GB-7
D
GB
F
NL
I
E
Notes on the flow rate curve
▷
If the gas density in the operating state differs
from that reflected in the flow rate curve, convert
the pressures according to the local operating
state.
p
B
= p
M
.
δ
B
δ
M
▷
δ
M
: Gas density reflected in the flow rate curve
[kg/m
3
(lb/ft
3
)]
▷
δ
B
: Gas density in operating state [kg/m
3
(lb/ft
3
)]
▷
p
M
: Gas pressure reflected in the flow rate curve
▷
p
B
: Gas pressure in operating state
•
Read off the gas pressure p
gas
and air pressure
p
air
from the enclosed flow rate curve for cold
air on the basis of the calculated flow rates.
[mbar ("WC)]
[m
3
/h (ft
3
/h)]
p
gas
p
air
p
air
p
gas
Q
air
Q
gas
▷
Note possible capacity changes due to positive
or negative pressures in the furnace/combustion
chamber. Add positive pressures or subtract
negative pressures.
▷
As not all the effects caused by the equipment
are known, setting the burner using the pressure
values is only approximate. It is possible to set
the burner precisely by measuring the flow rates
or flue gas.
Restrictors
▷
The air volume required for the low-fire rate at a
given air pressure is determined by the ignition
position of a butterfly valve, a bypass hole in the
air valve or an external bypass with restrictor.
Hot-air compensation
▷
The combustion air pressure
p
Air
must be in-
creased in hot-air operating mode (lambda =
constant).
0
100
200
300
400
100
150
200
250
T
Air
[°C]
p
Ai
r
[%]
▷
The gas pressure is increased by 5 – 10 mbar.
▷
The total burner capacity
P
B
rises as the air tem-
perature
T
Air
increases.
0
100
200
300
400
100
110
120
T
Air
[°C]
P
B
[%]
Setting the air pressure for low fire and high
fire
Shut off the gas and air supply.
▷
Air measuring nipple
L
, external dia. = 9 mm (0.35").
p
atm.
p
air
0
3
5
2
4
L
Loosen
the screw
2 turns.
Fully open
the air supply.
p
atm
=
atmospheric
pressure.
