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* SST® is a registered trademark of Purolite LLC
|Polymer Structure||Gel polystyrene crosslinked with divinylbenzene|
|Functional Group||Sulfonic Acid|
|Ionic Form||Na+ form|
|Dry Weight Capacity (min.)||4.0 eq/kg (Na+ form)|
|Moisture Retention||42 - 48 % (Na+ form)|
|Particle Size Range||300 - 1200 µm|
|< 300 µm (max.)||1 %|
|Uniformity Coefficient (max.)||1.7|
|Reversible Swelling, Na+ → H+ (max.)||7 %|
|Shipping Weight (approx.)||775 - 825 g/L (48.4 - 51.6 lb/ft³)|
|Temperature Limit||100 °C (212.0 °F)|
The pressure drop across a bed of ion exchange resin depends on the particle size distribution, bed depth, and voids volume of the exchange material, as well as on the flow rate and viscosity of the influent solution. Factors affecting any of these parameters— such as the presence of particulate matter filtered out by the bed, abnormal compressibility of the resin, or the incomplete classification of the bed—will have an adverse effect, and result in an increased head loss. Depending on the quality of the influent water, the application and the design of the plant, service flow rates may vary from 10 to 40 BV/h.
During up-flow backwash, the resin bed should be expanded in volume between 50 and 70% for at least 10 to 15 minutes. This operation will free particulate matter, clear the bed of bubbles and voids, and reclassify the resin particles ensuring minimum resistance to flow. When first putting into service, approximately 30 minutes of expansion is usually sufficient to properly classify the bed. It is important to note that bed expansion increases with flow rate and decreases with influent fluid temperature. Caution must be taken to avoid loss of resin through the top of the vessel by over expansion of the bed.