Effects of Low-Purge Vehicle Applications and ... - MeadWestvaco

Copyright © 2007 SAE International
ABSTRACT
20077051
2007-01-1929
Effects of Low-Purge Vehicle Applications and Ethanol-
Containing Fuels on Evaporative Emissions Canister
Performance
The California Air Resources Board (CARB) LEV II
regulations require less than 500 mg of vehicle
evaporative emissions which, typically requires canister
emissions of less than 200 mg. PZEV regulations
require less than 350 mg vehicle emissions and zero
emissions (< 54 mg) from the fuel system.
Activated carbon canister emissions of less than 20 mg
are typically required in order to meet PZEV regulations.
LEV II canister emissions levels can typically be
achieved through a combination of canister design,
sufficient purge volumes, use of the appropriate
activated carbon or combination of carbons, and in some
cases an activated carbon honeycomb.
INTRODUCTION
Activated carbon honeycombs are typically required to
further reduce canister emissions to levels necessary to
meet PZEV emissions regulations. Recent trends in
automotive technology have led to a reduction in the
amount of air available for regenerating or purging the
carbon canister. The new technologies include hybridelectric
vehicles and gasoline direct injection engines.
Hybrid vehicles have reduced gasoline engine runtime
and therefore use less intake air. The gasoline direct
injection technology requires less throttle air to operate
the engine. Under these reduced purge volume
conditions, current activated carbon canister and
honeycomb configurations may not be adequate to meet
PZEV or even standard LEV II requirements.
A relationship between canister purge volume and
emissions has been developed. The data show that
emissions for both the base canister and the canister
with honeycomb attached increase significantly with
decreasing purge volume. Relationships between
activated carbon honeycomb properties and canister
emissions have also been developed. This work
Reid Clontz, Moe Elum, Peter McCrae, Roger Williams
MeadWestvaco Corp.
demonstrates that properties such as total part
volume/capacity, part length, and diameter affect
honeycomb performance. Manipulation of these
properties led to improvements as compared to current
part design. Honeycomb configuration was also
investigated as a method of improving performance.
Multiple honeycombs tested in series also showed
improvements over current part design. These
performance improvements enable conformance to LEV
II and PZEV emissions standards under incrementally
reduced purge volume levels.
Activated carbon honeycombs were also resistively
heated and evaluated under severely limited purge
conditions. Test results indicate that resistively heating
the honeycomb enables achievement of PZEV
emissions levels from the canister under these restrictive
conditions.
Due to increased interest in and demand for renewable
fuels, the effects of ethanol content on the performance
of activated carbon canisters and activated carbon
honeycombs have been investigated and relationships
developed. The effects of fuel vapor pressure on
canister emissions were also investigated and
differentiated from the effects caused by ethanol
content.
As expected, the data showed that a strong relationship
exists between diurnal vapor generation and fuel
volatility regardless of ethanol content. Furthermore, the
canister emissions obtained were similar when fuels of
equivalent volatility but varying ethanol content were
utilized during a simulated diurnal emissions test. The
results indicate that the use of a honeycomb can
facilitate achievement of LEV II emissions levels from
the carbon canister tested under CARB flexible fuel
vehicle test conditions.
In a previous paper, the impact and control of bleed
emissions from evaporative emissions control devices
were discussed (1). A technique was developed to

study the level of bleed emissions specifically from
canister vent ports. Carbon type, canister design and
purge volume were shown to have a significant impact
on bleed emissions. Further, the incorporation of a
small auxiliary chamber in series with the primary
canister was shown to decrease bleed emissions
significantly (1).
Activated carbon honeycombs, typically incorporated as
separate auxiliary chambers, are currently being
successfully used to meet LEV II and PZEV regulations
in many vehicles. This technology has been shown to
be an effective means to control bleed emissions,
particularly in systems where large purge volumes are
not available.
Recent trends in vehicle technology have created
questions concerning the performance of the
evaporative emissions control canister system. Vehicle
technologies such as hybrid powertrains, direct fuel
injection, variable engine displacement, and
homogeneous charge compression engine technology
can have a significant impact on canister performance
due to reduced volumes of air available for canister
purge.
In addition to new developments in power-train
technology, increased interest in renewable fuels such
as ethanol have also led to questions concerning the
performance of activated carbon and activated carbon
honeycombs.
It should be noted that canister design can have a
significant impact on evaporative emissions. The
baseline canister used in this study was not a design
optimized to control bleed emissions. Thus, the
emissions results should primarily be taken on a relative
basis. The purpose of this paper was not to investigate
the effect of base canister design, but to optimize the
use of the activated carbon honeycomb under reduced
purge conditions and under conditions of exposure to
fuels of different volatility and ethanol content.
EXPERIMENTAL METHODS
Bleed emissions were evaluated using a laboratory test
method involving an initial canister gasoline preconditioning,
butane load, purge followed by a timecontrolled
soak, and emissions measurement during a
final canister vapor load simulating a diurnal loading
event.
The canisters used for testing purposes were all the
same design and contained 2.1 liters of BAX 1500
carbon. The canisters were used multiple times for
repeat testing. To ensure fuel blending was not a
concern, each canister was cycled with the appropriate
fuel unitl equilibrium was reached.
GASOLINE VAPOR AND BUTANE CYCLING
Gasoline vapor cycling was performed using automated
cycle test equipment that precisely controlled and
monitored all testing conditions. Gasoline vapors were
generated by bubbling air at a rate of 200 cc/min through
2 liters of certified test fuel heated to 36°C. For
example, a 62.1 RVP-certified test gasoline typically
resulted in a vapor generation rate of approximately 40
g/hr with a hydrocarbon concentration of approximately
50% by volume. The generated vapors were sent to the
canister until a breakthrough concentration of 5000 ppm
was detected using a flame ionization detector (FID). If
breakthrough was not detected after 90 minutes of vapor
loading, the liquid gasoline was replaced with a fresh 2liter
aliquot. After breakthrough was detected, the
canister was purged for a specified volume, typically 400
bed volumes, using dry air at a rate of 22.7 liters per
minute. The dwell time between load and purge events
was no more than 5 minutes. The ambient temperature
of the equipment, including the canister storage
compartment, was maintained at 20°C during all stages
of the testing.
DIURNAL TESTS
The diurnal test procedure, referred to as the simulated
real-time diurnal test, was used to subject a fuel tank
and canister to the CARB diurnal temperature profile
within a temperature-controlled environmental chamber.
This test procedure was published previously (1). The
test was designed to simulate the diurnal portion of the
CARB vehicle emissions test procedure in order to
generate quantitative emissions data isolated to only the
evaporative emissions canister.
Pre-conditioning for the simulated real-time diurnal test
included multiple gasoline vapor load and purge cycles
as described above. Following the gasoline cycles, the
canister was loaded with 50% butane vapor at a load
rate of 40 g/hr to a 5000 ppm breakthrough as measured
by an in-line flame ionization detector in preparation for
a two-day diurnal test. After the butane load, the
canister was allowed to soak for 60 minutes before
purging with a specified volume of air. Following the
purge, the canister was soaked at 20°C for 24 hours
before starting the diurnal test.
After the 24-hour soak, the canister was attached to a
commercial 60-liter steel fuel tank containing 24 liters
(40% fill) of the certified test fuel specified. The fuel
temperature was equilibrated to 18.3 °C overnight before
beginning the test. A Tedlar® bag was attached to the
atmosphere port of the canister as shown in Figure 1 to
collect the hydrocarbon emissions. During the 11-hour
temperature ramp from 18.3° C to 40.6° C, the canister
weight and emissions were measured several times.
During the portion of the diurnal when the temperature
decreased, the Tedlar® bag was removed in order to
allow the system to back purge.
During each emissions measurement, the Tedlar® bag
was removed and filled to a known volume with nitrogen.

The hydrocarbon concentration was determined by
evacuation of the bag contents into a flame ionization
detector. Once the concentration and volume were
determined, the mass of hydrocarbon was calculated
and recorded. The total test procedure incorporating
gasoline aging and diurnal testing takes approximately
one and a half weeks per canister test. Due to time
considerations, only a limited number of repeat tests
were performed. Where possible repeats were
performed and the nominal test value was reported.
The entire two-day CARB diurnal temperature profile
was used for canister purge volumes of 75 bed volumes
or greater. Figure 2 represents the CARB temperature
profile used for the environmental chamber containing
the test canister. It should be noted that canister design
can have a significant impact on evaporative emissions.
The purpose of this paper was not to investigate the
effect of base canister design, but to optimize the use of
the activated carbon honeycomb under reduced purge
conditions. All of the testing was performed with a
commercial 2.1-liter carbon canister filled with BAX 1500
automotive grade carbon.
RESISTIVELY HEATED ACTIVATED CARBON
HONEYCOMB
An activated carbon honeycomb was prepared for
resistive heating by attaching electrodes to the
honeycomb using conductive epoxy. Electrical current
was passed through the part using a constant 12-volt
power supply. Electrical current was applied only while
the canister was being purged.
ETHANOL FUEL BLENDS
In order to determine the effect of ethanol content and
fuel vapor pressure on canister emissions, fuels with a
range of ethanol content and volatility were evaluated
and are listed in Table 1.
Test
Fuel - #
RVP
(kPa) @
37.8 o C
1 34.5
2 48.3
3 48.3
4 55.2
5 62.1
6 62.1
Fuel Product
Code
Haltermann -
HF032
Haltermann -
HF087
Haltermann -
HF004
Haltermann -
HF087 and 40
CFR 86.1313-04
(FFV)
40 CFR 86.1313-
04
Haltermann -
HF115
Ethanol
Volumetric
Concentratio
n (%)
85
85
0
10
0
10
Table 1. List of fuels used to perform diurnal testing.
Tedlar Bag
Environmental Chamber
Canister 60-Liter Fuel Tank
Figure 1. Diagram of simulated CARB diurnal
evaporative emissions test.
Temperature ( o C) .
45
40
35
30
25
20
15
10
5
0
0 3 6 9 12 15 18 21 24
Time (hr)
Figure 2. Diagram of CARB Diurnal Temperature Profile.
RESULTS AND DISCUSSION
Previously published results showed that canister
evaporative emissions can be controlled by utilizing
high-capacity/low-heel wood-based carbons, optimizing
canister geometry, using an auxiliary chamber, and
increasing purge volume available to the canister (1).
This paper concerns the further optimization of bleed
control under conditions of reduced purge and also
describes results obtained with ethanol containing fuels.
EFFECT OF PURGE VOLUME ON CANISTER
EMISSIONS
The two-day simulated real time diurnal test was used to
evaluate the effect of purge volume on canister
hydrocarbon emissions. Each test involved
preconditioning of a 2.1-liter canister as described above
in preparation for the simulated diurnal test. In addition
to evaluating base canister performance, canisters were
evaluated with activated carbon honeycombs attached
to the vent port of the canister. The activated carbon
honeycombs are high-carbon content monoliths

specifically designed to reduce canister emissions. Two
commercially available activated carbon honeycomb
parts were evaluated. Dimensions for these two
cylindrical parts are 29 mm diameter x 100 mm length
and 41 mm diameter x 150 mm length. Both parts had a
nominal cell density of 200 cpsi. In order to evaluate the
effect of purge volume, the final purge volume before the
24-hour soak and subsequent diurnal test was varied
from 200 bed volumes to 75 bed volumes. The purge
time was kept constant at 21 minutes, while the purge
rate was changed in order to achieve the desired purge
volume. The test results are shown in Figure 3.
Day 2 Emissions (mg) .
500
450
400
350
300
250
200
150
100
50
0
Base Canister
29x100-200
41x150-200
75 100 150 200
Bed Volumes of Purge
Figure 3. Effect of Purge volume with base canister and
commercially available honeycombs.
The data in Figure 3 demonstrates the strong
relationship between purge volume and canister
emissions. The activated carbon honeycombs
significantly reduced canister emissions with purge
volumes of 100 bed volumes and greater. In addition,
the larger 41 mm x 150 mm honeycomb exhibited lower
emissions levels than the 29 mm x 100 mm honeycomb
at purge volumes of less than 200 bed volumes. Due to
the strong relationship between purge volume and
emissions, as purge volume is decreased, emissions
increase. As a result, there is a point for each of the
commercially available carbon honeycombs at which
purge volume will be insufficient to meet either PZEV or
LEV II emissions targets.
OPTIMIZATION OF CARBON HONEYCOMB
PROPERTIES FOR LOW PURGE VOLUME
APPLICATIONS
Alternative Honeycomb Geometry
The commercially available activated carbon
honeycombs evaluated with low levels of purge (

Honeycomb Configuration B (three 41x50 parts in series
and rotated 45°) showed a 32% improvement over the
baseline Configuration A. This performance
improvement is assumed to be the result of flow
redistribution and/or increased tortuosity of the flow path.
Honeycomb Configurations C (41x200) and D (50x150)
showed approximately 45% and 60% improvement as
compared to the baseline Configuration A. Both of these
honeycomb configurations have more total working
capacity due to their larger size as compared to the
baseline honeycomb. In addition, Configuration C has a
longer flow path for vapors diffusing out of the main
canister.
Results obtained with Configurations C and D confirm
earlier data indicating that increased diffusional flow path
length and/or total part capacity have an impact on bleed
emissions (2). This earlier work was performed with 27
mm diameter honeycombs of varying length at higher
purge volumes of 150 bed volumes. The results from
the earlier work are presented in Figure 5.
Day 2 Emissions (mg) .
200
180
160
140
120
100
80
60
40
20
0
No HCA 50 mm 75 mm
Honeycomb Length
100 mm 150 mm
Figure 5. Results obtained with 27 mm diameter
honeycombs evaluated with 150 bed volumes of purge.
The results obtained with the developmental honeycomb
configurations show that the following changes to the
baseline part improve emissions performance.
1. Increased honeycomb working capacity
2. Increased diffusional flow path length
3. Flow redistribution
4. Increased tortuosity
Further work is planned in order to better understand the
reasons for these performance improvements and to
develop a honeycomb with more robust performance at
low purge volumes.
Resistive Heating of the Honeycomb to Reduce Canister
Emissions
Resistive heating of activated carbon honeycombs has
been shown to improve performance over baseline
activated carbon honeycomb performance. This is
particularly effective at low purge volume levels because
an un-heated honeycomb may fail to achieve desired
performance. In order to demonstrate this concept, the
two-day simulated diurnal testing procedure described
earlier was repeated by resistively heating an activated
carbon honeycomb during the preconditioning purge.
This is possible with MeadWestvaco activated carbon
honeycombs due to their electrical properties. The
electrical conditions and temperatures achieved during
the purge cycles are summarized in Table 4 followed by
a summary of the results in Figure 6.
HCA Size
Heated HCA Configuration
41x150-200
Purge Air Temp ( o C) 70 - 90
Max HCA Temp ( o C) 200
Current (amps) @ 12v 1.8 -2.2
Table 4. Heated honeycomb conditions during purge
cycle.
Day 2 Emissions (mg) .
180
160
140
120
100
80
60
40
20
0
50 75 100 150 200
Bed Volumes of Purge
Heated 41x150-200
Baseline 41x150-200
Figure 6. Summary of emissions results obtained with
heated honeycomb configuration.
Figure 6 shows that emissions measured with the
heated activated carbon honeycomb were lower as
compared to the non-heated honeycomb. The
improvement in performance was most dramatic at lower
purge volumes. Resistively heating the honeycomb
allowed emissions of less than 20 mg for all levels of
purge evaluated. These emissions levels are significant
because they correlate well with performance required
for PZEV compliance on vehicles. The results obtained
with the resistively-heated activated carbon honeycomb
are due to a more complete removal of hydrocarbon
heel from both the activated carbon honeycomb and the

portion of the canister carbon bed closest to the
atmosphere port.
EFFECT OF CARBON HONEYCOMB ON CANISTER
WORKING CAPACITY
As a result of testing for canister bleed emissions
performance, it was discovered that activated carbon
honeycombs have a significant positive impact on
diurnal canister working capacity. The effect of the
activated carbon honeycomb on canister gasoline
working capacity is summarized in Figure 7.
Canister G W C (g) .
180
160
140
120
100
80
60
40
20
0
+4%
+11%
+13%
+19%
No HCA 29x100-200 41x150-200 50x150-200 Heated
41x150
Figure 7. Effect of activated carbon honeycomb on
canister working capacity.
The baseline gasoline working capacity of 138 g
presented in Figure 6 was obtained with a 2.1-liter
canister filled with BAX 1500 without an activated carbon
honeycomb attached. An increase in overall canister
working capacity of 4% to 19% was demonstrated with
the addition of an activated carbon honeycomb. The
increased capacity was proportional to the honeycomb
size and therefore the capacity of the honeycomb to
adsorb hydrocarbon vapors.
EFFECT OF ETHANOL FUEL BLENDS ON CARBON
BED PERFORMANCE
Adsorption of Ethanol
The adsorption and desorption isotherms for Ethanol
and Butane on BAX 1500 at 25°C, is shown in Figures 8
and 9.
Loading g/g Carbon
1.40
1.20
1.00
0.80
0.60
0.40
0.20
Adsorption
Desorption
0.00
10 100 1000 10000 100000 1000000
Concentration (ppm)
Figure 8. BAX 1500 Butane Equilibrium Isotherm.
Loading g/g Carbon
1.40
1.20
1.00
0.80
0.60
0.40
0.20
Adsorption
Desorption
0.00
10 100 1000 10000 100000 1000000
Concentration (ppm)
Figure 9. BAX 1500 Ethanol Equilibrium Isotherm.
Comparisons of these figures clearly show that, at equal
concentrations, ethanol is more readily adsorbed than
butane, the standard used to evaluate automotive
carbons (3, 4). More importantly, due to the
mesoporous nature of MeadWestvaco automotive
carbons, the desorption curves show that ethanol and
butane are readily removed from the carbon pores.
Ethanol Fuel Blends
There are two potential ways for ethanol to be present in
fuels:
1. Splash Blending. This is the straight addition of
alcohol to a non-alcohol-based gasoline. This has been
shown to significantly affect the vapor pressure of the
resultant mix as shown in Figure 10 (5).

Reid Vapor Pressure @ 37.8oC (kPa)
.
80
70
60
50
40
30
20
10
0
0 10 20 30 40 50 60 70 80 90 100
Ethanol Concentration (%)
Figure 10: Effect on Vapor Pressure by ethanol addition
to 9.0 RVP Fuel
Figure 10 shows that splash blending of ethanol up to
approximately 40% will cause an increase in the vapor
pressure of the resultant blend.
2. Blending to a fixed Vapor Pressure. This is the
addition of an ethanol to gasoline fuel that has been
altered so that the resultant solution has the same vapor
pressure as the unblended gasoline. For example, in
the case of Fuel - 6, the volatility of the non-ethanol
components of the fuel is reduced to compensate for this
effect of adding ethanol.
Regardless of the approach used, the most important
property of the fuel blend with respect to activated
carbon canister performance is the vapor pressure. The
vapor pressure, rather than ethanol content, determines
the resultant diurnal vapor generation from the fuel tank
and therefore the required working capacity of the
carbon canister.
Diurnal Vapor Generation
A range of fuels was tested for vapor generation rates by
following the diurnal test procedure of subjecting a fuel
tank and canister to the entire two-day CARB diurnal
temperature profile as described earlier. The RVP of the
fuels tested ranged from 34.5 to 62.1 kPa, with an
ethanol content of 0 to 85%. The diurnal vapor
generation results are shown in Figure 11.
Average Daily Vapor Load (g) .
40
35
30
25
20
15
Fuel - 1
Fuel - 3
Fuel - 4
Fuel - 2
Fuel - 5
10
20 25 30 35 40 45
RVP (kPa)
50 55 60 65 70
Figure 11. Diurnal vapor generation of fuels tested
As would be expected, this figure shows a strong
relationship between RVP and vapor generation. More
importantly, it shows that fuels of equivalent RVP will
generate similar total amounts of diurnal vapors
regardless of the ethanol content. For example, on the
average Fuel -2 generated 27.5 grams of vapor
compared to an average of 29.7 grams for Fuel - 3 with
an equivalent RVP. While similar total vapor generation
amounts have been observed for fuels with similar RVP,
it is understood that the fuels may have different
volatilities at the various temperatures experienced
during the CARB diurnal temperature profile. Based on
these results, if a canister is properly sized for use with a
62.1 RVP fuel, it should be adequately sized for ethanol
blends of an equal or lower RVP.
EFFECT OF ETHANOL FUEL BLENDS ON
HONEYCOMB PERFORMANCE
Initially, simulated diurnal testing was conducted using
standard Fuel - 5 and Fuel - 3 as specified by CARB
procedures for non-Flex Fuel Vehicles (FFV’s) to
establish baseline performance. Results obtained using
the 2.1-liter canister filled with BAX 1500 both with and
without a standard 41x150 honeycomb (Configuration A)
attached under these conditions were compared to
those obtained by cycling with the same Fuel - 5
followed by a two day diurnal using Fuel - 2. The results
are compared in Figure 12.
Day 2 Emissions (mg) .
180
160
140
120
100
80
60
40
20
0
BAX 1500 w / 41x150 HCA
BAX 1500
Cyc Fuel - 5 / DBL Fuel - 3 Cyc Fuel - 5 / DBL Fuel - 2

Figure 12. Diurnal emissions for equivalent RVP E0 and
E85 fuel blends with 150 bed volumes of purge.
Figure 12 shows that within the accuracy of the testing
(+/- 7.5 mg), use of an E85 fuel blend rather than the
standard CARB Fuel - 3 during the simulated diurnal test
does not have a significant impact on emissions. Based
on this data, bleed emissions appear to be independent
of ethanol content for both the main canister and the
honeycomb. In addition, the results show that the use of
a standard, commercially-available activated carbon
honeycomb (Configuration A) makes it possible to
reduce canister emissions to PZEV levels.
The simulated diurnal testing was repeated by
performing preconditioning cycling with the CARB Fuel -
2 mileage accumulation fuel followed by a diurnal with
the fuel type specified for evaporative emissions testing
of flexible fuel vehicles, Fuel - 4. These results were
compared to those obtained when a standard Fuel - 5
was used for the two-day diurnal test following
preconditioning cycles with Fuel -2 mileage
accumulation fuel. The results are shown in Figure 13.
Day 2 Emissions (mg) .
300
250
200
150
100
50
0
BAX 1500 w / 41x150 HCA
BAX 1500
Cyc Fuel - 2 / DBL Fuel - 4 Cyc Fuel - 2 / DBL Fuel - 5
Figure 13. Diurnal emissions for Fuel - 4 and Fuel – 5
with 150 bed volumes of purge.
The results provide further evidence that emissions are
independent of ethanol content for either the main
canister or the main canister in combination with the
honeycomb. More importantly, the results show that the
use of a standard, commercially available activated
carbon honeycomb (Configuration A) makes it possible
to reduce canister emissions to LEV II levels for FFV’s.
CONCLUSION
Recent trends in automotive technology have led to a
reduction in the amount of air available for regenerating
or purging the carbon canister. Under these reduced
purge volume conditions, current activated carbon
canister and honeycomb configurations may not be
adequate to meet PZEV or even standard LEV II
requirements. Improvements over the current
honeycomb technology such as the following facilitate
achievement of target emissions levels under the
reduced purge conditions:
• Higher capacity honeycombs
• Longer diffusional path length
• Flow redistribution
• Resistively-heated honeycombs
Further work is planned in order to gain a better
understanding about the relative importance of
diffusional flow path length and honeycomb capacity.
With regards to trends in renewable fuels and in
particular ethanol blends, the following was shown
• MeadWestvaco mesoporous automotive
carbons readily adsorb and desorb ethanol
• Based on the range of fuels tested, ethanol
content does not adversely affect the carbon
canister performance
• Canister emissions are driven primarily by the
fuel volatility rather than ethanol content
• MeadWestvaco commercially available
honeycombs can enable FFV’s to attain LEV II
compliance.
ACKNOWLEDGMENTS
The authors wish to express their sincere appreciation to
Joe W. Snead, who aided in the design, operation and
maintenance of the equipment used in the study. Dr.
James R. Miller, who provided support and
encouragement.
REFERENCES
1. R. S. Williams and C. Reid Clontz, “Impact and
Control of Canister Bleed Emissions,” SAE
Technical Paper 2001-01-0733, March 2001.
2. R. S. Williams, MeadWestvaco, Evaporative
Emissions Seminar, 2002.
3. Annual Book of ASTM Standards 2006, Volume
15.01, ASTM International, ISBN 0-8031-4224-2,
West Conshohocken, PA.
4. H. R. Johnson and R. S. Williams, “Performance of
Activated Carbon Canisters in Evaporative Loss
Control Systems,“ SAE Technical Paper 902119,
October 1990.
5. Robert L. Furey, “Volatility Characteristics of
Gasoline-Alcohol and Gasoline-Ether Fuel Blends,”
SAE Technical Paper 852116.
CONTACT

MeadWestvaco Specialty Chemicals Division
P.O. Box 140, Washington Street
Covington, VA 24426
800-336-2211
DEFINITIONS, ACRONYMS, ABBREVIATIONS
BAX 1500: 2mm pelletized MWV automotive carbon
with an ASTM BWC of 14.8 g/dl minimum
Bed Volumes: Volume of air used to purge the canister
divided by volume of carbon in main canister volume
excluding volume of honeycomb
CARB: California Air Resources Board
CPSI: Nominal cells per square inch
Cyc: Abbreviation for “cycled” for simulated driving
cycles used to precondition evaporative emission
canister
DBL: Diurnal Bleed Loss
E-10S: Splash Blended Fuel using 62.1 RVP (E0) and
pure ethanol to 10% Ethanol Concentration, uncontrolled
vapor pressure
E85: 85% ethanol blend
FFV 10%: “Flex Fuel Vehicle 10%,” Fuel blended to
10% ethanol concentration using 48.3 RVP E-85 and
62.1 RVP (E0)
GWC: Gasoline Working Capacity
HCA: Hydrocarbon Adsorber or Honeycomb
LEV: Low Emission Vehicle
PZEV: Partial Zero Emission Vehicle
RVP: Reid Vapor Pressure at 37.8°C (kPa)
SHED: Sealed Housing Evaporative Determination
Tedlar® : DuPont’s registered Polyvinyl Fluoride
products that are chemically inert