6 Common Problems with Reverse Osmosis Equipment – All the Answers You Need Are Here!

1.Why Do Sealing Rings Swell in Reverse Osmosis Equipment?

In reverse osmosis (RO) equipment, three types of sealing rings are used in the membrane housing to ensure isolation between sections. To reduce installation resistance, water or glycerol should be applied to the surface of the sealing rings during assembly.  

It is crucial to avoid using petroleum-based lubricants like Vaseline, as these can degrade freshwater pipes and cause the sealing rings to swell. While swollen rings do not directly affect system performance, they can make reinstallation difficult after disassembly, as the expanded rings may not fit back into their grooves.

2.Do All Components of an RO System Produce the Same Amount of Water?

In an RO system, there is a pressure difference (membrane pressure drop) between the feed and concentrate ends of the membrane elements. Additionally, the salt concentration in the concentrate stream increases along the system flow path.  

Assuming negligible permeate backpressure and osmotic pressure, the water production of each membrane element is proportional to the difference between its operating pressure and osmotic pressure. Consequently, the water output of each successive membrane element gradually decreases.  

3. How to Replace the Security Filter Cartridge in an RO System?  

Over time, the security filter cartridge may become clogged due to variations in water quality. Replacement is recommended when the pressure differential across the filter exceeds 0.03 MPa.  

Replacement Steps:  

1. Shut down the RO system.  

2. Depressurize the system by pressing the pressure relief valve until the pressure gauge reads zero.  

3. Use a specialized wrench to open the filter housing.  

4. Remove the old cartridge and install a new one.  

5. Securely tighten the housing with the wrench.

4.Is RO Equipment Effective for Fluoride Removal?

Excessive fluoride in drinking water can harm human health. RO systems can effectively remove fluoride, which primarily originates from the dissolution of surrounding rocks in groundwater. However, in high-salinity groundwater, RO’s fluoride removal efficiency may be limited. Compared to other methods, RO offers simpler operation and consistent treatment results.  

5. How to Operate an RO System During Initial Startup?

During the first run, use low pressure and low flow to purge air from the piping. Maintain a pressure of 0.2–0.4 MPa. Discharge both the produced water and concentrate into the drain.  

If pressure rises rapidly, it indicates trapped air in the membrane elements, which can generate radial hydraulic(impact force) and damage the membrane’s outer wrap. Always ensure the system includes an automatic low-pressure flushing function for the RO membrane upon startup.  

6.Does pH Affect RO Membrane Rejection Rate and Lifespan?

RO membranes are typically made of composite materials and function reliably within a pH range of 2–11. Staying within this range minimizes damage to the membrane.  

pH significantly impacts the rejection rate of certain ions due to their acidity, alkalinity, dissociation, and charge characteristics. For example, RO membranes cannot remove CO2. However, increasing the feedwater pH converts CO₂ to CO₃²⁻, which the membrane can reject. Note that this adjustment may increase scaling risks, requiring careful management.