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Understanding The EPA’s Evaporative Emission Standards And Requirements.

Last week I discussed some of the goings on at ABYC Standards week in Orlando. Well I’m back, but I woke up this morning with a few questions for myself….With all that’s going on with the EPA’s mandates to control evaporative emissions for all manner of things with engines, including boats, when exactly are boat builders supposed to do what to stay on the right side of the law? It’s a little confusing.

So, I went to the law that covers Control of Evaporative Emission for “off-road” equipment, CFR title 40, part 1060 and looked over the table contained therein that explains this. Let me share it with you:

Several things need some explaining related to the above table. First, the term “SI” simply refers to spark ignition, read, your gasoline fueled engine. Permeation is a term that describes the ability of the fuel vapors to migrate through a material such as fuel hose, or a plastic fuel hose.

Fluid doesn’t leak, but some vapors do, and yes they evaporate into the atmosphere. The bottom line here is that what has for years been described as a permeation rate of 100 grams/meter squared over a 24 hour period has been reduced to 15 grams /meter squared over a 24 hour period, a significant up specification.

The fuel line is currently available, plastic fuel tanks that meet this specification are not yet available, but the vendors basically have until January 1, 2011 to come up with some product.

For those not understanding the term “diurnal”, the ABYC describes it this way: “evaporative emissions that occur as a result of venting fuel tank vapors during daily temperature changes while the engine is not operating.” This will all be controlled by the charcoal filtration system I mentioned last week.

So, are you evaporating? Right now you are, but as you can see, over the next several years the EPA is going to slow that process down dramatically.

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