System and method for evaluating the presence of air in a liquid-state fuel stream

摘要

A system (21) for monitoring the quantity of air in a liquid-state fuel stream discharged from a dispenser (20). The dispenser includes a pump (26) that draws the fuel from a storage tank (22). The fuel stream discharged from the pump is applied to an air separator (38) in which the air and vapor-state fluids are removed from the fuel stream. The gas-removed fuel stream is allowed to flow to nozzle (44) for dispensing. The gas stream created by the air separator is flowed to an air elimination chamber (41). The fuel in the gas stream separates from the air in the air elimination chamber and is returned to an input side of the pump. The air in the air elimination chamber is vented through a fixed opening to the ambient environment. The monitoring system (21) includes a transducer (48) that monitors the rate of air flow through the air elimination chamber. This monitoring may be performed by monitoring the air pressure in the chamber upstream of an orifice through which the air is vented to atmosphere. If the air flow rate is greater than a set level, the system closes a valve (57) that regulates fuel flow to the nozzle (44). Thus, this system (21) prevents fuel that contains an excessive quantity of gaseous-state fluids from being dispensed.