BAM 1020-9800 Manual Rev W.docx
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6. If the results of the zero test indicate that the instrument LLD is higher than the factory
specified value or that the BKGD value has changed by more than 2 μg/m
3
since the
most recent field (not factory) zero-filter test, the user may wish to repeat the zero-filter
test. If the problem persists contact the factory.
7. Enter the new BKGD value into the SETUP > CALIBRATE menu on the BAM-1020.
Restore the CONC and FLOW type settings to their pre-test configuration, if
applicable. Save and exit back to the main menu.
7.8 The TEST Menu System
– Overview
The following sub-sections provide information for performing diagnostic checks on the BAM
1020 sub-systems using the TEST menus. Most of these tests are used for troubleshooting
purposes only, and are not necessary on properly functioning units. The TEST menu system
is accessed by the TEST soft-key from the main menu and is shown below. These screens
are used to perform calibrations and audits of various sensors, as well as some advanced
diagnostics to resolve failures and errors.
The TEST Menu
7.9 COUNT Test Menu
– Beta Detector Count Tests
The TEST > COUNT screen allows the user to check the function of the beta detector and
beta source separate from the rest of the mechanical or flow operations. Each count test will
take 4 minutes, and will show the number of beta particles counted as they accumulate. The
final count total will stay on the display after the counting is finished, and up to six count tests
can be displayed on the screen at once. Count tests are usually performed with a clean
section of filter tape between the source and detector, as in normal operation.
The GO soft key is pressed to start a new four-minute static count test. The COUNT value on
the screen will immediately begin to count rapidly if the detector is operational and
unobstructed. Typical four-minute count totals through clean filter tape are between 600,000
and 1,100,000 counts. The count total will be lower if the membrane is extended. After four
minutes the counting will stop and wait for the operator to initiate another count or EXIT.
The M value on the screen indicates if the membrane was extended (Y) or withdrawn (N)
during the count period. The MEMBRN and NO MEMBRN soft keys can be used to manually
extend or withdraw the span membrane foil before a count test if desired.
Dark Count Tests:
A steel shim such as Met One 7438 can be placed between the beta
source and detector to perform a dark count test. The shim blocks all beta particles, and only
counts created by noise or cosmic rays will appear. The total four-minute dark count value
should be less than 10 counts. If the total is more than 50 counts, contact technical service.
TEST MENU
COUNT PUMP TAPE DAC
CALIBRATE INTERFACE FLOW ALIGN
HEATER FILTER-T RH
SELECT EXIT
