1.1 These test methods cover four procedures for measuring the consistency of lubricating greases by the penetration of a cone of specified dimensions, mass, and finish. The penetration is measured in tenths of a millimetre.

Note 1-The National Lubricating Grease Institute (NLGI) classified greases according to their consistency as measured by the worked penetration. The classification system is as follows: NLGI Consistency Number Worked Penetration Range, 25°C (77°F) 000 00 0 1 2 3 4 5 6 445 to 475 400 to 430 355 to 385 310 to 340 265 to 295 220 to 250 175 to 205 130 to 160 85 to 115

1.1.1 The procedures for unworked, worked, and prolonged worked penetration are applicable to greases having penetrations between 85 and 475, that is, to greases with consistency numbers between NLGI 6 and NLGI 000. An undisturbed penetration test, described in X1, is similar to the unworked penetration test.

1.1.2 The block penetration procedure is applicable to greases that are sufficiently hard to hold their shape. Such greases usually have penetrations below eighty-five tenths of a millimetre.

1.2 None of the four procedures is considered suitable for the measurement of the consistency of petrolatums by penetration. Test Method D937 should be used for such products.

1.3 The dimensions of the equipment described in these test methods are given in inches and fractions of an inch. These units were retained because a vast body of data has been obtained using equipment with the dimensions shown. Metric equivalency tables are provided with each figure. Temperatures and other dimensions are given in the preferred SI units; the values shown in parentheses are provided for information.

1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.