Re: New EPA regulations on marine fuel tanks means higher costs
Not bunk! No plastic is 100% impermeable and some are more so than others. Current fuel tanks do indeed allow a small bit of "vapor" to pass through. Not enough that you will see a loss in the tank or weepage on the outside, but enough to notice. Don't believe it? Fill a six gallon tank with gas, cap it, and leave it in a closed garage for about a week. Then go and smell the garage. Leave it in your trunk for a day and you won't be able to get into the car without opening the windows.
Multiply that by the millions of small tanks in use and you have a significant amount of hydrocarbons being released into the air.
For just that reason, it took many years for certain plastic compounds to be approved by the ATF Bureau of Alcohol, Tobacco, and Firearms) here in the US to approve plastic bottles for booze.