CALIBRATION
CALIBRATION OVERVIEW
Although routine calibration of the Open Path Eclipse is
normally not required, the device supports non-intrusive
field zero calibration capability. Span calibration is not
required.
Zero Calibration
Zero Calibration is a one-step process consisting of
clean air (zero) condition adjustment only, which is per-
formed automatically by the device. This procedure
adjusts the "clean air" signal output only, and is normally
used if the 4 milliampere signal level has drifted. The
cause of drift is typically due to the presence of back-
ground gas during calibration. Ensure that the optical
path is clear of hydrocarbons prior to calibration initia-
tion to ensure an accurate zero (clean air) condition.
IMPORTANT CALIBRATION NOTES
NOTE
Ensure that the detector has been operating for at
least two hours before calibrating.
NOTE
Always ensure that the OPECL optics are totally
free of all hydrocarbons before initiating calibration.
CALIBRATION INITIATION
Calibration may be initiated by any of the following
means:
• The onboard magnetic calibration switch
• Digital communication via MODBUS communication
(consult factory for details)
• Remote calibration line.
Calibration Using Magnetic Switch
The Open Path Eclipse provides an onboard magnetic
calibration/reset switch for non-intrusive calibration
capability. The magnetic switch is actuated by holding
a calibration magnet at the specified located on the
device bulkhead. See Figure 1 for switch location. An
onboard tri-color LED provides status indication during
calibration.
For zero calibration, the magnetic switch must be actu-
ated for 2 seconds to initiate calibration (signaled by a
solid red LED). Upon initiation, the OPECL automatical-
ly performs the zero calibration adjustment, and then
signals with a green LED when this operation is com-
plete.
Digital Communication Calibration
MODBUS communication may be utilized to initiate
OPECL calibration (consult factory).
DETAILED CALIBRATION PROCEDURE USING
MAGNETIC SWITCH
Zero Calibration
1. Apply magnet for 2 seconds minimum to initiate cali-
bration.
A. The onboard LED turns to steady red.
B. The current output decreases to 1 mA.
2. When zero calibration is complete:
A. The onboard LED changes from steady red to
steady green.
B. Calibration is complete and current output
returns to 4 mA.
18 95-85561.1
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