Service and maintenance
9.1 Instrument verification
SITRANS SL
156
Operating Instructions, 12/2010, A5E01132948-04
Troubleshooting: Insufficient purging
If the oxygen concentration in the verification tube moves above 0.15 vol % after having
been purged with nitrogen, this may be due to an elevated oxygen content inside the
housing units. To remove that oxygen you can follow one of the two procedures below
depending on your permission to open the lids of the housing. If you are not permitted to
open the lids, you shall just keep on purging the verification tube with nitrogen until all
oxygen in the housing is gone. This may take several hours or even a whole day. Thus the
purging should be interrupted from time to time to test if the oxygen content has fallen below
0.15 vol %. If the test result is above 0.15 vol % within a 10 minutes time you must continue
purging with nitrogen.
If you are permitted to open the lids, you should first turn on the nitrogen flow. Then open the
lids such that the gas can easily enter the gap between lid and housing, but without risk of
the lids falling off. After 15 minutes of nitrogen purging the housing should be free of oxygen.
After purging first close the lids. Then turn off the nitrogen and wait for 10 minutes. If the
oxygen value remains below 0.15 vol %, the problem is solved. If not, repeat the procedure.
See also
Technical data (Page 181)
Verification Sheets (Page 198)