Thermo Scientific Accela PDA, Hardware Manual

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6
Routine Maintenance
Replacing the Lamps
Thermo Scientific Accela PDA Detector Hardware Manual 89
5. Using the Accela Pump, pump the nitric acid solution through the LightPipe flowcell.
6. After you have finished the cleaning procedure and before you return to the
chromatographic solvents, pump another 25 to 40 mL of water through the flowcell to
remove all traces of nitric acid. Monitor the pH of the outlet stream of the LightPipe
flowcell to ensure that the acid has been completely flushed out.
7. To reinstall the flowcell, see “Installing the LightPipe Flowcell” on page 17 .
Replacing the Lamps
As the deuterium lamp ages, there is a reduction in light output, which results in increased
baseline noise. If the noise level on your detector output signal is unacceptable, and cleaning
the flowcell does not help, use the data system’s diagnostic features to determine the cause of
the problem. If the light output becomes too low and adjusting the attenuators does not help,
replace the deuterium lamp. The light output from the tungsten-halogen lamp is relatively
stable as the lamp ages.
The detector keeps track of the number of hours each lamp has been operating. The
deuterium lamp has a lifetime of approximately 1000 hours and the tungsten lamp has a
lifetime of approximately 2500 hours. Lamp lifetime varies depending upon the application.
The deuterium (D2) and tungsten (W) lamps are located in the lamp compartment to the
right of the optical bench assembly, viewed with the detector chassis open as shown in
Figure 75 on page 92 .
CAUTION
Before you pump nitric acid solution through the LightPipe flowcell,
ensure that the column has been removed from the chromatographic system and that
water was the last solvent in the pump and solvent reservoir.
CAUTION Intense UV light can damage your eyes. Always turn off the PDA detector and
disconnect the power cord before you expose the lamp.
CAUTION There are electrical shock hazards inside the PDA detector’s housing. Always
turn off the PDA detector and disconnect the power cord before you pull the chassis out
of the housing.
CAUTION The lamp cover becomes very hot when the lamps are on. After you turn off
the lamps and the PDA detector, wait 30 minutes for the lamp cover to cool before
removing it.