Danfoss Oil pump BFP21 R3 071N0171

The Danfoss BFP21 R3 oil pump is a gear pump designed for small and medium-sized household burners with a fuel consumption of up to 42 l/h. It operates in single-pipe or two-pipe systems, drawing fuel through a filter and increasing its pressure via a gear mechanism. A diaphragm regulator maintains constant pressure within the range of 7000–20000 mbar, with factory settings at 10 ±1 bar. The pump features a shaft standard of EN225, a filter area of 11 cm² with a 200-micron cross-section, and operates within ambient temperatures of -20 to 70 °C, storage temperatures of -25 to 120 °C, and fuel temperatures of 0 to 70 °C. It has a protection class of IP40, a maximum inlet pressure of 2000 mbar, and a maximum pressure in the suction/return line of 2 bar.

When selecting a replacement oil pump of this type, ensure the shaft standard (e.g., EN225) matches the burner's coupling, and verify the shaft rotation speed range (2400-3450 min) is compatible with the motor. The pump's pressure range and fuel consumption must align with the burner's requirements, and the system type (single-pipe or two-pipe) must be confirmed, as the pump configuration differs (e.g., return line screw presence). Check the viscosity range of the fuel (1.8-12.0 cst) and the filter area/cross-section to ensure proper filtration. Also, confirm the inlet pressure does not exceed the maximum specified, and that the ambient, storage, and fuel temperatures are within the pump's limits.

Common failures in gear pumps of this kind include loss of pressure due to worn gears or a faulty diaphragm regulator, leading to incomplete combustion or burner pulsation. A clogged filter can cause fuel starvation, resulting in the burner failing to start or shutting down intermittently. Leaks in the shaft seal or diaphragm may cause fuel to drip, and a stuck normally-closed valve can prevent fuel flow, causing the burner to lock out. Check the filter for debris, inspect the diaphragm for damage, and verify the pressure settings against the burner's specifications.