BS ISO 48-5:2018 pdf free
BS ISO 48-5:2018 pdf free.Rubber, vulcanized or thermoplastic – Determination of hardness
Place the test piece on a flat, hard, rigid surface (e.g. glass). Hold the hardness meter in position with the centre of the indentor at least 12 mm from the edges of the test piece. Apply the pressure foot to the test piece as rapidly as possible, without shock, keeping the foot parallel to the surface of the test piece and ensuring that the indentor is normal to the rubber surface.
Apply a force sufficient only to obtain firm contact between the pressure foot and the test piece and take the reading at the specified time after the pressure foot is in firm contact with the test piece. The standard test time is 3 s for vulcanized rubber and 15 s for thermoplastic rubber. Other test times may be used, provided they are stated in the test report. Rubbers of unknown types shall be treated as vulcanized.
If the time interval after which each reading was taken is different from 3 s, record the individual values of the indentation hardness together with the time interval after which each reading was taken,and determine the median value and the maximum and minimum values obtained.
Press the instrument against a suitable flat, hard surface (e.g. glass) and adjust the reading on the scale to give a value of 100 IRHD. Continue the instrument check using a set of standard rubber blocks covering the measurement range from about 30 IRHD to 90 IRHD. All adjustments shall be made in accordance with the manufacturer’s instructions. The set of standard rubber blocks shall consist of at least six test pieces kept lightly dusted with talc in a suitable covered container away from light,heat, oil and grease. The standard rubbers shall themselves be calibrated against the dead-load gauge by the method specified in ISO 48-2 at intervals not exceeding 1 year or when a drift in excess of 1 unit is observed. Instruments in regular use should be checked at least each week gainst standard rubber blocks.BS ISO 48-5 pdf download.
