MAINTENANCE
6-9
6.4
Turning on the UV Lamp
The UV lamp is made of a glass envelope and a UV window
(salt crystal) on one end of the envelope. The inside of the lamp
is filled with low pressure gases. To turn on the lamp, a high
voltage electric field is applied from the outside of the glass
envelope. The molecules inside the lamp are ionized and
produce a glow discharge that generates the UV light. The
MiniRAE 2000 has a built-in sensing mechanism to monitor the
status of the UV lamp and display a “Lamp” error message if it
is not on.
If the UV lamp has not been used for a long period of time (> 1
month) or is cold, it may become slightly harder to turn on. If
such a condition occurs, the “Lamp” message will appear in the
monitor display during the power on sequence. This
phenomenon is more significant in 0.25” UV lamps used in
ToxiRAE and MultiRAE Plus products, because of the
relatively small lamp size. To solve this problem, simply turn
on and off the monitor a few times and the lamp should turn on.
After the UV lamp is turned on for the first time, it should be
easier to turn on the UV lamp next time.
It is possible that the UV lamp is actually on when the lamp
error message appears. This is because when the lamp becomes
old, the internal threshold level to detect lamp failure may have
shifted and cause a false alarm. To eliminate such possibility,
simply check to see the UV lamp is actually on. This can be
done easily by removing the sensor cap and observing the glow
light of the UV lamp in a dark place. The user can also feed the
monitor with calibration gas and observe if the sensor reading
changes. If the reading changes significantly with the gas, the
UV lamp is actually on.
A possible failure mechanism for the UV lamp is a leak
developed along the seal of the glass envelope. When such
condition occurs, the lamp will become very hard or impossible
to turn on and will need to be replaced.
Summary of Contents for MiniRAE 2000 PGM-7600
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