Normalized pressure drop membrane cleaning

Normalized pressure drop and NPF should be monitored simultaneously, and the membrane cleaned when the first of these measures reaches the 10% change in performance as compared to initial operating performance. 

Normalized salt passage is generally not used as the primary indicator of when to clean membranes. This is because normalized product flow and/or differential pressure drop (see below) will usually indicate problems with the membranes before product quality becomes an issue. However, normalized salt passage should be used in conjunction... 

Cleaning an RO membrane is generally based on the normalized permeate flow or the pressure drop (see Chapter 13.2.1). When the normalized... 

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