Metek 920, Operator'S Manual With Essential Health And Safety Requirements

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4-50 | Model 920 Multi-Gas Analyzer
To perform Manual Span for NO
x
using a calibration gas mixture for
which only the total NO
x
concentration is known (and previously
entered):
1. Turn on the Calibration gas mixture containing the NO
x
.
2. Press F5 2 and record the numeric value displayed for FlowCtrl.
Change the Flow Control setting to Continuous Calibration Gas #1 or
#2 mode. The will allow the flow of Calibration gas mixture contain-
ing the NO
x
to manually span the sample system.
3. To initiate the Manual Span, press F2 y , where ‘ y ’ = 2 or 3 (Calibration
gas for each component). The User Interface will prompt “ Man/
Span y ? ”. For this example, the concentrations of NO
2
and NO (com-
ponents 2 and 3, respectively) in the Calibration gas mixture must
previously have been set to ‘
0 ’.
Observe the NO
x
concentration reading on the bottom line of the User
Interface. When it has stabilized at or near the concentration of NO
x
in
the Calibration gas mixture, press:
Ent for Yes The IntTimer duration will count down to ‘ 0 ’ during
which time the reading is averaged if AdjDisable is set
to ‘ 0 ’. The calibration value for NO
x
will be adjusted au-
tomatically and the screen will revert to the CAL mode
normal display.
Esc for No The function is aborted and the calibration value for
NO
x
is not adjusted.
4. Turn off the Calibration gas. The Span for NO
x
is complete.
5. Return the analyzer to the original Flow Control mode by pressing
F5 2 Del n Ent where ‘ n ’ is the numerical value recorded earlier.

(FlowCtrl) CAL

F5 2

Del nn Ent Ent (where nn =
‘11’ for Calibration Gas #1 or
‘12’ for Calibration Gas #2).