NSF ANSI 42:2019 pdf free download – Drinking Water Treatment Units – Aesthetic Effects
4.2.2 Exposure water Systems and components shall be exposed to locally available tap water that has been adjusted to contain 50 ± 5 mg/L total dissolved solids (TDS) and 0.5 ± 0.05 mg/L free available chlorine (FAC), and to have a pH of 6.75 ± 0.25. Exposure water used to evaluate systems or components shall be 23 ± 2 °C (73 ± 3 °F). Any existing concentrations of extraction testing parameters listed in Tables 4.1, 4.2, and 4.3 found to be present in the exposure water shall be subtracted from the values obtained in the analysis of the extractant water.
4.2.3 Exposure
4.2.3.1 The system or component(s) of a system shall be installed, flushed, and conditioned in accordance with the manufacturer’s instructions using the exposure water specified in Section 4.2.2 at an initial inlet static pressure of 340 kPa (50 psig).
4.2.3.1.1 For media finer than 100 mesh, testing shall be conducted in flasks with a ratio of 200 g media to 1 L of exposure water specified in Section 4.2.2. Testing shall be completed at ambient atmospheric pressure and at a temperature of 23 ± 2 °C (73 ± 3 °F). Sufficient flasks shall be utilized to collect a minimum of 600 mL of water at each pour off, or the necessary volume for analysis, whichever is greater. The flasks shall be shaken vigorously for 1 min and allowed to settle for 24 h. After 24 h of exposure, the sample water shall be collected and retained. The flask shall be refilled with the same volume of exposure water that was extracted. The flasks will be shaken vigorously for one minute and allowed to settle for 24 h. A second water sample shall be collected and the flasks refilled. The flasks shall be shaken vigorously for 1 min and allowed to settle for 24 h. A third water sample shall be collected. All samples collected shall be composited and analyzed in accordance with Section 4.2.1. One control flask with 2 L of exposure water shall be processed in the same manner as above.
The maximum number of samples exposed shall not exceed 16 with 125 mL of extractant water drawn from each sample. If the components with a water holding volume that is less than 250 mL and is able to be identified as one that will only occur once in the flow path of dispensed treated water (such as diverters, faucets, RO shutoff valves, or specialty components) then a volume of 250 mL shall be drawn from each sample using a maximum number of eight samples.
4.2.3.4 All samples collected shall be composited and analyzed in accordance with Section 4.2.1. For multiple outlet systems, a composite sample shall be collected from all potable water outlets. The unit volume of the system shall be divided by the total number of potable water outlets and this amount shall be collected from each outlet.
4.2.3.5 Systems with adsorptive or absorptive media shall be tested with and without the media. Testing without media shall include removal of any granular adsorptive or absorptive media, and removal of any adsorptive or absorptive replacement elements.