The six-layer construction includes a vapor barrier that effectively contains hydrocarbon emissions.
Fuel tank for a tractor
Fuel tank for a handheld application
Walbro Engine Management is expanding its multi-layer fuel tank production capabilities around the world, including its Cass City, MI, plant. The move is in response to the growing demand for fuel tanks that meet increasingly stringent clean air standards.
“As tighter and tighter evaporative emission regulations are implemented and enforced, our multi-layer fuel tank technology provides customers with a reliable solution that ensures compliance to the end of a product’s life cycle, using a variety of fuels,” says Tony Martin, president and chief executive officer, Walbro Engine Management.
Walbro installed its third blow-molding machine in Cass City at the beginning of this year. A current expansion of the facility is now underway to house additional blow-molding machines. The fourth is scheduled for installation by year’s end. Walbro expects to produce one million tanks this year, two million in 2012 and three million in 2013 as demand continues to grow.
Overview of EPA evaporative emission standards
The EPA’s adoption of new HC+NOx exhaust emission standards began this year for Class II engines (exceeding 225cc). Standards for Class I engines (100 to 225cc) go into effect in the 2012 model year. EPA expects manufacturers to meet these standards by improving fuel systems and engine combustion, and in some cases adding catalysts. Visit the EPA website for further information.
Additionally, EPA is adopting new evaporative emission standards which include requirements to control fuel tank permeation, fuel line permeation and diffusion emissions. EPA is also requiring control of running losses for non-handheld engines.
Permeation emissions from fuel tanks may not exceed 1.5 g/m2/day when measured at a nominal temperature of 28° C, or 2.5 g/m2/day when measured at a nominal temperature of 40° C.
Visit the EPA website for more on evaporative emissions.
Adoption trending up
While multi-layer fuel tanks are relatively new to small engine equipment, they represent an established technology in the automotive industry where evaporative emissions standards first appeared. Walbro helped pioneer those efforts dating back to 1992.
Walbro’s multi-layer fuel tanks are now being used in recreational and marine products—along with lawn and garden. According to Chris Quick, Walbro Engine Management’s global fuel systems director, the company currently has six major global customers in the lawn and garden arena that are using its multi-layer fuel tanks. Three additional OEMs are expected to begin using the fuel tanks next year.
“We introduced our first multi-layer fuel tank to the lawn and garden market in 2006, and then issued our first full production run in 2007,” Quick says. “We started with a Japanese manufacturer. Oddly enough, that company was one of the last to come to the table in the automotive industry, but was the first when it came to lawn and garden.” Quick says that’s an indication of how pleased the company has been with the performance of this fuel tank technology.
Benefits of multi-layer technology
The six-layer construction includes a vapor barrier that effectively contains hydrocarbon emissions. This EVOH (ethyl, vinyl, alcohol) layer reduces permeation to below 0.5 g/m2/day, well within the EPA requirement. Then, the high-density polyethylene resin provides for durability.
Lawn and garden manufacturers do have other options, Quick concedes, but the performance of multi-layer technology in the automotive industry is helping position it as a frontrunner. “Once you assign a durability requirement, which in the case of fuel tanks is ‘end of life,’ multi-layer is a proven winner,” Quick says. Lawn and garden equipment life varies by engine class—anywhere from 125 hours of use up to 1,000, or five years. “Millions of multi-layer tanks are used in global automotive production annually, and are validated to meet expected vehicle life of up to 150,000 miles or 15 years,” Quick points out.
Multi-layer tanks also work well when it comes to ethanol. “Ethanol is very polar, so it likes to get through the EVOH barrier,” Quick explains. “But the high-density polyethylene resin stops it.” Quick says this is going to become an increasingly important benefit as the use of ethanol increases in coming years.
Other benefits of multi-layer fuel tanks include impact-, UV- and chemical-resistance; the ability to be molded into elaborate geometries to maximize fuel capacity; and their relatively light weight. Walbro’s multi-layer tanks specifically offer the added benefit of being blow-molded, eliminating the need to weld two tank halves.
While the EPA’s evaporative emission standards have been finalized and are taking effect this year and next, Quick says manufacturers shouldn’t rest on their laurels. “The auto industry has gone in four shifts when it comes to permeation,” Quick relates. “So everybody sees the train coming. There’s already discussion in marine about additional regulations that could be on the way.” There’s nothing new for lawn and garden yet—yet.