ASTM D1121-11 (2020) pdf free.Standard Test Method for Reserve Alkalinity of Engine Coolants and Antirusts.
Clean the glass electrodesor combination electrode at frequent intervals (not less thanonce every week during continual use) in accordance with themanufacturer’s instructions. Drain the calomel electrodes atleast once each week and fill with KCl electrolyte. Keep theelectrolyte level in the calomel electrode above that of theliquid in the titration beaker at all times.When not in use,immerse the lower half of the electrodes in water and do notallow them to be immersed in the titrated solution for anyappreciable period of time between titrations. Although theelectrodes are not extremely fragile, they should be handledcarefully at all times.A combination electrode system can also be used forthis test method.
Before and after using, blotthe glass electrode or combination electrode thoroughly with aclean cloth,or a soft,absorbent tissue,and rinse with water.Blot the calomel reference electrode with a cloth or tissue;carefully remove the ground-glass sleeve and thoroughly blotboth groundglass surfaces. Replace the sleeve loosely andallow a few drops of electrolyte to drain through to flush theground-glass joint. Wet the ground surfaces thoroughly withelectrolyte,set the sleeve firmly in place，and rinse theelectrode with water. Prior to each titration， soak the preparedelectrode in water for at least 2 min.Immediately before use,touch the tips of the electrodes with a dry cloth or tissue toremove excess water.
Turn on the instrument, allow to warm up, and adjustin accordance with the manufacturer’s instructions. Allowsufficient time for the temperature of the buffer solution andimmersed electrodes to equalize and set the temperature knobat the temperature of the buffer solution.Calibrate the assembly with a minimum of two buffer solutions to check thelinearity of the response of the electrode or incorrect tempera-ture compensation. The presence of a faulty electrode isindicated by a failure to obtain a reasonably correct value forpH of the second standard solution when the meter has beenstandardized with the first.A cracked electrode will often yieldpH values that are essentially the same for both standards.Adjust the standardization or asymmetry potential control untilthe reading of the dial corresponds to the known pH of thestandardizing buffer solution.
Pipet 10 mL of a thoroughly mixed sample into a 250mL tall-form spout-less beaker. Allow 1 minute drain time.Add about 90 mL of distilled water (Note 2).ASTM D1121 pdf download.