Viadrus G 90 Series, Эксплуатация и установка

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3. DUNGS MB-ZRDLE 412, A TWO-STAGE ELECTROMAGNETIC VALVE FOR BOILER WITH
10,12 and 15 SECTIONS
The main security is Dungs MB-ZRDLE 412, a two-stage electromagnetic valve which works in the
regime of a nominal/ reduced heat output and enables to mount a watcher of gas fitting tightness that
watches the tightness of gas valve seats. The watcher of gas fitting tightness can be screwed to the gas
multi-block either from the left-hand or the right-hand side k depending on the gas connection design.
In the fig. no. 6 there is displayed a valve with gas connection attached from the left-hand side In case of
a connection attached from the right-hand side the valve for pilot burner and the tightness watcher must be
turned in a specular symmetry.
Fig. no. 6 DUNGS MB-ZRDLE 412, a two-stage electromagnetic valve with gas fitting tightness
watcher
A law-emission pilot burner of Polidoro type provides the burner ignition and watches its operation. In
case that there is required the main burner ignition the pilot burner will catch fire automatically after the
waiting time T
w
= 10 sec has passed. A spark will ignite the pilot burner and its flame is sensed by a
ionisation electrode. After the pilot burner flame stabilization and closing the ionisation circuit there will open
the main valve for gas inlet into the main burner. In case that the pilot burner hasn’t ignited within the safety
time of T
s
= 50 sec, the automatics will close the gas inlet into the main burner and the pilot burner. In case
that during the normal boiler operation the flame has disappeared, the ignition automatics will repeat the
ignition cycle at the pilot burner. If there persists a permanent ionisation loss the boiler will get into a
breakdown condition (the pushbutton called „automatics with breakdown signalling unblocking“ on the control
panel is alight). After the waiting time (approx. 10 sec) has passed the breakdown condition can be annulled
manually by using the pushbutton called „automatics with breakdown signalling unblocking“. The pilot burner
is in operation together with the main burner.
In case that there is an electricity outage the gas inlet at the burner will close automatically. After the
electricity supply has been restored the boiler will start up automatically.
∅
nozzle (in mm)
nozzle ZP 0,45
The gas inlet into the pilot burner at the dimension of 8 sections has
∅
4 mm, at the dimensions of 10, 12
and 15 sections it has
∅
6 mm.
Openings for the connection with the multi-block
(at the gas fitting tightness watcher and multi-
block the packing must be removed)
4 pcs openings
for the fastening
screws
Packing
Valve for the
pilot burner
Gas fitting
tightness
watcher