BAM 1020-9800 Manual Rev W.docx
Page 57
F
Flow Error
Flow errors can occur due to a fault with the flow controller, the flow sensor, or the
vacuum pump. See section 7.5 for troubleshooting suggestions. The digital error log
contains the exact subcategory which generated the alarm.
The following minor flow alarms occur when a parameter was out of bounds, but the
sample was not stopped. Concentration data is still stored normally
•
5% out-of-regulation
- Flow > 5% out of regulation for more than 5 minutes.
•
AT Failure
– One minute average of the AT sensor was within 1 degree of the
sensor min or max range. May occur in extreme cold or hot environments.
•
Internal or External BP Failure
– One minute average of the barometric
pressure sensor exceeded the min or max range of the BP sensor.
•
Self-Test
– Self test flow rate less than 10 L/min.
The following critical flow errors result in the sample being terminated and the
concentration data being set to full-scale or as configured in the SETUP > ERRORS
menu (see section 6.5).
•
AT Disconnected
- Missing or incorrectly connected AT sensor.
•
Pump Off Failure
- Flow sensor indicates >5 L/min with the pump turned off.
This critical flow error results in the sample being terminated prematurely and the
concentration being calculated with a smaller sample volume of air.
•
Flow Failure
- Flow > 10% out of regulation for more than 1 minute.
P
Pressure Drop
Alarm
or
Delta-Pressure
Alarm
This error indicates that the pressure drop across the filter tape has exceeded the
limit set by the
“AP”
value and is often due to heavy particulate loading. Current
firmware will stop the sample early when this occurs, and make the concentration
calculation based on the partial volume, then wait for the next hour. This feature is
designed to stop the sample early if the vacuum capacity of the pump is about to be
exceeded, before flow errors occur. Firmware before Rev 3.6.3 would not stop the
sampl
e for the “P” alarm, and subsequent flow errors could occur due very high
concentration dust loading. The pump cycle must run for at least 5 minutes before a
pressure drop alarm event can occur. See Section 6.5.
D
Deviant Membrane
Density Alarm
or
BAM CAL alarm
This error indicates that the reference membrane span check measurement (
m)
for
that hour was out of agreement with the expected value (
ABS
) by more than ±5%.
These alarms are often caused by a dirty or damaged membrane foil. If the foil is
clean and undamaged, the alarm could indicate that the beta detector tube itself is
noisy or beginning to wear out, or that the membrane holder is not extending and
withdrawing fully. These alarms do not prevent the BAM from storing a valid
concentration for the sample hour because the dust mass is a completely separate
measurement, but the alarm should be investigated and resolved in order to ensure
proper beta detector operation.
C
Count Error
or
Data Error
This error indicates that the beta particle counting system is not operating properly,
and is activated if the beta count rate falls below 10,000 counts during any of the
mass, membrane, or stability measurements. The 4-minute beta count rate through
clean filter tape is usually more than 800,000 counts. This rare error occurs if the
beta detector, high voltage, or digital counter has failed or if the beta signal is
physically obstructed. This alarm sets the concentration value to full-scale.
The sub-
category “count, failed” occurs if the beta counter is still counting 10
seconds after the scheduled end of any count period, indicating a digital fault.
