VALTRONICS MODEL 2008SDH-2AP
CARBON DIOXIDE MONITOR
INSTRUCTION MANUAL
Copyright 2017 VTI-Valtronics Inc.
6
FIGURE 3
V. SERVICING
A. Zero Adjustment
If the accuracy of the unit is in doubt, “zero-check” it by using a cylinder of Nitrogen or
CO
2
-free air.
1.
Remove protective cap from the top of the nitrogen cylinder. Push and thread
pressure regulator valve onto cylinder outlet. Nitrogen is
ZERO
gas. Fresh air is
about
0.04% (400ppm)
CO
2,
2.
Connect plastic tubing from the pressure regulator outlet to the flow meter inlet
(bottom connection of flow meter).
3.
Connect plastic tubing from the flow meter outlet to the inlet of the gas cell.
4.
Before applying power, connect a voltmeter to the 0-1V signal output.
5.
Verify that the unit has had at least a 5-minute warm-up before attempting any
adjustments.
6.
Make sure the flow meter is in a vertical/upright position. Open the regulator flow
valve slowly while observing the flow meter.
7.
Adjust the flow to about 50 ml/min. (ml = cc), or about .1 SCFH (Standard Cubic
Feet per Hour).
8.
After 3 minutes of continuous nitrogen flow, the signal output should read 0 VDC
± 10 mV. Perform a zero adjustment if required.
9.
Depending on the signal output reading, turn the Fine Zero Adjustment (R11)
clockwise for an upscale adjustment or counter-clockwise for a downscale
adjustment. The process will reset the zero reading.
10.
Turn off the regulator flow valve and remove the pressure regulator valve from
the nitrogen cylinder.
