Diurnal Emission Control

October 7th, 2008

Sources of Hydrocarbon Emissions

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1. Permeation – through fuel tank walls2. Spillage/Spitback – during fuel fill3. Exhaust – during engine operation4. Diurnal emissions – due to daily

temperature cycles

California/EPA Diurnal Emission Limits

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Trailerable boats (<8.5ft beam & <26ft LOA):• Less than .4 grams per gallon per day of

hydrocarbon emissions.Non-trailerable boats (>8.5ft beam or >26ft LOA):• Less than .16 grams per gallon per day of

hydrocarbon emissions.

How to Meet Diurnal Emissions Standards

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Utilization of a carbon canister system• Currently the standard in the auto industry • Fairly easy installation with low risk

Pressurized fuel system (1 psi)• Higher risk if connections fail – potential of

significant fuel leakage in hull of vessel• May require alternative fittings or connection

methods• Currently not recommended by the USCG

Carbon Canister Basics

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• Required size of canister is determined by the length/width of the boat as well as the capacity of the fuel tank

• Liquid water must not enter the canister• Adequate care must be taken so that liquid fuel does not

enter the canister• The canister should be mounted above the top level of

the fuel tank• “Marine Grade” carbon is required• ABYC requires that the vent line be “self-draining”

Carbon Canister Sizing

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Canister (Liters)

Tank (Gallons)

Canister (Liters)

Tank (Gallons)

1 <25 1 621.5 37 1.5 932 50 2 1253 75 3 1874 100 4 250

Canister Sizing versus Fuel Tank Size

Trailerable Non-trailerable

Formula (round up to the next largest size)LitersCC= 0.04x Fuel tank LitersCC= 0.016x Fuel tank

Carbon Canister Available Sizes

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• 1L• 1.5L• 2L• 3L• 4L

Two or more canisters can be “daisy chained” together for increased capacity or to

facilitate installation

Installation Examples

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• Recent high-performance builder carbon canister installation examples:

Installation Examples

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Fit-up Key Findings

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Diurnal emission control does not allow for a “component solution”. A system

perspective is required.

Generation 1.0 Fuel System -- 2009

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22SEP08 Brunswick Confidential

Sean WhelanProduct Development Engineer

Hardware, Fuel & Trailering Categoriesphone/fax (616) 897-2275 / (616) 897-2218

In Line Surge Protector

P-Trap

2L Carbon Canister

Key Installation Notes

Builders will need to ensure no water of fuel comes in contact with the carbon canister

• A P-Trap vent or similar device should prevent water intrusion

• Surge protectors are needed to prevent fuel from entering the canister

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Summary

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• Each boat application presented different challenges, builders should not wait until the last minute to spec in the system

• There are alternative ways to meet various EPA guidelines, talk with your fuel system provider ahead of time to understand your options and minimize costs

• The proposals are now implemented, builders can’t take a wait and see attitude

• We recommend partnering with a systems provider vs. component supplier to ensure your boats meet the latest fuel system regulations

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