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O&M Manual
Rev-L (7/15)
Part 7 – System Maintenance
7.1
General
The Q45D/60 Dissolved oxygen System will generally provide unattended operation over
long periods of time. With proper care, the system should continue to provide
measurements indefinitely.For reliable operation, maintenance on the system must be
done on a regular schedule. Keep in mind that preventive maintenance on a regular
schedule is much less troublesome than emergency maintenance that always seems to
come at the wrong time.
7.2
AnalyzerMaintenance
No unusual maintenance of the analyzer is required if installed according to the
guidelines of this operating manual. If the enclosure door is frequently opened and
closed, it would be wise to periodically inspect the enclosure sealing gasket for breaks or
tears.
7.3
SensorMaintenance
Sensor maintenance is required for accurate measurements. The primary requirement is
simply to keep the sensor membrane clean. The membrane is a polymer material that is
resistant to anything that will be encountered in water streams. However, deposits or
biological growth can form on the surface of the membrane, and these deposits will
reduce the sensitivity to oxygen. Normally, these coatings can be removed by simply
wiping the membrane with a soft cloth or paper towel.
Should a coating form on the membrane that does not wipe off, it is best to change the
membrane. Chemical cleaning may work as well, but a new membrane is a more reliable
solution. To change a membrane, follow the Sensor Assembly procedure in this manual.
Do not reuse the electrolyte from the sensor when changing a membrane. Always refill
with fresh electrolyte. The electrolyte is stable and does not have a limited shelf life.
Even if no buildup is apparent on the membrane, it should be changed on a regular
schedule. The recommended membrane change interval is every 6 months.
The actual membrane life is often in excess of one year, but periodic preventive
maintenance will simply avoid having to do service on an emergency basis.
While the sensor is disassembled for membrane changing, examine the condition of the
o-rings on both ends of the electrolyte canister. If the o-rings show any signs of damage,
replace them with new ones from the spare parts kit. It is good practice to change these
o-rings once a year, regardless of their condition.
