ISO 16994:2015 pdf free

ISO 16994:2015 pdf free.Solid biofuels – Determination of total content of sulfur and chlorine
Solid combustion aid: After the mass of the sample is determined, add an appropriate amount of the aid (e.g. benzoic acid) and determine the added amount of the aid exactly by weighing. Mix the sample and the aid carefully and prepare a pellet of the whole mix as described above. Ensure that the weight of the pellet equals the weight of the sample and the weight of the aid.
一Add 1 ml water into the bomb [also see EN 14918 if the calorific value is determined simultaneously].Alternatively, the water can be omitted or more water (upto 5 ml) can be used. Ifthe content of chlorine or sulfur exceeds 2 % (m/m) alkaline solutions may be used to neutralize the acidic compounds produced. When ion chromatography is used for determination, the absorption solution may be the mobile phase, e.g. a carbonate/ bicarbonate solution. In all cases, the calibration of the method and the blank tests have to be done with the same amount and the same kind of receiving solution.Place the crucible in position and arrange the firing wire. Assemble the bomb and tighten the cover securely. Before ignition, the bomb is flled with 30 bar oxygen.
NOTE 1 If the chlorine content of the sample is very low, the cotton thread usually used for ignition may contribute significantly to the measured chlorine content. This can be avoided by using highly pure combustible sample holder without cotton threats.
NOTE 2 The bomb can be flushed with oxygen to reduce the nitrous oxide formation during the combustion process especially when the concentration of sulfur and chlorine is determined by ion chromatography (some peaks in the chromatogram might not be separated satisfactorily).
一After combustion, release the bomb pressure slowly before opening the bomb.
一Transfer the content of the bomb to a volumetric flask (50 ml or 100 ml).
一Thoroughly rinse the bomb, the cover, and the crucible including the combustion residues in the crucible with water and collect all the rinse water carefully. Transfer it into the volumetric flask and fill the flask to volume. While rinsing, take care that the ash that was formed after the combustion is collected in the flask as well.
If the sample contains high concentrations of sulfur and/or chlorine (>2 %), the combustion gas should be let through a gas washing bottle with a disk to ensure that all acidic gas components are dissolved. The solution from this gas washing bottle can be combined with the bomb washings or can be analysed separately from the solution of the combustion bomb.
NOTE 3 If the sample contains high amounts of ash (>5 %), then chlorine and sulfur can be trapped in the combustion residues. In that case, the combustion residue can be analysed for the chlorine and sulfur content, e.g. with XRF or an ash fusion procedure. Alternatively, a low sample intake in combination with a combustion aid can be used.
NOTE 4 Special care is necessary when samples with low contents of chlorine and/or sulfur (e.g. virgin wood) are analysed after samples with high contents of these elements (e.g. herbaceous samples or waste samples).The most efficient way of cleaning the bomb is multiple combustions of pure benzoic acid (see 8.1.3 blank test).ISO 16994 pdf download.