9. Procedure
9.1 Cleaning Immediately prior to weighing, clean the specimen with a solvent or cleaner and dry. Take care to remove all dirt or foreign matter or both from the specimen. Dry materials with open grains (some powder metals or ceramics) to remove all traces of the cleaning solvent, which may have been entrapped in the material. Steel specimens having residual magnetism should be demagnetized or not used.
9.2 Weigh the specimen to the nearest 0.001 g (0.0001 g for Procedure C).
9.3 Seat the specimen securely in the holder and add the proper weights to the lever arm to develop the proper force pressing the specimen against the wheel. This may be mea- sured accurately by means of a spring scale which is hooked around the specimen and pulled back to lift the specimen away from the wheel. A wedge should be placed under the lever arm so that the specimen is held away from the wheel prior to start of test. (See Fig. 2.)
9.4 Set the revolution counter to the prescribed number of wheel revolutions.
9.5 Sand Flow and Sand Curtain The rate of sand flow through the nozzles shall be between 300 g (0.66 lb)/min and
400 g (0.88 lb)/min. Do not start the wheel rotation until the proper uniform curtain of sand has been established (see Fig. 9 and Note 3).
9.5.1 The dwell time between tests shall be the time required for the temperature of the rubber wheel to return to room temperature. For Procedure B the dwell time shall be at least 30 min.