EMS 1304, Installation And Operation Manual

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24
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.