A-3-6
Appendix 3: ZO23 Trace Oxygen Analyzer Module
42/24-10 EN Rev. 9
Information for the Installation and Sample Conditioning,
Continued
Bypass
The gas analyzer is connected to a constant gas flow (approx. 40 l/h) in the
bypass. The needle valve is installed upstream of the branch to the gas analyzer,
and the bypass flow meter downstream of the branch to the gas analyzer.
The gas analyzer takes 8 l/h from the gas flow. There is a surplus of approx. 30 l/h.
If several ZO23 analyzer modules are supplied with gas in parallel (redundant
measurement), the flow must be set in such a way that the bypass has a surplus
of 30 l/h.
With a nominal diameter of 4 mm, the exhaust gas line from the outlet of the gas
analyzer should be longer than 3 m to prevent back diffusion from the ambient air.
On account of possible leaks, the flow meters are always placed in the bypass
feed path downstream of the branch to the gas analyzer, respectively, downstream
of the gas analyzer; they may on no account be installed in the sample gas supply
line upstream of the measuring cell.
Exhaust Gas
The sample gas and the bypass must be conducted to the atmosphere or to an
unpressurized exhaust gas collecting system at an adequate distance from the
gas analyzer. Long conduction paths and pressure variations must be avoided.
For measurement and safety-related reasons, sample gas and bypass may not be
discharged into the atmosphere in the proximity of the gas analyzer, since the
ambient air serves as reference air, and also in order to exclude asphyxiation as a
result of oxygen deficiency. It must be ensured that any exhaust gas which gets
into respiratory air is sufficiently diluted.
