Liquisys COM223/COM253 Dissolved Oxygen Commissioning Guide​

I.   Commissioning Procedure​​

​​(1)   Key Functions​​

•   ​​CAL Key​​: Activates calibration mode and displays the calibration menu.
•   ​​+ Key​​: Increases numerical values.
• ​​  - Key​​: Decreases numerical values.
• ​​  E Key​​: Confirms selections.
•   ​​REL1/REL2 Keys​​:
  • ​​  REL1​​: Manual operation of Relay 1.
  •   ​​REL2​​: Toggles Relay 2 between manual/auto modes.

​​(2)   Probe Inspection & Calibration​​

1.   Install the probe with a membrane cap filled with electrolyte.
2.   Expose the probe to ​​air​​ (avoid direct sunlight). Ensure ambient temperature is ​​20–25°C​​.
3.   Connect the probe to the transmitter and press ​​CAL​​. Enter password ​​22​​.
4.   Select ​​"Air Calibration"​​ and press ​​E​​ to confirm.
5.   The displayed value will start at ​​600​​ and gradually decrease to ​​0​​. If no error codes appear, calibration is complete.

​​Valid Calibration Parameters​​:

•   ​​Altitude​​: Display must stabilize between ​​6.00–11.20 mg/L​​ or ​​85–157% SAT​​.
• ​​  Salinity​​: Display must stabilize between ​​9.20–9.30 mg/L​​ or ​​102% SAT​​.

​​(3)   Range Setup​​

​​Step A: Unit Configuration​​

1.   From the main menu, press ​​E​​ → enter ​​Code 0​​ → press ​​+​​ until ​​22​​ → press ​​E​​.
2.   Navigate to ​​Setup1​​ → ​​E​​ → ​​Unit​​ → use ​​+/-​​ to select ​​mg/L​​ → press ​​E​​.

​​Step B: Output Configuration​​

1.   From the main menu, press ​​E​​ → enter ​​Code 0​​ → press ​​+​​ until ​​22​​ → press ​​E​​.
2.   Press ​​-​​ twice → navigate to ​​Output​​ → press ​​E​​ twice → select ​​4–20mA​​.
3.   Set the ​​4mA​​ corresponding value (e.g., minimum DO level) → press ​​E​​.
4.   Set the ​​20mA​​ corresponding value (e.g., maximum DO level) → press ​​E​​.

​​II.   Installation & Maintenance Guidelines​​

1.   ​​Weekly Maintenance​​:

   •   Gently rinse the DO probe with clean water.
   •   Replace the membrane cap immediately if damaged.
   •   Replace contaminated electrolyte promptly.
   •   Avoid applying tension to the probe cable.

2. ​​  Application Warnings​​:

   • ​​  Municipal Wastewater​​: Safe for standard use.
   •   ​​Industrial Wastewater​​: Verify water composition. Harmful substances (e.g., ​​H₂S, ammonia, benzene, phenol​​) can degrade the membrane.
   • ​  ​Hazardous Chemicals​​: Frequent membrane replacement is required in environments with aggressive agents.