Tariff classification of adsorption-based gas purification equipment turns on essential function, not temperature-based treatment.

Imported molecular sieve batteries used in an air separation plant were analysed for tariff classification by reference to their essential function. The equipment removed moisture, carbon dioxide and acetylene from compressed process air by adsorption after solid particles had already been filtered out. Because the dominant function was gas separation and purification, and not treatment involving heating, cooling, drying or any other change of temperature, the equipment was treated as filtering or purifying machinery for gases rather than machinery for temperature-based treatment. The importer's supporting authorities were found not to apply, and the classification was sustained under the gas-purification heading.

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Issues: Whether the imported molecular sieve battery was classifiable under Heading 84.19 as machinery for treatment of materials by a process involving a change of temperature, or under Heading 84.21 as filtering or purifying machinery for gases, and whether the exemption claimed under Notification No. 59/87-Cus. was admissible.

Analysis: The imported molecular sieve battery was used in an air separation plant to remove moisture, carbon dioxide and acetylene from compressed process air by adsorption after solid particles had already been removed by air filtration. The essential function of the equipment was separation and purification of gases, not treatment of materials by heating, cooling, drying or any other process involving a change of temperature. Heading 84.19 applies only where the machinery is designed for such temperature-based treatment, whereas Heading 84.21 covers filtering or purifying machinery and apparatus for gases. On the facts, the equipment answered the description of filtering or purifying apparatus for gases. The authorities relied on by the importer were held to be inapplicable.

Conclusion: The goods were correctly classifiable under Heading 84.21, sub-heading 8421.39, and not under Heading 84.19, sub-heading 8419.39. The appeal failed and the Revenue's classification was upheld.

Final Conclusion: The order confirmed the classification of the imported molecular sieve battery as gas filtering or purifying machinery and sustained the rejection of the importer's claim.

Ratio Decidendi: Where the essential and predominant function of imported equipment is adsorption-based purification of gas stream impurities, and no process involving change of temperature is undertaken, the goods fall under the tariff heading for filtering or purifying machinery for gases rather than the heading for temperature-based treatment machinery.

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