VALTRONICS MODEL 2008SDH-2AP
CARBON DIOXIDE MONITOR
INSTRUCTION MANUAL
Copyright 2017 VTI-Valtronics Inc.
7
B. Span Adjustment
Note:
It is not normally necessary to adjust the span on the Model 2008SDH-2AP. Once
the span has been properly adjusted at the factory, it does not require adjusting. All that is
normally required is a zero check or adjustment.
1
If the span adjustment is in doubt, please observe the following guidelines:
1.
Verify the zero set point (reference the previous section).
2.
Replace the nitrogen cylinder with a cylinder of the desired concentration, usually
mid or near full-scale, of carbon dioxide.
3.
Open the regulator flow valve slowly while observing the flow meter. The flow
meter should read about 50 ml/min.
4.
Allow the gas sample to flow through the unit for approximately 60 seconds
before any adjustments are made. Perform a span adjustment if required.
5.
Refer to the scale data charts (which can be found on the data/spec sheets on our
website) for the corresponding output voltage that matches the sample gas
concentration:
50% full-scale units:
http://www.valtronics.com/assets/2008SD50.PDF
;
100% full-scale units:
http://www.val-tronics.com/assets/2008S100.PDF
)
6.
Depending on the signal output reading, turn the Span Adjustment (R22)
clockwise for an up-scale adjustment or counter-clockwise for a downscale
adjustment. This process will reset the span.
7.
Turn off the regulator flow valve and remove the pressure regulator from the
cylinder.
This completes the checkout and adjustments procedures.
1
NOTE: Gas calibration should be done a minimum of once every (
6)
six months (at least for
ZERO
calibration). If you keep a calibration logbook and record how much zero & span drift occur, you can verify if
the calibration interval is correct. You may find that
ZERO
calibration every 6 months and
SPAN
once a year is
sufficient to maintain accuracy.
