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Backlight
The Backlight can be set as Automatic, Manual or Off. In Automatic Mode the backlight comes
on and stays on in low light conditions. In Manual Mode, pressing the Right or Left key turns
the backlight on for one minute.
Pump Speed
The pump can operate at low or high speed, ranging from about 300 to 420 cc/min with no filters,
respectively, 260 to 390 cc/min with a standard 0.45 µm filter in place, and about 240 to 350 cc/min
with both a benzene tube and 0.45 µm filter. Running at low speed is quieter and conserves a small
amount of power. There is almost no difference in sampling accuracy. High pump speed is
recommended for faster response when using an extension hose to sample, or when measuring
heavy compounds, which tend to have slow response because of adsorption on inlet surfaces.
NOTE
: During benzene tube measurements, the set pump speed is over-ridden and automatically
switched to high speed for the initial tube measurement and low speed for a follow-on STEL reading.
Use the Right key to enter Pump Speed, then Up or Mode to scroll on the list, Right to select, and
Left to save and exit. Note that each Pump Speed has its own Stall Threshold.
Set Pump Stall Threshold
The Pump Stall Threshold is the current-draw setting for a blocked
pump alarm. The default setting is 500. The actual, real-time pump
current draw is displayed in the upper right corner. Briefly block the
inlet probe with a finger and to observe the rise in pump current value.
Set the stall threshold about 50-100 units above the unblocked pump
reading, but lower than the blocked pump reading. Press the Up or
Mode key to increase or decrease each digit’s value, and the Right or
Left key to move the cursor. Then move the cursor to ‘
√
’ and press
Up to save and exit. Set a different pump stall threshold for each
pump speed.
3-Point Calibration
Normally a 2-point calibration gives adequate linearity in PID response, but a
3-point calibration (Zero, Span 1 and Span 2) can be enabled for more accuracy,
particularly in the high concentration range above about 500 ppm VOC where
response is less linear. Use the Right key to enter 3-Point Cal, then Up or Mode
to scroll to On or Off, Right to select, and Left to save and exit.
Below is the list of default 1
st
and 2
nd
Span points for each Measurement Mode. These settings can
be changed in the Calibration menu.
NEO BENZ Mode
Span
Span 2
VOC (Isobutylene)
10 ppm
1000 ppm
Benzene
5 ppm
50 ppm
Set Pump Stall
297
_ 5 0 0
√ ×
O
O f f
O n
3-Point Cal.