ADJUSTMENT
From the aforementioned working principle it is clear
that this valve automatically increases the supply of
gas if the air supply increases and automatically
reduces the gas supply if the air supply drops
Therefore the quantity of gas supplied at burner
"minimum" and at burner "maximum" must be
adjusted only be adjusting the combustion air
"minimum" and "maximum". In practice two "cams"
adjust the minimum and the maximum of the air
regulation servomotor.
Bearing this principle in mind, we advice you to adjust
the burner according to the following procedure. To
gain access to the adjustment screws, remove lid
"C". Adjust the gas/air ratio with screw "B". This
means turning regulation screw "B" for the ratio of
the gas pressure (at the blast-pipe) and the air
pressure (at the blast-pipe) and to set, as an indicative
initial regulation, reference index "A", between 0.4
and 0.8: so that more air than gas is being supplied.
NOTE: The air quantity, relative to the gas, is
increased by moving reference index "A" to
smaller values, while to increase gas
quantities, relative to the air, the reference
index "A" towards higher values. Switch on
the burner and run it with about a 90% of
maximum loading. Measure the CO
content and the CO in the fumes and correct
the calibrated ratio with screw "B", until the
value obtained is the best possible.
Set burner at minimum, check CO
as well as CO in the fumes and correct, if necessary,
with regulation screw "D" (the change effected with
screw "D" is shown on index "E"). Turning towards
(-) there is a parallel shift in the curve for gas reduction
(excess air). Turning to (+) there is a parallel shift in
the curve for gas increase (lack of air).
To obtain good CO
or O
2
necessary to carry out a large parallel working curve
change and check once again the adjustment of the
pressure ratio at 90% working.
INSTRUCTIONS FOR ADJUSTMENT OF GAS
VALVE MODEL SKP 70 ...
or O
2
and O
content
2
2
levels at low loads, it is
2
2
42
BT 8883
REV.: 06/11/1990