Ametek Thermox WDG-VC - Calibration and Aspirator Air Requirements

Installation Guide | 3-11
Calibration/Aspirator Air
Required Calibration Gases and Tubing
See Chapter 2 for information on calibration gases. The span gas is
the high gas; the zero gas the low gas.
The span gas must be 10 times greater than the zero gas. For example, if
the zero gas is 1% O
2
, the span gas must be 10% O
2
or higher.
O
2
Span Gas Instrument air (20.9%) or from 1.0% to 100% O
2
.
O
2
Zero Gas From .1 to 10% O
2
, balance N
2
Combustibles Span Gas
If using a WDG-VC analyzer, you must also have a combustibles
span gas as follows:
60 to 80% of the full combustibles operating range in certied
mixtures of CO, with an equal amount of O
2
, balance N
2
.
For example, if using an operating range of 0 to 2000 ppm combustibles,
use 1200 ppm CO, 1 to 2% O
2
, balance N
2
.
Methane Span Gas
• If using a WDG-VCM analyzer, you also must have a methane span
gas as follows:
- 2% CH
4
, 8 to 10% O
2
, balance N
2
.
ASPIRATOR AIR
DRAIN VALVE
INSTRUMENT AIR INLET
ELECTRONICS SECTION
C
L
LOCATION
C
L
[
[
[
[
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]
Figure 3-12. Sensor Inlet Connections (Wall/Flange Mount).
NOTE
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