Delavan 50.00GPH, 45B Düse

This is an oil nozzle from Delavan, listed as a 50.00 GPH nozzle with a 45B designation. Parts of this type are precision consumables that atomise fuel oil into a fine spray so it can burn completely within the combustion head. The nozzle is mounted on the burner’s oil line, downstream of the pump and solenoid valve, and directs the spray into the flame tube. Correct flame shape depends on three parameters: the flow rate (here stated as 50.00 GPH, measured at the reference pressure on the burner data plate), the spray angle, and the spray pattern (hollow, solid, or semi-solid). The 45B marking is a code for angle and pattern, but the exact interpretation should be verified against the burner manufacturer’s specification—do not assume it matches a particular degree or pattern without checking the original part or the burner manual. When replacing an oil nozzle, the three parameters must match the values on the burner data plate, not just the part number. A nozzle with the correct flow rate but the wrong pattern can cause sooting, pulsation, or unstable ignition. The thread size is also critical; most oil nozzles use a standard 1/8″ or 1/4″ BSP thread, but confirm compatibility with the burner’s nozzle adapter. Because the nozzle is a wearing part, always replace it with a unit of identical rating, angle, and pattern—do not substitute by flow rate alone. For this article, the brand is Delavan and the manufacturer code is 05000-45B0; the catalogue reference is 345.892.244. Ensure the replacement nozzle carries the same designations before installation.