Delavan 5.50GPH, 60W (7) nozzle

This is a Delavan 5.50GPH, 60W (7) oil nozzle, a precision consumable part that atomises fuel oil into a fine spray for complete combustion. Nozzles of this type are selected by three parameters that together determine flame shape and stability: flow rate (given here as 5.50 GPH at the reference pressure stated on the burner data plate), spray angle, and spray pattern (hollow, solid or semi-solid cone). The designation “60W (7)” on this article refers to the spray angle and pattern type, but these codes must be read against the manufacturer’s specification sheet or the burner’s original nozzle recommendation. In an oil burner, the nozzle is the final element in the fuel delivery path, mounted in the combustion head. The oil pump delivers fuel at high pressure; the nozzle then atomises it into droplets that mix with combustion air. A nozzle with the correct flow rate but wrong spray angle or pattern can cause sooting, pulsation or unstable ignition. When replacing a nozzle, always verify that rating, angle and pattern match the burner data plate—not just the part number. The thread size must also correspond to the burner’s nozzle holder; this article uses a standard thread common to most residential and light commercial oil burners. As a consumable, the nozzle should be replaced at regular intervals or whenever combustion quality deteriorates, because wear or carbon deposits alter the spray characteristics. The Delavan brand is widely encountered on oil burners in this market sector.