Light Oil Supply; The Loop Circuit - Riello RL 25/1 BLU Installation, Use And Maintenance Instructions

5.8

Light oil supply

Explosion danger due to fuel leaks in the pres-
ence of a flammable source.
Precautions: avoid knocking, attrition, sparks and
heat.
Make sure that the fuel interception tap is closed
before performing any operation on the burner.
The fuel supply line must be installed by qualified
personnel, in compliance with current standards
and laws.
WARNING
The burner is equipped with a self-priming pump which is capable
of feeding itself within the limits indicated in Tab. G.
There are three types of fuel water circuits:
– Dual pipe circuits (most common)
– Single pipe circuits
– Loop circuits.
Depending on the configuration of the burner/tank, also two sup-
ply systems can be used:
– siphon type (the tank is higher than the burner);
– suction type (the tank is lower than the burner).
Siphon dual pipe systems (A) (Fig. 17)
P should not exceed 10 metres so as not to overly stress the
pump sealing organ; V should not exceed 4 metres in order to al-
low the pump to self-prime also when the tank is almost empty.
Suction dual pipe systems (B) (Fig. 17)
Pump depression values should never exceed 0.45 bar (35 cm
Hg) since the fuel releases gas at high levels, the pump becomes
noisy and its life shortens. It is good practice to ensure that the
return and suction lines enter the burner at the same height; in
this way it is more difficult that the suction line fails to prime or
else stops.
5.8.1

The loop circuit

A loop circuit consists of a closed pipe departing from and return-
ing to the tank with an auxiliary pump that circulates the fuel un-
der pressure.
A branch connection from the loop goes to feed the burner. This
circuit is extremely useful whenever the burner pump does not
succeed in self-priming because the tank distance and/the height
difference are higher than the values listed in Tab. G.
Installation
+/- H
[m]
+4,0
+3,0
+2,0
+1,0
+0.5
0
-4.0
-3.0
-2.0
-1.0
-0.5
7
10
6
7
6
Key (Fig. 17)
H = Pump/Foot valve height difference
L = Line length Values calculated for light oil:
– Viscosity = 6 cSt / 20 °C
– Density = 0.84 kg/dm3
– Temperature = 0 °C
– Max. altitude = 200 m (a.s.l.)
Ø = Inside pipe diameter
1 = Burner
2 = Pump
3 = Filter
4 = Manual on/off valve
5 = Suction line
6 = Foot valve
7 = Return line
17 GB
L [m]
Ø [mm]
8 10
52 134
46 119
39 104
33 89
30 80
27 73
24 66
21 58
15 43
8 28
- 12
9 5
8
4
5
9
12
160
160
160
160
160
160
144
128
96
65
33
Tab. G
20156732
A
1
2
3
B
Fig. 17
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