关于附件 XVII 第 50 条中每次“重大操作变更”后控制 PAH/PCA 比率校准的要求，对“重大操作变更”的解释是什么？

关于附件 XVII 第 50 条中每次“重大操作变更”后控制 PAH/PCA 比率校准的要求，对“重大操作变更”的解释是什么？

What is an interpretation of the "major operational change" concerning the requirement to control the calibration of the PAH/PCA ratio after each "major operational change" under Entry 50 to Annex XVII?

如 2005/69/EC 指令（OJ L323，2005 年 12 月 9 日，第 51 页）第 8 条所述，目前尚无统一的测试方法来测量填充油中的 PAH，或测量含有此类油的轮胎中的 PAH。在出现合适的统一方法之前，唯一允许用于测量填充油中 PAH 含量的指定方法是 IP346 分析方法。如果满足某些附加条件，则允许使用此方法。这些附加条件是必要的，因为 IP346 方法并不直接测量 PAH 含量。事实上，IP346 测量的是多环芳烃化合物 (PCA) 的总含量，而不是 PAH 含量。PCA 是一类 PAH 所属的物质，但其中 PAH 的含量非常少。如果总 PCA 含量 < 3%，则认为填充油中多环芳烃 (PAH) 的法定限值已达到，即苯并芘 (BaP) 含量为百万分之一 (1 ppm)，总 PAH 含量为 10 ppm。换句话说，3% 的 PCA 含量可作为 10 ppm PAH 含量的替代测量值。只有当填充油中 PAH 和 PCA 含量之比已知且不随时间变化时，替代测量值才有效。因此，附加条件要求对该技术进行初始校准（测量 PAH/PCA 比率），并每隔六个月或在“重大操作变更”后重新校准，以确保测量结果始终有效。“重大操作变更”一词应理解为任何可能导致替代测量结果无效的材料或工艺变更。导致结果无效的主要原因是填充油中 PAH/PCA 比率的变化。然而，应该记住，IP346 不仅是测量 PAH 的代理方法，而且它所测量的量，即 PCA 含量，是以相当间接的方式测量的，即通过溶液折射率的变化，而 PCA 并不是影响溶液折射率的唯一物质。因此，获得无效结果的可能性相当高，应谨慎使用该方法。如有疑问，建议重新校准。每六个月控制一次 PAH/PCA 比率的校准是为了保证 IP346 结果的有效性，免受意外或未知变化的影响。这适用于制造工艺和所用材料保持不变的情况，并且没有理由预期 PAH/PCA 比率会发生变化。然而，可以想象，例如，轮胎制造商从其供应商处收到了重新配制的增量油，但并未意识到发生了变更，IP346 的测量结果可能因此失效。六个月的重新校准间隔被认为足以涵盖此类情况。结论：每次“重大操作变更”后，控制 PAH/PCA 比率的校准是为了确保 IP346 结果的有效性。因此，重大操作变更是指对材料或工艺的故意变更，这些变更可能会显著影响 PAH/PCA 比率，或以其他方式影响测量的有效性。此类变更的例子包括增量油的供应源发生变更，或油的使用方法发生变更。对于某一变更是否重要到需要重新校准的判断，必须根据具体情况进行，并需要专家意见。

As stated in Recital 8 of the Directive 2005/69/EC (OJ L323, 9.12.2005, p.51), there are at present no harmonized test methods for measuring PAHs in the extender oils, or for measuring PAHs in tyres that contain such oils. Until suitable harmonized methods are available, the only named method that is permitted for measuring the PAH content of extender oils is the IP346 analysis method. This method is permitted providing that certain additional conditions are met. These additional conditions are necessary because the IP346 method does not measure the PAH content directly. In fact IP346 measures the total content of polycyclic aromatic compounds (PCA) rather than the PAH content. The PCAs are a group of substances to which PAHs belong, but in which PAHs are present in only very small amounts. The legal limit for PAHs in extender oils, which is 1 part per million (ppm) of BaP and 10ppm total PAH content, is considered to be met if the total PCA content is <3%. In other words, the PCA content of 3% is taken as a proxy measurement for a PAH content of 10ppm. The proxy measurements will be valid only if the ratio between the PAH and PCA content in the extender oil is known and does not change over time. The additional conditions therefore require an initial calibration of the technique (measurement of the PAH/PCA ratio) and recalibration at intervals of six months, or after "major operational change", in order to ensure that the measurements remain valid over time. The term "major operational change" should therefore be taken to mean any change in materials or processes that could invalidate the results of the proxy measurement. The principle cause of invalid results would be a change in the PAH/PCA ratio in the extender oil. However, it should be remembered that not only is IP346 a proxy method for measuring PAH, but that the quantity that it does measure, namely PCA content, is meaaured in a rather indirect way, namely by a change in the refractive index of a solution, and that PCAs are not the only substances that affect the refractive index of a solution. The potential for obtaining invalid results is therefore quite high and the method should therefore be used with considerable caution. It would therefore be advisable to recalibrate in case of doubt. The provision to control the calibration of the PAH/PCA ratio every six months is to safeguard the validity of the IP346 results against unintentional or unknown changes. This would apply for the case where the manufacturing process and materials used remain the same, and where there is no reason be expect a change in the PAH/PCA ratio. However, it is possible to imagine, for example, that a tyre manufacturer receives a reformulated extender oil from his supplier without being made aware of the change that has been made, and the results from the IP346 could be invalidated as a consequence. A six month recalibration interval was considered sufficient to cover such occurrences. Conclusion: The provision to control the calibration of the PAH/PCA ratio after each "major operational change" is to safeguard the validity of the IP346 results. A major operational change is therefore a deliberate change to materials or processes that might be expected to significantly influence the PAH/PCA ratio, or otherwise affect the validity of the measurement. Examples of such a change would be where the source of supply for the extender oil is changed, or where the method of using the oil is changed. Judgment of whether a particular change is sufficiently important to trigger the need for recalibration will necessarily be made case-by-case and will require expert opinion.