EL3000 CONTINUOUS GAS ANALYZERS |  CI/EL3000-EN REV. C  105 
 
 
 
 
Checking gas path leak tightness 
 
When should gas paths be checked for leak tightness? 
The leak tightness of the sample gas path should be checked on 
a regular basis. 
 
We recommend that you check the leak tightness of the sample 
gas path prior to commissioning at the installation site, as it 
may have been affected during transport of the gas analyzer 
(for example, due to high vibrations).  
 
The leak tightness of the sample gas path must always be 
checked after the sample gas path has been opened inside the 
gas analyzer. 
 
 
Requisite Material 
•  Pressure gauge 
•  Hose, length approx. 1 m 
•  T-piece with stop cock 
•  Air or nitrogen 
 
 
Explosion hazard 
Explosion hazard due to mixing of air and flammable sample 
gas residues in the sample gas path. 
•  If the leak tightness test is to be carried out with air and 
the sample gas or test gas is flammable, the sample gas 
path must be rinsed with nitrogen beforehand! 
•  Otherwise the leak tightness test can be performed with 
 
 
Check leak tightness 
1.  Close off the sample gas output so it is gas-tight. 
2.  Connect the T-piece with stop cock to the sample gas inlet 
with the hose. 
3.  Connect the free end of the T-piece to the pressure gauge. 
4.  Blow air or nitrogen through the stop cock until the sample 
gas feed path is under a gauge pressure of approx. 50 hPa. 
Maximum gauge pressure = 150 hPa. 
5.  Close the shut-off valve. The pressure should not change 
measurably in 3 minutes. A sharp pressure drop is an 
indication of a leak inside the sample gas path. 
6.  Repeat steps 1 to 5 for all sample gas paths in the gas 
analyzer. 
 
 
 
 
 
Dichtigkeit  d 
Check the integrity of combustion gas 
path 
 
Combustion gas line 
 
The seal integrity of the combustion gas feed line must be 
regularly checked in accordance with the two following 
instructions, depending on whether the combustion gas is 
offered from a bottle or a central supply. 
 
Combustion gas supply from a cylinder 
1.  Switch off the gas analyzer power supply. Ensure that the 
shut-off valve in the combustion gas supply line is open. 
2.  Set the combustion gas pressure at 1.1 x the normal pressure 
of the combustion gas, i.e. at approx. 1.4 bar. 
3.  Mark bottle pressure display on the high-pressure 
manometer. 
4.  Close the valve of the combustion gas bottle. 
5.  Observe the display on the high-pressure manometer – it 
should not change measurably in 10 minutes. 
•  A measurable change in the display is an indication of a 
leak in the combustion gas path between the bottle 
pressure reducer and the combustion gas inlet valve of 
the gas analyzer.  
In this case the following measures are to be taken: 
–  Check the combustion gas line between the bottle 
and gas analyzer with a leak detection spray. A leak in 
this area must be remedied and another leak test 
must be performed before the gas analyzer is put into 
operation again. 
–  If no leak is found, that means the gas analyzer 
combustion gas inlet valve is leaky. 
 
Explosion hazard 
Explosion hazard if there is a leak in the combustion gas inlet 
valve. 
If a leak is detected at the combustion gas inlet valve: 
•  Disconnect the combustion gas supply. 
•  Do not restart the gas analyzer. 
•  Have the combustion gas valve replaced by the ABB 
 
6.  After conclusion of the seal integrity test, set the combustion 
gas pressure to normal pressure again, i.e. 1.2 bar.