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Operation and Maintenance Manual 85
Reaction Cell Cleaning
Over time, the reaction cell and UV pass filter (SCD) or IR pass filter (NCD)
will develop a build-up of material which should be removed for optimum
sensitivity. The cleaning schedule depends upon Detector use and the nature
of the analyses; however, it is recommended the cell should be cleaned
annually. The cleaning procedure requires removal of the photomultiplier
tube (PMT) from the Detector, and special precautions are required to prevent
damage to the PMT.
Exposure of a photomultiplier tube to bright light can result in damage to the
PMT, even when the high voltage is off. To avoid potential damage, minimize
light exposure. The black PMT cover included in the Detector accessories
package is recommended for this procedure. Carefully read all the instructions
below before attempting to remove the PMT. If you have any questions
regarding this procedure please contact Agilent.
To clean the cell and pass filter:
1 Disconnect the main power cord (if the vacuum pump is operated from an
independent power outlet, unplug the power to the pump as well).
2 Remove the right side panel from the Detector and disconnect the high
voltage and coaxial signal cables from the rear of the PMT housing (See
Figure 3 and Figure 15).
3 Turn off all room lights and minimize outside light sources.
4 Unscrew the PMT socket connector assembly. Carefully pull the socket
assembly and the PMT out toward the rear of the instrument at a slight
angle to remove the PMT/socket assembly from the housing.
5 Immediately place the black PMT cap over the PMT, being careful to avoid
placing fingerprints on the PMT window. Do not remove the PMT from the
socket assembly. After the PMT cap is in place, carefully place the PMT and
socket assembly on a soft surface inside a drawer or other dark location to
minimize exposure of the PMT to light. The room lights may be turned on at
this point.
WARNING
Any operation requiring access to the inside of the equipment, could result in injury. To
avoid potentially dangerous shock, disconnect from power supply before opening the
equipment.