Buse Monarch 5.50GPH, 60HO

This article is a Monarch oil nozzle, catalogue item 732.892.137, with a flow rating of 5.50 GPH and a designation of 60HO. Oil nozzles of this type atomise the fuel into a fine spray cone so that combustion can be complete and stable. They are precision consumables: the spray angle, flow rate and spray pattern together determine how the flame sits inside the combustion head. A nozzle with the correct rating but the wrong pattern or angle will cause sooting, pulsation or unstable ignition, so all three parameters must match the burner data plate exactly. When replacing a nozzle of this class, confirm that the flow rate (in GPH or kg/h at the reference pressure), the spray angle (typically 30–80 degrees) and the pattern (hollow, solid or semi-solid) are identical to the original part. The nozzle thread and the pressure at which the pump is set also affect performance. Because the nozzle directly shapes the flame, any deviation from the specified type will alter the heat release and may lead to flame failure, carbon build‑up or excessive flue gas temperatures. This part is fitted into the burner’s blast tube and connected to the oil pump via the high‑pressure line. In a typical oil‑fired system, the burner control energises the pump solenoid, and the nozzle atomises the pressurised fuel. The ignition spark from the electrodes must be correctly positioned relative to the spray cone. Always replace a nozzle at the interval recommended by the burner manufacturer and handle it with care to avoid damaging the precision orifice.