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5.12.4 Pressure variator
Calibration pressure on return line
With a servomotor position of 20°, the nut and the corresponding
lock nut 6)(Fig. 20), are fixed in contact with the eccentric 8).
During the rotation towards 130° of the servomotor, the eccentric
will push the modulator shaft, taking the pressure, read on the
pressure gauge 3)(Fig. 20), to the desired value.
To calibrate the eccentric, proceed as follows:
loosen the screws 7), turn the screw 4) until the desired
eccentricity is reached.
By turning screw 4) to the right (+) the eccentricity increases,
thereby increasing the difference between the maximum and
minimum capacity of the nozzle.
By turning screw 4) to the left (-) the eccentricity decreases,
thereby decreasing the difference between the maximum
and minimum capacity of the nozzle.
Calibration pressure on delivery line
To adjust the delivery pressure, operate on the pump as
described on page 22.
Example:
if you use a 650 kg/h nozzle and you want to obtain an output of
6650 kW, the pressure read on the pressure gauge 3)(Fig. 20)
(max. pressure on return circuit) must be approx. 16.5 bar.
The relevant delivery pressure read on the pressure gauge 2),
must be 20 bar (see Tab. I on page 18).
IMPORTANT
For a correct calibration, the eccentric 8) must operate on
the entire range of travel of the servomotor (20° ÷ 130°): a
pressure variation must correspond to each servomotor
variation.
Never drive the variator piston fully home: the stop ring 5)
determines the maximum stroke.
To check the nozzle delivery flow rate, proceed as follows:
open the burner according to the instructions of page 17,
position the nozzle, simulate start-up and then weigh at
maximum and minimum pressures.
If at the maximum delivery of the nozzle (maximum pressure
on the return line) pressure oscillations can be seen on the
pressure gauge 3), slightly reduce the pressure until they
disappear.
NOTE:
The burner is factory calibrated with maximum pressure on the
return line of approximately 16.5 bar and delivery pressure of
approximately 20 bar.
Installation
D8369
Key (Fig. 20)
1
Maximum oil pressure switch
2
Delivery pressure gauge
3
Return pressure gauge
4
Eccentric adjustment screw
5
Piston stop ring
6
Piston calibration nut and lock nut
7
Eccentric locking screws
8
Variable eccentric
21
GB
Fig. 20
20148124
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