Inspection/Cleaning Of Hydrocarbon Sensor Cell Optical Surface - Michell Instruments Condumax II User Manual

Condumax II User's Manual
4.3

Inspection/Cleaning of Hydrocarbon Sensor Cell Optical Surface

If the sensor cell optical surface is badly contaminated or damaged or if there is
uncertainty about its accuracy, then it should be replaced.
To clean the sensor cell follow the instructions below:
1. Isolate the incoming sample gas line by closing the sample inlet isolation valve
and allowing the system to depressurize. Isolate the power. NOTE: Always
refer to Appendix G.4 - Special Conditions of Safe Use.
2. Disconnect the LED and detector connectors from the main processor PCB.
3. Remove the four M6 stainless steel cap head screws at the top of the cell
retaining the optical housing and carefully withdraw the optical housing.
Caution: The quartz glass window within the optical housing is now free
to slide out - ensure this item is secured during removal. On occasion
the quartz glass window sealing O-ring may be adhered to the window.
4. The optical surface is now viewable and accessible for cleaning through the
top of the cell assembly. CAUTION: No attempt should be made to further
disassemble the cell, as this will invalidate any previous calibration.
5. Clean the surface using very light pressure with a laboratory grade wool cotton
bud moistened with a suitable solvent, e.g. laboratory grade acetone (99.9%,
HPLC grade) or Dichloromethane [methylene chloride] (99.9%, HPLC grade).
Caution: Cosmetic grade acetone (i.e. nail varnish remover) should not
be used as residues may remain on the optical surface which can effect
measurement performance.
Clean, using a gentle circular motion, beginning at the centre of the optical
surface and progressing to the outside. Clean repeatedly fi ve or six times
using a new area of cloth or cotton bud each time. Leave the optical surface
open to the atmosphere for 5 minutes after cleaning.
6. Ensure that any particulate matter from the use of the cloth or cotton bud is
removed.
7. Clean the quartz glass window with a clean dry cloth, taking care not to
scratch it.
8. Re-assemble the sensor cell optical housing in the reverse order. Ensure that
the quartz window O-ring is correctly seated and that the M6 screws are fully
tightened.
Michell Instruments
The power to the enclosure must be turned off before any
work is carried out in the measurement system enclosure.
Observe de-energize durations.
MAINTENANCE
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