Proctor Needles

Proctor needles are used for quick evaluation of maximum soil density in the field. Standard Compaction curves showing moisture contents versus densities are drawn in laboratory using standard compaction method and penetration of the proctor needles are correlated. Proctor needles are also known as Proctor Penetrometers.

The instrument consists of a needle attached to a spring loaded plunger, the stem of which is calibrated to read 0 to 40 kg division. Load stem is graduated at every 12.5 mm to read depth of penetration and for use with needles of larger areas. The small penetration stem is also graduated in 12.5 mm division and is used with needles of smaller areas. Needle points one each of 0.25, 0.5, 1.0, 1.5, 2.0, 3.5 and 6.0 sq. cm. and one tommy pin is supplied. Complete as above in a wooden carrying case.

This is identical to spring type, except that the penetration pressure on the needle is conveyed through a hydraulic system to a hydraulic pressure gauge. This system permits a greater control over rate of penetration because of better visibility of load indication.