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HQ 083952

March 22, 1990

CLA-2 CO:R:C:G 083952 CMS


TARIFF NO.: 8533.21.00

Mr. Paul Linet, Esq.
Shafner & Gilleran
75 Federal Street, 18th Floor
Boston, MA 02110

RE: Strain Gauges

Dear Mr. Linet,

This responds to your request on behalf of BLH Electronics, Inc. dated November 4, 1988, supplemented January 30, 1989 for a binding classification ruling for certain strain gauges. Our ruling follows.


The merchandise consists of thin metallic foil electrical circuits bonded to flexible organic backings. The articles are commonly referred to as "strain gauges". Strain gauges are sensor devices used to test or measure physical force or stress. The devices output an electrically measurable signal in response to a mechanical stress input. The mechanical stress input is measured by the increase in resistance which occurs when the foil circuit is stretched or otherwise subjected to force or stress.

Strain gauges have many applications. The devices can be attached to a material to test its response to stress (e.g., an airplane wing). They can also be used to measure stress when incorporated into an apparatus such as an electronic scale. Strain gauges commonly function as a part or component of a measuring or testing apparatus which converts the output signals into an intelligible form. The strain gauges under consideration are imported separate from the apparatus with which they function.


Are the strain gauges classified in Heading 9031 as measuring or checking instruments not specified elsewhere, or in Heading 8533 as resistors?


Heading 9031 describes measuring or checking instruments not specified elsewhere in Chapter 90. The Explanatory Notes to Heading 9031, p. 1531 provide that Heading 9031 covers electrical instruments which measure stress and strain. However, the Explanatory Notes at p. 1531 also provide that "...electrical resistors known as 'strain gauges' fall in heading 85.33." (emphasis in original). The strain gauges under consideration cannot be classified in Heading 9031 because they are merely the resistor component of measuring or testing apparatus and are imported separate from the apparatus with which they function.

Heading 8533 describes electrical resistors other than heating resistors. The Explanatory Notes to Heading 8533, p. 1385 provide that resistors are "...conductors whose function is to provide a given electrical resistance in a circuit (e.g., to limit the current flowing)." The strain gauges under consideration test or measure physical stress by detecting the increase in the metallic foil's electrical resistance which results from the amount of stress applied; the articles essentially rely on the phenomena of electrical resistivity and are properly described as resistors. The articles are also described in the Explanatory Notes to Heading 8533 by name; the Explanatory Notes, p. 1386 provide that Heading 8533 includes "[r]esistors known as 'strain gauges' being the sensitive elements of a strain measuring instrument."

Unlike variable resistors with which one can adjust the level of resistivity (e.g. rheostats), the strain gauges under consideration are fixed resistors. Their resistance level is predetermined and nonadjustable; their change in resistivity results from the strain or stress being measured or tested. The articles are fixed, non-carbon resistors classified in subheading 8533.21.00, HTSUSA.


The strain gauges are classified in 8533.21.00, HTSUSA.


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