Blowmolded three-layer plastic tanks receive CARB, EPA approval

CARB executive order Q-08-025 states that OEMs can use the material without the need for tank permeation testing. The EPA has also approved fuel tanks using this three-layer design. The supplier (Alpharetta, GA) says it expects the material technology to be commercialized for the first time in a three-layer tank by an unidentified U.S. lawn and garden equipment supplier by the first quarter of 2011.

According to Solvay, three-layer fuel tanks blowmolded of high-density polyethylene, with Ixef BXT 2000-0203 integrated in the middle layer to provide a vapor barrier, not only meet the relevant legal standards but also offer processors a lower-cost solution than other multilayer blowmolded tanks, or ones that are processed fluorinated. Tanks blowmolded using the Solvay material also meet the SAE J233 (-40°F cold impact) test.

Ixef BXT 2000-0203 exceeds the current CARB TP901 standard, which limits fuel-vapor emissions to 1.5 g/m²/day for small off-road engines, and the new EPA regulation for fuel CE10. The barrier material also maintains its mechanical properties in new fuels such as biodiesel and ethanol-based mixtures, reports Solvay.

We reported extensively on Solvay's work on this material in this earlier article from 2008, when the supplier still was working on development of two- or three-layer tanks pairing EVOH with Ixef; now it is able to meet the CARB standard without using EVOH. Three-layer HDPE/Ixef tanks use simpler head tooling than the established five-layer HDPE/tie layer/EVOH/tie layer/HDPE structures. And unlike EVOH, which is limited to continuous-extrusion blowmolding, Ixef BXT 2000-0203 can be run on both accumulator and continuous-extrusion machines.

Solvay also claims Ixef BXT 2000-0203 resin can be used as a barrier solution in two-layer structures with HDPE because it can withstand direct-fuel contact in applications such as fuel lines, filler pipes, low-permeation fuel hoses, and other fuel system components. —[email protected]