Activated
Carbon
for
Use
in
Marine
Evaporative
Control
Applications
MeadWestvaco
Corporation
2
Durability
 
A
carbon
has
been
specifically
developed
for
marine
and
other
high
humidity
applications
 
High
durability
­­
50%
harder
than
automotive
grade
carbons
and
is
30%
less
susceptable
to
generating
dust
during
high
vibration/
rugged
service
applications
 
High
working
capacity
 
Best
for
passive
purge
systems
 
Low
Moisture
Adsorption
Characteristics
 
Necessary
to
maintain
capacity
in
high
humidity
environment
0%

10%
20%
30%
40%
50%
60%
70%
80%
90%

Hardness
(%)
Marine
Carbon
A
Carbon
B
Hardness
Value
0.00
0.05
0.10
0.15
0.20
0.25
0.30
0.35
DA
Rate
(

mg/

min)
Marine
Carbon
A
Carbon
B
Dust
Attrition
Rates
0
2
4
6
8
10
12
14
16
BWC
(

g/

dL)
Marine
Carbon
A
Carbon
B
BWC
Value
3
Passive
Purge
Summary
 
During
the
diurnal
event,
the
air
and
vapors
in
the
fuel
tank
expand
and
contract
in
response
to
the
change
in
temperature
 
Vapors
load
onto
the
carbon
while
the
environment
is
heating,
and
up
to
68%

of
the
vapors
purge
back
into
the
fuel
tank
while
the
system
is
cooling
 
Passive
purge
is
a
simple
approach
for
modest
evaporative
emissions
containment
Filler
Neck
Carbon
Canister
Fuel
Tank
0
10
20
30
40
50
60
70
72
76
80
84
88
92
96
92
88
84
80
76
72
Temperature
(
deg
F)

Cumulative
Standard
Exhaled
Volume
(

L)
121.3
liters
200
gallons
60.7
liters
100
gallons
30.3
liters
50
gallons
18.2
liters
30
gallons
Passive
Purge
Volume
Fuel
Tank
Volume
Passive
Purge
Profile
for
100
gallon
Fuel
Tank
Filled
40%
with
7
RVP
Fuel
To
Engine
4
Passive
Purge
Example
 
100
gallon
tank
filled
50%
with
9.0
RVP
fuel
plus
3.0
Liter
Carbon
Canister
0
20
40
60
80
100
120
140
160
0
5
10
15
20
25
30
Diurnal
(
Day)
Number
Emissions
­

grams
Vapor
Generation
Back
Purge
Emissions
5
Passive
Purge
Hydrocarbon
Containment
Efficiency
 
Relationship
with
Tank
Volume
and
Canister
Volume
1
2
3
4
5
30
50
100
200
Canister
Volume
(
L)
Tank
Volume
(
gallons)

50
%
60%

40%

30%
72
º
F­
96
º
F­
72
º
F
EPA
Diurnal
53%

49%

44%

36%

25%

200
65%

62%

57%

49%

36%

100
68%

68%

67%

62%

49%

50
66%

66%

67%

67%

59%

30
5.0
L
(%)

4.0
L
(%)

3.0
L
(%)

2.0
L
(%)

1.0
L
(%)
Canister
Volume
Tank
Vol
(
gal)

°
A
2.0
L
canister
contains
almost
50%

of
the
vapors
from
a
100
gallon
tank
°
A
4.0
L
canister
contains
almost
50%

of
the
vapors
from
a
200
gallon
tank
°
30­
50
gal
tanks
achieve
maximum
containment
with
2.0­
3.0
L
canisters
6
0
0.2
0.4
0.6
0.8
1
1.2
0
20
40
60
80
100
Relative
Humidity
(%)

Adsorbed
Moisture
(

g/

g)
Effect
of
Humidity
on
Butane
Capacity
for
Marine
Grade
Activated
Carbon
0
20
40
60
80
100
120
140
0%
10%
20%
30%
40%
50%
60%

[
Butane]
(
vol%)

Butane
Capacity
(

g/

L)
100%
RH
0­
80%
RH
Requires
6500
L
air/
L
carbon
to
Saturate
with
Water
°
In
the
presence
of
hydrocarbons,
the
effect
of
humidity
on
carbon
capacity
is
relatively
small
 
over
65%
maximum
capacity
at
100%
relative
humidity
°
Passive
purge
systems
have
25
L
air/
100
L
tank
V
purge
available
°
Forced
purge
systems
typically
have
purge
volumes
of
at
least
100­
200
L
air/
L
carbon
°
Capacity
will
remain
relatively
unchanged
 
moisture
adsorption
will
be
low
Virgin
Marine
HC
Exposed
Moisture
Isotherm
for
Virgin
and
HC
Exposed
Marine
Grade
Carbon
Effect
of
Humidity
on
Butane
Isotherm
for
HC
Exposed
Marine
Grade
Carbon
Virgin
Automotive
7
Summary
 
Activated
carbon
canisters
are
a
viable
and
effective
means
for
significantly
reducing
evaporative
emissions
for
marine
applications
 
Attaching
the
canister
to
the
fuel
tank
and
allowing
the
canister
to
passively
vent
can
maintain
up
to
a
68%
reduction
in
evaporative
emissions
indefinitely
 
a
2.0
liter
canister
can
reduce
the
evaporative
emissions
from
a
100
gallon
fuel
tank
by
almost
50%

 
Marine
grade
carbons
will
not
exceed
a
20%
reduction
in
capacity
due
to
adsorption
of
moisture
from
the
air
 
under
normal
conditions,
the
decrease
in
canister
working
capacity
is
insignificant
 
Activated
carbon
canisters
have
been
successfully
used
to
control
evaporative
emissions
from
gasoline
fuel
tanks
in
automobiles,

motorcycles,
and
lawn
mowers
for
over
30
years
in
countries
all
over
the
world
and
may
be
successfully,
easily,
and
economically
used
for
marine
applications
