ASTM D937 standard test method for cone penetration of petroleum
8. Procedure
8.1 The surface of the sample must not be cut level nor worked in any other way, as this may affect the result. If the temperature of the penetrometer cone (that is, the room temperature) varies from 25°C by 2°C (77°F by 3°F) or more, adjust the cone temperature to 25 more or less 0.5°C (77 more or less 1°F) immediately before testing the sample. Frequent adjustment of the cone temperature may be necessary if the room temperature varies appreciably from 25°C (77°F).
8.2 Place the can of petrolatum on the penetrometer table, so located that the tip of the penetrometer cone is 25 to 40 mm (1 to 1 1/2 in.) in from the rim of the container (except for petrolatums having a penetration greater than 200 (see 8.4). Observe that the cone is in its "zero" position and adjust either the indicator assembly or the table, dependent on the type of instrument, until the tip of the cone just touches the surface of the sample. Watching the shadow of the tip is an aid to accurate setting. Finally, quickly release the plunger and hold for 5 s. Read the total penetration from the scale. Make at least three determinations.
8.3 With samples having penetrations less than 200, three tests (and sometimes more) may be made in one container by proper spacing. To prevent one test from being affected by the disturbed area of a previous test the tip of the cone must not be placed nearer the edge of a previous test than the penetration distance of the sample. Some harder petrolatums tend to form a marked depression in the center on solidifying; such samples should not be tested in this depression, as the results obtained may be different from those obtained in off-center positions on the level surface.
8.4 With samples having penetrations over 200, make only one test in a container and place the cone tip as exactly as possible at the center of the container.
