12
Bleed
Bleeding in two-pipe operation is automatic : it is assured by a bleed flat 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.
About the use of fuel pumps
Make sure that the by-pass plug is not used in a single pipe installation, because the fuel unit will not function properly and damage
to the pump and burner motor could result.
Do not use fuel with additives to avoid the possible formation over time of compounds which may deposit between the gear teeth,
thus obstructing them.
After filling the tank, wait before starting the burner. This will give any suspended impurities time to deposit on the bottom of the
tank, thus avoiding the possibility that they might be sucked into the pump.
On initial commissioning a "dry" operation is foreseen for a considerable length of time (for example, when there is a long suction
line to bleed). To avoid damages inject some lubrication oil into the vacuum inlet.
Care must be taken when installing the pump not to force the pump shaft along its axis or laterally to avoid excessive wear on the
joint, noise and overloading the gears.
Pipes should not contain air pockets. Rapid attachment joint should therefore be avoided and threaded or mechanical seal jun-
ctions preferred. Junction threads, elbow joints and couplings should be sealed with removable sg component. The number of jun-
ctions should be kept to a minimum as they are a possible source of leakage.
Do not use PTFE tape on the suction and return line pipes to avoid the possibility that particles enter circulation. These could depo-
sit on the pump filter or the nozzle, reducing efficiency. Always use O-Rings or mechanical seal (copper or aluminium gaskets) jun-
ctions if possible.
An external filter should always be installed in the suction line upstream of the fuel unit.
