Instruction manual

120-00004 REV A 10/6/2011 4000 DIGITAL MANUAL PAGE 26
(1) Data shown for H
2
S models with ranges higher than 0-1999 ppb
(2) Data shown for H
2
S models with ranges of 0-1999 ppb and lower
[N]
= Negative interference
‡
= Hydrocarbons
¤
= Rejection ratio can be improved electronically
Chart 2: Ethylene oxide (EtO) (C
2
H
4
O) analyzers
INTERFERING GAS
EtO ANALYZER
Cl
2
CO
CO
2
ethyl
alcohol
Freon
glutaraldehyde
isopropyl
alcohol
N
2
O
NH
3
25
[N]
20
>10
5
380
>10
5
5
1.1 ¶
>10
5
300
¶ Isopropyl alcohol represents the most significant interference on the ethylene oxide sensor, but in
nearly all cases, potential problems can be overcome. Typical remedial actions include:
a. Point shutdown/automatic restart, which allows the operator to temporarily interrupt monitoring at
points that could be affected when isopropyl alcohol is used. Monitoring restarts automatically on a
time-adjustable basis.
b. Selection of monitoring points away from those areas that may be unduly affected by isopropyl
alcohol.
Chart 1: CO, Cl
2
, ClO
2
, H
2
, H
2
S, NO, NO
2
, O
3
, SO
2
analyzers