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Calculation method HP 12 1. Write a balanced equation for the reaction that produces the gas. The general form of the equation is: rR + wW = pP + gG where R is the EUH029, EUH031 or EUH032 substance, W is water or an acid, P is a product of the reaction, and G is the gas released; r, w, p and g are the stoichiometric ratios that balance the equation. 2. Attribute molecular weights and stoichiometric ratios to the substances in the equation. 3. Divide (r × molar weight of R) by (g × 22,4). This gives the mass of R that will evolve 1 litre of gas. 1 mol of gas occupies 22,4 litres at standard temperature and pressure. 4. Divide this amount (in grams) by 1 000 (to convert to kilograms) and multiply it by 100 to give a percentage by weight, and thus the limiting concentration for HP 12 of substance R. Example calculation: A waste contains aluminium nitride (AlN). Aluminium nitride is an EUH029 substance which reacts with water to give ammonia gas. AlN + 3H2O = Al(OH)3 + NH3 aluminium nitride water aluminium hydroxide ammonia r = 1 mol of AlN, R = 41 g; g = 1 mol NH3. Limiting concentration of aluminium nitride in waste is ((1 × 41) / (1 × 22,4) / 1 000) × 100, which is 0,18 % (approximately 0,2 %).

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Source: EUR-Lex (Cellar) · retrieved 2026-09-25 · Text as adopted (Official Journal); later amendments are not incorporated in this text.