Table 5-3 Input Calibration For Range 3 - Honeywell 7866 Operation And Maintenance Manual

Calibration
Range 3: Hydrogen Percentage Ratio to Air
Range 3 is used to indicate the percentage of Hydrogen (H
is exposed to 100 % Hydrogen (0 % Air), the display should read 100 %. As Air is introduced, the display
should progress downscale.
Some confusion is possible as 100 % H
Zero. This is a carry over from the original analog circuitry.
Range 3 is used during normal operation to detect Hydrogen loss and therefore to detect potentially
dangerous process situations. The implication is that air is replacing the Hydrogen in the system. The
standard display range is 100 % to 75 % Hydrogen. Since Air represents a significant hazard due to its
Oxygen content, a mixture of 75 % Hydrogen and 25 % Nitrogen is used to calibrate the instrument at the
low operating range of the scale. Nitrogen is an acceptable substitute since its heat capacity characteristics
are very close to Oxygen. Since Air is composed of roughly 80 % Nitrogen and 20 % Oxygen, the error is
insignificant.
Span and Zero are reversed for this range as the initial input should be the same as the Range 2 Span. Calibration
progresses from Span to Zero for this range.
Step Press
1
2 SET UP
3 FUNCTION
4 or
5 FUNCTION
6 FUNCTION
7 FUNCTION
8 FUNCTION
9 FUNCTION
If, after the Zero or Span "live" value has stabilized, no change is made, you should still perform the same key-press
sequences. For example, if in Step 5 you make no change to the displayed value, continue to Step 7 by pressing the
FUNCTION key twice.
50 7866 Triple Range Digital H
is referred to as the span for Range 3 and 75 % H
2

Table 5-3 Input Calibration for Range 3

Connect the H source to the sensor.
2
until you see:
Upper Display: CALIBR
Lower Display: RANGE 3
You will see:
Upper Display:
Lower Display:
Select CALIB to begin manual calibration procedure for Range 3.
You will see R3 SPAN in the Lower Display.
The value shown in the Upper Display is a "live" reading. Wait until the value
becomes stable.
Captures the displayed value. The display will blink once indicating that you can
use the or keys to change to the desired zero value. (This ties the internal
counts processed for the input conversion to the desired value for Span.)
Saves Range 3 SPAN data.
You will see R3 ZERO in the Lower Display.
Connect the 75 % H /25 % N
2
Upper Display is a "live" reading. Wait until the value becomes stable.
Captures the displayed value. The display will blink once indicating that you can
use the or keys to change to the desired span value. (This ties the internal
counts processed for the input conversion to the desired value for Zero.)
Saves Range 3 ZERO data and processes the Range 3 calibration calculation.
and CO Analyzer/Indicator - Operation and Maintenance
2 2
) against a background of Air. When the sensor
2
Action
DISABL (default selection)
RANGE 3
source to the sensor. The value shown in the
2
is referred to as the
2
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