Instruction manual

120-00004 REV A 10/6/2011 4000 DIGITAL MANUAL PAGE 25
8.0 Appendix
Appendix A
INTERFERING GAS DATA
No analytical method is completely specific. Gases present in the environment, other than the "target"
gas of measurement, may affect analyzer response. Interferences are not necessarily linear, and may
also exhibit time dependent characteristics.
The charts that follow detail the approximate concentration in parts per million of interfering gas
required to cause a 1 ppm deflection in the chosen analyzer. In many cases, specificity can be
improved. Please note that the response values given are not absolute, and may vary depending on
sensor formulation.
The special case of how alcohols affect electrochemical sensors is discussed in this Knowledge
Base article. (www.gasdetection.com)
For further information on the effects of interfering gases, please contact the factory.
The charts follow the format, and grouping of gases, that was originally established in early Interscan
print brochures.
Chart 1: CO, Cl
2
, ClO
2
, H
2,
H
2
S, NO, NO
2
, O
3
, SO
2
analyzers
Chart 2: Ethylene oxide (EtO) (C
2
H
4
O) analyzers
Chart 3: Formaldehyde (HCHO) analyzers
Chart 4: HCl, HCN, hydrazine analyzers
Chart 5: C
2
H
4
(ethylene) analyzers