Office of Transportation EPA420-F-06-029
Untt"d"tat~s and Air Quality March 2006
Environmental
Agency
Program Update
on the
of for
50
The U.S. (EPA) has a
the of applying emission controls
to nonroad spark-ignition (SI) engines. The technical study concludes
that adding emission control technologies would not the risk of
fire and to fire due to with
refueling.
is the SI
This technical study assesses the incremental Impact on safety of apply-
ing the advanced emission control technology expected to meet the new
emission standards that EPA is considering for particular subcategories
of nonroad engines and equipment, focusing on the risk of fire and burn
to consumers. The study will be part of the rulemaking record for the up-
coming proposed standards and satisfies the provisions of section 205 of
PL 109-54, which requires EPA to assess potential safety issues, Includ-
ing the risk of fire and bum to consumers, associated with the proposed
emission standards for nonroad SI engines under 50 horsepower (hp).
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of and are by
the
This study evaluates new exhaust and evaporative emission standards for
nonhandheld and handheld equipment in the Small SI engine category
(such as lawn and garden equipment) and outboard and personal water-
craft engines and vessels in the Marine SI engine category.
of is
considering?
New catalyst-based standards to reduce exhaust emissions of hy-
drocarbons (HC) and oxides of nitrogen (NOx) from nonhandheld
engines.
New standards to reduce exhaust emissions of HC, carbon monoxide
(CO), and NOx from Marine SI engines.
New emission standards to reduce evaporative fuel emission from
most types of equipment and vessels in the Small SI and Marine SI
categories.
are the
For each new standard, we conclude that the anticipated emission stan-
dards may be implemented without any incremental increase in risk of
fire or burn to consumers. The testing and analysis further indicates that
compliance with the anticipated emissions standards could somewhat
reduce the risk to consumers using products in these subcategories.
are the to
for
We conducted the technical study of the incremental risk of catalyst-
based HC+NOx emission standards for nonhandheld Small SI engines on
several fronts. First, working with the Consumer Product Safety Commis-
sion (CPSC), we evaluated CPSC reports and databases and other outside
sources to identify those in-use situations which create fire and burn risk
for consumers. The following scenarios were identified for evaluation:
• Thermal burns due to inadvertent contact with hot surface on engine
or equipment
Fires from grass and leaf debris on the engine or equipment
• Fires due to fuel leaks on hot surfaces
Fires related to spilled fuel or refueling vapor
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* Equipment or structure fire when equipment is left unattended after
being used
• Engine malfunction resulting in an ignitable mixture of unburned
fuel and air in the muffler (engine misfire)
« Fire due to operation with richer than designed air-fuel ratio in the
engine or catalyst
Second, we conducted extensive laboratory and field testing of both
current technology (Phase 2) and prototype catalyst-equipped advanced-
technology engines and equipment (Phase 3) to assess the emission con-
trol performance and thermal characteristics of the engines and equip-
ment. We also contracted with Southwest Research Institute (SwRI) to
conduct design and process Failure Mode and Effects Analyses (FMEA)
comparing Phase 2 and Phase 3 compliant engines and equipment to
evaluate incremental changes in risk probability as a way of evaluat-
ing the incremental risk of upgrading Phase 2 engines to meet Phase 3
emission standards. Our technical work and subsequent analysis of all of
the data and information strongly indicate that catalyst-based standards
can be implemented without an incremental increase in the risk of fire or
burn to the consumer.
are the to
for Small SI
We also evaluated the incremental risk of fire and burn to consumers
for the evaporative emission standards we are considering for handheld
and nonhandheld equipment. For both subcategories, we are consider-
ing standards to control fuel tank permeation and fuel hose permeation
similar to those in place for other nonroad SI engines and vehicles,
such as all-terrain vehicles and off-highway motorcycles. In addition,
for nonhandheld equipment, we are considering requirements to reduce
emissions related to evaporation of fuel during operation. Working with
CPSC, we evaluated CPSC databases to identify those in-use situations
that create fire and burn risk for consumers. Fuel leaks from tanks or fuel
hoses on handheld and nonhandheld equipment were identified as the
major safety concern for evaluation.
Fuel tanks used on handheld and nonhandheld equipment are constructed
of different types of materials using different processes and each has a
potentially different approach to controlling tank permeation emissions.
EPA evaluated both current and treated fuel tanks in the laboratory for
several years and identified no incremental safety risk related to the
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technologies for reducing permeation emissions. Most fuel hoses meet
American Society for Testing and Materials (ASTM) and Society of Au-
tomotive Engineers (SAE) standards, and the types of fuel hoses needed
to reduce permeation are in widespread use today. In fact, some lawn and
garden equipment already uses low permeation hose.
Beyond this, in situations where custom fuel hoses are used, there are the
ASTM^ and manufacturer-specific test procedures and requirements that
ensure proper in-use performance. With regard to fuel tanks, there are
manufacturer-specific test procedures and requirements that manufactur-
ers apply to current products and will continue to use in the future. The
durability portion of EPA's permeation test procedures inherently in-
cludes the types of evaluations needed to identify the potential for leaks
in-use.
The Failure Modes and Effects Analysis conducted by Southwest Re-
search Institute also looked at systems interaction between engine modi-
fications and the fuel system and determined that permeation controls
and running loss controls for nonhandheld equipment would not increase
the fire and burn risk probability, but could in fact lead to directionally
better systems from a safety perspective. Overall, there is no incremen-
tal safety risk in applying advanced technology to reduced evaporative
emissions from handheld and nonhandheld engines and equipment.
are the to
for
The Coast Guard keeps a close watch over marine safety issues. The
Coast Guard, as well as organizations such as SAE, Underwriters Labo-
ratories, and the American Boat and Yacht Council (ABYC), already
have safety standards that apply to engines and fuel systems used in
these vessels. The four-stroke and two-stroke direct injection engine
technologies that are likely to be used to meet the exhaust emission
standards contemplated for outboard and personal watercraft engines
are in widespread use in the vessel fleet today. These more sophisticated
engine technologies are replacing two-stroke carbureted engines. The
four-stroke and two-stroke direct injection engines meet applicable Coast
Guard and ABYC safety standards and future products will do so as
well. The proposed emission standards must be complementary to exist-
ing safety standards, and our analysis indicates that this will be the case.
There are no known safety issues with the advanced technologies com-
pared with two-stroke carbureted engines. The newer-technology engines
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arguably provide safety benefits due to improved engine reliability. Based
on the applicability of Coast Guard and ABYC safety standards and the
good in-use experience with advanced-technology engines in the cur-
rent vessel fleet, we believe new emission standards would not create an
incremental increase in the risk of fire or burn to the consumer.
are the to
for
We also analyzed the incremental impact on safety for the standards
under consideration to reduce fuel hose permeation, fuel tank permeation,
and diurnal emissions. As with the exhaust emission standards, any EPA
emission standards must complement existing Coast Guard, ABYC, and
SAE performance and safety standards related to fuel hoses for marine
vessels and similar standards covering portable and installed fuel tanks.
All these standards are designed to address the in-use performance of
fuel systems with the goal of eliminating fuel leaks. The low-permeation
fuel lines needed to meet Phase 3 requirements would need to pass these
standards, and evidence indicates that this would occur. In fact, fuel lines
meeting these requirements are available today. The low-permeation fuel
tanks needed to meet the Phase 3 requirements would also need to pass
the applicable Coast Guard, Underwriters Laboratories, and ABYC stan-
dards. Work conducted by EPA and vendors supplying the marine tank
industry indicates that the technology needed to meet these standards can
be applied without an incremental increase in risk over current systems.
We are also considering diurnal emissions standards for fuel tanks used
on Marine SI vessels. For personal watercraft and portable outboard fuel
tanks, this would likely involve the use of fuel tank venting that is al-
ready commonly used. For vessels with installed fuel tanks, this would
likely involve the use of activated carbon canisters to capture vented fuel
vapors. Such canisters have been used safely on automobiles for more
than 30 years and a prototype fleet run by industry last summer on marine
vessels revealed no safety concerns. Overall, there should be no increase
in risk of fire or burn to consumers in applying advanced technology to
reduce evaporative emissions from these marine engines and vessels. In
fact, the reduction of permeation emissions is likely to decrease safety
risks from fire in the under-floor areas on boats where the tanks and hoses
are installed.
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the for
Review?
Yes. We contacted three individuals with considerable expertise that was
relevant to the scope of the safety study. Jim Hoebel spent 28 years at
CPSC, including a position as Chief Engineer for Fire Safety; he is also
a member of the National Association of State Fire Marshals. Mr. Hoe-
bel encouraged some broadened discussion of safety concerns, but noted
that the conclusions strongly support proceeding with Phase 3 exhaust
emission standards for nonhandheld engines. Sam Coates has 20 years of
experience in designing Small SI and Marine SI engines, and is currently
an engineering professor at Michigan Technical University. Dr. Coates
affirmed the study's approach and conclusions as well reasoned and well
supported. Ron Heck is currently acting as a consultant after working
in catalyst research and development for 31 years. Dr. Heck suggested
several ways of expanding discussion to account for various additional
factors and conditions. In addition, we have prepared the report in coor-
dination with staff from the Coast Guard and CPSC. The safety study ad-
dresses each of the comments received from peer review and inter-agency
review.
Are we to the
Yes. We will be holding outreach briefings with key stakeholders in the
week following publication.
can I
You can access this technical study on EPA's Office of Transportation and
Air Quality Web site at:
• Lawn and Garden Equipment: www.epa.gov/otaq/equip-ld.htm
* Gasoline Boats & Personal Watercraft: www.epa.gov/otaq/marinesi.htm
For further information on the study, please contact the Assessment and
Standards Division at:
U.S. Environmental Protection Agency
Office of Transportation and Air Quality
2000 Traverwood Drive
Ann Arbor, MI 48105
734-214-4636 (voicemail)
E-mail: asdinfo@epa.gov
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