1. Overview

The "CS301, Conductivity Too Low" alarm occurs when salinity falls below 10 PSU during Ballasting.

📌 When operating in low-salinity or freshwater areas, the A.P. Tank (Aft Peak Tank) must be pre-filled with seawater before starting Ballasting.

📌 If the A.P. Tank is not used for seawater storage, another designated W.B. Tank (Water Ballast Tank) may be used.

• Refer to the vessel's Piping Diagram to confirm the correct tank.

2. Preparation for Ballasting with the A.P. Tank

Step 1: Check BWTS Final Drawing (LOW SALINITY Section)

1. Verify the BWTS Final Drawing (Low Salinity Section) for the correct flow path.
   
2. Ensure the A.P.TANK is pre-filled with seawater before entering low-salinity or freshwater areas.
   
   • Confirm that at least 1.2% of the total ballast capacity has been ballasted into the A.P.TANK in general seawater conditions.
     
3. In low-salinity/freshwater conditions, only seawater from the A.P.TANK should be supplied to the ECU (Electro Chlorination Unit) for electrolysis.
   

📌 Why?
Maintaining a proper seawater supply to the ECU ensures effective electrolysis in low-salinity environments.

Step 2: Valve Lineup (Refer to Piping Diagram)

1. Close the EIP (ECU Inlet Port) valve to prevent freshwater inflow.
2. Open the necessary valves to allow sea water from the A.P. Tank to supply the ECU.
   
   
                          

📌 Why?
This configuration ensures that only seawater from the A.P. Tank is used for electrolysis instead of low-salinity water from the main pipeline.

3. Start Ballasting Using the A.P. Tank

1. On the touchscreen BALLAST tab, press "START".
2. Start ballasting using B/P (Ballast Pump).
3. Monitor SYSTEM STATUS:
   • Ensure CS301 (conductivity) exceeds 10 PSU.
   • Check that FM301 (Side Flow Meter) reading is increasing.
     

📌 Why?
Proper conductivity levels confirm that sufficient salinity is present for electrolysis.

4. Air Venting (If FM301 Shows 0 m³)

If FM301 remains at 0 m³, perform air venting at the Strainer and EBP.

Step 1: Air Venting at the Strainer (If Installed Before EBP)

1. Open the Strainer’s Air Vent Valve.
   
2. Release air until a continuous seawater flow is observed.
3. Close the air vent valve completely.

Step 2: Air Venting at the EBP

1. Immediately after starting Ballasting, slightly loosen the EBP’s Air Vent Plug.
   
2. Release air until a continuous seawater flow is established.
3. Tighten the Air Vent Plug completely.

📌 Why?
Removing trapped air ensures consistent water flow through the system.

5. Exiting Low-Salinity or Fresh Water Areas

• Once the vessel moves into normal seawater regions, restore the valves to their original positions.

6. Summary of Key Actions