Unigas K750A Manual Download

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PART I: SPECIFICATIONS

BURNERS FEATURES

Gas operation

The gas minimum pressure switch, installed upstream from the safety valves, ensures the network distributes the gas at a pressure sui-
table to switch on the machine start cycle.
In compliance with the regulations in force, the cycle starts with the pre-ventilation phase.

(Burners fitted with gas proving system). The gas safety valves proving system can be executed during this phase and/or at the burner
shut-off, according to the device setting. Failing which a safety interlock is tripped.

The fan starts and the air damper, driven by the servomotor, opens as far as the high flame position. The air pressure switch, detecting
a pressure, ensures the fan's operation. Failing which a safety interlock is tripped.
At the end of preventilation, in sequence, the burner management system moves the servomotor to the ignition position, supplies the
ignition transformer and orders the opening of the gas safety valve group.
The gas from the net passes through a filter, the double safety valves and the pressure regulator. The regulator holds the gas head
pressure within the use limits.
Fuel and comburent are channelled separately till they meet in the flame development area (combustion chamber) where the spark,
discharged by the ignition electrodes located on the burner's head, must ignite the flame in a safety time of less than 3 s, as provided
for by the reference regulations.
The flame is detected by a sensor that can be an ionization or UV or IR sensor. Failing which a safety interlock is tripped. From now on
flame detection will be continuous, until the burner is switched off.
At the end of the safety time, the control unit de-energizes the ignition transformer, moving the servomotor to the low or high flame posi-
tion according to system demand.
The burner operation is now controlled by the modulator, if any, or by the boiler controller (i.e.: high-low flame thermostat).
The dedicated actuators move, simultaneously and proportionally, the air damper, the fuel butterfly valve, the head position (if the bur-
ner include this option) and the VSD optimizing exhaust gas values and obtaining efficient combustion.

The position of the combustion head, set manually or automatically (if the option is included in the supply), contributes to adjust the bur-
ner's output.
If the monitored variable (pressure or temperature) of the boiler/generator/oven fluid exceeds a preset value, the machine switch-off
phase is started. The flame control unit moves the servomotor to the low flame position (minimum power supplied), closes the safety
valves and starts the post-ventilation phase, if any.
At the end of this stage, the burner remains in stand-by waiting for a new start-up sequence

For further details, see the attached equipment manual.

PART I: SPECIFICATIONS

Note: the figure is indicative only

Control panel with startup switch

Gas train

Electrical panel

Cover

Blast tube + Combustion head

Flange

Silencer

Actuator

Air pressure switch