BAM 1020-9800 Manual Rev W.docx
Page 44
µsw:
This is called the mu-switch value, and is the factory-set mass absorption coefficient
used by the BAM 1020 in the concentration calculations. The value is typically around 0.3
and may vary slightly from one BAM 1020 to the next. Older units built before 2007 had a
µsw value near 0.285.
K:
K is the factory-set, instrument specific calibration factor for the BAM 1020
concentrations. K is determined by running the BAM 1020 against a calibration standard
while both are sampling from a smoke chamber over a wide variety of concentrations. K
ranges typically from 0.9 to 1.1.
BKGD:
BKGD is used to compensate for measured mass concentration output in the
absence of PM. It is determined by operating a BAM 1020 for several days (48-72 hours) in
the absence of PM (achieved by equipping the BAM 1020 inlet with a hepa-filter). The
average mass concentration of the 48 or 72 1-hour readings multiplied by -1 will be the
calculated BGKD. With a properly set BKGD a BAM 1020 making multiple readings of air with
zero PM should read on average 0 μg/m
3
.
STD TEMP:
This is the value of standard air temperature, used only for standard flow control
or standard concentration calculations. STD TEMP is generally set to 25C. Depending on
local regulations it may have different values however.
HEATER:
This setting selects which operation mode the Smart Inlet Heater is used in.
This value must be set to AUTO for all PM
2.5
, PM
10
and PM
10-2.5
monitoring. When set to
AUTO, the Smart Heater can use the filter RH and/or temperature sensors to control the inlet
tube heating. The setup parameters for the Smart Heater logic are located in the separate
SETUP > HEATER menu, which will not appear as an option in the SETUP menu unless this
HEATER mode is set to AUTO.
HEATER should not be set to MANUAL.
6.4 EXTRA1 Setup Screen
The settings in the EXTRA1 screen are special settings for specific unusual applications and
must not be changed under normal sampling conditions. Below is a brief explanation of
these settings and the factory set values. These settings should never be modified without
first consulting Met One Instruments for guidance.
e1
Low Concentration Limit: This is the lowest concentration value the BAM 1020 is
allowed to store or display and must always be set to match the OFFSET value in the
SETUP > SAMPLE menu. The default value is -0.015 mg.
e2
Not used: The default value is 0.500.
e3
Membrane OFF Delay: The default value is 0.000.
e4
Membrane Time Out: The time the BAM 1020 allows for the membrane assembly to
move before generating an error. The default value is 15.00 seconds.
6.5 ERRORS Setup Screen for the Analog Output
The SETUP > ERRORS screen allows the option of encoding BAM 1020 errors onto the
analog output signal when used with an external analog data logger. Using this method, the
