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Instruction Manual
IM-105-4000, Original Issue
August 2005
OPM 4000
3-4
ZERO/SPAN
CALIBRATION CHECK
The zero calibration has been set at the factory by placing the instrument on
an optical bench using the flange-to-flange dimensions specified by the
customer and recorded in the customers final test report. This zero value is
critical as it can offset smoke measurement plus or minus if not correctly set.
The measurement reflector contains an aperture that is chosen during the
factory calibration and is fixed. The transceiver is aligned with the beam
centered on the retro reflector and the electronics is adjusted to produce a
zero opacity value.
The calibration zero reflector is then adjusted to provide a low value - typically
1-2% and the span filter up scale value is recorded. The values are entered in
the Quick Menu under "Zero Cal Value" and " Span Cal Value". When the
system enters a manual or auto cal check cycle, the current zero and span
values are checked against the stored values. If either the zero or span
current value exceeds the stored value by ±2% opacity, the fault system will
energize.
To verify initiate a manual cal cycle by pushing the AUTO/MAN key. The
Alarm LED will light and the Left/Right Bargraph will blink, this is normal
because a manual cal is considered a fault condition. Pressing the ACK key
will cause the ALARM LED and the bargraphs to stop blinking. The message
display will read MANUAL CAL ALARM. Push the DIS key to return to display
opacity.
After the cal cycle is complete pushing the ACK key should clear any alarms.
If no alarms are present the system is working properly.