Figure 58 – Optical filter removal and cleaning
3. Turn the reaction cell upside down and remove the four screws fastening the optical filter from
the cell.
4. Clean the filter and the inside of the cell with high purity isopropyl alcohol.
5. Ensure that all traces of the isopropyl alcohol have been removed by either blowing it out with
clean oil free compressed air or by gently heating the assembly.
6. Reassemble the reaction cell in reverse order to the steps above.
7. Recalibrate the analyser.
6.4.8 Clean Pneumatics
The valve manifold will require disassembling and cleaning. Ideally the vales and manifold should be
cleaned in a sonic bath with soppy water. Once clean, rinse with distilled water and dry before
reassembling. A leak test should be performed once the analyser is ready for operation.
If the tubing shows signs of significant contamination, then it should be replaced with new tubing.
6.4.9 Pressure Sensor Check
Pressure checks are needed to ensure that the pressure sensor is accurately measuring pressure
inside the instrument.
During normal operation ensure that the Pressure and Flow Menu indicate the following
parameters. Ambient should display the current ambient pressure at site. Cell should indicate current
cell pressure. Depending on the pump condition and location, a value of between 50 torr and 200
torr is recommended. The manifold pressure is normally about 20 torr below ambient.
To navigate to the pressure and flow menu: Enter Main Menu Analyser State Pressures and
Flow.
1. A simple way of checking the pressure sensors response is to disconnect the exhaust and sample
tubing from the back of the analyser. After 2-5 minutes observe the pressure readings: ambient,
cell and manifold. Ensure that they are reading the same ± 3 torr (± 0.4 kPa).
2. If the readings are outside this level then perform a pressure calibration (refer to Section 5.6).
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