Emerson OPM4001 Installation And Operation Manual page 7

I N S T R U C T I O N M A N U A L R E V 4 . 2
INTERNAL CALIBRATION SYSTEM, ZERO MODE
Zero and span calibration checks can be initiated manually, automatically or by a PLC or computer. During the zero calibration mode
a calibrated zero reflector is placed in front of the transceiver optical package testing all optical surfaces and electronic components
to assure zero point has not changed.
INTERNAL CALIBRATION SYSTEM, SPAN MODE
In the span mode a Span filter of known Neutral Density is placed in the measurement path and produces a specific upscale reading
in accordance with the latest E.P.A. requirements. The zero and span cycle provides a continuous check of all the optical
components and surfaces, the main lamp, the detector, interconnecting wiring, control unit and computation analysis.
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