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4.2
Choice of nozzle
In order to set the flow field in which the noz-
zle is to function, it is necessary to regulate
the maximum and minimum pressure of the
fuel on the nozzle return according to dia-
gram (see Fig. 13).
RECOMMENDED NOZZLES
• BERGONZO, type B5;
• FLUIDICS, type W2.
Intermediate flow rates may be obtained by
choosing the nozzle with a nominal flow rate
slightly higher than that actually required.
Complete range of nozzles:
Bergonzo B5 45° - 200 - 225 - 250 - 275 -
300 - 325 - 350 - 375 - 400 - 425 - 450 - 475
- 500.
We normally recommend 45÷60° angles of pulverisation; for narrow combustion chambers use nozzles with 30÷35° angles.
4.3
Pressure variation
Key:
1 -Nozzle delivery pressure gauge
2 -Nozzle return pressure gauge
3 -Position indicator (0 ÷ 90) of pressure variator
(connected axially to the servomotor shaft )
4 -Maximum oil pressure switch on return circuit
If a servomotor needs replacing, the work must be carried out by an
authorised technical service using personnel trained specifically for set-
ting the control (see page 16 - 17).
The pressure variator integrated into the valve unit of the oil circuit
makes it possible to vary the pressure on return of the nozzle depending
on the flow rate required.
Governing of the pressure on return is obtained with the variation of a
section by rotating the servomotor 7) which simultaneously also controls
the butterfly valve 3) page 5.
• Pressure governor at 0° (maximum opening) minimum pressure on nozzle return.
• Pressure governor at 90° (minimum opening) = maximum pressure on nozzle return.
The servomotor is operated by the electronic cam; by means of this device it is possible to set calibration points synchronised
with the air gate valve servomotor 8) page 5.
• In adjusting with gas it is advisable to set the servomotor 7)(Fig. 2 page 5) at 90° in order to reduce losses from the gas butterfly
valve (the losses on page 8 refer to a completely open valve).
• In regulating with oil, setting is made depending on the type of nozzle used and on the modulation required. Under the condi-
tions of minimum firing rate, 20° rotation may be sufficient.
4
CAPITOLO
Fig. 13
Fig. 14
1
D9083
BERGONZO B5 - 45°
Delivery pressure: 25 bar
Nozzle delivery
kg/h
2
3
4
Fuel supply
D1610
11
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