Danfoss Oil pump BFP21 R5 071N7173

The Danfoss BFP21 R5 oil pump (SKU 071N7173) is a gear-type pump designed for small and medium-sized household oil burners with fuel consumption up to 42 l/h. It operates within a viscosity range of 1.8-12.0 cst (mm2/s) and a pressure range of 7000-20000 mbar, with a factory setting of 10 ±1 bar. The pump features a filter area/cross-section of 11/200 cm2/microns, a maximum inlet pressure of 2000 mbar, and a maximum pressure in the suction/return line of 2 bar. It is suitable for single-pipe or two-pipe systems and includes a normally closed solenoid valve and a diaphragm regulator to maintain constant pressure. The shaft is made of EN225 material and rotates at speeds between 1400 and 3450 min.

When selecting an oil pump of this type, ensure the shaft standard (e.g., EN225) and rotation speed range match the burner's drive. Verify the pressure range and factory setting align with the burner's requirements, and confirm the fuel consumption rating (up to 42 l/h) is sufficient. The pump must be compatible with the system type (single-pipe or two-pipe) and the viscosity of the fuel used. Check the inlet pressure does not exceed the maximum specified (2000 mbar) and that the ambient, storage, and fuel temperatures are within the given limits.

Common failures in oil pumps of this kind include loss of pressure due to worn gears or a stuck diaphragm regulator, leading to incomplete combustion or burner shutdown. A clogged filter can cause fuel starvation, resulting in pulsating flame or no ignition. Leaks in the shaft seal or diaphragm may cause fuel to drip, and a faulty solenoid valve may fail to open, preventing fuel flow. Symptoms include irregular burner operation, soot formation, or the burner not starting. Check the filter, pressure settings, and valve operation when diagnosing issues.