- 4 -
FLOW AND SERVICE PRESSURE CONTROL
1 - GAS/CO
2
/CO/NO
X
FLOW CONTROL AND SERVICE PRESSURE CONTROL
Po
V
Pi
K
PL
ZE
M
-5
4-
0
1
PL
2
P_OUT
P_IN
P_IN
=Gas network pressure
Natural gas H (G20): 20 mb
ar,
P_OUT
= Gas outlet pressure to the burner.
PL
= Air pressure auto. control (fan- gas valve)
1
= Adjustment of the slope of the air/gas ratio characteristic when
the burner
is at maximum rate
. This setting is performed in
factory for type H natural gas (G20) or propane (G31). It can
be used to correct the pressure P_OUT to obtain the required
gas flow (section 1.2 - page 6 - chapter I - FLOW AND SERVI-
CE PRESSURE CONTROL -
SERVICING MANUAL).
Turn to decrease the gas flow
2
= Adjustment of the parallel offset only when the burner
is at mi-
nimum rate
. This screw is preset in the factory. Its setting
must not normally be changed. If necessary, perform this ope-
ration with a small scale manometer 0-10 mmCE, and a CO2,
CO analyser.
To modify the setting, if necessary, remove the protective
screw, then
turn to increase the gas flow
. When the settings
are made replace the protective screw.
!
Fig. 2
P
i
= Gas network pressure
Natural gas H (G20): 20 mba
r,
P
o
= Gas outlet pressure to the burner.
PL
= Air pressure auto. control (fan- gas valve)
V
= Adjustment of the slope of the air/gas ratio characteristic when
the burner
is at maximum rate
. This setting is performed in
factory for type H natural gas (G20) or propane (G31). It can
be used to correct the pressure Po to obtain the required gas
flow (section 1.2 - page 6 - chapter I - FLOW AND SERVICE
PRESSURE CONTROL -
SERVICING MANUAL).
Turn to increase the gas flow
K
= Adjustment of the parallel offset only when the burner
is at mi-
nimum rate
. This screw is preset in the factory. Its setting
must not normally be changed. If necessary, perform this ope-
ration with a small scale manometer 0-10 mmCE, and a CO2,
CO analyser.
Turn to increase the gas flow
SIEMENS/LANDIS
GAS VALVE
ref : VGU87A0236
SIT GAS VALVE
ref.: 848 SIGMA
!
Summary of Contents for THI 2-17 B 120
Page 19: ... 19 V PARTS LISTS THI 2 17 B 120 ...
Page 23: ... 23 PARTS LISTS CONTROL BOX ...
