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Portable Tanks and Primer Bulbs
Under the new EPA regulations portable gasoline tanks
must have vents that remain closed until at least 5 psi inter-
nal pressure. This creates enormous pressure in a tank, re-
sulting in both fuel leaking through the hose and overflowing
a connected engine and creating surging fuel (a geyser)
when the cap is loosened under pressure.
ABYC’s new H-25 standard addresses the venting options for
portable tanks. A manual relief or automatic relief of pres-
sure is allowed and accepted by the EPA. The EPA has indi-
cated that they will reference ABYC H-25 regarding portable
Primer bulbs used on smaller gasoline engines, are subject
to the same emissions requirements as hoses and plastic
tanks and any other fuel-system component. Final details on
primer bulbs are due out in 2012.
Meeting the Standards on Custom Boats?
What do you do if you’re a custom builder and you’re build-
ing a gasoline boat? You can purchase a complete gasoline
fuel system (such as those from Perko or Attwood). This may
be the simplest way to comply.
Alternately, for most installations, creating a 5% to 8% ul-
lage at the top of the
tank will ensure that fuel
will not remain in the fill
hose. A “forced” ullage
will thus be created by
extending the vent pipe
(and the fill) down into
the tank below the tank
top to the height of the
desired ullage. When the
fuel reaches the level of
the extended vent pipe,
pressure will build and
the fill nozzle will auto
shutoff. If the vent pipe is
located at the geometric
center of the tank top, it
should cause proper shut-
off and proper venting at
the required angles, par-
ticularly for boats over 26
A carbon canister can
then be added to the vent
line, to meet diurnal
emissions requirements,
and a P-Trap vent fitting
to ensure water doesn't
All these new require-
ments are
based. Accordingly, you
can try simple approaches as above, but remember the
word “performance.” You can’t just build a fuel system lik
this and assume it will work. You MUST test it to demon-
strate it actually complies with all the requirements.
Home-built boats must meet these criteria as well, with t
home builder as the builder of record on the compliance
label at the helm.
Not Applicable to Older Boats
New tanks and fuel lines are not subject to the new EPA
requirements when installed in older boat built prior to th
implementation of the standard.
The Last Word
ABYC’s standards H-24 and H-25 cover all the requireme
for a installed or portable gasoline fuel system. ABYC’s p
EPA Regulations for Recreational Boats
, covers t
full range of EPA regulations applicable to pleasure boat
This article was made possible by information provided
ABYC vice president and Tech Department director, Joh
Adey, and by the work of the ABYC PTC committees, whi
in coordination with industry and the EPA, produced the
est versions of H-24 and H-25
The Pressure-Relief System Option
There is an option in 40 CFR to seal the fuel system to 1 psi instead of a using a carbon cani
ter. This method has been employed in the PWC industry for years. It is an option that builde
are currently exploring. H-24 does not give details; however, it does not preclude using this
method. Companies are moving closer and closer to this option for certain types of boats. A
is investigating several issues surrounding this method and will be adding more detailed tes
ing and information as the results dictate.
Courtesy Attwoo