The tariff classification of an air separator from Italy

N359513 March 25, 2026 CLA-2-84:OT:RR:NC:N1:105 CATEGORY: Classification TARIFF NO.: 8421.29.0065 Lucinda Swartz Scarbrough International 7280 NW 87th Ter, Ste. 300 Kansas City, MO 64153 RE: The tariff classification of an air separator from Italy Dear Ms. Swartz: In your letter dated March 6, 2026, on behalf of your client, Caleffi North America, Inc., you requested a tariff classification ruling. Descriptive literature was provided for our review. The item under consideration is described as The DISCAL air separator, model 551-5517-NA 551 Series, which is a device engineered for the continuous removal of entrained air, including micro-bubbles, from water or glycol-based fluids in closed-loop hydronic heating and cooling systems. Micro-bubble formation frequently occurs in system components such as boilers and devices operating under cavitation conditions. This separator removes air down to the micro-bubble level with minimal head loss, attributed to its specialized internal body design. Key components include a polypropylene air vent float, peroxide-cured EPDM (Ethylene Propylene Diene Monomer rubber) seals, and stainless-steel linkages and guide pins, ensuring unimpeded float movement and resistance to residue accumulation. The device operates by combining fluid velocity reduction and coalescence. As fluid enters the larger separator body, its velocity decreases, facilitating the release of dissolved air as micro-bubbles, consistent with Henry’s Law, which states that lower pressure and higher temperature promote gas release from a liquid. The fluid then passes through an internal mesh element with concentric surfaces, which induces a “whirling” motion, causing micro-bubbles to adhere. These adhered bubbles coalesce, increasing in volume until their buoyancy overcomes the adhesion force. The enlarged bubbles subsequently rise into a large air chamber at the top of the unit. A float-operated automatic air vent then releases the accumulated air to the atmosphere while preventing the escape of the system fluid. The device is designed for a maximum working pressure of 150-200 psi and an operating temperature range of 32°F to 270°F. The applicable subheading for the DISCAL air separator 551-5517-NA 551 Series will be 8421.29.0065, Harmonized Tariff Schedule of the United States (HTSUS), which provides for “Centrifuges, including centrifugal dryers; filtering or purifying machinery and apparatus, for liquids or gases; parts thereof: Filtering or purifying machinery and apparatus for liquids: Other: Other: Other: Other.” The general rate of duty will be free. The duties cited above are current as of this ruling’s issuance. Duty rates are provided for your convenience and are subject to change. The text of the most recent HTSUS and the accompanying duty rates are provided at https://hts.usitc.gov/. This ruling does not address the applicability of any additional duties, taxes, fees, exactions and/or other charges, which may apply to the goods discussed herein. This includes, but is not limited to, tariffs and other duties as provided for in Subchapter III to Chapter 99, HTSUS. Thus, for example, in addition to the classification stated above, the merchandise covered by this ruling may also need to be reported with either the Chapter 99 provision under which an additional tariff applies or one of the Chapter 99 provisions covering exceptions to such tariffs. For further information to assist with the importation process, please refer to the frequently updated Cargo Systems Messaging Service (CSMS) messages at https://www.cbp.gov/trade/automated/cargo-systems-messaging-service and the Trade Remedies page at https://www.cbp.gov/trade/programs-administration/trade-remedies. The holding set forth above applies only to the specific factual situation and merchandise description as identified in the ruling request. This position is clearly set forth in Title 19, Code of Federal Regulations (CFR), Section 177.9(b)(1). This section states that a ruling letter is issued on the assumption that all of the information furnished in the ruling letter, whether directly, by reference, or by implication, is accurate and complete in every material respect. In the event that the facts are modified in any way, or if the goods do not conform to these facts at time of importation, you should bring this to the attention of U.S. Customs and Border Protection (CBP) and submit a request for a new ruling in accordance with 19 CFR 177.2. Additionally, we note that the material facts described in the foregoing ruling may be subject to periodic verification by CBP. This ruling is being issued under the provisions of Part 177 of the Customs and Border Protection Regulations (19 C.F.R. 177). A copy of the ruling or the control number indicated above should be provided with the entry documents filed at the time this merchandise is imported. If you have any questions regarding the ruling, please contact National Import Specialist Jason Christie at jason.m.christie@cbp.dhs.gov. Sincerely, (for) James Forkan Designated Official Performing the Duties of the Division Director National Commodity Specialist Division