50  AO2000 CONTINUOUS GAS ANALYZERS  |  OI/AO2000-EN REV. B 
 
 
 
Shut-off valve in the combustion gas supply line 
A shut-off valve must be installed in the combustion gas supply line to in-
crease the safety in the following operating states: 
•  Shutting down the gas analyzer, 
•  Failure of the instrument air supply, 
•  Leakage in the combustion gas feed path inside the gas analyzer. 
This shut-off valve should be installed outside the analyzer house in the vi-
cinity of the combustion gas supply (cylinder, line).   
ABB recommends the use of a pneumatic shut-off valve which is actuated by 
the instrument air. This shut-off valve can be purchased from ABB: Part 
number 0769440. 
If a pneumatic shut-off valve of this kind cannot be installed, precautionary 
measures must be taken, so that the overall status or the "failure" status of 
the gas analyzer is monitored (see section "Fidas24: Troubleshooting" (see 
page 335)). 
Test gases 
Zero-point calibration 
Quality  Nitrogen, Quality 5.0, synthetic air or catalytically cleaned 
air with an organic C content < 1 % of span 
Inlet pressure  p
e
 = 1000 ± 100 hPa 
Flow  130 to 250 l/h 
End-point calibration 
Quality  Sample component or substitute gas component in ni-
trogen or synthetic air with concentration adjusted to the 
measuring range 
Inlet pressure  p
e
 = 1000 ± 100 hPa 
Flow  130 to 250 l/h 
NOTE 
The notes for calibrating (see page 238) must be considered. 
Gas connections 
see section "Fidas24: Gas connections" (see page 83)