ISO 2781:2018 pdf free

ISO 2781:2018 pdf free.Rubber, vulcanized or thermoplastic一Determination of density
If fabric is attached to, or embedded in, the sample, it shall be removed before cutting out the test pieces. The method of removal shall preferably avoid the use of a swelling liquid, but, if necessary, a suitable non-toxic liquid of low boilling point may be used to wet the contacting surfaces. Care shall be taken to avoid stretching the rubber during the separation from the fabric, and the liquid, if used, shall be allowed to evaporate completely from the rubber surfaces after separation. Cloth-marked surfaces shall be made smooth by buffing in accordance with ISO 23529.
Suspend the test piece (see Clause 6) from the hook on the balance (5.1) using a suitable length of filament so that the bottom of the test piece is about 25 mm above the straddle (5.2). The filament shall be made from a material which is insoluble in water and which does not absorb a significant amount of water. It shall either be counterbalanced or be weighed and, if weighed, its mass shall be deducted from subsequent weighings of the test piece (see 11.2.3).
Weigh the test piece to the nearest milligram in air. Repeat the weighing with the test piece (and sinker, if required, see 11.2.4) immersed in freshly boiled and cooled distilled water or deionized water at a standard laboratory temperature (23 °C±2 °Cor 27 °C±2 °C) contained in the beaker (5.3), placed on the straddle. Remove air bubbles adhering to the test piece (see 11.2.5 and 11.2.6) and weigh to the nearest milligram, watching for a few seconds to make sure that the reading does not drift gradually as a result of convection currents.
Where the filament used has a mass less than 0,010 g, such as is the case with thin nylon filament,the correction to account for its mass is not necessary to ensure the stated accuracy of the final result.However, when the test piece is smaller than the one specified (e.g. when the density of small O-rings is to be measured), this can lead to inaccuracies and the mass of the filament needs to be taken into account in the final calculation. If a means of suspension other than a filament is used, the volume and mass of the suspension shall be taken into account in making the final calculation.ISO 2781 pdf download.