9-2 Chapter 9: Inspection and Maintenance 42/24-10 EN Rev. 9
Checking Gas Path Seal Integrity
When should gas
path seal integrity be
checked?
Gas path seal integrity should be checked periodically. It must be verified after the
gas paths inside or outside the gas analyzer have been opened (e.g. after
removing or installing an analyzer module).
What materials are
needed?
1 pressure gauge, 1 plastic tubing, approx. 1 m (3 feet) in length, 1 tee with shut-off
valve, air or nitrogen
CAUTION!
If the seal integrity test is to be carried out with air and there is the possibility
of a combustible gas being present in the gas paths or if a combustible gas
is to be introduced later, the gas paths should first be purged with nitrogen.
Otherwise the seal integrity test can be performed with nitrogen.
The following instructions apply to all gas paths in the gas analyzer, therefore to all
sample gas paths and – in the Caldos25 and Uras26 analyzer modules – to the
reference gas path.
Step Action
1 Plug the outlet of the gas path to be tested (7 in the example).
2 Connect plastic tubing with a tee fitted with a shutoff valve to the inlet
of the gas path to be tested (4 in the example).
3 Connect the free end of the tee to the pressure gauge.
Blow air or nitrogen through the shutoff valve until the gas path is
pressurized to p
e
≈ 50 hPa (= 50 mbar). Close the shutoff valve.
Maximum pressure p
e
= 150 hPa (= 150 mbar).
4
Limas11 with quartz sample cell: Gauge pressure p
e
≈ 400 hPa
(= 400 mbar), maximum gauge pressure p
e
= 500 hPa (= 500 mbar).
The pressure should not change measurably in 3 minutes. A sharp
pressure drop is a sign of a leak in the gas path being tested.
5
Limas11 with quartz sample cell: Test duration 15 minutes.
Checking Gas Path
Seal Integrity
(see example in
Figure 9-1)
6 Repeat steps 1-5 for all gas paths in the gas analyzer.
Figure 9-1
Seal Integrity Test
(Example: Sample Gas
Path in Magnos27)
1
2
3
4567
8
9
10
11
12
14
13
Luft / Air
50 hPa
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