15
20197230
GB
Hydraulic systems
6.3
Two-pipe system
The two-pipe vacuum systems (Fig. 12) have a negative fuel
pressure (depression) at the burner input.
Usually the tank is lower than the burner.
The return line should terminate in the oil tank at the same level
as the suction line; in this case a non-return valve is not required.
Should however the return line arrives over the fuel level, the
non-return valve is indispensable.
This solution however is less safe than previous one, due to the
possibility of leakage of the valve.
6.3.1
Priming pump
On the system in Fig. 12 switch on the burner and wait for the
priming. Should lockout occur prior to the arrival of the fuel, await
at least 20 seconds before repeating the operation.
Tab. H
H
difference of level
L
maximum length of the suction line
I.D.
internal diameter of the oil pipes
NOTE:
Tab. H shows the maximum approximate lengths for the supply
line, depending on the difference in level, length, and the diame-
ter of the fuel conduit.
CAUTION
You are advised to use additional filters on the fuel
supply line.
The Manufacturer recommends the use of a good
quality fuel filter on the tank (Fig. 12), and a sec-
ondary filter (60
for light oil) to protect the burner
pump and nozzle from contamination.
WARNING
Before starting the burner make sure that the re-
turn pipe-line is not clogged: any obstruction
would cause the pump seals to break.
WARNING
The pump vacuum should not exceed a maximum
of 0.4 bar (30cm Hg).
Beyond this limit gas is released from the oil.
H
metres
L metres
I.D. (8 mm)
I.D. (10 mm)
0
35
100
0.5
30
100
1
25
100
1.5
20
90
2
15
70
3
8
30
3.5
6
20
max.
4 m
H
H
D5308
Fig. 12
Summary of Contents for 3749251
Page 2: ...Original instructions...
