What is delta P (ΔP) and what does it mean when logging RO data? The differential pressure (dP) is the pressure lost due to friction as water passes through the system. You take a reading before the pressure vessels and after the pressure vessels of each stage, and that tells you how much pressure was lost across that stage.
A very high concentrate flow rate will result in a high dP because of the high friction. From a fouling perspective, scale, suspended solids, and biological growth, etc… build up in the feed channels and interfere with flow, thereby increasing friction and resulting in pressure losses.
If you are concerned about scale, then you should be monitoring your normalized permeate flow, not your dP. Monitoring normalized permeate flow allows you to detect scale formation and address it well before it is detectable by an increasing dP. Once your dP has increased, the scale will have already become very thick and will become more difficult to clean. The opposite is true for suspended solids, where you may see a significant increase in dP with minimal impact on normalized permeate flow.
AWC provides the RO membrane community with RO chemical solutions for optimizing system operation. Be sure to contact us today at (813) 246-5448 to learn more.
See also:
What is the procedure for cleaning RO membranes? What CIP chemicals should be used?
How can we determine whether the membranes in our Reverse Osmosis system are damaged?
When does it make sense to clean elements, and when is replacement the only option in high purity applications?
We recently installed new RO membranes in our system and observed that the permeate water tested positive for coliform bacteria. Is it possible in your experience that RO membranes could be damaged during installation and cause contamination of the water distribution system by bacteria and pathogens?