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SECTION E - ASSISTANCE AND MAINTENANCE
9. ASSISTANCE AND MAINTENANCE
9.1 FIRST START-UP OF THE APPLIANCE
The first ignition must be carried out exclusively by
an authorized Technical Assistance Center or by
professionally qualified personnel.
Before starting the generator, have it checked by
professionally qualified personnel:
- that the plate data correspond to those of the
electricity and gas supply networks; Established
correctness of the installation and of the required
installation data, the authorized Technical
Assistance Center can proceed with the first
start up of the appliance and with the verification
of its correct functioning. In particular, he will have
to check:
- that the data of the static and dynamic pressure of
the gas network fall within the required range;
- that the calibration values of the gas valve
correspond to what is indicated in Table 16;
- that the combustion air supply e the fumes are
evacuated correctly as established by the current
regulations;
- the correct functioning of the evacuation duct
of the fumes. If the calibration values of the gas
valve do not they correspond to those indicated
in Table 16, it is advisable to adjust the combustion
parameters as reported in the relative paragraph
8.2. The generator is set up for operation a
methane (G20): in the case of plants that provide
for a type of gas supply different from that of
preparation, it is necessary to perform the gas
Technical features of the gas valve
Gas of use:
T ° environment:
Inlet pressure max:
Gas inlet / outlet:
Pressure sockets:
Air signal connection:
Degree of protection:
2nd / 3rd family
0-60 ° C
60 mbar
fil. male G3 / 4 B ISO 228
diameter 9 mm
diameter 7 mm
IP 40 with connector
NAC 504 and gasket
change procedure (paragraph 8.3) and the relative
regulation of the parameters (paragraph 8.2).
9.2 HOW TO MAKE THE ADJUSTMENT OF THE
GAS VALVE (or the combustion parameters)
Gas valve operating principle
The gas valve (fig.31) installed in the MEC MIX
series generators is a 1: 1 gas/air control type whose
operating principle is to maintain the PINT output gas
pressure constantly equal to the air pressure signal
Pa increased of the set value on the offset screw.
In formula:
where Os is the value adjusted on the offset screw.
The relation can be represented in a Pa / PINT graph
(fig.30).
In the case where Os (offset) is set to zero and in
the hypothesis that the relation flow volumetric / fall
of air pressure and gas follow in first approximation
of the same law, the volumetric gas/air ratio is kept
constant for any value of Pa. In other words, the ratio
Qg / Qa, where Qg and Qa are respectively the flows
in volume of gas and air, is constant over the entire
range of the air signal Pa.
REPORTING OF THE AIR SIGNAL GAS PRESSURE
36
PINT = Pa + Os
air signal Pa
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