Page 4 - WestlawnMasthead20_Dec11

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Evaporative emissions are fuel that escapes from the fuel
system through permeation through the walls of hoses or of
plastic tanks or, as a result of ventilation. On small gasoline
fuel systems, the primer bulb can also be a source of evapo-
rative emissions.
Diurnal Emissions are the daily emissions of fuel that es-
cape through the vent. They are daily or diurnal as the cycles
in temperature from day to night (during a 24-hour period)
cause regular expansion and contraction of the fuel. This
results in gasoline vapor and droplets escaping through the
vent. (Diurnal means recurring every day, or having a daily
Fueling spitback or wellback is spitting or splashing of fuel
back out of the fill pipe past or around the fill nozzle.
Evaporative Emissions
Fuel-line hoses were identified as one of the ways in which
gasoline vapors could escape into the atmosphere. Standard
USCG/SAE marine fuel hose was rated A1 or A2 or B1 or B2.
The A and B indicate fire rated or not. The 1 and the 2 are
USCG permeability ratings. Under SAE (Society of Automo-
tive Engineers) standard J-1527, the 1 equals 100 grams
per square meter permeation rate per day, the 2 equals 200
grams per square meter permeation per day. The EPA deter-
mined that only 15 grams per square meter per day was
After extensive testing, it was found that most (but not all)
standard A1 USCG fuel already in use actually met the 15 g/
sq.m per day requirement. New marine fuel hoses must now
all meet the 15 g/sq.m. per day standard. These new hoses
must be marked:
A or B and 1, plus “-15” for the EPA standard.
Compliant fuel hose marking is:
USCG TYPE A1-15 J1527 (or ISO 7840)
The A = USCG fire test
The 1 = USCG permeation test rating
The -15 = EPA
ermeation requirements.
A “B” instead of an “A” would indicate that the hose did not
have a fire resistant cover to pass the 2-1/2-minute burn
Traditionally, marine fuel hose with the “1” rating was ex-
pected to have fuel in it a good portion of the time, while
“2”-rated hose was not intended to have fuel in it. Hose
rated 2 will not meet the -15 EPA requirement, so A2 an
B2 hose can now primarily only be used on diesel boats. I
fact, you will not find an A2 or B2 hose that had the addi-
tional “-15” marking required for use on gasoline system
The exception is A2 fill hose for fill lines. If it can be dem
strated that the fill hose will not contain or hold fuel itself
A2 can be used. (This brings us to auto fuel-nozzle shut-o
covered below.)
Metal fuel tanks do not suffer from permeation, but plast
gasoline fuel tanks can. ABYC began a working group to
identify the challenges of creating a tank that meet the E
permeation rating while still maintaining the safety and r
ability of cross-linked polyethylene. After several meeting
became clear that technology was becoming available to
meet the permeation ratings while passing the current te
and maintaining the current properties of plastic tanks. A
tanks must now meet the traditional tests as well as the
EPA permeation requirements.
One nice aspect of this is that the new permeation rate f
well below the threshold for the ventilation required of
spaces containing gasoline equipment. It will no longer b
necessary to vent a space containing a plastic gasoline t
once these tanks meet the EPA permeation requirement
As with hoses, many tanks (though not all) met the EPA
threshold for years even though there was no requireme
do so.
Diurnal Emissions
Carbon Canisters
In order to reduce the hydrocarbons escaping into the at-
mosphere as a result of diurnal emissions, it was found t
a carbon canister should be added to the gasoline vent li
In fact, this is the same as automotive carbon canisters.
USCG A1-15 Fuel Hose
Courtesy Trident Hose
Carbon Canister
Courtesy Attw