Where are vent restriction devices installed in relation to the UST?

Vent restriction devices are specifically installed at the vent opening of a UST (Underground Storage Tank) to manage the flow of air and vapors. Their primary purpose is to limit the release of vapors into the atmosphere while allowing for proper venting during tank filling and emptying operations. This is crucial for safety and environmental reasons, as it helps prevent over-pressurization or vacuum conditions that could affect the integrity of the tank or lead to potential spills and leaks.

Installing the vent restriction device at the vent opening ensures that it can effectively control the vapor emissions without interfering with the operations of the fill pipe or any connected systems. Proper installation at the vent opening also enhances the tank's overall compliance with regulatory requirements focused on minimizing air pollution and protecting public health.