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HQ 954974

January 13, 1993

CLA-2 CO:R:C:M 954974 MMC


TARIFF NO.: 8418.99.00

Dr. Paul J. Murphy
Janis Research Company, Inc.
Two Jewel Drive
P.O. Box 696
Wilmington, MA 01887

RE: Dilution refrigerators; EN 84.18; Note 2 Section XVI

Dear Dr. Murphy:

This is in response to your September 3, 1993 letter requesting a ruling for a dilution refrigerator insert under the Harmonized Tariff Schedule of the United States (HTSUS). Literature describing articles similar to the one in question was included with your letter.


Refrigerators used to cool articles below 0.1 degree Kelvin (K) cannot use compression and expansion of gases to create cold. Because at lower temperatures it is impractical or impossible to use gases, liquid or solid working materials are used. The process of compressing a liquid or solid material to cool involves adiabatic demagnetization of paramagnetic ions in solids, using electron-spin paramagnets. McGraw-Hill Encyclopedia of Science & Technology 549 (McGraw-Hill Inc. 6th ed. 1987). It is our understanding that the subject article, a Helium-3/Helium-4 dilution refrigerator, uses this process to cool by compressing a liquid-solid mixture of helium-3.

According to the submitted literature, helium-3 systems are primarily used for extending experiments from pumped helium-4 temperatures down to lower temperatures so that many samples may be examined in the course of a single experimental run. This results in a large saving both in cryogen and time for the experimentalist.

The literature states that the helium-3 insert operates in a bath of liquid helium at 4.2K. The working parts are thermally isolated from the main helium reservoir by an inner vacuum chamber. The sample is mounted on the top loading probe which is designed to load directly into the liquid helium-3 through the central access of the insert.

The 1K pot is filled from the main bath via a needle valve, pumped by a rotary pump. The pot may be continuously filled from the bath for extended periods of operation. The sorption pump (sorb), is warmed to a temperature above 40K so that it will not absorb gas, or will release absorbed gas, and the helium-3 is allowed into the sample space. It condenses on the 1K pot and runs down to cool the sample to @1.2K. The sorb is now cooled by drawing liquid helium-3 from the main bath through a heat exchanger, and it begins to reduce the vapor pressure above the liquid helium-3 and so the sample temperature drops.

When all the helium-3 has evaporated, the sample starts to warm. This can be controlled by stopping the flow of coolant to the sorb and switching on the sorb heater. The absorbed gas is released again as the sorb warms, and the process of condensation is repeated.

According to your letter, you are importing the refrigerator insert because you already have the gas handling system and pumping system.


Whether the dilution refrigerator insert is classifiable as a part of a refrigerator?


Classification of merchandise under the HTSUS is in accordance with the General Rules of Interpretation (GRI's), taken in order. GRI 1, HTSUS, states in part that for legal purposes, classification shall be determined according to the terms of the headings and any relative section or chapter notes. Chapter 84, HTSUS, provides for machinery and mechanical appliances.

Heading 8418, HTSUS, provides in pertinent part for refrigerators, freezers, and other refrigerating or freezing equipment, electric or other...and parts thereof. In understanding the language of the HTSUS, the Harmonized Commodity Description and Coding System Explanatory Notes may be consulted. The Explanatory Notes (EN), although not dispositive, are to be used to determine the proper interpretation of the HTSUS. 54 Fed. Reg. 35127, 35128, (August 23, 1989). EN 84.18, provides in pertinent part that:


The refrigerators and refrigerating equipment of this heading are in the main machinery or assemblies of apparatus for the production, in a continuous cycle of operations, of low temperatures (in the region of 0 C or less) at the active cooling element, by the absorption of the latent heat of evaporation of liquefied gasses, (e.g. ammonia, halogenated hydrocarbons), of volatile liquids, or in the case of certain marine types, of water...

This heading also includes refrigerating equipment operating by vaporization of liquefied gas in a enclosed space and consisting generally of one or more liquefied-gas tanks, a thermostat, an electro-magnetic valve, a control box and electric switches and a perforated spreader tube. These components are classified here if presented together.

Based on the submitted literature, it is our understanding that the refrigerator in question operates by the vaporization of liquified gas in an enclosed space. However, only the refrigerating insert will be imported. Therefore, the imported articles may be classified in subheading 8418.99.00, HTSUS, which provides for parts of heading 8418, HTSUS, if it meets the dictates of Note 2, section XVI.

Note 2, Section XVI, states in pertinent part that "parts of machines (not being parts of the articles of heading 8484, 8544, 8545, 8546, or 8547) are to be classified according to the following rules: (a) Parts which are goods included in any of the headings of chapters 84 and 85 (other than chapter 8485 and 8548) are in all cases to be classified in their respective headings.

(b) other parts, if suitable for use solely or principally with a particular kind of machine, or with a number of machines of the same heading... are to be classified with the machines of that kind. However, parts which are equally suitable for use principally with the goods of heading 8517 and 8525 to 8528 are to be classified in heading 8517.

(c) All other parts are to be classified in heading 8485 or 8548.

We are of the opinion that dilution refrigerator insert is classifiable as a part suitable for use solely or principally with refrigerators. Therefore, according to Note 2(b) Section XVI, the article in question should be classified in subheading 8418.99.00, HTSUS, which provides in pertinent part for refrigerators, freezers, and other refrigerating or freezing equipment, electric or other...[p]arts; [o]ther.


The dilution refrigerator insert is classifiable as a part of a refrigerator under subheading 8418.99.00, as refrigerators, freezers, and other refrigerating or freezing equipment, electric or other...[p]arts; [o]ther.


John Durant, Director

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