What is the main difference between a Stage I and a Stage II vapor recovery system?

The main difference between a Stage I and Stage II vapor recovery system lies in their functions during the refueling process. A Stage I vapor recovery system is designed to capture vapors that are displaced from the storage tank during the delivery of fuel to the tank. This means that when a fuel truck delivers gasoline to a storage tank at a fueling station, any vapors that would normally escape into the atmosphere are captured and returned to the delivery vehicle, preventing environmental contamination.

In contrast, a Stage II vapor recovery system is focused on capturing vapors emitted from the vehicle during the actual refueling process. When a driver fills up their car with gasoline, vapor is released from the vehicle’s fuel tank. The Stage II system is designed to capture these vapors and redirect them back to the fuel dispensing system, thereby preventing these vapors from escaping into the atmosphere.

Overall, the correct option highlights that Stage I captures vapors at the tank during delivery, while Stage II targets vapors from the vehicle during refueling, clearly delineating their distinct roles in vapor recovery and emission reduction. This understanding is critical for effective environmental management and compliance with regulations aimed at reducing air pollution from fuel emissions.