Where Did the Fuel Go?

CARB estimates that each year, literally tons of vaporous emissions escape from small portable fuel tanks and therefore requires thicker plastic in the side-walls of jugs as additional prevention. So, we decided to set up a back-yard experiment and see for ourselves.

We took two jerry jugs from the same manufacturer and put them to the test. One jug was CARB-compliant and the other was non-CARB. The only difference between the two was specially treated polyethylene plastic in the CARB jug that is intended to reduce fuel evaporation through the tank walls. Other than the treatment, both cans were identical. We filled both cans with an equal amount of 87% octane fuel, weighed them and put them in the sun for a few months. The results surprised us.

After four months of exposure to direct sunlight in the day and cool temperatures at night the CARB jug had no change in weight. The untreated non-CARB jug lost nearly a pound. There were no leaks, drips or puddles around the can – it simply evaporated, right through the jug! This simple test convinced us that the thicker CARB jug did its job in preventing vaporous emissions.