Buse Delavan 0.75GPH, 45B (1)

This is a Delavan oil nozzle with a nominal flow rate of 0.75 GPH and a 45-degree spray angle, identified by the manufacturer codes P0075-45B1, 3042056, and 345.892.126. The “B” in the designation refers to the spray pattern type, which together with the flow rate and angle defines how the atomised fuel cone sits inside the combustion head. Nozzles of this type are precision consumables; the flow rating is typically given at a standard reference pressure (often 100 psi / 7 bar for domestic burners), so the actual delivered flow depends on the pump pressure set in the appliance. An oil nozzle’s function is to atomise the fuel into a fine mist that mixes with combustion air for complete burning. The three selection parameters—flow rate, spray angle, and pattern (hollow, solid, or semi-solid)—must match the burner data plate. Using a nozzle with the correct rating but an unsuitable pattern can cause sooting, flame instability, or ignition failure, because the flame shape no longer matches the combustion head geometry and airflow pattern. The spray angle (here 45 degrees) determines how wide the flame cone opens, and the pattern controls the fuel distribution across that cone. When replacing a nozzle of this type, always verify that all three parameters match the burner manufacturer’s specification. The nozzle threads into the end of the oil pump or nozzle holder; do not overtighten. Handle the nozzle by its body, never touch the orifice or the spray tip, as oil residue or dirt can distort the spray pattern. After replacement, check the flame shape and combustion readings to confirm correct operation.