CLA-2 CO:R:C:M 957651 DWS
Mr. Jeff Hesseltine
A.I. Scientific Co., Inc.
424 Second Street, Suite D
Davis, CA 95616
RE: Hydrogen, Nitrogen, Pure Air, and Multiple Gas Generators;
    "McGraw-Hill Dictionary of Scientific and Technical Terms";
    Water Gas; Producer Gas; Explanatory Notes 84.05, 84.21(II),
    and General Note (VI) to section XVI; HQ 951195; Section XVI,
    Note 3; GRI 3(c); 8405.10.00
Dear Mr. Hesseltine:
     This is in response to your letter of December 20, 1994, to the Area Director of Customs,
New York Seaport, concerning the classification of hydrogen, nitrogen, pure air, and multiple gas
generators under the Harmonized Tariff Schedule of the United States (HTSUS).  Your letter was
referred to this office for a response.
FACTS:
     The merchandise consists of hydrogen, nitrogen, pure air, and multiple gas generators, for use
in laboratories for chemical analysis and, in particular, gas chromatography.  With regard to the
hydrogen generator, hydrogen is obtained by electrolysis of demineralized water through a cell
with patented multilayer electrodes.  Waste oxygen is dissipated into the atmosphere, and the
hydrogen, after having been dehumidified, is conveyed to its specific application.  With regard to
the nitrogen generator and the pure air generator, nitrogen and pure air are obtained by their
separation from the ambient air through the use of molecular sieve filters.  The filters, similar to
chromatographic columns, absorb useless gases allowing a storage of pure gas in a small
reservoir.  In the nitrogen generator, nitrogen is produced by filtering the air through carbon
molecular sieves and trapping all that is not nitrogen.  In the pure air generator, compressed air is
passed through an alumina bed so that humidity and all impurities are removed.  The multiple gas
generator is a modular unit which combines standard hydrogen, nitrogen, and pure generator units
in single housing.  It is our understanding that the multiple gas generator may be imported in the
following combinations: pure air and nitrogen generators; hydrogen and pure air generators;
hydrogen and nitrogen generators; and hydrogen, nitrogen, and pure air generators.
     The subheadings under consideration are as follows:
     8405.10.00: [p]roducer gas or water gas generators, with or
                 without their purifiers; acetylene gas 
                 generators and similar water process gas
                 generators, with or without their purifiers.
     The general column one rate of duty for goods classifiable
     under this provision is 2.2 percent ad valorem.
     8421.39.80: [f]iltering or purifying machinery and apparatus
                 for gases: [o]ther: [o]ther.
     The general column one rate of duty for goods classifiable
     under this provision is 3.1 percent ad valorem.
     8543.30.00: [e]lectrical machines and apparatus, having 
                 individual functions, not specified or included
                 elsewhere in this chapter; parts thereof:
                 [m]achines and apparatus for electroplating,
                 electrolysis or electrophoresis.
     The general column one rate of duty for goods classifiable
     under this provision is 3.6 percent ad valorem.
ISSUE:
     Whether the hydrogen gas generator is classifiable under subheading 8405.10.00, HTSUS, as a
producer gas or water gas generator, or under subheading 8543.30.00, HTSUS, as an electrical
machine for electrolysis.
     Whether the nitrogen and pure air gas generators are classifiable under subheading
8405.10.00, HTSUS, as producer gas or water gas generators, or under subheading 8421.39.80,
HTSUS, as filtering or purifying machinery for gases.
     Whether the various combinations of multiple gas generators are classifiable under subheading
8405.10.00, HTSUS, as producer gas or water gas generators, under subheading 8421.39.80,
HTSUS, as filtering or purifying machinery for gases, or under subheading 8543.30.00, HTSUS,
as electrical machines for electrolysis.
LAW AND ANALYSIS:
     Classification of merchandise under the HTSUS is in accordance with the General Rules of
Interpretation (GRI's).  
GRI 1 provides that classification is determined according to the terms of the headings and any
relative section or chapter notes.
                     HYDROGEN GAS GENERATORS
     In the "McGraw-Hill Dictionary of Scientific and Technical Terms" (5th Ed.), water gas and
producer gas are defined as follows:
     water gas A mixture of carbon monoxide and methane produced 
               by passing steam through deep beds of incandescent
               coal; used for industrial heating and as a gas
               engine fuel.
  producer gas Fuel gas high in carbon monoxide and hydrogen,
               produced by burning a solid fuel with a deficiency
               of air or by passing a mixture of air and steam
               through a bed of incandescent fuel; used as a 
               cheap, low-Btu industrial fuel.
     In understanding the language of the HTSUS, the Harmonized Commodity Description and
Coding System Explanatory Notes may be utilized.  The Explanatory Notes, although not
dispositive or legally binding, provide a commentary on the scope of each heading of the HTSUS,
and are generally indicative of the proper interpretation of these headings.  See T.D. 89-80, 54
Fed. Reg. 35127, 35128 (August 23, 1989).  In part, Explanatory Note 84.05 (pp. 1146 - 1147),
HTSUS, states that:
     [t]his heading covers self-contained apparatus and plant for
     generating any kind of gas (e.g., producer gas, water gas
     and mixtures thereof, or acetylene) whatever the intended
     use of the gas produced . . . . 
                   (A) PRODUCER GAS GENERATORS
     These usually consist of a closed cylinder, generally fitted
     with a refractory lining or a water-cooled double wall
     enclosing a grate (either of fixed, shaking or revolving
     type), with provision for passing a current of air (or of
     air and steam) by suction or blowing.  A thick bed of fuel
     is burned on the grate and the flow of air and steam is
     regulated so that combustion is incomplete, the resultant
     mixture of carbon monoxide, hydrogen and nitrogen (producer
     gas) being drawn off at the top of the apparatus. . . 
                     (B) WATER GAS GENERATORS
     These are of similar construction, but are arranged so that
     air and a spray of water or steam are blown in alternate
     phases into the apparatus.  The gas resulting from the water
     phase is a mixture of hydrogen and carbon monoxide (water 
     gas) having a higher heating power than producer gas.  It 
     may be collected separately from the producer gas obtained
     during the air phase or the two gases may be mixed.
     It is our position that the hydrogen generator, which  creates hydrogen through water
electrolysis and is neither water gas nor producer gas as defined above, is not described under
subheading 8405.10.00, HTSUS.  We note that Explanatory Note 84.05 provides that heading
8405, HTSUS, covers apparatus for generating any kind of gas.  However, in HQ 951195, dated
June 15, 1992, in which we dealt with the classification of a gas generator for an automobile air
bag restraint system under the HTSUS, we stated that:
     [i]t is our position that the subject gas generator is not         classifiable under subheading
8405.10.00, HTSUS.  Although         the note states that heading 8405, HTSUS, covers
apparatus         generating "any kind of gas", heading 8405, HTSUS, is very         specific in only
providing for producer gas generators,            water gas generators, acetylene gas generators, and
similar        water process gas generators.  The subject gas generator,          which produces gases
from the combustion of chemical               pellets, is not provided for under heading 8405,
HTSUS.  The       language of Explanatory Note 84.05, HTSUS, should not be           interpreted
to expand the language of heading 8405, HTSUS.
     Therefore, we find that the hydrogen generator is precluded from classification under
subheading 8405.10.00, HTSUS.
     As previously noted, subheading 8543.30.00, HTSUS, provides for electrical machines for
electrolysis.  Because the hydrogen generator produces hydrogen through the use of water
electrolysis and the hydrogen generator is not classifiable more specifically elsewhere under the
HTSUS, the hydrogen generator is classifiable under subheading 8543.30.00, HTSUS.
                 NITROGEN AND PURE AIR GENERATORS
     As with the hydrogen generator, because the nitrogen and pure air generators neither operate
similar to water gas or producer gas generators nor produce water gas or producer gas, they are
precluded from classification under subheading 8405.10.00, HTSUS.
     In part, Explanatory Note 84.21(II) (pp. 1181 -1182) states:
       (II) FILTERING OR PURIFYING MACHINERY AND APPARATUS,
                       FOR LIQUIDS OR GASES
     Much of the filtration or purification plant of this heading
     is purely static equipment with no moving parts.  The 
     heading covers filters and purifiers of all types (physical
     or mechanical, chemical, magnetic, electro-magnetic, 
     electro-static, etc.).  The heading covers not only large
     industrial plant, but also filters for internal combustion
     engines and small domestic appliances.  The heading does
     not, however, include filter funnels, milk strainers, 
     vessels, tanks, etc., simply equipped with metallic gauze
     or other straining material, nor general purpose vessels,
     tanks, etc., even if intended for use as filters after
     insertion of a layer of gravel, sand, charcoal, etc. . . 
     (A) xxx
     (B) Filtering or purifying machinery, etc., for gases.
         These gas filters and purifiers are used to separate 
         solid or liquid particles from gases, either to recover
         products of value (e.g., coal dust, metallic particles,
         etc., recovered from furnace flue gases), or to 
         eliminate harmful materials (e.g., dust extraction, 
         removal of tar, etc., from gases or smoke fumes, removal
         of oil from steam engine vapours). . . 
     The nitrogen and pure air generators use filtering systems to produce the nitrogen and pure air,
respectively.  With regard to the nitrogen generator, nitrogen is produced by filtering the air via
carbon molecular sieves and trapping all that is not nitrogen, such as humidity and hydrocarbons
(liquid particles), oxygen, carbon monoxide, and carbon dioxide.  With regard to the pure air
generator, compressed air is filtered through an alumina bed so that impurities such as humidity
and hydrocarbons (liquid particles), etc., are removed.  The removal of these impurities through
the filtering process ensures that the gases will be proper for their respective applications.
     Therefore, because heading 8421, HTSUS, covers filtering apparatus of all kinds, static or not,
it is our position that the nitrogen and pure air generators are classifiable under subheading
8421.39.80, HTSUS.
                     MULTIPLE GAS GENERATORS
     Section XVI, note 3, HTSUS, states that:
     [u]nless the context otherwise requires, composite machines
     consisting of two or more machines fitted together to form a
     whole and other machines adapted for the purpose of
     performing two or more complementary or alternative 
     functions are to be classified as if consisting only of that
     component or as being that machine which performs the
     principal function.
     Because the various combinations of multiple gas generators consist of two or more machines
adapted for the purpose of performing two or more functions in a single housing, we must
determine the principal function of each combination generator.  However, because all of the
combinations contain generators which play a primary role in the operation of each multiple gas
generator, we find that no component imparts the principal function of a multiple gas generator.
     In part, General Explanatory Note (VI) to section XVI 
(p. 1133) states that:
     [w]here it is not possible to determine the principal
     function, and where, as provided in Note 3 to the Section,
     the context does not otherwise require, it is necessary to 
     apply General Interpretative Rule 3(c); . . . 
     GRI 3(c) states that:
     [w]hen goods cannot be classified by reference to 3(a) or          3(b), they shall be classified
under the heading which
     occurs last in numerical order among those which equally
     merit consideration.
     With regard to the pure air and nitrogen generator combinations, because both articles are
classifiable under subheading 8421.39.80, HTSUS, that combination multiple gas generator is so
classifiable.  With regard to the last three combinations of multiple gas generators, because the
provision to occur last in numerical order is subheading 8543.30.00, HTSUS, those combination
multiple gas generators are so classifiable.  
HOLDING:
     The hydrogen generator is classifiable under subheading 8543.30.00, HTSUS, as an electrical
machine for electrolysis.
     The nitrogen and pure air generators are classifiable under subheading 8421.39.80, HTSUS, as
filtering or purifying machinery for gases.
     The pure air and nitrogen combination multiple gas generator is classifiable under subheading
8421.39.80, HTSUS, as filtering or purifying machinery for gases.
     The following three combinations of multiple gas generators are classifiable under subheading
8543.30.00, HTSUS, as electrical machines for electrolysis: the hydrogen and pure air generators;
hydrogen and nitrogen generators; and hydrogen, nitrogen, and pure air generators.
                            Sincerely,
John Durant, Director
                            Commercial Rulings Division