1. Overview

The "FM301, Side Line Flow Too Low" and "FS301, Side Line Flow Switch Abnormal" alarms typically occur when seawater is not properly supplied to the ECU (Electro Chlorination Unit) during Ballasting.

Common causes include:

• Valve misalignment
• Air pocket formation
• Flow meter (FM301) issues
• Pump malfunction
• Pipeline blockage

Follow the troubleshooting steps below.

2. Troubleshooting Steps

Step 1: Check Valve Alignment

1. Verify EBP (ECU Booster Pump) Selection

   • The vessel's engine room contains two EBP units (EBP601 & EBP602).
   • During Ballasting, only one EBP should be in operation, and only its associated valves should be open.
   • EBP601 is the primary pump, while EBP602 is for redundancy.
   • If the main pipeline branches into the EBP, check the EIP valve and EBP inlet valve alignment.
     

2. Check Sea Chest Valve Alignment

   • If the EBP intake is connected to the Sea Chest, ensure the S/C valves and EBP valve are properly aligned.
     

3. Verify HEU (Heat Exchanger Unit) Valve Alignment

   • If seawater temperature is below 20°C:
     • Open the HEU Inlet/Outlet valves.
     • Close the Bypass valve.
       
   • If seawater temperature is above 20°C:
     • Close the HEU Inlet/Outlet valves.
     • Open the Bypass valve.
       

4. Check ECU Valve (EV104) Operation

   • When starting BALLAST mode, the EV104 valve in the ECU should open.
   • If the valve does not open, it will blink orange on the BALLAST screen.
     
   • If the valve opens successfully, the indicator turns yellow.
     
   • Additionally, check the Limit Switch Box on-site:
     • Yellow (OPEN) indicates the valve is functioning correctly.
       
   • If the valve is malfunctioning, refer to the Pneumatic Valve Troubleshooting Guide.

5. Ensure ECU Outlet Valve Alignment

   • Chlorinated water from the ECU is injected into the main pipeline via the ECU Outlet pipe.
     
   • Ensure proper alignment of the following valves:
     • EOP valve on the main pipeline is open.
       
     • If the ECU Outlet pipe runs from the Engine Room to the Weather Deck, ensure the U-Seal section valves on the Weather Deck are open.
       

Step 2: Perform Air Venting

1. If a strainer is installed before the EBP

   • Open the Strainer's Air Vent Valve and release air until a continuous seawater flow is observed.
     
   • Then, close the air vent valve completely.

2. After starting BALLAST mode

   • Slightly loosen the EBP's Air Vent Plug to release trapped air.
     
   • Release until a continuous seawater flow is established.
   • Tighten the Air Vent Plug completely.

Step 3: Check FM301 (Flow Meter) Status

1. Go to SYSTEM STATUS screen and check if FM301 is in NORMAL state.
   
2. If FM301 shows ABNORMAL, inspect the local FM301 display:
   • Check if the display is ON.
     
   • Verify that the 4–20mA signal is outputting correctly.

Step 4: Verify EBP Operation

1. After starting BALLAST mode, check if the EBP upper fan is rotating.
   

Step 5: Inspect for Pipeline Blockage

1. If there are no issues in all the above steps, pipeline blockage may be the issue.
2. Inspect the following pipe sections:
   • EIP (ECU Inlet Port) → EBP (ECU Booster Pump)
   • ECU Outlet Pipe → EOP (ECU Outlet Port)
3. Ensure seawater is not leaking into equipment or cables.

3. Summary of Key Actions