Two CNG tanks on General Motors pickup trucks exploded last winter during refueling, and the Chrysler design changes reflect what the industry has learned from those two accidents.
For 1995, the rear-wheel-drive CNG full-sized van won't get any stone shield, and the front-wheel-drive minivans will get a smaller deflector, said Mike Clement, Chrysler's manager for alternative fuel vehicle sales.
Clement said that under the old design, which was like a bathtub under the tank, drain holes could get plugged. Any accidental corrosive materials such as road salt or spilled battery acid could be trapped next to the tank and weaken it. Something similar is suspected as the cause of the burst GM tanks.
Comdyne Inc. of West Liberty, Ohio, supplies tanks to both GM and Chrysler. The tanks, meant to contain as much as 3,600 pounds per square inch of pressure, come with 'a complete pedigree,' said Clement.
A Comdyne spokesman said it typically takes two to three weeks to build a tank, although it can take four to five months for a new design. Aside from the stone shield design, Clement said, Chrysler's tanks differ from GM's in having a coat of epoxy paint.
Clement predicts that sales of CNG minivans and full-sized vans will treble in the coming model year, just as they trebled for 1994.
For 1994, Chrysler has sold more than 1,000 full-sized CNG vans and 450 minivans, compared with 445 full-sized CNG vans the year earlier. So far, all those tanks have held together.