42/24-10 EN Rev. 9 Appendix 3: ZO23 Trace Oxygen Analyzer Module A-3-5
Information for the Installation and Sample Conditioning, Continued
Legend for Figures
A-3-2 and A-3-3
1 Sampling point with primary
shut-off valve
2 Multi-way ball valve
3 3-way ball valve
1)
4 Fine-control valve
5 Flow meter with needle
valve and alarm contact
6 2-way ball valve
1)
7 2-way ball valve
1)
8 Air filter
1)
9 Gas analyzer
10 Flow meter without needle valve, with alarm
contact
11 Test gas cylinder with N
2
1)
12 Test gas cylinder with e.g. 2 ppm O
2
in N
2
2)
13 Test gas cylinder with 8 ppm O
2
in N
2
1)
14 Pump
1)
15 Needle valve
1)
1) Option
2) A hard-mounted test gas cylinder is normally adequate. The annual check of
the reference point (see page A-3-7) can also be carried out by means of a
non-stationary air supply
.
The following information for installation and sample conditioning has to be
observed when executing measurement and controlled calibration (manual,
automatic and externally controlled calibration). Manually operated valves have to
be replaced by controlled valves which are suitable for trace oxygen measurement
if required.
Gas Sampling The nominal diameter of the line from the sampling point to the first switch-over
valve should be 4 mm.
A bypass can be placed upstream of the first switch-over valve to obtain a faster
analysis. With a nominal diameter of 4 mm, the bypass should be longer than 3 m
to prevent back diffusion from the ambient air.
The sample gas pressure must be reduced at the sampling point. A heated adjust-
able pressure regulator is also to be provided if samples are taken from liquid gas
lines.
Sample Gas
Supply Line
The sample gas supply line must consist of stainless steel tubing, be as short as
possible and have the fewest joints possible.
The diameter of tube from the beginning of the first switch-over valve should be
3 mm externally and 2 mm internally. The sample gas connection to the gas ana-
lyzer is specified for a tube with an external diameter of 3 mm. Swagelok
®
fittings
should be used for the connections.
The trace oxygen analyzer module ZO23 may not be series-connected to other
ZO23 analyzer modules or other gas analyzers.
For the gas analyzer version without internal pump and flow sensor, a fine-control
valve must be provided to set the flow (see section “Sample Gas Flow Rate”,
page A-3-2). The primary pressure must be kept constant in or
der to obtain a
stable flow rate.
Gas Outlet Line Flexible tubing can be used for the gas outlet line. With a nominal diameter of
4 mm, its length should be more than 3 m to prevent back diffusion from the
ambient air.
Continued on next page
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