ASTM D1287 Standard Test Method for pH of Engine Coolants and Antirusts
3. Summary of Test Method
3.1 A sample, as received or after dilution with a specified volume of distilled water, is placed in a beaker or sample cup and the pH measured with a pH meter and combination electrode or associated glass-saturated calomel electrode pair.
NOTE 3 - The readings of the meter in the case of the concentrated products arc not pH values according to the accepted definition, but arc apparent pH values which are useful in the interpretation of the condition of the product.
4. Significance and Use
4.1 pH is a measure of the hydrogen ion concentration and indicates whether an engine coolant, antirust, or a solution of these compounds is acidic, alkaline, or neutral.
4.2 The pH range includes values from 0 to 14. Values from 0 to 7 represent the acidic half of the scale. Values from 7 to 14 represent the alkaline or basic half of the scale. The pH value 7 is considered neutral, as it is neither acidic nor alkaline.
4.3 pH is sometimes used for production quality control. It is generally desirable that engine coolants have an alkaline pH.
4.4 pH is not significant from the standpoint of predicting service life. The pH of used engine coolants or antirust solutions is not a dependable indication of either existing effectiveness or remaining life of the solution.
