IRHD Hardness Testers - International Rubber Hardness Degrees
International Rubber Hardness Degrees (IRHD) test method provides a highly repeatable measurement on rubber parts of various shapes and sizes. It is especially important in determining the hardness of rubber O-rings. The IRHD method employs an initial test load that is applied to the specimen via an indenter. The test is zeroed at this indentation position, then the test force is applied. The distance between the two applied forces is measured and coverted to an IRHD hardness value. Preload forces are 0.85 gf for micro scales and 30.5 gf for regular scales. Total test forces are 15.63 gf for micro and 581 gf for regular scales.