ASTM D1177 Test Method for Freezing Point of Aqueous Engine Coolants
8. Procedure
8.1 Assemble the apparatus as shown in Fig. 1, with no refrigerant and no sample of coolant yet in place. Check the operation of the stirring mechanism after assembly to be sure that all parts operate freely.

8.2 Fill the Dewar flask surrounding the freezing tube with the refrigerant liquid, adding pieces of solid carbon dioxide from time to time to maintain conditions mentioned in Note 4. Temporarily remove the stopper from the freezing tube and introduce 75 to 100 mL (2.65 to 3.4 oz.) of the sample.

NOTE 6 - The sample may be precooled to approximately 8°C (15°F) above the expected freezing point before introducing it into the freezing tube.

8.3 Start the stirrer and adjust it to operate at 60 to 80 strokes per min (Note 7). As soon as stirring is begun, observe and record the temperature at regular intervals of time. As the expected freezing point is approached, the time intervals should be quite short, 15 s if possible. At the expected freezing point, seeding should be started to prevent supercooling. This can be accomplished by introducing a wire which has a small portion of the solution being tested frozen on its tip. It is most convenient to freeze this solution in a small test tube inserted directly into the cooling bath.

NOTE 7 - A stroke is considered as a complete cycle of one upward and one downward motion of the stirrer.

NOTE 8 - The cooling rate must be less than 1°C (2°F)/min at the time the solution is seeded.

8.4 Continue temperature readings at regular intervals for at least 10 min after the apparent freezing point.