Tariff classification of filters under Heading 84.21 prevailed because specific heading coverage excluded machine-specific headings.

Filters used for air and liquids remained classifiable under Tariff Heading 84.21 as filtering or purifying machinery and apparatus for liquids or gases because they were specifically covered by that heading. Section Note 2(a) of Section XVI governed parts expressly mentioned in a tariff heading, while Section Note 2(b) applied only to parts not specifically covered elsewhere. As the filters fell within Heading 84.21, they could not be moved to the headings of the machines with which they were solely or principally used. The Revenue's classification was upheld.

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Issues: Whether filters used for air and liquids in different machinery were classifiable under Tariff Heading 84.21 as filtering or purifying machinery and apparatus for liquids or gases, or under the headings of the machines with which they were solely or principally used by applying Section Note 2(b) of Section XVI.

Analysis: The applicable rule was held to be Section Note 2(a) of Section XVI, which governs parts specifically mentioned in a tariff heading, unless they fall within excluded headings. Section Note 2(b) was treated as applying only to other parts, meaning parts not specifically covered by any tariff heading. Since the filters were specifically covered by Tariff Heading 84.21, they could not be shifted to the machine-specific headings merely because they were used with particular machines.

Conclusion: The filters were correctly classified under Tariff Heading 84.21. The appeal failed and the classification made by the Revenue was upheld.

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