methanol breakthrough times is based on the 1000 ppmC breakthrough
concentration. Breakthrough times measured at 1000 ppmC were considerably
longer than those measured at 100 ppmC as shown in Tables A-1 and A-2 of
Appendix A.

13


APPENDIX B


Isobutylene
Toluene/N2
Methanol/Np

a
ot
a
3
a

To
Fume Purge
Hood Manifold

LILTIVTTITITL

Fuel Manifold

LLITITIriri

Purge
Total of 12 Fuel “Fie
Mini-Canisters Flow ow
Mini~ HC
Canister Analyzer

To }
Fume
Hood

Figure 2. Flow schematic of charcoal evaluation apparatus


The working capacity of each type of charcoal was also measured with the
HC blend (three times) and with the HC-methanol blend (once). Working
capacity is defined as the weight of hydrocarbons that can be purged off after
loading to breakthrough. It was calculated by subtracting the canister weight
after purging from the weight after loading to breakthrough. The results are
shown in Table B-3 in Appendix B and illustrated in Figure 8. The working
capacity of the four charcoal types was reduced from 10 to 52 percent relative
to the hydrocarbon blend when the methanol blend was used. The working
capacities of the Chrysler and GM charcoals were affected to a greater degree
by the presence of methanol. They were 35 to 52 percent lower than with the
hydrocarbon blend. The working capacities of Ford and Toyota charcoals were
10 to 16 percent lower when the methanol blend was used compared to the
hydrocarbon blend. Working capacities for individual mini-canisters are
reported in Appendix A, Table A-6. It should be noted that some of the mini-
canisters were loaded beyond the breakthrough point, since loading times were
determined by the charcoals with the longest breakthrough times.

Another method for measuring working capacity is the Ford butane
working capacity procedure. According to this method, standard size canisters
are first purged at 120°F and 2 ft3/min (57 liters/min) until weight loss is less
than 1.2 g in five minutes. The canisters are then saturated with butane. This
process is repeated two more times. To determine working capacity, the
canisters are weighed after the last butane load cycle, then purged for 20
minutes, and finally weighed again. The difference in these two weights is
called working capacity. Table B-4 in Appendix B compares the working
capacities of new Chrysler, Ford, and GM charcoals measured with this method
and working capacities measured using the SwRI method with mini-canisters.

“DRAFT

}
ft aa itn

17


ABSTRACT

This program involved the evaluation of four types of unused evaporative
canister charcoal with a hydrocarbon-only blend and a hydrocarbon-methanol
blend. The HC blend consisted of 77% paraffins (butane), 18% olefins
(isobutylene) and 5% aromatics (toluene) by weight. The HC-methanol blend
was composed of 73% butane, 17% isobutylene, 5% toluene, and 5% methanol by
weight. Tests were conducted on a bench-scale apparatus designed to load each
blend onto separate sets of twelve reduced-size mini-canisters, and to
subsequently purge off the hydrocarbons. The charcoals were evaluated by the
measurement of retained charcoal weight gain after purging, time to
hydrocarbon breakthrough, and charcoal working capacity. The mini-canisters
which were loaded with the methanol blend, had shorter breakthrough times,
retained less weight gain after purge, and had lower working capacities than did
mini-canisters tested with the hydrocarbon blend only. These methanol blend
mini-canisters also underwent less simulated aging than the hydrocarbon blend
canisters in this program, since they were only exposed to 40% as much total

DRAFT |

Na amen a let al aca

iv


TABLE A-5. INDIVIDUAL MINI-CANISTER RETAINED WEIGHT GAIN WITH HC-METHANOL BLEND

Retained Weight Gain, g°

ia
wo

pRetained weight gain = mini-canister weight after purging-clean mini-canister tare weight

cMini-canister 3 filled with Teflon chips to measure breakthrough time of mini-canister system
Load cycle = 120 min, purge cycle = 110 min

Chrysler Ford Toyota
Cumulative Cycles 1 2 4 6 7 9 10 12
HC Blend only for 2 1/2 days to establish breakthrough time
1 107 min load w/
108 min purge 2.09 1.90 0.63 0.67 0.56 1.93 1.85 0.23 0.22
Avg 2.00
2 136 min load w/
110 min purge
3 +118 min load w/
110 min purge
+118 min load w/
110 min purge
4 +112 min load w/
109 min purge 4.19 3.75 0.95 0.85 4.18 3 3.84 0.33 0.39
Avg 3.97 3
Overall Avg T0
HC-Methanol Blend
2 5.02 4.53 1.27 - 1.12 5.40 4.98 0.46 0.52
Avg 4.78
5 5.08 4.67 1.24 1.08 5.67 5.14 0.41 0.56
Avg 4.88
8 5.25 4.88 1.38 1.44 1.23 5.99 5.57 5.52 0,42 0.68
Avg 5.07 1.35 5.69
11 5.20 4.84 1.31 1.43 1.16 5.91 5.42 5.36 0.39 0.70
Avg 5.02 1.30 5.56
14 5.54 5.17 1.72 3.76 1.49 6.43 5.91 5,86 0.68 0.94
Avg 5.36 1.66 6.07
Overall Avg 3.0 3.6


Darl

‘eta! ore a a ay ee

The effect of the repetitive loading and purging of a hydrocarbon blend
and a hydrocarbon-methanol blend on evaporative canister charcoal was
measured by canister weight gain and hydrocarbon breakthrough time. The
mini-canisters were weighed after the last load-purge cycle of each day. From
one to three load-purge cycles were accomplished each test day. Canister
weight gain was calculated daily by subtracting the initial clean canister weight
from the weight after the last load-purge cycle. Breakthrough time was
defined as the length of time for hydrocarbons to break through the bottom of
the mini-canisters at 1000 ppmC with a fuel blend flowrate of about 40 mg/min
per canister. This loading was equivalent to approximately 5g of HC or HC-
methanol per mini-canister.

I. RESULTS

Variations in canister weight gain and breakthrough times were noted
between charcoal types and between fuel blends (HC, HC-methanol). However,
canister weight gains and breakthrough times were relatively constant over the
course of the program for each individual mini-canister. The only major
exception to this finding was the increased weight gain after purge associated
with the 110-minute loading on day 8 with the HC-only blend. The first set of
mini-canisters received a cumulative hydrocarbon loading of about 155 g of
hydrocarbons per canister, and the second set was loaded with about 65 g of the
methanol blend and 23 g of the HC-only blend. Appendix A lists the load-purge
cycles necessary to achieve these loading levels. Average charcoal weight
gains after purge using the hydrocarbon fuel and the hydrocarbon-methanol fuel
are compared in Table B-! of Appendix B and in Figure 6 for charcoal from
Chrysler, Ford, GM, and Toyota mini-canisters. The canisters containing the
smaller mass of lower-density Chrysler and GM charcoals retained greater
amounts of hydrocarbons (and/or methanol) after purging than did the Ford and
Toyota canisters for both fuels. In addition, all four charcoal types retained
more weight after purge when only hydrocarbons were loaded than when the
hydrocarbon-methanol blend was loaded to breakthrough. The effect was
greater in the cases of the Ford and Toyota charcoals, for which the average
weight gain after purge for the hydrocarbon blend was 3 to 7 times that for the
methanol blend. The weight gains measured for the Chrysler and GM charcoals
using the hydrocarbon blend were 54 and 25 percent higher than with the
methanol blend, respectively. Retained weight gains for individual mini-
canisters using the HC and the HC-methanol blend are listed in Tables A-3 and
A-5 of Appendix A.

Hydrocarbon breakthrough times were shorter with the methanol blend
than with the hydrocarbon blend for all charcoal types. This finding is
illustrated in Figure 7 and Table B-2 of Appendix B. Average breakthrough
times for Chrysler, Ford, GM, and Toyota charcoals with the methanol blend
were 44, 22, 29, and 20 percent lower, respectively, than with the hydrocarbon
fuel, The denser Ford and Toyota charcoals had the longer breakthrough times.
Breakthrough times are listed in Tables A-l, A-2 and A-4 of Appendix A for
individual mini-canisters. At the end of testing, a single load-purge cycle with
the HC blend was conducted on the mini-canisters which had been previously
exposed to the HC-methanol blend. Breakthrough times as shown in Table A-4
of Appendix A did not return to the longer times experienced with the HC blend
(working capacities were not measured).

14


APPENDIX A


Breakthrough Time, min.

Breakthrough Time, min.

A
Tested with HC Fuel, RA

RS i opine ake Sang)
Tested with HC-Methanol Fuel

10. 150
100 100
50 50

0 0

Chrysler Charcoal Ford Charcoal

10 fr 150 -
100 100
50 50

ub.

GM Charcoal Toyota Charcoal

Figure 7. Average daily breakthrough time of four types
of evaporative canister charcoal
16


(ie

Lyd

c

TABLE A-6,. INDIVIDUAL MINI-CANISTER WORKING CAPACITY WITH HC BLEND

Working Capacity, a

Chrysler Ford GM Toyota
Day Cumulative Cycles 1 2 3 4 5 6 7 8 9 10 il 12
16 179 load/purge cycles
(load = 15 min, purge =
25 min)
+280 min load, purge
25 min to 3600 ppmC 2.76 2.82 4.77 4.86 4.90 4.76 2.05 1.90 2.02 5.00 4.65 4.77
17 216 min load, purge
124 min to 410 ppmC 2.10 2.05 4.20 4.34 4.28 3.99 1.59 1.47 1.43 4.46 4452 4.35
18 111 min load, purge
143 min to 300 ppmC 3.32. 3.31 5.51 5.52 5.50 5.43 2.66 2.54 2.67 5.61 5.50 5.58
Avg 2.7 ° 4.8 ~ 2.0 4.9
INDIVIDUAL MINI-CANISTER WORKING CAPACITY WITH HC-METHANOL BLEND
Chrysler 1. Ford GM Toyota
1 2 3” 4 5 6 7 8 9 10 11 12
7 14 load/purge cycles

(load = 120 min, purge =
110 min) 1.39 1.29 4.29 4.60 3.91 1.33 1.24 1.26

4,39 4.15 3.69

Avg 1.3 4.3 1.3

4.1

avorking capacity is defined as the weight of hydrocarbons that can be purged after loading

to breakthrough.

ploaded beyond the breakthrough point.
Mini-canister 3 filled with Teflon chips to measure breakthrough time to mini-canister system

It should be noted that due to the procedure used, some canisters were

[ oom


ee r

t+ { 7

i rt

f i

=

4 5

Tr"le a 6 4 4 0
Time, min

Figure 4. Hydrocarbon breakthrough at 100 ppmc

g BY


2. Composition of Hydrocarbon and Methanol Blends

The targeted composition of the simulated fuel was based upon a
hydrocarbon speciation study performed by EPA-RTP in which hot soak
evaporative emissions were measured on forty six 1975 to 1982 model year
gasoline vehicles. 2) Overall, the hot-soak emissions were composed of 70
percent paraffins, 21 percent olefins, and 9 percent aromatics by mass. The
flowrates of the fuel gases were set with the goal of achieving these available
hot soak weighting factors. Butane was chosen to represent paraffins,
isobutylene for olefins, and toluene for aromatics. Feed gas flows were
monitored continuously with flowmeters. Heavier hydrocarbons (also
representative of hot-soak emissions) were not included in the simulated fuels
because of the inability to accurately measure vaporization and delivery of such
compounds to the canister system.

The targeted level of methanol in the methanol blend was based on
data from two research projects. A study on the alcohol content of gasoline in
the Houston area showed the fraction of methanol in one brand of methanol-
containing fuel to be about 5% (by volume).(3) Another study measured SHED
methanol concentrations from vehicles fueled with methanol-gasoline blends.' 4)
This study indicated that the mass fraction of methanol in hot soak evaporative
emissions was approximately equivalent to the volume percent of methanol in
the fuel. Thus, a 5% methanol concentration by mass was targeted for the
simulated methanol fuel vapors.

3. Load and Purge Cycles

The laboratory procedure was loosely modeled after the Code of
Federal Rysulations SHED test, which measures evaporative emissions from
vehicles.(9) The SHED test cycle consists of a diurnal segment during which
the fuel tank is heated from 60-84°F, an FTP driving cycle for purging fuel
vapors from the evaporative canister, and a hot soak segment in which the
carburetor, at temperatures of 150-200°F, emits fuel vapors to the canister.

The laboratory procedure developed for evaluating canister charcoal
combined the two fuel loading segments of the SHED test into a single load
cycle. An approach was to simulate and monitor fuel loading and purging cycles
similar to the SHED test until hydrocarbons broke through the charcoal.
However, the possibility that a SHED-type cycle might not ever show
breakthrough became apparent. Therefore, the load cycle was redefined as the
length of time until hydrocarbons broke through the mini-canisters. This
change was incorporated into the program with the approval of the project
officer. After breakthrough, the canisters were purged until the rate of change
of purge hydrocarbon concentrations became small in relation to that observed
at the start of purging (from over 600ppmC/min to less than 10 ppmC/min).
These revisions in the load and purge cycles still provided the opportunity to
observe the change in canister weight as the charcoal was aged with repetitive
loadings and purgings. In addition, cycle by cycle breakthrough times could be
observed. The hydrocarbon blend was loaded onto each mini-canister for a
cumulative total of about 155 g. This weight is roughly equivalent to the
amount of hydrocarbons that a canister would be subjected to over 69 repetitive

3


Day

TABLE A-4,

Cumulative Cycles

1000 ppmC BREAKTHROUGH LEVEL

Breakthrough Time, min

INDIVIDUAL MINI-CANISTER BREAKTHROUGH TIMES WITH HC-METHANOL BLEND

Chrysler

Ford

GM Toyota

1 2

4 5 6 7

8 9 10 ll 12

L-v

3¢

4c

rw

HC Blend only for 24 days to establish

107 min load w/108 min
purge to 270 ppmC :
Avg

136 min load w/110 min
purge to 300 ppmC
Avg

118 min load w/110 min
purge to 300 ppmC
Avg

112 min load w/109 min
purge to 320. ppmC
Avg

140 min load w/114 min
purge to 300 ppmC
Avg

Overall Avg

Avg

breakthrough times

58 64.6 94.9 111.5 89.6 64.2 58.5 64 115.2 106.7 98.2
61 99 62 107
-> 50 121139112 44 48 45 144.5 138 124
50 124 46 136
58 58 104 121 (103 58 58 58 123 120110
58 109 58 118
55.5 54 102.116 95.4 53.5 52.3 52.3 121 111105
55 104 53 112
66 59 118 136114 58 53. 61 +149 142 130
62 123 57 140
57 112 55 122
HC-Methanol Blend
46 4l 92.2 101 84 4l 41 43110 102 95.9 fir
40 38 91.6 100.3 79 38 40 38101.3 96.3 95.6 }
41 91 40 100
45 4, 92.7 107.3 83.4 43 4. 45 115 106.5 101.6
—_— 88.8 98.2 85 ~~~---~-------> 108.1 95.4 89.9
42 35 78.7 92 74.8 33.9 32.3 33.6 104.5 95.9 88.7
41 89

Liywiq

“ara
|
a

oO


~v

TABLE A~-2,

- Breakthrough Time, min

INDIVIDUAL MINI-CANISTER BREAKTHROUGH TIMES WITH HC BLEND
1000 ppmC BREAKTHROUGH LEVEL

Chrysler ' Ford GM Toyota
Day Cumulative Cycles 1 2. 3 4 5 6 7 8 9 10 iL 12
16 179 cycles w/purge
+280 min loading, purge
25 min to 3600 ppmC
+216 min loading ,purge
124 min to 410 ppmC
17 111 min loading, purge
143 min to 300 ppmC 63 52.5 108 101 100 100 43 42 46.5 109 111 111
Avg 58 102 44 110
18 120 min loading, purge
120 min to 295 ppmC 61 70.5 112 108 104.5 107.5 47 4749 117.6 116.5 122.5
Avg 66 108 48 119
125 min loading, purge
120 min to 190 ppmC 67 71 121.108 107  ~=107 51 51. 55 126122 126
Avg 69 111 52 125
19 140 min loading, purge
108 min to 285 ppmC 75 74 132.5 124 132 127 54 52 61 141 137.5 140
Avg 74 129 56 140
140 min loading, purge
122 min to 330 ppmc 75 75 124-122) 122121 51 4752 137__ 135 «134
Avg 75 122 50 13500
Overall Avg 68 114 50 126

Lyd

—

oe


Figure

wn

+

LIST OF FIGURES

Several Views of the Charcoal Evaluation Apparatus
Flow Schematic of Charcoal Evaluation Apparatus

Purge Cycle Monitored on 10,000 ppmC and 1000 ppmC
Ranges

Hydrocarbon Breakthrough at 100 ppmC
Hydrocarbon Breakthrough at 1000 ppmC

Average Daily Weight Gain After Purge of Four
Types of Evaporative Canister Charcoal

Average Daily Breakthrough Time of Four Types of
Evaporative Canister Charcoal

Average Daily Working Capacity of Four Types of
Evaporative Canister Charcoal

vi

10
ll
12

15

16

18


TABLE OF CONTENTS

Page
FORE WORD iii
ABSTRACT iv
LIST OF FIGURES vi
I, INTRODUCTION 1
IL PROCEDURES AND INSTRUMENTATION 2
A. Development of Procedure and Instrumentation 2
1. Fuel Delivery 2
2. Composition of Hydrocarbon and Methanol
Blends 3
3. Load and Purge Cycles 3
4, Mini-Canisters 4
B. Description of Charcoal Evaluation Apparatus 5
1. Mini-Canisters 5
2. Charcoal 5
3. Hydrocarbon and Methanol Blend Compositions 9
4. Hydrocarbon Breakthrough 9
ttm RESULTS 14
REFERENCES 19

APPENDICES


Continuation of

timed load cycle:

1 - t ed 1 —t
128 126 124 122 120 118 116
Time, min
Figure 5. Hydrocarbon breakthrough at 1000 ppmc

12


IL PROCEDURES AND INSTRUMENTATION

The work plan called for the development of a bench scale apparatus to
evaluate charcoal from evaporative canisters. The apparatus that was
developed allowed delivery of hydrocarbon vapors to twelve mini-canisters
containing fresh charcoal from standard-size evaporative canisters. After the
HC vapors broke through the charcoal, the canister system was designed to
permit hydrocarbon vapor purge by pulling room air in the reverse direction
through the mini-canisters.

A. Development of Procedure and Instrumentation

The goal of the program was to determine the effect of repetitive
hydrocarbon loading and purging cycles (aging) on four types of canister
charcoal. The variables that were measured during the aging process were:
time to hydrocarbon breakthrough, retained weight gain of the canisters, and
charcoal working capacity. Two feed gases were used for canister loading, a
hydrocarbon blend of butane, isobutylene, and toluene vapors, and a
hydrocarbon-methanol blend composed of the hydrocarbon blend mixed with
methanol vapors.

1. Fuel Delivery

The original work plan called for the development of a fuel
containment vessel equipped with a temperature programmer designed to
deliver unleaded gasoline vapors and gasoline-methanol vapors to twelve mini-
canisters. As a result of discussions with the EPA project officer concerning
safety, the plans for a fuel source were changed from a simulated gas tank
filled with gasoline to hydrocarbons supplied by pressurized cylinders. The new
fuel delivery system still satisfied the requirements for maintaining consistent
fuel vapor composition and vapor volume per cycle while reducing the
possibility of a fire hazard.

The hydrocarbon sources, as mentioned previously, were compressed
gases and vaporized toluene and methanol. Butane and isobutylene were
supplied from pressurized cylinders (both 99.0% pure), and toluene and methanol
were delivered to the mini-canisters by bubbling nitrogen through the
respective liquids. Gas flows were measured with soap bubble meters and
monitored with flowmeters.

Several delivery systems for toluene and methanol were evaluated
before a decision was made to use nitrogen saturated with toluene and methanol
at room temperature. Initially, the liquids were heated to produce pure gas
vapors. However, since the remainder of the canister system was not heated,
the vapors condensed before reaching the canisters. A second method involved
bubbling nitrogen through liquid toluene and methanol in a system heated to
30°C, but the same condensation problem occurred. To avoid vapor
condensation, liquid methanol and toluene were placed in separate containers at
room temperature, and separate flows of nitrogen were bubbled through each
liquid. Toluene made up approximately 1.5% of the toluene-nitrogen flow (by
volume) at a nitrogen flowrate of 38 milliliters /min, and methanol constituted
about 6.8% of the methanol-nitrogen flow by volume with a nitrogen flowrate
of 42 milliliters/min,

2


a Tested with HC Fuel

a Tested with HC-Methanol Fuel

8.0 8.0
6.0 & 6.0
4.0 & 4.0
2.0 & 2.0
; _ =
Chrysler Charcoal Ford Charcoal
8.0 - 8.0
6.0 6.0
4.0 4.0
2.0 & 2.0
Lia.
GM Charcoal Toyota Charcoal
Figure 8. Average daily working capacity of four types

of evaporative canister charcoal

18



United States Office of Mobile Source Air Pollution Control EPA 460/3-84-014
Environmental Protection Emission Control Technology Division January 1985
Agency 2565 Plymouth Road

Ann Arbor, Michigan 48105

Air

SEPA The Effect of Methanol on
Evaporative Canister Charcoal
Capacity

Disclaimer

The data presented in this report should be viewed with care,
and any possible conclusions based on these data should be
considered tentative at best due to the inconsistent treatment
of the charcoal samples during the test program. A more
consistently performed extension of this study is underway at
Southwest Research Institute, which may confirm the data in
this report.


mini-canisters. Preliminary experiments were performed using only butane and
isobutylene to determine breakthrough times. During initial experimentation
with the hydrocarbon blend (butane, isobutylene, and toluene in nitrogen), the
mini-canisters were found to leak hydrocarbons at the cap. The plastic caps
were apparently not sealing with the additional flow of nitrogen and toluene
through the mini-canisters. A heavier mini-canister design with a threaded
aluminum cap was used in all subsequent testing to prevent leaks. The all-
plastic canisters were selected initially due to their low filled weight (70 g).
The new mini-canisters, though heavier (220-250 g), could still:be weighed
accurately after hydrocarbon loading.

B. Description of Charcoal Evaluation Apparatus

The bench scale apparatus for evaluating evaporative canister charcoal is
shown in several views in Figure 1. The mini-canister system is composed of a
hydrocarbon source (liquids and compressed gases); a series of valves,
flowmeters, and tubing to direct equal flows to the mini-canisters; a vacuum
pump for purging; and a hydrocarbon analyzer and recorder. The flow
schematic of the apparatus is shown in Figure 2. The fuel and delivery gases
were set to 20 psig at the cylinder regulator and were individually controlled
with needle valves to achieve the desired proportion of butane, isobutylene,
toluene, and methanol (as needed). Load and purge cycles were controlled by a
timer which automatically switched the purge pump and the fuel solenoid valves
on and off. Total hydrocarbon concentrations could be monitored at the exit to
individual canisters or in the purge manifold before the pump. A sample line to
the HC analyzer allowed sequential hydrocarbon analyses to determine break-
through time for each mini-canister. A second vacuum pump, which was
manually operated, was used to remove hydrocarbons which broke through the
mini-canisters.

Background hydrocarbon levels were monitored in the lab and generally
ranged from about 15 to 25 ppmC. Room temperature was 75°F 20°F, and
relative humidity generally varied from a daily high of about 60 percent to a
daily low of 50 percent.

1. Mini-Canisters

The mini-canisters that were used during experimentation were
made of an acrylic tube (5 3/4 in. long, 1 in. diameter) with a threaded
aluminum cap. The volume of each mini-canister was approximately 74
milliliters. The bottom of the canister was capped by a polypropylene cap with
a large hole cut from the center. A metal screen was inserted into the cap to
retain the charcoal while allowing vapors or air to pass freely. A large ‘hole
(5/8 in.) was drilled into the canister top for a purge outlet, and a smaller hole
(1/16 in.) was drilled in the side of the canister top for fuel delivery. A screen
was placed in the purge opening to prevent charcoal from being pulled off while
under vacuum. In addition, glass wool was used at the purge opening and at the
bottom cap to prevent the loss of charcoal dust.

2. Charcoal

Four types of activated charcoal were evaluated in the mini-
canisters. The charcoals were obtained from new evaporative canisters ordered

5


SHED tests.2 Due to time restrictions, a total of only 68 g of the methanol
blend was loaded onto each mini-canister, an equivalent of about 29 SHED
tests.2 At the end of testing, a single load-purge cycle with the HC-only blend
was conducted on the mini-canisters which had been previously exposed to the
HC-methanol blend.

Prior to the decision to alter the load and purge cycles, vapor flow
from the carburetor during the hot soak cycle was measured on two vehicles, a
1980 Mercury Cougar and a 1981 Chevrolet Monte Carlo. Vapor flowrate was
measured using a 10 ml soap bubble meter attached to the carburetor bowl
(where the carburetor vents to the evaporative canister). Vapor volumes
produced by the Cougar were measured and found to be 0.1 ml, 0.3 ml, and 0.75
ml over approximately 10 minutes of the hot soak on three tests. Vapor flow
was measured at 0.3 ml on the Monte Carlo within a period of about 10
minutes.b The carburetor bow! was found to produce negligible amounts of
vapor from the carburetor during the hot soak. In addition, canister vacuum
was monitored on the two vehicles during a hot FTP using a vacuum transducer
teed into the line connecting the canister to the engine. The average vacuum
was 4 in, Hg on the Cougar and 2 in. Hg on the Monte Carlo. The disparity in
the amount of vacuum applied to the canisters appeared to be due to the
relative size of the purge ports (Cougar purge port was larger than the Monte
Carlo purge port) and to the engine size. To relate canister vacuum to the
bench-scale apparatus it was necessary to determine purge flowrates, A bench
evaluation of new Ford and GM canisters produced flowrates of 4 £t3/min (113
liters/min) and 2 £t3/min (57 liters/min) at applied vacuums of 4 in. Hg and 2 in.
Hg, respectively. This range of flowrates is consistent with the Ford test
procedures for testing the "Working Capacity" of Evaporative canisters.
According to these procedures, canisters are purged at 2 ft?/min. The total
flowrate of purge air through the mini-canister system was set at about 3.5
£t3/min (99 liters/min). Each mini-canister, which was approximately 1/12 the
size of a standard-size canister, was purged at about 0.3 ft/min (8.5
liters/min). This rate is within the flow range measured on the Ford and GM
canisters on a proportional volume basis.

4, Mini-Canisters

The bench-scale apparatus was designed to test twelve mini-
canisters. With this setup, multiple positions could be used to evaluate each
type of charcoal. Miniature canisters were used instead of standard size
canisters in an effort to minimize total flow rates and apparatus size. Mini-
canisters were initially made of polypropylene tubing (about 6 in. long) with
plastic caps on each end. The caps were modified to allow flow through the

@Based on two vehicles tested with four fuels, the average increase in & ister
weight during each SHED test was 27 g (sum of hot soak plus diurnal).(6) The
value is divided by twelve for mini-canister comparisons.

bvapor volume was also measured on a third vehicle, a 1981 Ford Mustang. This
car produced 0.2 ml of vapor over 15 minutes.

4


9-V

TABLE A-3 (CONT'D).

INDIVIDUAL MINI-CANISTER RETAINED WEIGHT GAIN WITH EC BLEND

Retained Weight Gain, g°
GM

Chrysler Ford Toyota
Day Cumulative Cycles 1 2 3 4 5 6 7 8 9 10 11 12
13b 160 7.65 7.05 4.69 4.69 4.61 4.60 6.98 6.65 6.68 4.18 4.17 4.24
Avg, 7.35 4.65 6.77 4.20
14b c —---c c -------c
15> c Cc Cc ro
164 Total of 179 cycles
with purge +280 min
loading, purge 25 min
to 3600 ppmC + 216 min
loading, purge 124 min .
to 410 ppmC 8.07 7.42 4.88 4.86 4.79 4.79 7.36 6.97 7.07 4.29 4.26 4,37
Avg 7.75 4.83 7.13 4,31
174 111 min loading, purge
143 min to 300 ppmC 8.41 7.87 5.27 5.21 5.16 5.13 7.58 7.09 7.47 4.54 4.49 4.61
Avg 8.14 5.19 7.38 4.55
1s4 120 min load, purge
120 min to 295 npmC
+ 125 min load, purge .
120 min to 190 ppmC 8.28 7.75 5.11 5.07 5.00 4.99 7.28 6.73 7.18 4.48 4.41 4.53
Avg 8.02 5.04 7.06 4,47
194 140 min load, purge
108 min to 285 ppmC oT eo
+ 140 min load, purge j 7
122 min to 330 ppmC 8.12 7.69 4.96 4.94 4.88 4.87 7.26 6.75 7.12 4.36 4,29 4.42%
Avg 7.91 4.91 7.04 4,36
Overall Avg. ‘ =U
from Day 8 to 7.6 4.8 7.0 4.3 {
Day 19
aRetained weight gain = mini-canister weight after purging - clean mini-canister tare weight T |
Breakthrough level 100 ppmC, load cycle = 15 min, purge cycle = 25 min
CNo weight measurement tne

Breakthrough level = 1000 ppmC

eer Ee -


S-V

TABLE A-3, INDIVIDIAUL MINI-CANISTER RETAINED WEIGHT GAIN WITH HC BLEND
Retained Weight Gain, g*
Chrysler Ford GM Toyota
Day Cumulative Cycles 1 2 3 4 5 6 7 8 9 10 11 12
yb 11 2.75 2.71 0.41 0.41 0.40 9.42 2.55 2.53 2.58 0.15 0.18 0.13
Avg 2.7 0.4 2.6 0.2
ab 22 3.25 3.17 0.47 0.48 6.47 0.50 3.01 3.00 2.95 0.18 0.23 0.17
Avg 3,2 0.5 3.0 0.2
3 35 3.45 3.36 0.58 0.59 0.60 0.61 3.18 3.11 3.03 0,23 0.28 0.23
Avg, 3.4 0.6 3.1 0.2
4c 42 c ——: c c ad
sb 53 2.17 2.02 0.32 0.32 0.29 0.31 1.86 1.75 1.67 0.18 0.20 0.17
Avg 2.1 0.3 1.8 0.2
6b 64 2.36 2.18 0.37 0.34 0,34 0.36 1.98 1.85 1.82 0.20 0.23 0.18
Avg 2.3 0.4 1.9 0.2
7 81 3.35 3.22 0.61 0.62 0.61 0.63 2.86 2.77 2.69 0,28 0.38 0,28
Avg 3.3 0.6 2.8 0.3
gb 3 hours of continuous loading without purge to check flow rates
83 7.69 7.07 4,62 4.64 4.56 4.56 7.14 6.90 6.95 4.14 4.19 4.16
Avg 7.38 4.60 7,00 4.16
gb 95 7.90 7.29 4,68 4.69 4.61 4.59 7.22 6.87 6.93 4.16 4.20 4.21
Avg 7.60 4.64 7.01 4.19
19> 114 7.83 7.26 4.67 4.68 4.60 4.60 7.24 6.96 7.00 4.18 4.18 4.22 |
Avg 7.55 4.64 7.07 4.19 >
ub 131 8.19 7.58 4.78 4.80 4.74 4.72 7.54 7.15 7.10 4,21 4.21 4,28;
Ave 7.89 4.76 7.26 4,23
12b 150 7.28 6.64 4.56 4.56 4.47 4.45 6.54 6.14 6.09 4.13 4.11 4,19 |
6.96 4.51 6.26 4.14



I, INTRODUCTION

Evaporative emissions from gasoline vehicles are controlled by the use of
charcoal canisters. The Sealed Housing for Evaporative Determinations (SHED)
test was developed to measure vehicle evaporative emissions. This test is used
to confirm canister effectiveness in controlling evaporative emissions during
simulated vehicle operation. A study conducted by the Department of Energy
in 1980)* with 10 percent methanol in gasoline raised concerns over whether
methanol in gasoline reduces canister effectiveness.

The purpose of this program was to design a laboratory bench-scale
apparatus for evaluating the effects of a methanol-hydrocarbon blend on
charcoal from evaporative emissions canisters. Two sets of mini-canisters were
filled with activated charcoal from new evaporative canisters and aged by
repetitively loading and purging with the hydrocarbon and the methanol-
hydrocarbon blends, respectively. Hydrocarbon breakthrough times and
charcoal weight gains (after purging) were monitored throughout the program.
In addition, charcoal working capacity was also measured.

The first part of testing involved operation of the mini-canister apparatus
with a gaseous hydrocarbon blend composed of butane, isobutylene, and toluene
in nitrogen. After breakthrough times and weights were monitored for
repetitive hydrocarbon loading and purging cycles, the mini-canisters were
refilled with fresh charcoal. Methanol in nitrogen was added to the
hydrocarbon blend, and the mini-canisters were once again subjected to
repetitive load and purge cycles. The comparison of hydrocarbon and methanol-
hydrocarbon blends using breakthrough times and charcoal weight gains
provided a preliminary indication of the effect of methanol on canister
performance.

*Numbers in parentheses designate references at the end of this report.


Charcoal Weight Gain, g

Charcoal Weight Gain, g

DiXAF

| Tested with HC Fuel

| Tested with HC-Methanol Fuel

8.0 8.07
6.0F 6.0
4.0 4.0
2.0 2.0
0 0 EZ
Chrysler Charcoal Ford Charcoal
8.0— 8.0
6.0 6.0
4.0L 4.0
2.0, 2.0
0 0 : 8

GM Charcoal Toyota Charcoal

Figure 6. Average daily weight gain after purge of

four types of evaporative canister charcoal

15


TABLE B-3. AVERAGE DAILY WORKING CAPACITY (g)

Type of Charcoal HC Blend HC-Methanol Blend Percent Difference@

Chrysler 2.7 1.3 -52%
Ford 4.8 4.3 -10%
cM 2.0 1.3 -35%
Toyota 4.9 4.1 -16%

® percent differences were calculated relative to working capacities
using the HC blend.

TABLE B-4. WORKING CAPACITIES OF STANDARD SIZE (NEW) CANISTERS USING THE BUTANE
WORKING CAPACITY PROCEDURE AND OF MINI-CANISTERS USING THE SWRI PROCEDURE

wo
& Charcoal Auto HC Blend HC-Methanol Blend
Manufacturer Manufacturer SwRI SwRI
Specified Specified Mini-canisters, Mini-canisters,
Type of Charcoal Virgin BWC, g/100 ml Virgin BWC, g/100 ml g/100 ml g/100 ml
Chrysler - 14x35 Westvaco wood 9.0 8.2 3.9 1.8
Ford - 6x16 Calgon coal 6.8 --2 6.8 6.1
GM - 10x25 Westvaco wood 8.5 8.5 2.9 1.9
Toyota - description unknown 2 --3 6.8 5.7

‘pata not available



TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)

T. REPORT NO, z IS. RECIPIENT'S ACCESSION NO.
EPA 460/3-84~-014
4. TITLE AND SUBTITLE IS. REPORT DATE
The Effect of Methanol on Evaporative Canister January 1985
Charcoal Capacity JS. PERFORMING ORGANIZATION COOE
7, AUTHORIS) 8. PERFORMING ORGANIZATION REPORT NO,

Mary Ann Warner-Selph

ig. PERFORMING ORG NIZATION NAME AND ADORESS 10. PROGRAM ELEMENT NO.
Southwest Research Institute
Department of Emissions Research tH SONTRACTGRANT NO
6220 Culebra Road
Ann Arbor, Michigan 48105 68-03-3162

12, SPONSORING AGENCY NAME AND ADDAESS 13, TYPE OF REPORT AND PERIOD COVERED
Environmental Protection Agency Final (Feb. 1984 - Aug. 1984)
2565 Plymouth Road 74. SPONSORING AGENCY CODE

Ann Arbor, Michigan 48105

16, SUPPLEMENTARY NOTES

ha-xestaxer

This program involved the evaluation of four types of unused evaporative canister
charcoal with a hydrocarbon~only blend and a hydrocarbon-methanol blend. The

HC blend consisted of 77% paraffins (butane), 18% olefins (isobutylene) and 5%
aromatics (toluene) by weight. The HC-methanol blend was composed of 73% butane,
17% isobutylene, 5% toluene, and 5% methanol by weight. Tests were conducted

on a bench~scale apparatus designed to load each blend onto separate sets of
twelve reduced-size mini~canisters, and to subsequently purge off the hydrocarbons.
The charcoals were evaluated by the measurement of retained charcoal weight

gain after purging, time to hydrocarbon breakthrough, and charcoal working
capacity, The mini~canisters which were loaded with the methanol blend, had
shorter breakthrough times, retained less weight gain after purge, and had

lower working capacities than did mini-canisters tested with the hydrocarbon

blend only. These methanol blend mini-canisters also underwent less simulated
aging than the hydrocarbon blend canisters in this program, since they were

only exposed to 40% as much total vapor.

17,

KEY WORDS AND DOCUMENT ANALYSIS

ja. DESCRIPTORS 1D. (OENTIFIERS/OPEN ENDED TERMS |{c. COSAT! Field/Group
Alr Pollution Evaporative Canisters
Methanol

Wa, OISTRIGUTION STATEMENT 79. SECURITY CLASS (This Report) 21, NO. OF PAGES.
Unclassified 36
Release Unlimited 20. SECURITY CLASS (This page) a2. PRICE
Unclassified

Charcoal Evaluation

EPA Form 2220-1 (9-73)



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7.6
7.9

8.1
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5.4 _8.8

4.3
4.4
4.7

44

8.6
A-2

10.1
9.3 10
9.2 8.5

9.8
9.3 9.8
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11.7 10.1 13.1

9
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9.3

5.2
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55.
6.3

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5.1

4
7
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Avg
Avg

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3 hours of continuous loading without purge to check flow rates

74
81
83

72
8?


FORE WORD

This project was conducted for the U.S. Environmental Protection Agency
by the Department of Emissions Research, Southwest Research Institute. The
work was carried out between February and August 1984 under EPA Contract
No. 68-03-3162, Work Assignment 12, It was identified within Southwest
Research Institute as Project 03-7338-012. The EPA Project Officers were Mr.
Robert J. Garbe and Mr. Craig A. Harvey of the Office of Mobile Source Air
Pollution Control, Emission Control Technology Division, Environmental
Protection Agency, 2565 Plymouth Road, Ann Arbor, Michigan. The Southwest
Research Institute Project Manager was Charles T. Hare, and the Project
Leader was Mary Ann Warner-Selph.

dit


for four vehicle types. Charcoal weights and volumes contained in the canisters

are listed as follows:

1983 Chrysler Reliant K
1983 Ford Escort

1983 Chevrolet Monte Carlo

Typical Standard Approximate Approximate
Size Canister Volume of Density
Charcoal Weight, g Charcoal, ml g/ml
344 1270 0.27
407 1030 0.40
438 1500 0.29
362 870 0.42

1983 Toyota Corolla

Initially, charcoal samples were provided by some of the auto manufacturers'
charcoal suppliers for use in the mini-canisters. A visual comparison to actual
canister charcoal, however, showed differences in size and shape of the
charcoal pieces. Because of these variations, the mini-canisters were tested
with charcoal from actual evaporative canisters. The weights of fresh charcoal
used in the mini-canisters are shown below:

Type of Mini-Canister Charcoal Weight,
Charcoal Number HC Blend HC-Methanol Blend
Chrysler 1 19.7 18.9
Chrysler 2 19.7 17.2
Ford 3 27.9 74,58
Ford 4 27.5 28.4
Ford 5 27.9 31.1
Ford 6 27.9 26.5
GM 7 19.5 22.3
GM 8 18.5 20.5
GM 9 19.5 2.1
Toyota 10 29.1 34.1
Toyota i 29.0 31.8
Toyota 12 28.8 29.1

@Mini-canister number 3 was filled with Teflon chips (when using the
HC-methanol blend) to measure breakthrough time of the mini-canister
system. This breakthrough time was found to be less than one minute.

Charcoals from Ford and Toyota canisters are apparently denser than Chrysler
or GM charcoals, since a greater mass fills the same mini-canister volume. In
addition, Ford and Toyota charcoal particles were generally larger than

Chrysler or GM charcoal particles.


Hy

a
iauueeenl

Range 1000 ppmc

LONG Le Lr Oem op 6 4 2
Time, min

Figure 3, Purge cycle monitored on 10,000 ppmc and 1000 ppmC ranges

10


This report is issued by the Environmental Protection Agency to report
technical data of interest to a limited number of readers. Copies are available
free of charge to Federal employees, current contractors and grantees, and
nonprofit organizations - in limited quantities - from 2565 Plymouth Road, Ann
Arbor, Michigan 48105.

This report was furnished to the Environmental Protection Agency by Southwest
Research Institute, 6220 Culebra Road, San Antonio, Texas, in fulfillment of
Work Assignment No. 12 of Contract No. 68-03-3162. The contents of this
report are reproduced herein as received from Southwest Research Institute.
The opinions, findings, and conclusions expressed are those of the author and
not necessarily those of the Environmental Protection Agency. Mention of
company or product names is not to be considered as an endorsement by the
Environmental Protection Agency.

Publication No, EPA 460/3-84-014

ii


TABLE B-1. AVERAGE DAILY WEIGHT GAIN

HC Blend HC-Methanol Blend

Weight Gain as Weight Gain as Percent

Number Percentage of Number Percentage of Difference

Type of of Mini- Weight Clean Charcoal of Mini-, Weight Clean Charcoal in Weight
Charcoal canisters Gain, g Weight canisters Gain, g Weight Gains
Chrysler 2 7.7 41% 2 5.0 26% -35%
Ford 4 4.8 17% 3 1.4 5% -71%
GM 3 7.0 35% 3 5.6 28% -20%
Toyota 3 4.3 14% 3 0.6 2% -86%

?0ne mini-canister was filled with Teflon chips to measure breakthrough time of the mini-canister

system

Percent differences were calculated relative to weight gains using the HC blend

ed

TABLE B-2, AVERAGE DAILY BREAKTHROUGH TIME (minutes)

Type of Charcoal HC Blend HC-Methanol Blend

Percent Dif ference”

Chrysler 68 38
Ford 114 89
GM 50 36
Toyota 126 102

44%
-22%
-28%
-20%

3Loaded at about 40 mg/min with hydrocarbons or methanol blend
Percent of differences were calculated relative to breakthrough

times using the HC blend

wvwa



2.

3.

4,

5.

6.

REFERENCES

Stamper, Ken R., "Evaporative Emissions from Vehicles Operating on
Methanol/Gasoline Blends", Paper 801360 presented at the SAE Fuels &
Lubricants meeting, Baltimore, Maryland, October 20-23, 1980.

Sigsby, J.E., Tejada, S., Ray, W., Lang, J., and Duncan, J., "Volatile
Organic Compound Emissions from 46 In-Use Passenger Cars." Publication
Preprint.

Urban, Charles M., "Volatility of In-Use Gasoline and Gasoline/Methanol
Blends," EPA Report 460/3-84-009, September 1984.

Dietzmann, Harry E., "Gasoline Volatility Analysis," Final Data Report,
Task 1 and 2 Work Assignment No. 4, September 1984.

U.S. Code of Federal Regulations. Title 40--Protection of Environment
Chapter I--Environmental Protection Agency; Subchapter C--Air
Programs; Part 86--Control of Air Pollution from New Motor Vehicles and
New Motor Engines: Certification and Test Procedures. Federal
Register, Vol. 90, No. 129, pp. 342-569, October 23, 1977.

Cantwell, E.N., Letter to EPA with additional information for DuPont's
waiver application for gasoline-alcohol fuels, October 11, 1984.

19


EPA 460/3-84-014

ADACT .
DRAFT |
The Effect of Methanol on Evaporative
Canister Charcoal Capacity

by
Mary Ann Warner-Seiph

Southwest Research Institute
6220 Culebra Road
San Antonio, Texas 78284

Contract No. 68-03-3162
Work Assignment 12

EPA Project Officers: Robert J. Garbe
Craig A. Harvey

Prepared for

ENVIRONMENTAL PROTECTION AGENCY
Office of Mobile Source Air Pollution Control
Emission Control Technology Division
2565 Plymouth Road
Ann Arbor, Michigan 48105

January 1986


TABLE A-4 (CONT'D), INDIVIDUAL MINI-CANISTER BREAKTHROUGH TIMES WITH HC-METHANOL BLEND
1000 ppmC BREAKTHROUGH LEVEL

Breakthrough Time, min

8-V

Chrysler Ford GM Toyota
Day Cumulative Cycles 1 2 3 4 5 6 7 8 9 10 11 12
5c 6 48 37 98.5 109.4 88.9 39.7 39 40.8 114.4 108.1 103.8
7 41.4 35.2 86.5 103.3 81.8 34.9 31.1 32.8 113.3 91.1 91.1
8 39.6 33.9 83.7 115 79 33.3 31.3 32.7 114.3 94 84.1
Avg 39 94 35 102
6c 9 46.4 40 101.6 113.8 93.8 40 38 41.4 127.9 117.2 108.5
10 28 25 75.2 87.7 62.9 22 22 24 96.3 85.7 78.8
11 36.7 32.1 78.7 _ (93.5 71.8 30.3 30 31.5 105.6 92.2 87.8
Avg 35 87 31 100
7 12 43 38.5 93.5 103.4 83.8 39.4 37 40.9 123.2 115 104
13 40 34.5 82 90.5 73 32.5 30.8 33.1 112.4 96.6 91.8
14 36 33 79.8 93.8 73.5 29.4 28.5 31 107.9 94.8 86.6
Avg 38 86 34 104
Overall Avg with
HC-Methanol Blend 39 89 36 101
HC-Blend
8 1 39.7 47,5 88.8 111.2 79.6 29 30 33 109.9 104.5 90.9
Avg 44 93 31 TOL

avini-canister 3 filled with Teflon chips to measure breakthrough time of mini-canister system : ,
No data : :
“Load cycle = 120 min, purge cycle = 110 min



INDIVIDUAL MINI-CANISTER BREAKTHROUGH TIMES WITH

HC BLEND 100 ppmC BREAKTHROUGH LEVEL

TABLE A-1 (CONT'D).

Toyota
il

10

9

r

Breakthrou:
3

Ford

sler-

Ch:
i

Cumu=
lative
cles

Day

oom
neo

TOs
~oo

Nw st
ono
ais)

AAD
ANN

Colo
ANN

N
no 0

7.1

3.2

8.7

4.2

nun
won

tN
won

nta
wonr

© 1H

9.1

4.3

Avg

non
wneo

now

wow

RAR

116
125
131

113

2.8

9.3

4.6

Avg

133
144

123

6.6

2.8

9.3

4.6

Avg

151
156

137

7.0

8.4

4.5

Ir

Is

5.

Overall Avg

a
b

Load Cycle = 15 min, purge cycle = 25 min

No data

A-3


Measuring Hydrocarbon Breakthrough Toluene and Methanol Delivery System

Figure 1. Several Views of the Charcoal Evaluation Apparatus


3. | Hydrocarbon and Methanol Blend Compositions

The composition of the hydrocarbon and methanol blends, (by volume) was
about 16 percent butane, 4 percent isobutylene, 0.7 percent toluene, and for the
methanol blend, 2 percent methanol. The remainder was nitrogen carrier gas.
The flowrate of hydrocarbon vapors plus nitrogen carriers to the mini-canisters
was on the order of 70 milliliters/min. The actual mass flowrates were
determined using the weight of blend loaded onto the mini-canisters, volume
percentages, molecular weights of the compounds, and the assumption that the
gases obey the ideal gas law. Resulting mass flows are shown below. Due to
the low vapor pressure of toluene, the fraction of toluene in the blends was only
5 percent by mass instead of the 9 percent initially desired.

Mini-Canister Flow, mg/min

Hydrocarbon Component HC HC-Methanol
Butane 31 29
Isobutylene 7 7
Toluene 2 2
Methanol 2 2

Total 40 40

4, Hydrocarbon Breakthrough

Hydrocarbon vapors were delivered to the canisters at the above
flowrates to establish hydrocarbon breakthrough times. The length of the load
cycle was based on the longest breakthrough time of the four types of charcoal.
The longest average breakthrough time with the HC blend was for Toyota
charcoal, at 110 to 140 minutes. The load cycle for methanol blend testing was
set at 120 minutes. The purge cycle with the HC blend was set with the
intention of reaching a hydrocarbon concentration in the purge manifold of
approximately 300 ppmC. The mini-canisters were purged for 108 to 143
minutes to achieve this level. This level of hydrocarbons represented a drop
from over 10,000 ppmC at the beginning of the purge cycle. The purge cycle
with the HC-methanol blend was set at 110 minutes. The slope of the
logarithmic shaped hydrocarbon purge rate curve leveled out in the 300 ppmC
range, as illustrated in Figure 3.

Initially, breakthrough was defined as the emission of hydrocarbons
from the bottom of the mini-canisters in excess of 100 ppmC for 10 seconds.
The increase in hydrocarbon concentration with time was observed on a
recorder, and it appeared that 100 ppmC HC was an adequate indicator of
breakthrough. During the preliminary evaluations, breakthrough times were
defined at the 100 ppmC level; however, additional experiments were conducted
which indicated that 1000 ppmC was a more appropriate definition of break-
through. Traces of HC breakthrough on the 100 ppmC and 1000 ppmC ranges
are illustrated in Figures 4 and 5, respectively. Comparison of the HC and HC-