E8500 Instruction & Operations Manual
version 1.010
Page 39 of 45
B. Condensation removal
Most of the water vapor in the stack gas will condense inside the extraction probe and
sampling line. However, any additional excess water vapor will condense inside the
thermoelectrically operated chiller, which is located in the front of the drawer
compartment. All this water condensation will collect inside the small water trap that is
located at the bottom of the chiller assembly. It will then be automatically removed by
the peristaltic pump, which operates intermittently to discharge the water through the
bottom of the analyzer.
C. Sensor replacement
This should be an infrequent operation, since the sensors have a typical life of several
years.
If you receive an error message for one of the sensors during instrument operation, do
not attempt to replace the sensor immediately. Instead, wait a few minutes and then
autozero the analyzer again. If you get an error message again, then investigate and
determine if moisture has entered the sensor area. If so, wait a few hours for the
moisture to evaporate and then autozero again. If the sensor failure persists then you
must replace the sensor.
To access the sensor compartment you must remove the top section of the instrument
case. Before opening the analyzer case, first pull the drawer half way open and
disconnect the wire connector right behind the back corner of the chiller fan. The
top section of the analyzer case is held to the bottom section by a total of four retaining
screws. With both hands, slide off the vent covers on each side. Use a Philips
screwdriver to remove both pairs of retaining screws (one pair on each side of the
case). It is best to remove the bottom pair of screws first. Carefully lift the top of the
instrument case together with the attached aluminum mounting shielding plate
especially since the top & bottom cases pieces are connected with cables/wires. When
the plastic case is open, be careful when near the main board because some of the
resistors on the board can get significantly hot. The location of the gas sensors on the
manifold is shown in the figure in Chapter 6.
To replace a sensor locate its correct position on the manifold. Carefully lift the small PC
board that is mounted on top of the sensor. Grab the sensor with your fingers and lift it
twisting it out of its bayonet fitting.
Take a new sensor. Remove any springs that may be shorting the sensor pins. Install it
on its mount and connect the small PC board on top of it.
Replace the top section of the case and secure it with the four screws.
Wait the following time periods before autozeroing the analyzer:
O
SENSOR 10 minutes
CO SENSOR 30 minutes
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