1.1 This test method defines the requirements for portable instruments that are intended to be used to measure the Rockwell or Brinell hardness of metallic materials by performing indentation tests on the surface of materials in the field or outside of a test lab, or in cases where the size or weight of the test piece prevents it from being tested on a standard E10 or E18 hardness tester. 1.2 The principles used to measure the Rockwell or Brinell hardness are the same as those defined in the E18 standard test method for Rockwell or E10 standard test method for Brinell. Note 1: Standard test methods E10 and E18 will be referred to in this test method as the standard methods. 1.3 The portable hardness testers covered by this test method are verified only by the indirect verification method. Although the portable hardness testers are designed to employ the same test conditions as those defined in the standard test methods, the forces applied by the portable Rockwell and Brinell testers and the depth measuring systems of the portable Rockwell testers may not meet the tolerance requirements of the standard methods. Portable hardness testers shall use indenters that meet the requirements of the standard test methods.