1. Overview

The "CS301, Conductivity too low" alarm occurs when the salinity level drops below 10 PSU during Ballasting.

📌 When operating in low-salinity or fresh water regions, the SCU (Salt Control Unit) must be used to prepare high-concentration saltwater, align the required valves, and ensure proper operation.

📌 SCU Installation Locations:

• Engine Room
• Upper Deck

2. SCU Preparation Steps

Step 1: Check SCU Tank Size

1. Refer to the Final Drawing on board to confirm the SCU Tank size.
   
2. The vessel’s BWTS manual provides saltwater preparation guidelines:
   
   
   • For a 1m³ SCU Tank:
     • 0.8m³ of fresh water
     • At least 209kg of salt
     • Can treat approximately 2,000m³ of ballast water

Step 2: Mix Salt and Water in SCU

 
(Example: SCU Tank Size = 1m³)

1. Open the Freshwater Inlet Valve (CV108) and fill with 0.8m³ of fresh water, then close CV108.
2. Close CV102 below SCU panel (upstream of SIP901).
3. Open the Compressed Air Supply Valve (CV109) to aid in dissolving the salt.
4. Move 209kg of salt (20kg x 11 bags) to the SCU Tank and pour it in.
5. Supply compressed air for at least 1 hour to ensure complete dissolution of the salt.
6. Once the salt is fully dissolved, close CV109 and open CV102.

📌 Why?
Salt must be fully dissolved before being injected into the Ballast system.
And the salt water have to be made before 3 days for Ballasting.

3. Valve Line-up for SCU Ballasting

1. Ensure that the following SCU panel valves are set correctly:

   • CV101, CV102, CV103 must always remain OPEN.
     
     
   • Select switch inside the SCU panel should always be set to AUTO.
     

2. Open the SCU Outlet Valve located before the EBP(ECU Booster Pump) in the Engine Room.
   
   

3. Ensure the Sea Inlet Valve is always open.

📌 Why?
Proper valve alignment ensures correct saltwater injection into the Ballast system.

4. Start Ballasting Using SCU

1. On the touchscreen BALLAST screen, press "START".
2. When the "LOW SALINITY REGION?" pop-up appears, select "YES".
   
   

📌 Why?
Selecting YES activates SCU-assisted Ballasting.

5. Monitor System Status

1. During Ballasting, monitor the SYSTEM STATUS screen:
   • Ensure CS301 (conductivity) exceeds 10 PSU.
   • Check that FM301 (Side Flow Meter) reading is increasing.
     

📌 Why?
A conductivity level must exceed at least 10 PSU to operate Ballasting.

6. 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 in BALLAST screen, 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 flow through the SCU and Ballast system.

7. Exiting Low-Salinity or Fresh Water Areas

• Once back in normal seawater regions, close the SCU Outlet Valve to stop saltwater injection.

8. Summary of Key Actions