Delavan 3.50GPH, 90B (7) nozzle

This is a Delavan 3.50GPH, 90B (7) nozzle, catalogue article 345.892.047, manufacturer code 00350-90B7. It belongs to the category of oil nozzles, which are precision consumable parts used in oil-fired burners. The nozzle atomises fuel oil into a fine spray cone so that it mixes with combustion air and burns completely. It is installed in the combustion head and directly determines how the flame sits and behaves. Because the nozzle is a wear item subject to heat and pressure, it should be replaced at regular service intervals to maintain clean combustion. Parts of this type are selected by three parameters: flow rate (given in US gallons per hour at a reference pressure), spray angle (typically between 30 and 80 degrees), and spray pattern (hollow, solid, or semi-solid cone). All three must match the burner manufacturer’s specification on the data plate. A nozzle with the correct flow rate but the wrong angle or pattern can cause sooting, pulsation, unstable ignition, or flame impingement. When replacing a nozzle of this class, the exact rating, angle, and pattern of the original part should be verified, and the thread size (standard 1/8” BSP or NPT on most domestic oil nozzles) must also be compatible with the burner’s nozzle adapter. The nozzle works with the oil pump, which pressurises the fuel, and the solenoid valve, which opens to admit oil during the start cycle. On burners with a preheater, the oil may be pre-warmed before reaching the nozzle to improve atomisation. During commissioning or troubleshooting, a heating engineer should check that the nozzle is clean, correctly seated, and free of carbon deposits. Using a part with the wrong parameters can lead to lockout or inefficient operation, so careful selection based on the burner’s original data is essential.