7.1 The ionic form of an ion-exchange material affects both its equivalent mass and its equilibrium water content. These in turn influence the numerical values obtained in exchange capacity determinations, in density measurements, and in the size of the particles. To provide a uniform basis for comparison, therefore, the sample should be converted to a known ionic form before analysis. This procedure provides for the conversion of cation-exchange materials to the sodium form and anion-exchange materials to the chloride form prior to analysis. These forms are chosen since they permit samples to be weighed and dried without concern for air contamination or decomposition. If other ionic forms are used this fact should be noted in reporting the results.
1.1 These test methods cover the determination of the physical and chemical properties of ion-exchange resins when used for the treatment of water. They are intended for use in testing both new and used materials. The following thirteen test methods are included:
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| Sections |
| Test Practice A—Pretreatment | 6 – 10 |
| Test Method B—Water Retention Capacity | 11 – 18 |
| Test Method C—Backwashed and Settled Density | 19 – 26 |
| Test Method D—Particle Size Distribution | 27 – 35 |
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