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CI-154 User’s Manual
Page 76
6.1.3 Long term storage
Nickel metal hydride batteries, like other types of batteries, will discharge gradually
when left in circuit. A deep discharge of the battery could damage it. The battery
should be disconnected whenever the instrument is to remain out of service for
more than a month to avoid deep discharging. A battery left in-circuit for two
months or more may discharge excessively, shortening the life of the battery.
To disconnect the battery, first disconnect the AC power cord. Place the unit on its
side, and remove the battery compartment door. Remove the battery and then
unplug the battery connector. Put the battery back in the battery compartment with
the battery connector loose. Replace the door and secure it finger-tight with the four
screws. You may want to place a Post-It
TM
note on the unit to remind people to
reconnect the battery when it is put back into use.
Please refer to the Service and Maintenance section of this manual for instructions
on long term storage.
6.2 Analyzing counting irregularities
6.2.1 High counts, limited to the 0.3  m channel
The normal distribution of counts in ambient air is roughly a decade increase in
particle counts for each smaller particle channel. For example, if there were 10,000
counts registered in the 0.3
 m channel in cumulative count mode (equal to or
greater than 0.3  m), then we would expect to see roughly 1,000 counts in the 0.5
 m channel. If we see several hundred or several thousand counts in the 0.3  m
channel, with few if any counts in the 0.5  m channel, this would point to a problem
with the particle counter.
Since there is high immunity to electronic noise, such high counts are often caused
by a stray fiber that has entered the particle counter and has been caught on the
inlet. The fiber wiggles back and forth in the airflow, scattering light around the
edge of the laser beam, causing the stray counts. Such fibers can often be dislodged
by a blast of filtered air, with the air source held
a few inches above the inlet. Do
not apply compressed air directly to the inlet .
High counts can also result if the particle counter is placed below a bright light
fixture, with no tubing over the inlet. What the particle counter is picking up is the
light turning off and on; with newer ballasts this occurs many thousands of times
per second. This problem is resolved by not placing the particle counter directly
under the light fixture, or by using the sample probe that came with the instrument,
so that there is no direct path for the light to enter. A 6–8 inch length of black Bev-
a-Line® tubing can also be placed on the inlet; the natural curve of the tubing will
block direct light from entering the sensor.
If having tubing is awkward for a sampling application, Climet offers a sample probe
that fits directly over the inlet without tubing, and contains a light blocker (P/N
01249500 for the CI-154 and other 1 CFM models). This patented device blocks light
without trapping 5
 m particles. Other designs that have been implemented to block
light have a serious problem with 5  m loss.
6.2.2 Similar counts on two or more channels
If the counts are over a million (1,000,000), and the 0.3  m and 0.5  m channels
count nearly the same, the sensor is probably being operated in a non-clean area