Delavan 4.00GPH, 60W (7) nozzle

This article is an oil nozzle from Delavan. In an oil burner, the nozzle is the component that atomises the fuel into a fine spray cone so that it mixes with combustion air and burns completely. It is located at the end of the blast tube inside the combustion head, connected to the high-pressure oil line coming from the oil pump. The nozzle is a precision consumable part: its flow rate, spray angle and spray pattern together determine how the flame sits in the combustion head and how well it stabilises. Parts of this type are selected exclusively by the three parameters that appear on the burner data plate: the flow rate at the reference pressure, the spray angle (commonly between 30° and 80°), and the spray pattern (hollow cone, solid cone or semi-solid cone). The thread size must also match the nozzle holder. A nozzle with the correct delivery rate but the wrong spray angle or pattern will cause sooting, pulsating combustion or unstable ignition. For this reason, when replacing a nozzle, all three parameters must be verified against the original part or the burner specification. The nozzle works together with the oil pump, the solenoid valve and, on preheated systems, the fuel preheater. Correct nozzle selection also affects the oil pressure at the pump, because the pump maintains a set pressure and the nozzle’s orifice size governs the actual flow. Always handle the nozzle with care — the orifice and internal swirl passages are easily damaged by dirt or mishandling, which will degrade the spray quality.