BS ISO 20463:2018 pdf download – Rubber and rubber products — Determination of combustion energy and carbon dioxide emission from biobased and non-biobased materials
6.4 Procedure
6.4.1 Preparation of test sample Weigh out 0,3 g to 0,8 g of the sample to the nearest 0,1 mg. Block, sheet, powder or liquid sample can be used. The amount of sample shall correspond to the measurable energy range of the calorimeter used.
6.4.2 Calibration of calorimeter Weigh approximately 1 g of benzoic acid pellet certified for combustion energy measurement and place it on a combustion dish in the bomb. Settle an ignition wire so that it touches this pellet and connects to the ignition electrode of the ignition circuit. Close the vessel body and tighten the closure ring firmly. Connect the pipe from the oxygen pressure regulator to the valve of the combustion bomb.
The pipe shall be certified to perform under 3,5 MPa pressure and have a branched purge line with an on-off valve. Open the bomb valve and control the regulator to gradually fill oxygen in the bomb.
When the pressure reaches 2,5 MPa to 3,0 MPa, close both the bomb valve and the regulator valve, and remove the pipe from the bomb. Immerse the sealed, assembled bomb in the water vessel. Watch for babbles in water and make sure there is no oxygen leak. When the water temperature has become stable, combust the benzoic acid pellet by applying voltage to the ignition wire. Adjust the obtained combustion energy as 26 460 J/g of benzoic acid. Repeat the same procedure for another pellet until two consecutive measured values fall within 26 460 J/g ± 80 J/g.
6.4.3 Measurement of combustion energy Place the accurately weighed test sample (6.4.1) on the combustion dish in the bomb. Settle the ignition wire so that it touches the sample and connects to the ignition electrode of the ignition circuit. Close the vessel body and tighten the closure ring firmly. Connect the pipe from the oxygen pressure regulator to the valve of the combustion bomb.
The pipe shall be certified to perform under 3,5 MPa pressure and have a branched purge line with an on-off valve. When the amount of carbon dioxide emission is to be measured afterwards (see Clause 7), purge the inside air with oxygen. To do that, connect an oxygen bottle, introduce ca. 0,2 MPa oxygen and evacuate the oxygen and the inside air together either by removing the pipe or by using the branched purge line. Repeat the process at least twice.
Open the bomb valve and control the regulator to gradually fill oxygen in the bomb.
When the pressure reaches 2,5 MPa to 3,0 MPa, close both the bomb valve and the regulator valve, and remove the pipe (if a purge line is equipped, release oxygen before removing the pipe). Immerse the sealed, assembled bomb in the water vessel. Watch for babbles in water and make sure there is no oxygen leak. When the water temperature has become stable, combust the test sample by applying voltage to the ignition wire. Read the measured value for combustion energy. Repeat the measurement procedure for the same test sample and compare the results. When the difference falls into ±160 J/g, finish the measurement and take the mean value as the total combustion energy.
6.4.4 Measurement of biobased carbon content To determine the biobased combustion energy (E B ) of the test sample, information on its biobased carbon content (x B ) is indispensable. If the sample’s chemical formulation and the resource of each component (i.e. the biobased carbon content of each component) is available, the biobased carbon content of the sample can be calculated in accordance with ISO 19984-1. When those are unavailable, the biobased carbon content shall be measured in accordance with ISO 19984-2.