Instruction Manual MM850402 ed. 08b
20
4.1.2
Water Trap & Line Filter
The gas flows through an external combined water trap and line filter to avoid the presence of condensation and
suspended solid particles in the analysis section of the instrument. A cylinder is positioned at 15 cm from the instrument
gas inlet it is divided into two parts: the water trap and the line filter.
The
water trap
works using the expansion principle: the gas flow decreases its speed inside the cylinder and it will cool;
the humidity will condense and the solid particles fall down. The section of the water trap must be periodically drained off
to avoid water from entering the analysis section. Pull the rubber plug (cat. EE650081) and shake slowly the trap to drain
any condensation. Push the rubber plug to close the trap hole.
The
line filter
is positioned after the water trap and before the electrochemical cell. Its function is to stop the smallest
solid particles before the analysis. Remember to change the filter (cat. EE650074) every time it is dirty.
Line filter
cat. EE650074
Rubber plug
cat. EE650081
WARNING
T
HE WATER TRAP MUST BE KEPT IN A VERTICAL POSITION DURING GAS SAMPLING
.
A
N INCORRECT POSITIONING OF THE TRAP CAN
ALLOW THE WATER TO ENTER INSIDE THE ANALYZER AND DAMAGE THE ELECTROCHEMICAL SENSORS
.
NEVER
MAKE ANY ANALYSIS WITHOUT THE DRAINING RUBBER PLUG
.
THE MEASUREMENTS WILL BE INCORRECT
.
W
HEN YOU FINISH THE ANALYSIS
,
REMEMBER TO DRAIN THE WATER TRAP
.
B
EFORE PUTING THE GAS PROBE IN THE CARRYING CASE
,
REMOVE THE CONDENSATION WATER FROM THE PROBE HOSE
.
T
O OPEN THE WATER TRAP GENTLY ROTATE THE TWO PARTS
:
DON'T
FORCE THEM
T
HE LINE FILTER SHOULD BE REPLACED WHEN DIRTY
.
N
EVER MAKE ANY ANALYSIS WITHOUT LINE FILTER AND
/
OR WATER TRAP
,
AS IT
CAUSES AN IRREVERSIBLE DAMAGE TO THE ELECTROCHEMICAL SENSOR
.
4.1.3 Gas
Sensors
The analyzer uses long life sensors for O
2
, CO (H
2
compensated), NO, NO
2
and SO
2
. The sensor do not need special
maintenance but must be replaced after the expected lifetime.
However a full maintenance and certification of the instrument is recommended once a year
.
The gas sensors are electrochemical cells composed by two electrodes (anode and cathode) and an electrolyte solution.
The sampled gas goes through a selective diffusion membrane.
The oxidation process produces an output electrical signal proportional to the gas concentration. The signal is evaluated
by the electronics, converted to digital, processed by the microprocessor, displayed and printed with a 0.1% volume
resolution.
The flue gas must not be at a pressure that could damage or destroy the sensor. Measurements are always carried out
under "pressureless" conditions. The maximum permissible excess/reduced pressure is ±100 mbar.
Each sensor has a different response time:
O
2
= 20s to 90% of reading
CO (H
2
comp.) = 50s to 90% of reading
CO
= 50s to 90% of reading
