Riello RDB4 Installation, Use And Maintenance Instructions page 44

On the systems in Fig. 15 and Fig. 16 start the burner and wait
for the priming.
Should lock-out occur prior to the arrival of the fuel, await at least
20 seconds before repeating the operation.
The pump suction should not exceed a maximum
of 0.4 bar (30 cm Hg). Beyond this limit gas is re-
leased from the oil.
WARNING
Oil pipes must be completely tight.
In the vacuum systems (Fig. 15) the return line should terminate
within 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 arrive over the fuel level, a
non-return valve is required. This solution however is less safe
than previous one, due to the possibility of leakage of the valve
H
meters
0
0.5
1
1.5
2
3
3.5
difference of level
H = ;
max. lenght of the suction line
L =
I.D. interminal diameter of the oil pipes
=
20071933
Hydraulic systems
meters
L
I.D. I.D.
8 mm 10 mm
35 100
30 100
25 100
20 90
15 70
8 30
6 20
;
.
D1842
.
D5740
14 GB
Fig. 15
Fig. 16