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concentration is below 90 %, either the water has not had enough time to dissolve the salt or there is not enough salt in the brine tank . If necessary , add salt and wait until the concentration is above 90 % prior to starting the study . Make certain to mark or measure the water level in the brine tank prior to start of regeneration . This can be used to calculate the volume of brine used during the process to compare and confirm the volume versus the manufacturer ’ s specification . Create a log sheet ahead of the procedure that records time in minutes and percent saturation . For the actual study sampling , choose a sample point after the multiport valve on the discharge pipe prior to drain for the most accurate concentration measurements . Make certain there is enough flow during the brine rinse to fill a 250 ml cylinder in less than three minutes . |
Study procedure
The beginning of the brine draw can sometimes be difficult to determine based on the type of softener control . The brine rinse cycle , however , always follows the backwash and is typically indicated by a drop in the discharge flow rate . Softener flow controllers are either mechanical or digital . Mechanical
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controllers will typically have pins that indicate the cycle position , and digital controllers may have an LED display indicating the brine draw cycle . Once this starts , the sampling procedure is as follows : 1 . Sample the discharge water every three minutes by collecting the sample and placing the salometer in the cylinder . Allow the salometer to settle for a few seconds 2 . Take the reading from the salometer at eye level , record the time and the percent saturation on the log sheet 3 . Continue to collect samples at three-minute intervals , recording and logging the results 4 . Once the salometer readings are stable at less than 2 % for three consecutive measurements , record the final reading 5 . Note the time the system changes from brine rinse to fast rinse and record 6 . As soon as the last salometer reading is recorded , measure the level of water in the brine tank with a measuring tape and record Using either graph paper or a spreadsheet programme like Microsoft Excel , create a graph of concentration (% NaCl ) on the Y axis and time ( in minutes ) on the X axis . In a properly functioning regeneration cycle , the data recorded and graphed should |
Figure 1 -Elution curve interpretation
Figure 2
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