???
vapor recovery systems (stage 2) recover vapors and any condensed or slurped product to go back to the tank...this system does NOT drain the hose or product piping....modern single hose MPDs (multiple product dispensers) have a blender mechanism that blends low grade and high grade fuels to get the desired mid grade. this saves cost and requires a station to only have 2 tanks...and makes fuel deliveries easier. so basically the hose and a little bit of piping in the dispenser itself will be the amount of low grade is dispensed when you select high grade (assuming previous customer selected low grade). so figure hose length = L, 1" hose contains === 3.14 x (1/12)^2/4 x 7.48 x L gallons
but hey, it's not like I work in the business for the last 25 years