PUMP ALE

The gear set draws oil from the tank through the built-in fi lter and transfers it to the
nozzle line via the cut-off solenoid valve. A pressure regulating valve is used to
dump all oil which is not required at the nozzle.
In two-pipe operation, the by-pass plug must be fi tted in the return port, which
ensures that the oil by-passed by the regulating valve is returned to the tank and
the suction line fl ow is equal to the gear set capacity.
In one-pipe operation, the oil which does not go through the nozzle line is returned directly
to the gear inlet and the suction line fl ow is equal to the nozzle fl ow. In that case, the
by-pass plug must be removed from the return port, and the return port sealed by
steel plug and washer.

Bleed
Bleeding in two-pipe operation is automatic : it is assured by a bleed fl at on the piston.
In one-pipe operation, the plug of a pressure gauge port must be loosened until the
air is evacuated from the system.

Cut-off
The solenoid valve of the ALE pump is of the “normally closed” type and is situated
in the nozzle line. This design ensures extremely fast response and the switching
can be selected according to the burner operating sequence and is independent
of motor speed.
When the solenoid is non-activated, the valve is closed and all oil pressurized by
the gear set passes through the regulator to the suction or return line, depending
upon pipe arrangement.
As soon as the solenoid is activated, oil passes to the nozzle line at the pressure
set by the pressure regulating valve.

Nozzle line pressure relief
The nozzle line pressure relief function operates only when the installation is fi tted
with a nozzle incorporating a cut-off function which opens at 4 bars or above. Any
subsequent expansion of the oil due to residual heat from the preheater or the boiler
is discharged through the relief valve in the pump which opens at a lower pressure
than the nozzle opening pressure.
Note : For a boosted pump, the overpressure applies to the safety shut-off device
and the relief valve.