 - Barrier at the Base of theAir Cleaner Snorkel Hydrocarbon vapors are heavier than air and tend to preferentially settle down. Abarrier at thebase of the snorkel deters the loss of emissions out the snorkel.
Other controls to limit air cleaner overflow such as decreasing carburetor bowl volume and use of louvers in the hood for ventilation are suggested in Table IX. Theywere not included in this program.Control No.

1* 

### 2*
3* 4 5 

### 6* 7* 8* 

### 9* 10 11 

### 12*
13 14* 

### 15 Source Air cleaner overflow Air cleaner overflow Air cleaner overflow Air cleaner overflow Air cleaner overflow Canister overflow Canister overflow Canister overflow Canister overflow Canister overflow Canister overflow Canister overflow Canister overflow Carburetor leaks Carburetor leaks TABLE IX**~1ETHODS** FOR**CO~ITROL** OF EVAPORATIVE E1ISSIONS
Description Vent carburetor bowl to canister. Ventilating engine compartment with a fan during hot soak. Barrier at base of snorkel. Decrease bowl working volume. Louvers inhood for ventilation. Increase size of carbonbed. Increase purge rate. Close bottom of canister and vent to top of unit. Control**~o.** 2 Controls No. 4 and 5 Heat purge air. Minimize heat input to fuel tank. Shield tank from hot muffler, etc. Minimize vapor space in the fuel tank. Close spaces around shafts with boots, caps, etc. Use a diaphragm type accelerator pump in lieu of the plunger type.
*Controls demonstrated in this program. Remarks

Less vapors generated because of lower carburetor bowl temperatures.
Less vapors generated. Less vapors generated. Two canisters used in parallel.

Apply for ECS with carburetor bowls vented to the canister. For ECS's with vented bowls to the canister.
Less vapors generated.- 28 -

2. Carbon Canister Overflow Eight techniques are suggested for control of an overloaded carbon canister. These are shown as Control 6 through 13 on Table IX and described below: Control No. 6 - Increase Size of Carbon Bed This modificationwill increase the working capacity of the system. (Working capacity is the maximum weight of hydrocarbon that can be handled in the storage unit.) Inmany cases, it is not necessary to increase purge rate to realize an increase inworking capacitywith a larger canister. This is the casebecause,even though the purge flow rate is lower per unit of charcoal with a larger bed, the average hydrocarbon loading on the charcoal during the purge cycle is higher, resulting inmorehydrocarbon being removed from the canister. Control No. 7 - Increase the Purge Rate This technique will increase the working capacity of those canister storage units which currentlyhave lowpurge rates. ECS's which utilize air cleaner purge systems, Type III and VI, generally have low purge volumes. Inmany instances, it may be necessary to utilize carburetor or PCV purge systems to raise the purge volume to the desired level. Control No. 8 - Close the Bottomof Open Canisters This would prevent seepage or migration of hydrocarbon from the bottomof the open canister. Asketch of a coverwith a vent pipe is shown on the following page.

### - 29

-

CAP PREVENTS LOSS FROM BOTTOM OF CANISTER



### Inlet PurgeAir

G.M. Canister

--

Cap for Open Bottom

Controls No. 10through 13 in Table IX outline additional controls to handle canister overflow. These controls were not used in this programwith exception of Control No. 12 which was applied to Vehicle No. 17. 3. Carburetor Leaks Two controls are suggested for carburetor leaks as indicated below: Control 14

- Use of Flexible Boot and Covers Carburetor leaks around accelerator pump shafts can be prevented by use of a flexible boot around the shaft to seal the opening. In cases where a boot will not suffice, a cover such as the one shown in Figure 7 can be used.- 30

- 

### FIGURE NO. 7 SKETCH OF ASEAL FORCARTERCARB. LEAK.

- CAR NO. 11



### I



# ---·--r... Accel. Pump Shaft

------ 

### I**~~~-=~~~** 

### I I Carb. Body

Carb. Base

Throttle Shaft and Linkage

Cover Design: The two sides and bottomwould be cast into the carburetorbase. Front sidewould beheld inplacewith a snap clip.- 31

-
Control 15

- Use of a Diaphragm Type Accelerator Pump Use of a diaphragm type accelerator pump such as on Ford carburetors in lieu of the piston type onRochester Products and Carter units will prevent leakage. Itwill require retooling inmost cases.B. Vehicle Selection andModification 1. Selection Six vehicleswere selected from the 20 car group for ECS modification. The evaporative emissions and ECS's of these vehicles are representative of the 20 vehicle group. The vehicles are shown below: Table X Vehicles for Modification ECS Car No. Make Year**~** Purge 

### 1 Ford 

### 75 VI Air Cleaner 2 Pontiac 

### 75 I Carburetor 3 Chrysler 

### 75 IV Carburetor 11 AMC 

### 74 III A.C. Snorkel 

### 15 Mazda 

### 74 VII 

### (1) 17 Volvo 

### 74 IX (2) (1) Modified Type VII system. (2) Fuel injected. Canister for tank vapors. Itwas necessary to return Car No. 3 before completion of the test. Avehicle of same make, model and year was obtained for completion of the work. This is Vehicle No. 21 in the report. 2. Current Emissions The following table summarizes the original evaporative emissions of the vehicles selected to bemodified:- 32

- Table XI Evaporative Emissions from Six Test Vehicles SHED Test Emission Source Car No.

1 2 3 11 15 17 21 Grams % % Air Total Diurnal Hot Soak Cleaner

6.7 50 50 N 7.5 5 95 y 17.1 45 55 y 10.7 5 95 y 10.6 0 100 y

7.5 60 40 y 13.9 40 60 3. IndividualVehicleModification for Improved EmissionControl Canister Carburetor y Slight Slight y y y N y N N N

The most promising hardware based on engineeringjudgment was installed on each test vehicle for the first modification. Additional modifications were thenmade as necessary to bring the SHED test level to 2.0 grams or less. The modifications were prototype innature and not a finished hardware. For example, a manually operated clamp on the carburetorvent line performed thejob of the carburetor vent valve. (Vent valveswere on the factory carburetor for Vehicle No. 1, 3, and 9.) Also, the underhood fan was activatedmanually. The primary goal of this workwas to demonstrate an ECS system modified to exhibit an emission level of 2.0 grams or less/SHED test. However, no attempt was made to test the longevity of the modifications. In addition, themodified systems were not optimized for best exhaust emissions and/or for driveability. Adescription of themodifications performed on each of the sixvehicles is outlined in Tables XII to XVIII. Table XII MOdification for Vehicle No. 1 - LTD Component Factory ECS (1) Carbon canister 3 tube Ford (lowpressure drop)
(2) Purge (3) Carburetor (4) Air cleaner Air cleaner Leak around choke shaft Leak sources at base of snorkel and other fittings (1) Sketchof cover inFigure8. Modification Replaced with 4 tube Vega canisterwith purge control valve. Bottomof canister capped. Changed to PCV purge. Cover fitted over leak source(l). Sealedwith silicone sealant.

### - 33

-
FIGURE NO.8 PROPOSED SEAL FOR CHOKE ROD PASSAGE THROUGH AIR HORN

Cover

- CliQS

..------ Over Walls to SealShaft

-----_Walls Cast Into Air Horn to Form Seal

ChokeRod- 34

-

Comments: APCV purgewas installed after flow tests had indicated that air cleaner only and an air cleaner-snorkel combination purge were inadequate. This is discussed inAppendix V. The 4 tubeVega canisterwas obtained from a 

### 1974 model vehicle in daily service. Photographs of these modifications are shown inFigures 9 and 10. Table 

### XIII Modifications for Vehicle No. 2 - Pontiac Component (1) Carbon canister
(2) Purge (3) Carburetor

(4) Air cleaner (5) Other

Comments: Factory ECS Delco 

### 2 tube

Carburetor Small leakaround accelerator pump shaft.

Small leaks Modification Replaced with 

### 3 tube Chrysler canister. Bottom of unit capped. No change. Boot installed around shaft. Carburetor bowl vented to the carbon canister. Leak sources sealed with silicone sealant. Underhood fan installed to ventilate underhood and lower carburetor bowl temperature during hot soak.

Underhood fan used to demonstrate the feasibility of decreasing hydrocnrbon vapor generation in the carburetor bowl by lowering bowl temperature. No modification of the carburetor purge is required in this installation. SeeFigures 

### 11 and 

### 12 for details of this installation and alsoAppendixV. After completion of tests with the above system, a Vega canister was installed and tests were conductedwithout use of the underhood ventilating fan. Results of the testswith this systemwere also less than 2 grams/test.**r:::GuR~:** 

### 9 COVER OVER CHOKE LINK.\GE TO PREVENT**HYDROCAE.BO~** 1&-\KAG::::: 0::.-r THE LTDFIGURE 11**FAJ.~** FOR Ul:\'DERHOOD VENTILATION A;ID CARSURLTOR NODIFICATION FOR THE PONTIAC

### F:GURE 12 CARBON**Cfu~ISTER** 

### (3 TUBE) FOR THE**PONTL~C**- 39

-
Table XIV Modifications for Vehicle No. 21

-**Chrysle~** Component Factory ECS (1) Carbon canister One 3 tube

(2) Purge (3) Carburetor
(4) Air cleaner

Comments: Carburetor Leak around accelerator shaft. Some small leaks Hodification Two 3 tube canisters in parallel were used. Bottoms of canisters capped. No change. Boot installed. Second carburt:!tur uowl veuteu directly to canister. Sealedwith silicone sealant. Barrier installed at base of snorkel.

The large volume fuel tank and the large carburetor bowl volume for this car generate too much hydrocarbon vapor for one standard size canister to handle. (Purge volume is already high.) Consequently, two canisters were utilized. In actual practice, itwould bemore feasible to use one canisterwith a larger bed. It was necessary to vent the second carburetor bowl directly to the canister because the balance tubes between the bowls and the air cleaner permitted an excessive amount of vapors to enter the air cleaner with a single vent. Details of this modification are shown in Figures 13 and 14 and Appendix V. Table XV Modifications for Car No. 11

- Hornet Component Factory ECS (1) Carbon canister 2 tube AMC
(2) Purge (3) Carburetor
(4) Air cleaner

(1) See Figure 15. Air cleaner snorkel Leak around accelerator pump shaft linkage. Several small leaks Modification Changed to a 4 tube Vega with a purge control valve. Bottom capped on canister. Modified to a PCV system. Cap installed over linkage.(I) Carburetor bowl vented to canister. Leaks sealed with sealant. Barrier installed at the base of the snorkel.**r:c~RE** 

### 15 CARBURETOR BOWI. VENTAND COVER FOR**ACCELE?~TOR PU}~**  

### LINKAGE FOR THE HORNET- 43 -

Comments: Purge flow tests indicated insufficient flow rate from the snorkel evenwith modifications to increase flow. The Vega canister used here was obtained from a 1974 Vega which had been driven daily. See details of this modification in Figures 15, 16, and 17 and Appendix

### V. Table XVI Modifications for Car No. 15

- Mazda Component (1) Carbon canister

(2) Purge (3) Carburetor
(4) Air cleaner (5) Other
Comments: Factory ECS Small carbon canister in top of air cleaner for diurnal cycle only.

Crankcase Bowls vent to air cleaner. Modifications No change in the diurnal ECS. Added a 

### 4 tube Vega canister for vapors from the carburetor bowl. Bottom of Vega canister capped. PCV line used for the purge for Vega canister. Each bowl individually vented to the Vega canister. No change. Afanwas installed to ventilate underhood during hot soak.
This vehicle utilizes a small carbon canister on the top of the air cleaner for storage of diurnal cycle vapors. No changewas made in this part of the original ECS. The (large volume) two bowl carburetor required separate vents withminimum resistance from each side to transfer vapors into the canister. Even then, anunderhood fanwas used to cool the carburetor bowl to retard the rate of hydrocarbon vapor release. Without the fan, hydrocarbon vapors from the balance tubes and for drippage in carburetor throat caused the SHED level to exceed the 2 gram level. For additional details, see Appendix V, and Figures 18, 19, 20, and 21.**F~GURE** 16 CARBURETOR**HODTFH~ATTON** AND !ARRmi r.MJTC:TFR FOR TRP HORN"f<T....-\

FIG1JRE 17 EARY
..IERAT THE BASE OF THE**S~~ORKEL** OF TE:: HORNET AIR**CLEA.i~E R** **-~** 00(1) (2) (3) (4) (5) - 50

-
Table XVII Modifications for Vehicle No. 17

- Volvo Component Carbon canister Purge Carburetor Air cleaner Fuel tank Factory ECS Small one tube carbon canister. Intake manifold None

- fuel injected. No leaks. Uses an equalizing valve regulating tank pressure to about 1.0 psi (6.9 kPa). Modification Changed to a 2 tube AHC canister. No change.
No change. Pressure of equalizing valve modified to 0.5 psi (3.5 kPa). Baffle installed between fuel tank and muffler. Comments: The factory canister was ineffective. (It did not change weight during the test period.) Consequently the AMC canister was utilized. The high fuel tank pressure resulting from the original equalizing valve pressure of 1.0 psig caused hydrocarbon vapors to escape through the gas cap and other fittings. The lower pressure for the modified equalizing valve corrected this hydrocarbon loss. For additional details, see Appendix Vand Figures 22 and 23.
C. Emissions fromModified Vehicles 1. Evaporative Emissions
a. Total Evaporative Emissions SHED test results for the sixmodified vehicles averaged 1.5 grams with a high of 1.9 and a low of 1.1 grams. These data are an average of two or more tests and include vehicle background. Individual car data are compared with unmodified results as follows:CARB00i c,'._\liSTER INSTA.LL\TI00i FOR VO:.VOHEr\.T SHII:LD "FOR VOLVO f1_:EL**TA~G** \J1 N

# •

Car No.

1 2 11 15 17 21 

### - 53

- Table XVIII Comparison of "Modified" Emissions and "As Received" Total Grams/SHED Test Make Year Modified As Received LTD 75 1.2 6.7 Pontiac 75 1.9 7.5 Hornet 74 1.2 10.8 Mazda 74 1.5 12.2 Volvo 74 1.1 7.7 Chrysler 75 1.9 14.0 b. Adjustment for Background Levels The SHED data above were adjusted for background levels using the background data from the initial SHED test work (TableV) with the exception of Car No. 15. Because of the exceptionally high initial background for this vehicle, itwas retested. Background adjustments are shown below:

Car No.

1 2 11 15 17 21 TableXIX Total Evaporative Losses Adjusted for.Background

Make LTD Pontiac Hornet Mazda Volvo Chrysler Before Background Adj., Grams 1.2 1.9 1.2 1.5 1.1 1.9 Background, Grams

0.1 0.5 0.2 0.1

c. Loss by Mode of Operation After Background Adj., Grams 1.2 1.9 1.1 1.0 0.9 1.8

The hot soak and diurnal losses for themodified vehicles are shown in the following table.- 54

- Table XX Diurnal and Hot Soak Data Car SHED2 Grams(!) No. Make Year Total Diurnal Hot Soak

1 LTD 75 1.2 0.2 1.0 2 Pontiac 75 1.9 1.2 0.7 11 Hornet 74 1.2 0.3 0.9 15 Mazda 74 1.5 0.6 0.9 17 Volvo 74 1.1 0.7 0.4 

### 21 Chrysler 75 1.9 0.6 1.3 (1) Not adjusted for background. 2. Exhaust Emissions Modifying the ECS caused some changes in the exhaust emissions of themodified vehicles. The greatest changewas in the CO levels. The CO level: (1) decreased for the threevehicles with catalystbeds, (2) increased for onevehicle, and (3) did not change for the remaining two vehicles. Only minor changes in the HC and NOx levels were noticed. A summary of the exhaust emissions data is shown below: TableXXI Exhaust Emissions

- Modified Vs. As Received Exhaust Emissions, Car ECS Grams/Mile(1) No. Make Year Modified 

### co HC NOx

1 LTD 75 Yes 4.44 0.52 1.87 No 6.75 0.54 1.62 2 Pontiac 75 Yes 4.05 0.68 1.36 No 6.95 0.80 1.31 21 Chrysler 75 Yes 13.3 1.10 1.83 No 23.2 2.32 1.98 11 Hornet 74 Yes 26.9 1.51 1.13 No 24.5 1.50 1.24 15 Mazda 74 Yes 9.90 1.82 0.65 No 11.7 2.11 0.88 17 Volvo 74 Yes 22.6 1.24 1.58 No 13.3 0.91 2.15 (1) Average of two or more tests.- 55

-
This programwas not of sufficient duration to identify the factors causing the above changes. The changes might be due to: Alteration in the Induction System For each car, the canisterwas changed as the vehicle was modified. This could change the purge rate and, in turn, may affect manifold vacuum. (There were no noticeable effects on driveability during the Federal Procedure.) In the case of Car No. 1, 11, and 15, major changes were made in the ECS. Increase in ECS HydrocarbonLevels The improved ECS in each case requires the engine to handle a greater amount of hydrocarbon from the storage systems. This might affect the A/F ratio and subsequently exhaust emissions. D. Conclusions from VehicleModificationWork The experience gained inmodifying ECS systems can be summarized as follows: 1. Larger carbon canisters (activated carbon) were required in many cases. 2. Induction systemcontainment of carburetor hot soak emissions does not appear to be an adequate control for carburetor emissions. 3. All air cleaner and carburetor leak sources must be eliminated. 4. Air cleaner and air cleaner snorkel purge systems are inadequate purge systems for a stricter control of evaporative emissions.· 5. Under very severe underhood temperature conditions, it may be necessary to minimize heat input to the carburetor by mechanical means such as by an underhood fan. E. Estimated Costs, Effectiveness, and Durability of Modifications We have estimated the costs for each of the modifications shown inTable IX. Cost data are outlined inTable XXII. The basis for the cost data has been estimated as manufacturer's cost times two. In the case of carburetor modifications, the indicated figures were obtained from Exxon's automotive consultantwho is highly knowledgeable in this field and has been associatedwith a major carburetor manufacturing company before retirement. The cost of the fan was obtained from an automotive manufacturer. In the case of carbon canisters, the cost informationwas obtained from a major manufacturer of these devices.

### TABLE XXII ESTIMATED COSTS, EFFECTIVENESS, AND DURABILITY OF**~10DIFICATIO~S**



### Modification A. Air Cleaner Overflow: Control No. 1

- Bowl vent to canister Control No. 2

- Ventilatewith fan Control No. 3 - Barrier at base of snorkel Control No. 

### 4 - Smaller bowl Control No. 5


### - Ventilatewith louvers B. Canister Overflow: Control No. 6 - 

### Increase carbonbed 50% Control No. 7 - Increase current purge Control No. 8


### - Close canisterbottom Control No. 

### 9 - Control 2 Control No. 10

- Control 3 Control No. 11

- Heat purge air Control No. 12

- Minimize heat input to fuel Control No. 13

- Minimize tankvapor space 

## c. Carburetor Leaks: Control No. 14

- Seal shafts with boot Control No. 15

- Use diaphragm accel. pump tank Estimated Costs(l) $


### o.so(l) 17.00(2)

0.20 o.2o(l) 

### 0.0

4.00(3) 

### o.60(1)(4) o.2oCl) 17.oo(2)

o.2oCl) o.soCl) 1.OO+(l) 15.0(5)

o.3oC1) 1.ooC1) Estimated Potential Effectiveness High High High High Low High High High High High Fair High Poor High High Anticipated Durability

Good Good Good Good Good

Good Good Good Good Good Good Good Poor

Good Good (1) Basis for estimated cost in case of carburetor and ECS modifications is two times the cost to manufacturer. (2) Vehicle retail price estimate from an automotivemanufacturer. Capacity- 100 CFM (47.2 dm3/s). (3) Cost increment based on cost information from a charcoal canister manufacturer. (4) In cases where an existing canister is replaced by the Vega canister, cost is $1.00. (5) Not a firm estimate. \..., C\- 57

-
The estimated costs for the actual modifications for each of the six vehicles are shown below. The costs vary from a low of $2.00 to a high of $25.20. The two vehicles with underhood fans, the Pontiac and Mazda, have cost figures substantially above the other vehicles. Following these tests, the Pontiac was equippedwith a Vega canister to replace the fan. Use of this canister also resulted in emissions less than 2 grams/test. The cost figures shown in Table XXII were used in estimating the modification price for each vehicle. Details for the modification costs for eachvehicle are given inAppendixVI. Table XXIII Estimated Costs of Modifications Car No.

1 2 11 15 17 21 Make LTD Pontiac Hornet Mazda Volvo Chrysler Modification Year Costs, $

75 2.00 75 18.30 or 2.30(l) 74 2.50 74 25.20 74 2.00 75 5.7o(2) (1) $18.30 uses an underhood fan. $2.30 system uses a Vega canisterwhich eliminates the fan. (2) Assumes one canister of larger than current capacity would be used in lieu of two units as per this work. The potential effectiveness and durability of each of the modifications is shown in Table XXII. In our opinion, most modifications are expected to be effectivewith a good durability rating. The basis for the ratings include personaljudgment and field experiencewithmodifications of similar nature. 

### No longevity runs were performed as part of this program. VI. EMISSION LEVELS OF MODIFIED VEHICLES UNDER SEVERE TEST CONDITIONS The performance of two of themodified vehicles has been evaluated under the severe test conditions of (1) use of a fuel of higher RVP than Indolene, and (2) raising the maximum temperature of the diurnal cycle. For this work, Vehicles 

### No. 1 and 2were selected. Vehicle

### No. 2was equippedwith the underhood fan for these tests. Test conditions were standard SHED with the exception of the higher volatility fuel in one case and the higher temperature range for the diurnal in the second case. For the high volatility fuel, butanewas added to Indolene to raise its RVP from 62.1 to 71.7 kPa (9.0 to 10.4 psi). Inspections for this fuel are given inAppendix II. Standard Indolene was used for the high temperature diurnal cycle runs. For these, the diurnal range was 15.6 to 35°C (60 to 95°F) in lieu of the standard SHED range of 15.6 to 28.9°C (60 to 84°F).- 58

-

The results from this work indicate that Vehicle No. 2, the Pontiac, had more reserve storage capacity aftermodification than the LTD, Vehicle No. 1. The 1.4 psi (9.65 kPa) increase inRVP**incrP~R~~** SHED emissions 1.0 gram for the Pontiac and 4.5 grams for the LTD. Extending the diurnal cycle increased SHED losses 2.1 grams for the Pontiac and 3.2 grams for the LTD. Data are summarized below and presented in detail inAppendix VII and in Table XXIV.

Car No.

1 2 Table XXIV Higher Losses Under Severe Test Conditions

Make LTD Pontiac Increase Loss, Grams/SHED Test High High Temp. RVP Diurnal 4.5 1.0 3.2 2.1 The more severe test conditions described above did not significantly affect exhaust emissions with these two vehicles, both of which have catalytic reactors to control tailpipe emissions. Exhaust emissions data are included inAppendices No. VII"and VIII. VII. HALOGENATED HYDROCARBONS IN EVAPORATIVE EMISSIONS Abrief analytical study has been carried out to measure the level of halogenated hydrocarbons in the evaporative emissions from leaded fuels. Two halogenated hydrocarbons, ethylene dichloride and ethylene dibromide,are part of the lead scavenger package of most leaded gasolines. The concentration of these scavengers is about 0.1wt. %of a fuel containing about 3.0ml/TEL per gallon. The ethylene dichloride is present at twice the concentration level of the ethylene dibromide. An exploratory analytical procedure was developed to measure the scavenger level in the evaporative emissions of a vehicle. For this, a gas chromatograph equippedwith a sensitivemicrocoulometer detector was used. The source of the evaporative emissionwas a full size car hot soaking in a SHED for one hour. The fuel was a full boiling range gasoline containing about 3.0ml/TEL gallon as Motor Mix. The hydrocarbon level in the SHED was 300 ppm Cafter the hot soak. The concentration of ethylene dichloride in the SHED was 0.128**~g/1.** This is about 0.1% of the hydrocarbonvalue in the SHED. We detected but did not quantify the ethylene dibromide. The boiling point for the ethylene dibromide ismuch higher than the ethylene dichloride- 131.7°C vs. 83.7°C. Because of the low level of scavengers in evaporative emissions, itwas decided not to conduct additionalwork in this area at this time.

### APPENDIX NO. I-1 SURVEY OF CARS AI'l"D LIGHT TRUCKS FOR EVAPORATIVE**CO~i':::RO:L** 

### SYSTEhS F = 

### Full Size I = 

### Intermediate 

## c

## =Compact Canister Purge Fuel**Ian~** 

### \'apor Displ. 1.1

### of 2 3 

### 4 Purge Line To:**~ear** 

### Return Make Yr. :1odel Litres Bbls. Tube Tube Tube Valve? PCV Carb Air Cl. Litres Exh. line? Line?**~** 

## -- -- Ford 73 I 5.75 4 

### I I 85.2 

### ,-**~** 

### III 

## ... 73 F 

### 6.56 2 

### I I 85.2 N y 

### III 73 F 

### 7.03 4 

### I I 85.2 N y 

### III 74 I 5.75 2 

### I I 83.3 y K 

### III 74 F 6.56 2 

### I I 83.3 N N 

### III 75 I 5.75 2 

### I I 90.8 N N 

### VI 75 F 

### 6.56 2 

### / 

### / 90.8 N N 

### VI 75 I 4.95 2 

## ..; I 85.2 N N 

### III V1**~** 

### 74 

## c 3.33 1 

### I I 49.2 N N 

### I 73 

## c 1.

### 60 1 

### I I 41.6 N N 

### III 74 

## c 2.29 2 

## ..; I 49.2 N N 

### III 75 I 4.10 1 

### I 

### ..; 90.8 N N 

### III Mercury 73 F 7.03 4 

### I I 83.3 N y 

### III 74 F 7.54 4 

## ..; I 83.3 N y 

### III 74 I 5.75 2 

### I 

## ..; 100.3 N N 

### III 75 I 5.75 2 

### I I 100.3 N N 

### III 75 

## c 3.33 2 

### I I 49.2 N N 

### I 73 I 4.95 2 

### I 

### ..; 85.2 N N 

### III Lincoln 75 F 7.54 4 

### / I 100.3 N y 

### VI

### APPENDIX NO. I-2 SURVEY OF CARS AND LIGHT TRUCKS FOR EVAPORATIVE**CO~TROL** 

### SYSTEHS F

## =Full Size I 

## =Intermediate 

## c• Compact Canister Purge Fuel Tank \"apor Displ # 

### of 2 3 

### 4 Purge Line To: Near Return Make Yr. Hodel Litres Bbls. Tube Tube Tube Valve? PCV Carb Air Cl. Litres Exh. Line? Line?**~** 

### Plymouth 73 I 3.69 1 

### I I 60.6**~** :\ 

### IV or 75 I 3.69 1 

### I I 60.6 N 

## -- IV Dodge _, 

### 75 I 3.69 1 

### I I 60.6 N X 

### I 74 F 5.21 2 

### I I 60.6 N**~** 

### I 74 F 5.90 4 

### I I 79.5 N ,,. 

### I ·' 

### 73 F 6.56 2 

### I I 79.5 N**~** 

### IV 73 F 6.56 4 

### I I 79.5 N K 

### IV 75 F 7.21 4 

### I I 79.5 N K I 0\ 

### Chrysler 74 F 6.56 4 

### I I 73.5 N K 

### IV 0 I 

### 75 F 7.21 4 

### .; I 98.0 N N 

### I 74 F 7.21 4 

### I I 98.0 N N 

### IV 73 F 7.21 4 

### I I 98.0 N N 

### IV
AHC 

### 73 

## c 3.80 1 

### I 

### .; .; 39.7 N**:~** II 

### 75 I 

### 4.23 1 

### .; .; 60.6 N N 

### VI 75 I 4.98 2 

### .; I 94.6 N N 

### III 74 I 5.90 4 

### .; I 92.7 N N 

### III 74 I 4.98 2 

### .; .; 64.3 N N 

### III

### APPENDIX NO. I-3 SL'RVEY OF CARS AJ.'m 

### LIGHT TRUCKS FOR EVAPORATIVE CONTROL SYSTENS F

## =Full Size I Intermediate 

## c=Compact Canister**Pur~e** 

### Fuel Tank**r~--~** C.:-'-- 

### Displ. fl 

### of 2 3 4 Purge Line To:**~ear** Ret·..:r:-_ 

### Hake Yr. Hodel Litres Bbls. Tube Tube Tube Valve? PCV Carb Air Cl. Litres Exh. Line? ' 

### . . L:..:-.e. 

### -:zype Chevrolet 75 

## c 4.10 1 

### I y 

### I 79.5 y**~** II 

### 74 I 

### 4.10 1 

### I y 

### I 79.5 y ,. II ·' 

### 73 I 4.10 1 

### I y 

### I 83.3 :-; ,. II 

### ·' 75 F 5.74 2 

### I N 

### I 83.3 N 

### :\ I 

### 75 F 5.74 4 

### I N 

### I 83.3 N y I 

### 74 F 

### 6.56 4 

### I N 

### I 98.4 N y 

### I 73 F 5.74 4 

### I N 

### I 98.4 N :-; 

### n· 73 F 6.56 2 

### I y 

### I 98.4 N y II 

### 74 F 5.74 2 

### I N 

### I 83.3 N**~** 

### I 0"' !-' 

### Vega 75 

## c 2.29 2 

### I y 

### I 60.6 y y 

### IV 73 

## c 2.29 1 y 

### I 41.6 y y II 

### Monza 75 

## c 2.29 2 

### I N 

### I 70.0 y N 

### I 75 

## c 2.29 2 

### I N 

### I 70.0 y N I 

### Pontiac 74 F 4.10 1 

### I N 

### I 95 N N 

### I 73 I 

### 5.74 2 

### I N 

### I 95 N i\ I 

### 73 F 6.56 2 

### I N 

### I 95 y y I 

### 73 F 

### 6.56 4 

### I N 

### I 95 N y I 

### 75 F 6.56 4 

### I I 95 N y 

### I 75 F 6.56 4 

### I I 95 N y I 

### 75 F 6.56 2 

### I I 95 N y 

### IV

### APPENDIX NO. I-4 SURVEY OF CARS**&~D** 

### LIGHT TRUCKS FOR EVAPORATIVE CONTROL SYSTID1S F

## =Full Size I

## =Intermediate 

## c

## =Compact Purge Fuel Tank Vapor Displ. if 

### of 2 3 4 Purge Line To: Near Return r-1ake Yr. Model Litres Bbls. Tube Tube Tube Valve? PCV Carb Air Cl. 

### Litres Exh. Line? Line?**~** 

### Cadillac 73 F 7.74 4 

### .; .; 102 K**~~** 

### I 75 F 8.20 4 

### / I 

### 104 N y 

### Ir y 

### Olds 73 I 

### 5.71 4 

### .; .; 83.3 N 

### N I 73 F 7.46 4 

### .; I 79.5 N y 

### I 74 I 4.10 1 

### .; I I 79.5 y N II 

### 75 I 5.74 4 

### .; I 83.3 N 

### N IV 75 F 7.46 4 

### .; .; 98.4 N y 

### IV 0\ N 

### Buick 74 F 

### 5.74 2 

### .; I 83.3 N y III 

### 75 I 4.29 2 

### I I 91.0 N y I 

### 75 I 

### 5.74 4 

### .; I 98.4 N y I 

### 73 F 7.46 4 

### .; I 98.4 N y 

### I 73 I 

### 5.74 2 

### .; I 83.3 N y I 

### 73 F 

### 5.74 4 

### .; .; 98.4 N y III 

### 75 F 

### 5.74 4 

### I 

### I 98.4 N y II 

### 75 I 3.80 1 

### .; .; 98.4 N N IAPPENDIX NO. I-5 S'L'RVEY OF CARS
. .'VJ)LIGHT TRL"CKS FOR EVAPORATIVE**ENISSIO~** CONTROLS
Purge Fuel Tank Var::- Displ. 1; of 

### 2 3 

### 4 Purge Line To: Near Retu:-::.**~ke** Yr. Model Litres Bbls. Tube Tube Tube Valve? PCV Garb Air Cl. Litres Exh. Line? Line:**~** 

### \w 73 Bug 

### 1.5 1 

### I ' 

### 40.1 y N :\ 

### 75 Bug 

### 1.6 1 

### I I 40.1**~ ~**  

### 75 Rab. 

### 1.5 1 I 

### / N 

### ,. y 

### ·' Fiat 

### 75 1800 1.8 1 / 

### I**~** y 

### 75 1300 1.3 1 

### I I N y**~** ... Opel 

### 74 Hanta 

### 1.9 1 

### I I 45 y K 

## : Hitsubishi 

### 75 Colt 

### 2.0 2 

### I I N y ::II Peugeot 

### 73 504 1.97 2 

### I I N N I Volvo 

### 74 I 

### 1.98 F.I. 

### I I 59.8 N K I C\ (.,..) Datsun 

### 74 210 2.1 2 Crankcase Storage 

### I 43.9 N N \.III British Leyland 

### 75 MG 

### 1.8 2 

### I I 53 N N II Toyota 

### 74 2.6 2 

### I I 45 y N II 

### 75 2.6 2 

### / I 45 y N II Audi 

### 74 1.5 2 

### I I 45 III 

### 75 1.5 2 

### I I 45 III BMW 

### 74 2.0 2 

### I I 72 I Honda 

### 75 1.5 2 

### I I 41.7 N N 

### I Nazda Acondenser tank in trunk collects and condenses tankvapors. Excess vapor from condenser tank goes to PCV valve then to atmosphere. Carburetor vapors stored in induction system. >lercedes-:Oenz Acompensating tank and a combinationvalve**~v~tPm ~ondense**  vanors and store**ex~ess** in the

### APPENDIX NO. I-6 SURVEY OF CARS fu."ffi 

### LIGHT TRUCKS FOR EVAPORATIVE ENISSIOK CONTROLS Purge Fuel Tank Vapor Displ. II 

### of 2 3 

### 4 Purge Line To: Near Return Make Yr. Model Litres Bbls. Tube Tube Tube Valve? PCV Garb Air Cl. Litres Exh. Line? Line?**~** 

### Ford 75 F250 4.92 1 

### I I 72.5 N 

### N III 74 FlOO 3.93 1 

### I I 72.5 N N III
International 73 Travall 5.65 

### I I 79.5 N N 

## v 0\ 

### 74 Travall 6.56 

### I I 79.5 N N 

## v .J::'- 

### Dodge 75 Van 

### I 87.1 

### N N 

## v

Chevrolet, Dodge, Plymouth and Ford light trucks same as cars.

### Inspections Reid Vapor Pressure Distillation(Z), Temp. for ind. D

### + L: IllP 5 

### 10 15 20 30 40 50 90 FBP - 65

-

APPENDIX II VOLATILITY INSPECTIONS FOR TEST FUELS

Indolene Unmodified Cars 62.1 kPa (9.0 psi)

36.1°C (9rF) 48.9°C (120°F) 55.6°C (132°F) 62.8°C (145°F) 69.4°C (lsrF) 82.2°C (180°F) 93.9°C (201°F) 105.0°C (221°F) 158.9°C (318°F) 211.7°C (413°F) Modified Cars 62.1kPa (9.0 psi)

33.3°C (92°F) 46.7°C (ll6°F) 54.4°C (130°F) 62.8°C (145°F) 70.6°C (159°F) 86.1°C (187°F) 97.8°C (208°F) 105.6°C (222°F) 161.7°C (323°F) 206.l°C (403°F) High RVP(l) Fuel 71.7 kPa (10.4 psi)

31.1°C (88°F) 43.3°C (ll0°F) 52.2°C (126°F) 61.1°C (142°

# .n 70.0°C (158°I') 86.1°C (lsr:n 97.8°C (208°F) 105.6°C (222°F) 161.7°C (323°F) 206.l°C (403°F)

(1) This fuel prepared for thewok presented in part VI of this report. (2) ASTM Designation D-86.- 66

-


### APPENDIX III PROCEDURE FOR QUANTIFYING EVAPORATIVE LOSSES
The procedure for quantifying losses involves collecting the vapors and adsorbing them on activated carbon. This is carried out in such a manner as to minimize the disturbance of the flow of hydrocarbon from the leak source. Vapors are drawn into the collector at a carefully controlled flow rate. They pass through a dryer and then into the carbonbed. Non-adsorbed sample is returned to the shed. Provision is made to check the sample leaving the carbonbed for the presence of non-adsorbed vapors. Asketch of the equipment is shown inFigure I. The flow rate in the collector is critical. Too high a rate will lead to excessive losses from the leak source. Too low a rate will allowvapors to escape into the shed. The range of operable rates is 2.5 to 25 cfh. (71 to 710 L/h). The low rate is effective for 1.0 g/hr or less and thehigher rate for 10+ g/hr. The collector flow rate ismatched to the source loss rate. If the F.I.D. trace for a hot soak shows a high loss rate for the first fifteenminutes of a run followed by a low loss rate the remainder of the soak, the collector flow rate is sethigh for 15 minutes and then lowered. Formost vehicles, the collection equipment canbe installed prior to the run so as to minimize the length of time the hood is open during a run. Small leaks in the air cleaner are sealedbefore the test. The carbonfor the collector is activated, non-polar carbon of 10-20mesh. It is dried prior to use. Volume of carbon is varied with the amount of vapor to be collected.

### · Vehicle Canister (Open Bottom)

From Vapor

Collector - 67

- 

### APPENDIX Ill FIGURE I EQUIPMENT FOR QUANTIFYING EVAPORATIVE 

### LEAKS

Flexible

Tubing

Rotameter Pump Equipment

Controls SHED Carbon

Drierite

Dryer Flow to tRotameter

F.LD.

### Test SHED 1) SHED 

### 112 2.66 2) Quantifying Ill 0.12 3) Quantifying 

### 112 0.08 4) Quantifying 

### 113 0.18 5) SHED 113 

### 4.21 APPENDIX IV
TABLE I SUMMARY OF EVAPORATIVE EMISSION DATA Make: Ford LTD Year: 75 No.: 1 Displ. cu. in./Litre: 351/5.75 No. Cyl.: 8 

### No. Venturis: 2 Diurnal, Grams Hot Soak, Grams A.C. Loss From Canister Other

3.06 1.27(2) 4.01 SHED 3.56 0.48 0.48 1.50 2.90 Loss From A.C. Canister

0.0 2.94 0.0 0.92(2) 0.82 3.42 Other Total Grams Background Grams Cold Hot Remarks 6.22 0.74(1)1.39(l) 6.60 2.75(2) 9.93(3) 7.11 

### (1) High background due to fuel contaminationon floor carpet. Afuel canhad beenplaced on the floor of the vehicle as an auxiliary fuel tank after SHED Test 113. 

### Spillage from this can occurred some time prior to thebackground testwhichwas run after the SHED testing. (2) Heated air tube fron exhaust manifold inadvertently closed off at air cleaner snorkel during this run. Postulated that the increase inpressure drop in.the air**~leaner** 

### purged the canister to a greater extent than for a normal run. (3) Flow rates to collectorhydrocarbonbeds too high for this run. This tends to pullvapors from air cleaner and canister.

### Test SHED (1) SHED 

### 111 0.41 (2) SHED 1!2 

### 0.37 (3) Quantifying #1 0.46 (4) Quantifying 112 

### 0.41 (5) Quantifying 113 

### 0.20 APPENDIX IV
TABLE II
SUMMARY OF EVAPORATIVE EMISSION DATA Make: Year: No.: Pontiac 75 2 

### Displ. cu. in./Litre: 400/6.56
Diurnal, Grams Hot Soak, Grams Loss From Loss From A.C. Canister Other SHED A.C. Canister 6.83 7.40 0.20 1.

### 77(2) 3.62 (3) 

### 0.45 1.95(2) 4.60 0.23 0.22 0.19 1.61(2) 4.80 0.35 Background Total Grams Other Grams Cold Hot Remarks 7.24 0.50(l) 0.84(l) 7.77 :::-- 

### 1.77(2) -.c 

### 6.05 1.95(2) 7.64 1.61(2) 7.37

(1) Results from the background tests very high. Afuel canhadbeenused in the vehicle after the SHED testing. Spillage from this can contributed to highbackground test whichwas run after the SHED testing. (2) Carburetor leakaround accelerator pump shaft. Vapors escaped to the SHED because the leak is unaccessible from a quantifying standpoint. (3) Collector for hydrocarbon inadvertently omitted.

### Test SHED (1) Quantifying fll 

### 0.08 (2) Quantifying f/2 

### 0.32 (3) Quantifying f/3 

### 0.17 (4) SHED f/2 

### 7.30 (5) SHED f/3 

### 8.63 APPENDIX IV
TABLE III
SUMMARY OF EVAPORATIVE EMISSION DATA Make: Chrysler NYer Year: 75 No.: 3 

### Displ.-cu. in./Litre: 440/7.21 No. Cyl.: 8 No. Venturis: 4 Diurnal, Grams Hot Soak, Grams Loss From Loss From A.C. Canister Other SHED A.C. Canister 

## o.o 6.46 2.10(l)

## o.o<2) 

## o.o<2) 0.0 3.50 1.34(l) 0.32(2) 

## o.o<2) 0.0 3.88 2.01(l)

## ·o.o<2

### > 0.0(2) 10.63

7.76 Back&round Total Grams Other Grams Cold Hot Remarks 2.10(l) 8.64(2) 0.03 0.13 1.34(l) 5.48(2) 2.0l(l) 6.06(2) 17.93 16.39
(1) Carburetor leak

- vapors escape from around carburetor accelerator pump shaft as it passes through the airhorn. Vapors escape to the shed because the leak is unaccessible from a quantifying standpoint. (2) Carburetor bowl maximum temperature during the hot soak is 15 to 20°F (-9.4 to -6.7°C) lower for quantifying**r~ns** 

### than regular SHED tests. This is becausehood must be raised to attach hydrocarbon collection equipmentwhen quantifying; consequently, less hydrocarbon is lost from the carburetor bowl. -...! 0

### Test SHED (1) SHED 

### ill 2.31 (2) SHED 112 1.50 (3) 

### Quantifying Ill 

### 0.16 (4) Quantifying 112 

### 0.33 (5) 

### SHED 113 

### 1.82 APPENDIX IV
TABLE IV**SL~Y** 

### OF EVAPORATIVE EMISSION DATA Make: Year: No.: Pinto 74 

### 4 Displ. cu. in./Litre: No. Cyl.: 4 

### No. Venturis: 2 

### 122/2.0
Diurnal, Grams Hot Soak, Grams Loss From Loss From A.C. Canister Other SHED A.C. Canister Other 4.62 3.95 

## o.o 0.50 0.34 

## o.o<1) 

## o.o 0.0 0.32 

## o.o<1

### > 4.39 Background Total Grams Grams Cold Hot

6.93 5.45 1.0 (1) 

### 0.65(1) 

### 6.21 0.0 0.16 Remarks

(1) Carburetor bowl maximum temperatures are 8 to 12°F (-13.3 to -11.1°C) lower for quantifying runs than for**~HLV** 

### tests. This is due to heat loss from engine compartment when hood is raised to attach collection equipment for quantifying runs.



# ...

### Test SHED (1) SHED Ill 

### 0.39 (2) SHED 112 

### 0.58 (3) Quantifying 

### Ill 0.15
New Carburetor Installed (4) SHED #3 0.28 (5) Quantifying 

### 112 0.25 (6) Quantifying {13 

### 0.28 (7) 

### SHED #4 0.25 APPENDIX IV
TABLE V SUMMARY OF EVAPORATIVE EMISSION DATA Make: Nova Year: 

## ---:r4 No.: 5 

### Displ.**~in./Litre:** 

### 250/4.1 No. Cyl.: 6 No. Venturis: 1 Diurnal, Grams Hot Soak, Grams Loss From Loss From 

### A.C. Canister Other SHED A.C. Canister 15.10 11.40 0.43 0.32 6.95(2) 0.71 0.13

10.04 0.56 5.96(2) 

### 1.11 o.o 2.20 5.6oC2) 5.81(4) 1.

### 82 1.1.

### 35 (1) Carburetor to intakemanifoldbolts tightened after this run. 

### •

Backgrouad Total Grams Other Grams Cold Hot Remarks 15.49 o.o 0.11 (1) 11.98 6.95(2) ....... 

### 8.67(3) (2) N



### 10.32 5.96(

### 2) 7.88(4) (2) 

### 5.6oC2) 15.71(4) 11.60

(2) Carburetor leaks

- the carburetor bowl is vented to the atmosphereupon slight pressure increase in the bowl. Other leaks occurred around the accelerator pump shaft. Unable to quantify carburetor leaks consequently, vapors enter shed. (3) Hot soaklosses lower on quantifying runs 1 and 2 than SHED tests because of lower maximum carburetor bowl temperatures. Raising the hood to attach thevapor collection equipment lowered bowl temperature zooF (-6.7oC). (4) For this run, vapors from the externalventwere collected along with vapors from air cleaner snorkel. The collecting systempulled HC from thebowl due to too high a flow rate.

### Test SHED (1) SHED til 

### 0.28 (2) 

### SHED 1!2 

### 0.82 (3) 

### Quantifying Ill 

### 0.11 (4) 

### Quantifying 112 

### 0.21 (5) 

### SHED 1!3 

### 0.41 APPENDIX IV

TABLE VI SUMMARY OF EVAPORATIVE EMISSION DATA Make: Chevrolet Impala Year: 74 No.: --6- Displ.**~in./Litre:** 

### 350/5.74**~o.** 

### Cyl.: 8**~o.** 

### Venturis: 2 

### Diurnal, Grams Hot Soak, Grams A.

## c. Loss From Canister Other



### 2.97(2) 2.80(2) SHED 4.69 4.09 0.56 0.52 5.56 

### A.C.

7.36(2) 7.70(2)Loss From Canister Other

1.71(2) 1.

### 61(2) Total Grams 4.97 4.91 12.71(2) 

### 12.84(

### 2)



### 5.97 Background Grams Cold Hot

(1) (1) 

### Remarks

(1) Background tests for this carwere extremely highbecause of fuel spillage on carpet floor. Afuel canhad been used as an auxiliary fuel tank after SHED Test #3. Background tests (3+ grams hot and cold) were run after SHED testing. (2) Collection systempulledvapors from the canister and air cleaner snorkel during the quantifying runs due to too high a flow rate.

### Test SHED (1) 

### SHED 

### Ill 0.50 (2) SHED 1/2 

### 0.44 APPENDIX IV TABLE VII SUMMARY OF EVAPORATIVE EMISSION DATA Make: Plymouth Duster Year: 74 No.: 7 Displ. cu. in./Litre: 225/3.69 No. Cyl.: 6 No. Venturis: 1 Diurnal, Grams Hot Soak, Grams Loss From Loss From A.C. Canister Other SHED A.C. Canister 0.73
1.

### 32 Back&round Total Grams Other Grams Cold Hot Rer.arks 1.

### 23 0.66(l) 0.73(l)
1.

### 76

(1) Background results are abnormally highbecause of gasoline spillageon carpet floor of vehicle from a fuel**ca~** 

### after completion of SHED tests and before running thebackground tests. '-I J:-.

### Test SHED (1) 

### SHED Ill 

### 0.90 (2) Quantifying fll 

### 0.20 (3) 

### Quantifying f/2 0.33 (4) Quantifying 113 

### 0.21 (5) SHED f/2 0.57 APPENDIX IV TABLE VIII SUMMARY OF EVAPORATIVE EMISSION DATA Make: BuickLeSabre Year: 75 No.: 8 Displ. cu. in./Litre: 350/5.74
Diurnal, Grams Hot Soak2 

### Grams Loss From Loss From A.C. Canister Other SHED A.C. Canister 5.16 1.88(l) 1.4o<2>6.52(l) 2.13(l) 1.68(l) 2.58(2)3.39 0.49 1.56(2)4.57 0.0 7.34 Total Other Grams 6.06 1.40(2) 12.13(l) 2.58(2) 8.47(l) 1.56(2) 6.02 7.98
(1) Hydrocarbon collecting equipment rate too high. Some HC drawn from canister and air cleaner. Background Grams Cold Hot Remarks 0.06 0.29

(2) Carburetor leak

- carburetor accelerator pump shaft and collar on airhorna very loose fit. No feasibleway to trap this leak. '-.1 U1

### APPENDIX IV TABLE IX SUMMARY OF EVAPORATIVE EMISSION DATA**Make~** 

### Vega Year: 

### 75**No.~** 

### 9 Displ.**cu.-in./Litre~** 

### 140/2.29
Diurnal, Grams Hot Soak, Grams Background Loss From Loss From Total Grams Test SHED A.C. Canister Other SHED A.C. Canister Other Grams Cold Hot Remarks 

### (1) SHED til 

### 0.33 3.49 3.82 

## o.o 0.57 (2) Quantifying fl1 

### 0.23 0.45 7.17(l) 7:8S.1,2) 

### (3) Quantifying

### #2 0.18 0.50 0.25(2) 0.93(2) (4) Quantifying 113 

### 0.30 0.35 0.16(2) 0.81(2) (5) SHED ff2 

### 0.21 5.46 5.67

(1) Vapor collectionrate too high in this case. 

### (2)**~arburetor** 

### bowl temperatures are 15 to 

### 20°F (-9.4 to 

### -6.7°C) lower for quantifying runs than for SHED tests. Hood was partially open to accommodate vapor collection equipment. 'J c-

### Test SHED (1) 

### SHED Ill 0.49 (2) 

### Quantifying 

### Ill 0.41 (3) Quantifying 112 0.25 (4) SHED 112 0.43 APPENDIX IV TABLE X 

### SUMMARY OF EVAPORATIVE EMISSION DATA Make: Year: No.: Displ. Olds "98" 73 li) 

### cu. in./Litre: 455/7.46
Diurnal, Grams Hot Soak2 

### Grams Loss From Loss From A.C. Canister Other SHED A.C. Canister 9.11 1.69(l) 6.92 0.0 1.67(l) 6.78 0.0 9.98 Backsround Total Grams Other Grams Cold Hot Remarks 9.60 0.15 0.31 1.69(l) 9.02 1.67(l) 8.70 10.41

(1) Carburetor leakaround acceleratorpump shaft. Vapors**esca~ed** 

### to the shedbecause the leakis unaccessible from a quantifying standpoint. -...,J -...,J

### Test SHED (1) SHED IF1 

### 0.20 Carburetor-- to air cleaner (2) SHED 1!2 

### 0.73 (3) 

### Quantifying f!l 

### 0.13 (4) Quantifying 112 

### 0.12 (5) Quantifying 1!3 

### 0.18 (6) 

### SHED 1!3 

### 0.22 APPENDIX IV TABLE XI SUMMARY OF EVAPORATIVE EMISSION DATA Make: Hornet Year: 74 No.: 11 Displ.**~in./Litre:** 

### 232/3.80
Diurnal, Grams Hot Soak, Grams Loss From Loss From A.C. Canister Other SHED A.C. Canister 12.33 gasket replaced. Original one cracked and leaking. 10.11

6.73(1)19.10(2) 6.52(1) 4.57 6.95(1) 4.23 10.54 Background Total Grams Other Grams Cold Hot Remarks 12.53 0.0 0.11

10.84 6.73(l) 25.96(2) 6.52(1) 11.21 6.95(1) 11.36 10.76
(1) Carburetor leakaround acceleratorpump shaft. Vapors escaped to shed as leak is unaccessible from a quantifying standpoint. (2) Flow of hydrocarbonvapors to collector too high. -....J 00

### Test SHED (1) SHED 

### Ill 4.61 (2) Quantifying Ill 

### 1.31 (3) Quantifying 112 

### 0.86 (4) SHED 112 

### 3.50 APPENDIX IV TABLE XII**Su~Y** 

### OF EVAPORATIVE EMISSION DATA Make: Plymouth Fury III Year: 73 No.: 12 Displ.**~in./Litre:** 

### 360/5.90
Diurnal, Grams Hot Soak, Grams Loss From Loss From A.C. Canister Other SHED A.C. Canister 2.79 2.70 2.oo(l) o.o 2.41 1.45(2) 1.

### 70(l) 0.0 1.

### 65(2) 2.26 Background Total Grams Other Grams Cold Hot 7.40 0.07 0.66 2.00(1) 8.42 1.7o(l) 5.63(2) 5.76(3)
(1) Carburetor leakaround accelerator pump shaft. This loss inaccessible from a quantifying standpoint. Remarks

(2) Run No. 3, QuantifyingRun 112 

### is 3.0 grams lower than QuantifyingRun No. 1 because the charcoal canister adsorbed 3.0 grams more for the second run. The hydrocarbon level in the canister decreased fromRun Ill to Run 112. 

### (3) The total loss for SHED Test 2 is less thanfor SHED Test 1 because theworking capacity of the canisterhas increased during this series of tests. This is indicatedby lower canisterweights for SHED Test 2 than 1. ....... 

# ""

### APPENDIX IV TABLE XIII**S~UffiY** 

### OF EVAPORATIVE EMISSION DATA Make: Dart Year: 74 No.: 

# --u Displ. cu. in./Litre: 318/5.21
Diurnal, Grams Hot Soak, Grams Background Loss From Loss From Total Grams Test SHED A.C. Canister Other SHED A.C. Canister Other Grams Cold Hot Remarks (1) SHED Ill 

### 0.16 2.85 3.01 0.0 0.11 1.33(1) 1.33(l) co 

### (2) Quantifying 

### ill 0.13 1.82 3.28 0 I (3) 

### Quantifying 112 

### 0.29 1.30(l) 1.57 1.

### 3Q(1) 3.16 

### (4) SHED 112 

### 0.18 2.57 2.75

(1) Carburetor leak

- hydrocarbon leakaround accelerator pump shaft.

### Test SHED (1) SHED #1 1.25 (2) Quantifying Ill 

### 0.53 (3) Quantifying 112 

### 0.79 (4) SHED 112 

### 0.90 APPENDIX IV TABLE XIV SUMMARY OF EVAPORATIVE EMISSION DATA Make: Datsun Year: 74 No.:**~**



### Diurnal2 

### Grams Hot Soak, Grams Loss From Loss From A.C. Canister Other SHED A.C. Canister 2.19 

# o.o 1.57 0.0 0.58 1.21 0.0 1.80 Backsround Total Grams Other Grams Cold Hot Remarks 3.44 0.11 0.20 2.10 co f-' 

### 2.58 2.70

### Test SHED APPENDIX IV TABLE XV**Sl~~fARY** 

### OF EVAPORATIVE EMISSION DATA Hake: Hazda Year: 74**~0.:** 

### 15 Displ.**~**

### in./Litre: Rotary
Diurnal, Gra:ns Hot Soak, Grams Loss From Loss From A.C. Canister Other SHED A.C. Canister Background Total Grams Other Grams Cold Hot**Rer::ar~s** 

### (1) SHED fi

### 1 0.54 11.56 12.10 0.46(!) 1.10(1) (?'

_) 

### Quantifying

# n 1.36 1.,36(2) 7.79(3) 1.36(Z) 10.51(3) (3) 

### Quantifying fl2 

### 0.51 1.13

### < 2

### >7.60(3) 1.13(2) 9.24(3) (4) SHED :f2 

### 0.86 11.44 12.30
(1) Evidenceof gasoline spillage inthe trunkprior to this work. Thiswould account for highbackground. (2) Carburetor leaks. (3) Carburetor bowl temperatures 12-15°F (-11.1 to -9.4°C) lower for quantifying runs than SHED tests because hood**~as** 

### partially open during the hot soak to accommodate the collectionequipment. co N

### Test (1) SHED If

### 1 (2) 

### Quantifying tfl (3) Quantifying 

### i/2 (4) SHED 112 (5) SHED 

### 1!3 APPENDIX IV TABLE XVI**SL~UffiY** 

### OF EVAPORATIVE EMISSION DATA Hake; Comet Year; 74 No.; 

### 16 Displ.**~in./Litre:** 

### 250/4.10
Diurnal, Grams Hot Soak, Grams Loss From Loss From SHED A.C. Canister Other SHED A.C. Canister 0.21 20.33 0.16 2.65(1) 11.44 0.50 2.5l(l) 12.79 2.12(3) - 14.49 0.17 14.08 Total Other Grams 20.54 2.65(1) 14.25(2) 2.51(1) l5.so<2) 17.61(2) 14.25(2)
(1) Carburetor leakaround acceleratorpump shaft. Inaccessible from a quantifying standpoint. Background Grams Cold Hot 0.0 0.12

(2) Several openings in the air cleaner sealed after SHED Test 

### 1!2 which accounts for the lower total emissions for these runs than SHED ill. 

### (3) Tank drain disconnect fitting leaking during diurnal cycle. Re:::arks

CXl w

### Test SHED (1) SHED 

### Ill 6.54 (2) 

### Quantifying 

### 1!1 2.89 (3) Quantifying 112 0.77 (4) SHED 112 4.87 (5) 

### SHED 

### /13 4.49 APPENDIX IV TABLE XVII SUMMARY OF EVAPORATIVE EMISSION DATA Make: Volvo Year: 74 No.: 17 Displ.**~in./Litre:** 

### 121/1.98
Diurnal, Grams Hot Soak, Grams Loss From Loss From A.C. Canister Gas Cap SHED A.C. Canister 4.97 0.37 0.19 1.34(l) 1.63 1.87 0.0 0.60 0.32 2.33(l) 1.24 3.77 0.30 3.84 2.62 Background Total Grams Gas Cap Grams Cold Hot 11.51 0.09 0.12 0.40(l) 8.69(2) 1.1ll) 10.50(2) 8.31(2) 7.11<2) (1) Fuel tankpressure builds up quickly to 1.0+psig during diurnal cycle and is relieved through the fill cap or any other fittings thatmay leak temporarily. Fuel tankpressure is 1.0+psi (6.9+kPa) at beginning of the hot soak also. Tank temperature increases 9-10°F (-15.0 to -14.4°C) durinf Federal cycle. Remarks

(2) After SHED test Ill (before Quantifying#1 run), the clamps for the flexible portionof the fill pipewere tightened to eliminatea leak. Consequently, subsequent runs are lower in total evaporative emissions. (X)**~**Test 

### SHED 

### (1) SHED 1!1 

### 3.70 (2) 

### Q•Jantifying 1fl 

### 0.51 (3) 

### Quantifying 

### ii2 

### 0.5Cl (4) 

### SP.ED 

### p ,_ 0.56 (5) SHED 

### f!3 

### 1.07 APPENDIX IV 

### TABLE XVIII**SL~~~y** 

### OF EVAPORATIVE EMISSION DATA Make: Ford Year: 

### 75**~o.:** 18 

### Displ.**~in./Litre:** 

### 460/7.54
Diurnal, Grarr.s Hot Soak, Grams Loss F.co;:; 

### Loss From A.C. 

### Canlster Other SHED 

### A.C. Canister 

### 31.15 2.23 14.04(2) 4.90 2.13 15.29(2) 4.38 0.98 25.75 

### 29.84 I3ackground Total Grams Other Grams Cold llot**IZc:::_.-::·~.s** 

### 34.85(1) 0.0 0.13 

### 14.04(2) 23.81 co**~,** 

### 15.29(2) 21.15 26,31 

### 30.91 (l) Losses 

### higher for this run than subsequent runs because of leaks in the air cleaner, Thesewere scaled for**quan~ifyi~g** 

### and later 

### SHED tests, 

### (2)**Carb~retor** 

### leaks

- vapors escapearound the 

### linkage for the choke plate 

### and bowl vent to the canister,

### Test SHED (1) SHED 

### Ill 0.56 (2) SHED 1!2 

### 1.15 (3) 

### SHED 

### 113 0.41 APPENDIX IV TABLE XIX SUMMARY OF EVAPORATIVE EMISSION DATA Make: VW Year: 

## 75 No.: 19 Displ. cu. in./Litre: 97/1.6 (Fuel Injected)
Diurnal, Grams Hot Soak, Grams Loss From Loss From A.C. Canister Other SHED A.C. Canister Other
1.43 1.46 1.14 Background Total Grams Grams Cold Hot Remarks

1.99 0.69(l) o.ao(l) 2.61 1.55
(1) To verify thehighbackground levels for this car, emissions weremonitored for 24 hours. For bothhot and cold background tests, the rate ofhydrocarbon emissionhad not diminished significantly after 24 hours. Further testing showed that essentially all of thehydrocarbonwas being emitted from the outside of the vehicle. co 

# "'

### Test SHED (1) SHED Ill 4.41 (2) Quantifying ill 

### 0.38 (3) Quantifying 112 

### 0.35 (4) SHED 112 

### 0.91 (5) SHED 113 1.09 APPENDIX IV
TABLE XX SUMMARY OF EVAPORATIVE EMISSION DATA Make: Monarch Year: 75 No.: 20 Displ. cu. in./Litre: 302/4.95
Diurnal, Grams Hot Soak, Grams Loss From Loss From A.C. Canister Other SHED A.C. Canister 6.30 2.28 3.94(l) 1.86 1.34 3.26(l) 2.48 8.62 6.51

(1) Carburetor leakaround chokeplatelinkage. Background Total Grams Other Grams Cold Hot Remarks 10.71 0.0 0.0 3.94(l) 8.46 3.26(l) 7.43 00

....... 

### 9.53 7.60I.

### a. 

### b. c. II.

### d. APPENDIX V TABLE I SUMMARY OF EVAPORATIVE EMISSIONS FROMMODIFIED VEHICLES
Make: Ford "LTD" Year: 75 No.: 1 

### Displ. cu. in./Litre: 351/5.75

Modifications Purge from inside air cleaner element. Barrier in air cleaner atbase of snorkel. Choke shaft passage sealed. Steps a, b, c Air horn to body gasket modified to allowmore bowl vapors to be stored in air cleaner. Evap. Emissions, g/SHED Test


### 6.1

9.6 Remarks

III.e. Purge to air cleaner snorkel as well as air cleaner.

IV. Measurements weremade of purge rates for both an air cleaner and a snorkelpurge system. Next. a curve of grams removed from canistervs. totalpurgevolumewas made. From these data itwas estimated that a combination air cleaner-snorkelpurge systemwould remove 13 to 15 grams from the canister during the SHED preconditioning period (4-LA-4s). This is not an adequate systembecause the combined diurnal and hot soak input to the canister is about 

### 23 grams for themodifiedvehicle.**Consequently~** 

### a PCV purge systemwas installed using a 1974 Vega canisterwhichhad been in daily usage up to this time. PCV purgewithVega canister. The bottomof the canister is capped. An 

### unmodified carburetorbody to airhorn gasket used alongwithmodifications b and c above. l.l 1.2APPENDIX V TABLE 

### II Sill-NARY OF EVAPORATIVE EHISSIONS FROH HODIFIED VEHICLES**~fake:** Pontiac Year: 75 No.: 2 Displ.**~in./Litre:** 400/6.56**~fodifications** I.a. Vented carb. bowl to canister. b. Sealed leak around accel. pump shaft. II. Steps a and b c. Restriction in line from bowl to canister. 

### III.d. e. Steps a, b, c Underhood ventilatedwith 

### a fan. Bottom on canister 

# ) Evap. Emissions, g/SHED Test
10.5 (diurnal)

3.4
1.6 2.5 

### 1.7 Remarks

Canister dried up before run.
Fan lowers carb. bowl temp. about 30°F (-l.l°C).

### APPENDIX V TABLE III SUMMARY OF EVAPORATIVE EMISSIONS FROMMODIFIED VEHICLES

Modifications Make: Chrysler Year: 75 No.: 3 

### Displ.**~in./Litre:** 

### 440/7.21 Evap. Emissions, g/SHED Test Remarks I.a. Underhood ventilatedwith fan. 10.8 (diurnal) 12.0 (diurnal) Fan only lowered c.b. temp. 5-l5°F. Not blowing directly at carburetor.

II.

### b. Carb. bowl volume lowered c. Barrier installed at base of a.c. snorkel. d. Accel. pump shaft leak sealed. At this point itwas determined that one canister would not have sufficient capacity to handle total evap. emissions. With a single canister, preconditioning removes 36-40 grams from a fully charged canister. The lastLA-4 removes only 1 to 2 grams. Combined diurnal and hot soak losses are 50 grams. AChrysler canister from a 1975vehicle in dailyusagewas used as a second canister.
e. Two canisters installed inparallel. 

# I f. Second carb. bowl vented directly to canisters. \ g. Bottom installed on canisters. 1 

### Steps b, c, and d above also used (1) 

### 2.1(1) 2.5

(1) Exhaust emission datawere very erratic. Inasmuch as this vehiclehad to be returned to the rental agency, a second carwill be obtained for further tests. \.0 0

### APPENDIX V TABLE IV SUMMARY OF EVAPORATIVE EMISSIONS FROH HODIFIED VEHICLES
:Hake: Chrysler Year 75 No.: 21 Displ.**~in./Litre:** 

### 440/7.21

I Original ECS Original ECS

IIHodified ECS: Hodif

### ications

(a) Two canisters inparallelused (b) Second carb. bowl vented directly to canister (c) Bottomon each canister (d) Barrier atbase of snorkel (e) Accel. pump shaft leak sealed Evap. Emissions, g/SHED Test 13.4 14.6

1.9 

### 2.0 Remarks Diurnal- 6.3 g, H.S.

- 7.1 g Diurnal- 4.4 g, H.S.

- 10.2 g

### APPENDIX V TABLE V SUMMARY OF EVAPORATIVE EMISSIONS FROH HODIFIED VEHICLES

Hodifications I.a. Carb. bowl vented to the canister. b. Accel. pump shaft leak sealed. Make: Year:**~o.:** 

### Displ. Hornet 

### 74 11 

### cu. in./Litre:

II. Steps a and b above

- restriction in line from carb. bowl to canister. c. Barrier installed in air cleaner at base of snorkel. 

### III.d.

IV. Steps a, b, c above Bottom of canister closed. ECS modified to a PCV purge systemusing a 

### 1974 Vega canister. Steps a, b, c, and d above also continued. 232/3.80 Evap. Emissions, g/SHED Test 3.9
3.1

2.5 1.2 1.3 

### RemarksI

II

III

IV**APPE~1HX** V TABLE VI SUMMARY OF EVAPORATIVE ID1ISSIONS FROM MODIFIED VEHICLES Make: Mazda Year: 

### 74**~0.:** 15 Displ. Cu ln./Litre: 80/1.31 (Rotary)
Modifications Both carburetor bowls vented to a 3 tube canister (Chrysler). Purge is through existing purge line to PCV. Original ECS used for diurnal. Evap. Emissions g/SHED Test

4.8, 3.8 Remarks Hydrocarbon vapors escaping from snorkel.

Next, themodifications indicatedbelowwere tested. In each case, the hydrocarbon level from the SHED test exceeded 

### 2.0 grams. 

### 1. Canistermoved outside of engine compartment to a cooler environment. 

### 2. Canister dried up on vacuum pump prior to diurnal and hot soak. 

### 3. Air cleaner canister closed off and 

### 3 tube canister used for both diurnal and hot soak. At this point, additional source determination tests indicated hydrocarbonvapors emanating from carburetor throat due to fuel drippage. To alleviate pressure in the carburetor bowl, a fan installed to lower bowl temperatureby ventilating the underhood engine compartment. Modifications for Step 

### I. Underhood fan to ventilate underhood. 

### 2.8

At this point, the 3 tube**canist~r** was changed to a 4 tubeVega with a purge control valve. (Used canister from 

### 1974 Vega.) High diurnal losses in above runs due to tankvapors passing into engine crankcase, then through PCV purge line into 3 tube canister. Vapors thenmoved out of the canister into the carburetor bowl and air cleaner through the vent line from the bowl to the canister. The purge control valve prevents this migration of vaporsinto the carburetor bowl and air cleaner. Modifications for Step I with exception of replacing 3 tube canisterwith a 4 tube unit. Fan to ventilate underhood. 1.8, 1.3

### APPENDIX V TABLE VII SUMMARY OF EVAPORATIVE EHISSIONS FROM MODIFIED VEHICLES
Nake: Year: No.: Displ.

Modifications Volvo 74 

### 17**~in.**

### /Litre:

I.a. Equalizingvalvemodified so as to relieve fuel tank pressure at 0.5 psig. b. Baffle installed between fuel tank and muffler.
c. AmericanMotors canister used. 121/1.98 

### Evap. Emissions, g/SHED Test 

### 0.4

1.7 Remarks CO and HC exhaust levels higher withmodified ECS.Car No.

1

2

21

11 - 95

- APPENDIX VI ESTIMATED COSTS FOR VEHICLE MODIFICATIONS

Make LTD

PontI:w

Chrysler

Hornet Modification Canister replacement(l) Seal-carb. leak Barrier-snorkel base Air cleaner sealing Canister bottom capTotal

Bowl v<:>nt to canistC'r**SC'dl-<·:~rb.** I<>.Jk (';tit[HIt•r f,clllom ''·'I' AI 1· ,.,''·'""r**!I<'<~**I IJif'. 

### "'"'' 'l't>ldl Canister replacement(3) Canister bottom caps Bowl vent to canister Barrier-snorkel base Seal-carb. leak Air cleaner sealingTotal

Canister replacement(4) Seal-carb. leak Bowl vent to canister Air cleaner sealing Canister bottom cap Barrier-snorkel base Total $ 1.00 0.30 0.20 0.30 0.20 $ 2.00
$ 0.50

0.30 0.!0 Il. 10 I],00(I .Oil)(.') $18.30(2. 10)(L) $

### t,.00

0.40 0.50 0.20 0.30 0.30 $ 5.70
$ 1.00

0.30 0.50 0.30 0.20 0.20 $ 2.50

l'i Mazda Bowl vent to canister (two) $ 1.00 7.00 17.00

0.20

17 Volvo Canister Fan Canister bottom capTotal Canister Replacement(S) Bafflebetween tank

and mufflpr Total (1) Price difference between 3 tube and 4 tube canister. $25.20 $1.00

1.00 $ 2.00
(2) Numbers in parenthesis are costs associated with the Vega canister system. (3) Price difference between original 3 tube canister and 3 tube with SO% larger capacity. (4) Price difference between 2 tube and4 tube canister. (5) Price differencebetween 1 tube and 2 tube canister.- 96 - 

### APPENDIX VII HIGH RVP FUEL IN SHED TEST Fuel RVP: 71.7 kPa (10.4 psi)

I 

### SHED Results SHED Test, Grams Car No. Make Total Diurnal Hot Soak 1 

### LTD 6.2 2.6 3.6 5.2 2.1 3.1 2 Pontiac 4.4 3.2 1.2 2.1 0.9 1.2 2.3 1.3 1.0

II Exhaust EmissionData Grams/Mile(!) Car No. Make 

## co HC**~** 1 

### LTD 5.19 0.46 1.45 2 

### Pontiac 4.69 0.76 1.16

(1) Average of two tests.

### - 97

-

APPENDIX VIII HIGH TEMPERATURE DIURNAL SHED TEST DATA

Diurnal Cycle: 15.6

- 35°C (60-95°F)

I 

### SHED Results SHED Test, Grams Car No. Make Total Diurnal Hot Soak 1 

### LTD 4.8 1.9 2.9 4.0 2.3 1.7 2 Pontiac 4.2 3.2 1.0 3.7 2.4 1.3
II Exhaust Emission Data Grams/Mile(l) Car No. Make 

## co HC**~** 

### 1 LTD 5.28 0.44 1.95 2 Pontiac 3.83 0.88 1.19

(1) Average of two tests.TECHNICALREPORTDATA (Pleaseread!RS.UUctionsonthe**re~·erse**beforecompleting) 1 ''' I'OH1r,o 

# _r 3. RECIPIENT'SACCESSION-NO.

EI'A-460/3-76-:::014

- II IIII I f.• jr; ".1UBTITL E 5. REPORT DATE

1nvestigalion and Assessment of Light Duty Vehicle May 

### 1976 (Approved) Evaporative Emission Sources and Control 6. PERFORMINGORGANIZATIONCODE

-------------- - 7 AUTHOH(S) 8. PERFORMINGORGANIZATION REPORTNO.



### P. J. Clarke**~PLRF-OR-MlNG**ORG**~-NIZA.TION** NAMEANDADDRESS 10.PROGRAM ELEMENTNO. Exxon Research and Engineering Company P. 

### 0. Box 8 11.CONTRACTI Linden, New Jersc•y 

### 68-03-2172 

### - 1--

--- ----- -- ----- - ------ - --.**-~ ----~-**  - ----------- 12 SPONSOiliNGACOl:NCY NAME ANOADDRESS 13.TYPEOF REPORTANDPERIODCOVERED



## u.s. Environmental Protection Agency Final Report O(fict.• of Air and Water Programs 14.SPONSORINGAGENCY CODE Mobile Source Air Pollution Control

### x~~s~~ggr**CoAURt_Ql~ch~§t8_~Y** Division 15.SUPPLEMENTARY NOTES

To be presented in the form of an APCA paper in June 

### 1976 (Portland meeting).
16.ABSTRACT**-;~** This study has assessed the effectiveness of current Evapt'lrative Control Systems (ECS) and has shown the feasibility of various hardware approaches which control evaporative emissions to a very low level. The performance of ECS's in current use was evaluated by using the Sealed Housing for Evaporative Determinations (SHED) procedure on twenty 

### 1973-75 cars with representative control systems. The measured emissions ranged from 

### 0.5 to 

### 30.6 grams per test, and the twenty car average was 

### 8.7 grams per test. Hardware was then developed t;o improve ECS performance. Six production vehicles were modified to demonstrate the feasibility of improving current systems. These modifications were successful in lowering the evaporative emissions to less than 

### 2.0 grams per test for each of the sixmodified vehicles. This six car group consisted of vehicles manufactured by General Motors, Ford, Chrysler, American Motors, Volvo and Mazda; and the costs of required hardware has been estimated at 

### $2, $2, $6, $2, $2, and 

### $25, respectively.

17. KEYWORDSAND DOCUMENTANALYSIS**-~----** -- --**-------------~--- -----~**  -- a DESCRIPTORS b.IDENTIFIERS/OPEN ENDEDTERMS c. COSATIl:icld/Group

- -- --- ---**~-** ----**----~---** ------- -- -

Air Pollution Evaporative Emissions Motor Vehicles Light Duty Vehicle Hydrocarbons Emission Control Air Pollution Control Equipment

1'3. UISTHII:lUTIONSTATEMENT 19.Sf-CURITYCLASS (Thi.l'Rt•porl) 21 NO.or PAGES -100 1---:-·

-- -------- Release Unlimited 20.SECURITYCLASS (Thispage) 22. PRICE

EPA Form2220·1 (9·73)