ASTM D1287-11 (2020) pdf free.Standard Test Method for pH of Engine Coolants and Antirusts.
Rinse the electrodes with distilled water and touch thetips with a dry cloth or tissue to remove excess water. Immersethe electrodes in a second standard buffer solution.The readingof the meter shall agree with the known pH of the secondstandard buffer solution within 0.05 unit without changingthe setting of the standardization of asymmetry potentialcontrol. If it does not agree or if the meter gives a slowresponse time and drifts, the electrode should be cleaned inaccordance with the manufacturer’s instructions.
The presence of a faulty electrode is indicated byfailure to obtain a correct value for the pH of the secondstandard buffer solution after the meter has been standardizedwith the first.A cracked electrode will often yield pH valuesthat are essentially the same for both standard buffer solutions.9.2 Multi-point standardization allows measurements to beperformed over a very broad pH range,but required theadditional effort of carrying out further standardizations. Withmultiple buffer points，the meter uses the electrode slopeapplicable to the pH range of the current sample.This linearsegments method is always in pH operation. When standard-ization by auto recognition of U.S. standard buffers or custombuffers is selected, three buffer points are usable. With auto-recognition of NIST buffers or a combination of U.S. standard,custom, and NIST buffers, or manual entry of buffers, up to fivestandardization buffers are permitted.A pencil-type glass electrode 125 mm to 180 mm inlength and 8 mm to 14 mm in diameter. The body of theelectrode shall be made of a chemically resistant glass tubewith a wall thickness of 1 mm to 3 mm.The end dipping intothe solution shall be closed with a hemisphere of glass sealedon the electrode tube and the radius of this hemisphere shall beabove 7 mm.The thickness of the glass in the hemisphere shallbe great enough so that resistance of the hemisphere is 100 m2to 1000 m at 25 °C. The electrode shall contain areproducible， permanently sealed liquid cell for making elec-trical connections with the inner surface of the hemisphere.Theentire electrical connection, from the sealed contact cell to themeter terminal,shall be surrounded by an electrical shield thatwill prevent electrostatic interference when the shield isgrounded.ASTM D1287 pdf download.