Petroleum waxes differ in hardness. Needle penetration is a measurement of hardness. United States 1 6. Apparatus 6. The apparatus shown in Fig. The loaded needle must fall, when released, without appre- ciable friction.
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A number in parentheses indicates the year of last reapproval. This standard has been approved for use by agencies of the U. Department of Defense. This testmethod is applicable to waxes having a penetration of notgreater than Cone methods applicable to greases and to petrolatum are described inTest Methods D and Test Method D, respectively.
Mercury, orits vapor, may be hazardous to health and corrosive tomaterials. Caution should be taken when handling mercury andmercury containing products.
It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use. Referenced Documents2. The penetration force is determined by thetotal mass g of the needle, plunger, and 50 g weight.
Summary of Test Method4. Current edition approved July 1, Published July Originally approvedin Last previous edition approved in as D — DOI: United States1container, and then air cooled under controlled conditions. Thesample then is conditioned at test temperature in a water bath. Penetration is measured with a penetrometer, which applies astandard needle to the sample for 5 s under a load of g.
Significance and Use5. Needle penetrationis a measurement of hardness. Hardness may have a significanteffect upon other physical properties. The apparatus shown in Fig. The loaded needle must fall, when released, without appre-ciable friction. The instrument shall be provided with levelingscrews and a spirit level to maintain the plunger shaft in a truevertical position. The indicator scale shall be calibrated intenths of a millimetre division and shall have a range of at least tenths of millimetres.
Alternatively,a stop watch graduated in 0. The axis of the cone shall becoincident with the shaft axis within 0. The tapered sectionof the needle shall be made from fully hardened and temperedstainless steel, Grade C or equal, Rockwell hardness C57to After tapering, the point shall be ground off to atruncated cone, the smaller base of which shall be from0. The conical surface and thetruncation shall be finished to a smoothness of 0.
The final weight of the needle shall be 2. The total weight of the plunger shall be NOTE 2—The National Institute of Standards and Technology willmeasure and certify the accuracy of penetration needles in accordancewith these permissible variations.
To prevent slippage of very hard wax, a few screw threads orgrooves shall be cut into the center part of the inside wall of thecylinder. The cylinder shall be placed on a base plate of brass,wetted with an equal volume mixture of glycerin and water,when casting a test specimen. The water bath should be made of glass or othersuitable transparent material, or have a window to permit ahorizontal view of the specimen. It shall be possible toimmerse the test specimen in the bath to a depth of not less than mm 4 in.
The bath also shall be equipped with a rigid perforated testshelf about 51 mm below the water level to support thespecimen during the penetration by the needle. The specimen support is placed on aninsulating material, such as corks or rubber stoppers during thecooling period.
Preparation of Test Specimen7. Make sure the sample ishomogeneous and free from air bubbles. In the test room orcabinet maintained at Place the test specimen container on the plate and then pour themelted wax into it in such a way that a convex meniscus isformed.
Allow the container and contents to cool in the roomat After 1 h of cooling, shave anyexcess wax from the top of the container and remove the brassplate. Place the smooth wax surface up. Condition the speci-men in the bath at the test temperature within 0. NOTE 3—Very hard waxes occasionally will shrink away from the wallsof the test specimen container; in such cases, it is permissible to wedge thespecimen in the container. NOTE 4—The sample temperature prior to pouring into the testspecimen container can impact the wax tunneling severity.
It maybe necessary to place a weight on the base of the penetrometerto counterbalance the head Note 6.
Level the penetrometerand the perforated shelf in the water bath. NOTE 5—Alternatively, the penetrometer may be placed in the waterbath. Likewise, a small bath may be placed on the penetrometer standprovided the test temperature within 0. Emergent stem corrections shall be applied when the correctionequals or exceeds 0. One of the above alternatives will berequired if the penetrometer is the adjustable table type.
Make certain that the container or test shelf cannotteeter during testing. Adjust the water level so that it is at least25 mm 1 in. Adjust either the indicator assembly or the table,depending upon the type of instrument, until the tip of theneedle nearly touches the surface of the specimen. Securelylock the movable assembly in this position. After ensuring the bath temperature is within the properspecifications, release the needle shaft and hold it free for 5. Then gently depress the indicator shaft untilit is stopped by the needle shaft and read the penetration fromthe indicator scale.
Before each test, wipethe needle carefully toward its point with a clean, dry cloth toremove all adhering wax, position the needle as described in8.
Also report theactual test temperature used. Precision and Bias