ASTM D1287-11(R2020) pdf free download

ASTM D1287-11(R2020) pdf free download.Standard Test Method for pH of Engine Coolants and Antirusts
6. Reagents
6.1 Purity of Reagents—Reagent grade chemicals shall be used in all tests. Unless otherwise indicated, it is intended that all reagents shall conform to the specifications of the Commit- tee on Analytical Reagents of the American Chemical Society, where such specifications are available. 3 Other grades may be used, provided it is first ascertained that the reagent is of sufficiently high purity to permit its use without lessening the accuracy of the determination. 6.2 Purity ofWater—Unless otherwise indicated, references to water shall be understood to mean distilled water or water of equal purity. Distilled water shall be boiled thoroughly, or purged with carbon dioxide-free air, to remove carbon dioxide and shall be protected with a soda-lime tube or its equivalent while cooling and in storage. The pH of the water shall be between 6.2 and 7.2 at 25 °C. 6.3 Standard Buffer Solutions—The buffer solutions for calibrating the pH meter and electrode pair shall be prepared from salts sold specifically for use, either singly or in combination, as pH standards. The salts shall be dried for 1 h at 110 °C before use, except in the case ofborax which shall be used as the decahydrate. The solutions with pH less than 9.5 shall be stored in chemically resistant bottles. The alkaline phosphate solution shall be stored in glass bottles coated on the side with paraffin. N OTE 5—Commercially available buffer tablets or prepared buffer solutions may be used. 6.4 Standard Buffer Solution pH = 1.68, (Buffer pH 1.68 from Fisher Scientific FC Part Number 13–620–836) or equivalent could be used. 6.5 Potassium Hydrogen Phthalate Buffer Solution (0.05 M, pH = 4.01 at 25 °C)—Dissolve 10.21 g of potassium hydrogen phthalate (KHC 8 H 4 O 4 ) in water, and dilute to 1 L. Standard Buffer Solution pH = 4.0, Potassium Hydrogen Phthalate (Red, pH 4.01) from Fisher Scientific (FC Part Number: SB 101–500; NIST–SRM 185 g) or equivalent could be used. 6.6 Neutral Phosphate Buffer Solution (0.025 M with re- spect to each phosphate salt, pH = 6.86 at 25 °C)—Dissolve 3.40 g of potassium dihydrogen phosphate (KH 2 PO 4 ) and 3.55 g of anhydrous disodium hydrogen phosphate (Na 2 HPO 4 ) in water and dilute to 1 L. Standard Buffer Solution pH = 6.86, Potassium Phosphate (pH 6.86 from Fisher Scientific, or NIST–SRM 186 le/lle) or equivalent could be used.
8. Preparation of Electrode System
8.1 Maintenance ofElectrodes—Clean the glass electrode or combination electrode at frequent intervals (not less than once every week during continual use) in accordance with the manufacturer’s instructions. Drain the calomel electrode at least once each week and fill with KCl electrolyte. Keep the electrolyte level in the calomel electrode above that of the solution being tested at all times. When not in use, immerse the lower halves of the electrodes in distilled water, or the appropriate buffer solution recommended by the manufacturer. Do not immerse the electrodes in the solution being tested for any appreciable period of time between determinations. Al- though the electrodes are not extremely fragile, they should be handled carefully at all times. 8.1.1 A combination electrode system can also be used for this test method. 8.2 Preparation ofElectrodes—Before and after using, wipe the electrode or combination electrode thoroughly with a clean cloth, or a soft absorbent tissue, and rinse with distilled water. Follow the manufacturer’s recommendations if further prepa- ration is required. Prior to each pH determination, soak the prepared electrode in distilled water for at least 2 min. Immediately before use, touch the tips of the electrodes with a dry cloth or tissue to remove excess water.