Patent ID: 6805173
Filing Date: 2004-10-19
Classification: B67D

Abstract:
A passive pressure control method for controlling pressure in ullage vapor space of a volatile liquid fuel underground storage tank (â€œUSTâ€ ) comprising the steps of:removing liquid fuel from the UST, including for delivery into a vehicle fuel tank, delivering into the ullage vapor space of the UST, to replace the volume of liquid fuel removed, a gaseous flow comprising at least one of: (a) fuel vapor and air, e.g. displaced from the fuel tank by delivery of the liquid fuel; and (b) air; and, during periods of increasing ullage vapor space pressure, allowing vapor to flow from the ullage vapor space into an auxiliary vapor space of variable volume defined at least in part by a resilient wall member, the flow of vapor into the auxiliary vapor space causing deflection of the resilient wall member, thereby increasing the combined vapor storage volume of the ullage vapor space and the auxiliary vapor space.