Danfoss BFP 21 LE-S Data sheet

Data sheet

Oil Pump type BFP 21 LE-S

- size 3 and 5

Application BFP 21 LE-S oil pumps are designed for small/

domestic oil burners up to 42 l/h.

Function

H

A

Pressure Suction Return

Before the burner starts the oil is heated in the
oil preheater and in the nozzle line. This causes
the oil to expand. The safety shut-off valve in
the preheater prevents the oil from dripping
out of the nozzle because the check valve B in
the solenoid valve opens and thus makes a
connection to the return or suction side of the
pump.
The preheater valve opens at a pressure ≥ 6 bar.
The check valve B in the solenoid valve NC
opens at a pressure of max. 2 bar.
When the burner starts the required atomizing
pressure in the pump is built up and this
pressure ensures that the check valve B closes
and remains closed during the whole operating
period. The pressure in the pump will always be
≥ the pressure in the nozzle line.
When the burner stops and the pressure in the
pump drops to suction pressure, the LE-S
system may again become active if the nozzle
and preheater are heated due to radiation from
the boiler or due to residual heat in the
preheater.
If the pump is used without a shut-off valve in
the preheater, the valve B in the solenoid valve
will never become active and thus there will be
no risk that, even with an overlying tank, the oil
is released to the combustion chamber
unintentionally.

O

BFP 21 LE-S features:

• Light oil and kerosene

• 1 or 2-pipe operation

• 1-stage

• Solenoid valve cut-off

• Cartridge filter

• Low emission at start and stop

Danfoss

70-887.12

B

When the burner stops, the voltage to the
NC-valve is cut off and the oil fl ow to the nozzle
outlet is cut off immediately.

Bleeding

In 2-pipe systems the pump is self-priming, i.e.
bleeding is performed via the constriction (O) to
the return outlet (R).
In 1-pipe systems with plugged return outlet
(R), bleeding must be performed through the
nozzle outlet (E) or the pressure gauge port (P).

Warranty

For pumps used outside the stated technical
data and used with oil containing abrasive
particles Danfoss cannot give any warranty.

Note!
Do not mount the pump with the solenoid valve
pointing downwards.
The solenoid valve must be replaced after 250.000
operations or 10 years (approved life expectancy).

© Danfoss | 2019.06

VD.DK.J3.02 | 1

Data sheet Oil Pump type BFP 21 LE-S - size 3 and 5

Identification

Technical Data

BFP 2 1 L 5 L LE-S

R:L:right hand nozzle outlet

left hand nozzle outlet

3:5:capacity 24 l/h

capacity 42 l/h

R:L:clockwise rotation

counter-clockwise rotation

1: with one solenoid valve

2: cartridge filter, pressure adjustment on front

Nozzle capacity at 4.3 cSt., 10 bar, 2800 min

-1

BFP 21 LE-S 3 5

Oil types

Viscosity range (measured in suction inlet)

1)

Standard fuel gas oil and fuel gas oil acc. to

DIN V 51603-6 EL A Bio-10 (max. 10% FAME)

(1.3) 1.8 to 12.0 cSt. (mm2/s)
Filter area/mesh 11 cm2/200 µm
Pressure range

2)

7 to 20 bar
Default setting 10 ±1 bar
Max. pressure in suction inlet/return outlet 2 bar
Speed 2400 to 3450 min

-1

1400 to 3450 min
Max. starting torque 0.1 Nm 0.12 Nm
Ambient/transport temperature -20 to +70° C
Temperature of medium 0 to +70° C
Coil power consumption 9 W
Rated voltage (other voltages on request) 230 V, 50/60 Hz
Coil enclosure IP 40
Shaft/neck EN 225

1)

Special pumps for Kerosene.

2)

Max. 12 bar at 1.3 cSt., max. 15 bar at 1.8 cSt.

-1

Nozzle capacity Operating torque Power consumption

2 | © Danfoss | 2019.06

VD.DK.J3.02