AZI Customer Service 800-528-7411 or 602-470-1414
Page 9 of 56
The sample air passes through a filter (removing any acidic gases which interfere with the
sensor's response to mercury) and is drawn over the gold film sensor. The sensor absorbs the
Mercury Vapor. Nine seconds after starting, the sample solenoid bypass closes and the
remainder of the sample is drawn through the scrubber filter and the flow system. The
instrument determines the amount absorbed and displays the measured concentration on the
digital meter in milligrams per cubic meter (mg/m
3
) of mercury. An internal DIP switch can be
used to change the digital meter display from mg/m
3
to nanograms of mercury (see page 22).
The instrument’s microprocessor automatically re-zeroes the digital meter at the start of each
sample cycle and freezes the meter reading until the next sample cycle is activated, thus
eliminating drift between samples.
During the sample mode cycle, bars on the LCD represent the percentage of sensor saturation.
Depending on the concentrations, approximately sixty-five samples containing 0.1 mg/m
3
Hg
may be taken before the sensor reaches saturation. After absorbing approximately 500
nanograms of mercury, the sensor becomes saturated and needs to be cleaned. This is
accomplished by a manually activated 10-minute heat cycle, or sensor regeneration that burns the
mercury from the sensor. This mercury is absorbed on internal filters to prevent any external
contamination. The solenoid bypass closes during the sensor regeneration cycle, causing the air
to pass through the scrubber filter, providing clean air for the regeneration process. The flow
system's final scrubber prevents contamination to the atmosphere from the desorbed mercury.
The heat generated during the regeneration may cause some low level thermal drift. To ensure
maximum sample accuracy, wait 30 minutes after regeneration before zeroing and using the
instrument.
Zero Air Filter
The Zero Air Filter removes mercury vapor, mercaptans, and hydrogen sulfide from the air
sample. Readings with the filter installed should be near zero.
Because air that is cooler than the instrument will cause low readings and warmer air will cause
higher readings, the Zero Air Filter should be used to equilibrate the unit to ambient air.
Continuous sampling with clean air will not cause saturation of the gold film sensor but will
equalize temperatures faster to allow accurate analysis to begin sooner.
The Zero Air Filter can also be used to identify contamination within the instrument. If the
readings do not reduce to near zero with the filter installed, contamination should be suspected.
If the readings do drop to near zero with the filter installed but elevate with the filter removed,
the presence of Mercury Vapor at the sampled location is confirmed.
For more information on the use of the Zero Air Filter, contact customer service at 1-800-528-
7411, 1-602-470-1414, or visit our web site at http://www.azic.com.
