Analysis of Common Issues in RO (Reverse Osmosis) Equipment Operation

Reverse osmosis (RO) systems are key components of pure water, purified water, and ultrapure water equipment. They are also prone to operational problems. Below are common issues with RO equipment and their potential causes.

I. Common Equipment Failures and Troubleshooting

1. Low Feed Water Pressure: Possible causes:

(1) Inappropriate feed water flow rate

(2) System leakage

(3) Insufficient inlet water pressure at the high-pressure pump, or leaks in the pump (water or air)

(4) Clogged precision filter cartridge

(5) High-pressure pump malfunction

2. High Feed Water Pressure: Possible causes:

(1) Improper adjustment of the high-pressure pump outlet valve

(2) Blockage in the piping between the high-pressure pump and the RO unit

(3) Concentrate flow control valve is too tightly closed or blocked, resulting in low concentrate discharge flow

(4) Low recovery rate

3. Low Recovery Rate: Possible causes:

(1) Excessively high feed water flow rate

(2) Low feed water pressure or low feed water concentration

4. High Recovery Rate: Possible causes:

(1) Excessively high feed water pressure

(2) Insufficient feed water flow rate

5. High Pressure Drop Across the RO System: Possible causes:

(1) High concentrate flow rate

(2) Membrane element fouling

6. High-Pressure Pump Stops Operating: Possible causes:

(1) Excessively high pump outlet pressure (greater than 1.7 MPa)

(2) Inlet water pressure is too low (less than 0.05 MPa)

7. Decreased Water Production: Possible causes:

(1) Low feed water temperature

(2) Low feed water pressure

(3) High concentration of concentrate, causing high osmotic pressure

(4) Membrane fouling

8. Increased Water Production: Possible causes:

(1) High feed water pressure

(2) High feed water temperature

9.  Simultaneous Increase in Product Water and Concentrate Conductivity: Possible causes:

(1) Blockage in the concentrate pipeline or concentrate control valve

(2) Excessively high recovery rate

10. High Product Water Conductivity with High Concentrate Conductivity and Pressure Drop: Possible cause: Membrane element fouling, restricting concentrate flow.

11. High Product Water Conductivity with Increased Pressure Drop Across Each Vessel and Low Water Production: Possible cause: Membrane element fouling.

12. Large Pressure Drop Across Each Pressure Vessel with Low Water Flow and Increased Product Water Conductivity: Possible cause: Fouling or blockage in membrane channels.

II. Component Failures and Solutions

1. Raw Water Booster Pump Won't Start: Possible causes:

(1) The thermal relay of the booster pump has tripped. Check and reset the thermal relay.

(2) The pump is operating without one phase. Check the power supply to the pump.

(3) The raw water tank's liquid level is below the lower limit. Check the water supply pipeline and level controller.

(4) The pure water tank's liquid level is above the upper limit. Wait for the level to drop, then restart the operation.

(5) No power supply. Check for power outages and check if fuses are blown.

2. Feed Water Flow Meter Not Reaching Design Capacity: Possible causes:

(1) Pump rotation is reversed. Swap any two phases of the three-phase power supply.

(2) Blockage in the water supply pipeline. Check and unblock the pipeline.

(3) The liquid level in the raw water tank is below the lower limit. Check the water supply pipeline and level controller.

(4) The pure water tank's liquid level is above the upper limit. Wait for the level to drop and restart the system.

(5) Air intake in the pump. Check the inlet pipeline and pump for leaks.

(6) Blockage in the discharge pipeline. Remove the blockage.

3. High-Pressure Pump Won't Start: Possible causes:

(1) The thermal relay of the high-pressure pump has tripped. Check and reset the thermal relay.

(2) The pump is operating without one phase. Check the power supply.

(3) The raw water tank's liquid level is below the lower limit. Check the water supply pipeline and level controller.

(4) The pure water tank's liquid level is above the upper limit. Wait for the level to drop, then restart.

(5) No power supply. Check for power outages, check the air switch and fuses, and check if the inlet pressure is too low. Ensure the upstream piping is clear. Check if the outlet pressure is too high or if the membrane is clogged.

4. High Feed Water Conductivity: Possible causes:

(1) High feed water conductivity. Stop production and replace the clogged security filter cartridges.

(2) Damaged O-ring on the fresh water side of the RO membrane. Replace the O-ring.

(3) RO membrane fouling. Clean the membrane with appropriate chemicals.

5. High Feed Water Pressure: Possible causes:

(1) Membrane fouling. Clean the membrane.

(2) Overloaded water production. Adjust the concentrate control valve to increase concentrate discharge.

(3) Excessive inlet flow to the high-pressure pump. Adjust the inlet valve to reduce the flow.