Profiling and probing

Profiling and probing are two techniques typically used together to determine if and where in an RO system membranes are scaled or leaking. These techniques should be used when the conductivity in the product of an RO system is high. 

Probing involves determining the permeate concentration at various points within the pressure vessel. The most common points 

1st Stage 1st Stage 1st Stage 1st Stage 2nd Stage 2nd Stage 

A pressure vessel with no leaks or scaling would show a slight increase in conductivity from the feed end to the concentrate end. This is a result of the feed water becoming more concentrated (and hence, the product 

A pressure vessel with a leaking or missing O-ring at the feed end (or any place in the vessel) would show a spike in conductivity at that point, but then show a drop in conductivity as the distance increases away from the leak. The curve then takes on the general shape of a pressure vessel with no leaks or scale. 

1st stage 1st stage 1st Stage 1st Stage Znd Stage 2nd Stage 

Scaled membranes would show a more rapid increase in conductivity than a pressure vessel with no leaks or scale. 

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Reverse osmosis skids are typically contained within a frame of galvanized or urethane-coated steel. Skids should be designed for easy access for monitoring and maintenance. Access to controls, instruments, valves, the pump and motor, and membranes is essential. Access to the permeate from each pressure vessel is often overlooked. Without such access, profiling and probing used to troubleshoot poor performance is not possible (see Chapter 14.7). 

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