BAM 1020-9800 Manual Rev W.docx
Page 66
temperature. One should make sure that the ambient temperature sensors (BX-592, BX-596,
or BX-597) are placed in the same environment from which the air is sampled.
When the weather makes it difficult (rain, mist, very high humidity, high dew point....) to
perform the zero-filter test at the monitoring site with the smart-heater engaged ( and running
in "simmer mode") and with the BX-302 zero filter assembly outside the shelter on the top of
the standard inlet tube , then we recommended performing the zero-filter test at the
monitoring site with the smart-heater engaged ( and running in "simmer mode") on the shorter
inlet tube (1.5 foot long inlet tube which accompanies each BAM 1020 to sample room air)
and with the BX-302 zero filter assembly on the top of this shorter inlet tube .
Make sure that the ambient temperature sensors (BX-592, BX-596, or BX-597) are placed in
the same environment from which the air is sampled.
The user may decide to perform subsequent, periodic zero tests with fewer 1-hour values.
Averaging fewer 1-hour values however will result in a less accurate BKGD calculation.
It is recommended that the BAM-1020 be operated for at least 24-hours before commencing
the zero-filter test. A leak check and flow check should be performed before proceeding on to
the following steps for the zero-test. Although it is not necessary to reset the existing BKGD
value to 0 for the purpose of conducting the zero-test, the user may wish to do this in order to
minimize the chance of a miscalculation.
1. Enter the SETUP > CALIBRATE menu.
a. Record the existing BKGD value, then change it to 0.0000 (optional).
b. Note the Conc type and set it to Actual if it is not.
c. Note the Flow type and set it to Actual if it is not.
d. Save and exit back to the main menu.
2. Install the BX-302 zero filter assembly onto the top of the inlet tube.
Note: when it is necessary, don't forget to put a rain cap on the BX-302 zero filter
assembly to avoid aspiration of water through the zero filter.
3. Allow the BAM-1020 to sample for 48-72 consecutive hours, not counting the warm-up
period for the initial zero-test. For the zero-test to be valid, no errors should be logged
either during the warm-up period or during the 48-72-hour sampling period. For
subsequent zero tests the user may decide to use fewer valid data points (such as 24
for example).
4. Calculate the average of the hourly BAM-1020 concentrations to the nearest 0.1
μg/m
3
. The new BKGD value is the negative of this average. For example, the
average of the data sample below is 0.0021 mg (2.1
g), so the correct BKGD value is
-0.0021. Record the new BKGD value.
Note: If the BAM-1020 is being deployed for the first time, replace the factory-set
BKGD with the new BKGD value. As Met One Instruments runs the initial factory zero-
test without the smart heater engaged, the initial zero-test performed by the end user
may differ from this value if the end user used a smart heater during the test.
5. Calculate the standard deviation of the sample (STDEV on MS Excel) to the closest
0.1 μg/m
3
. Confirm that the LLD of the BAM-1020 meets the factory specified value.
Note: Older non-FEM compatible units may not meet these noise specifications.
