Chapter 90 covers optical, photographic, cinematographic, measuring, checking, medical or surgical instruments and apparatus, precision instruments and apparatus; parts and accessories thereof. This chapter has an extremely broad scope, ranging from eyeglasses and microscopes to medical equipment and industrial measuring instruments. The core characteristic is that these goods are usually precision, technical, and specialized, used for measuring, analyzing, controlling, medical, and other purposes. Vehicle thermostats, as automatic regulating devices for controlling temperature, fall within the scope of automatic regulating or controlling instruments and apparatus of this chapter. Heading 9032 covers automatic regulating or controlling instruments and apparatus, including thermostats, pressure regulators, hygrostats, and other automatic regulating or controlling instruments and apparatus. These devices are used to automatically maintain physical quantities such as temperature, pressure, and humidity at set values, whether or not they use electricity. Thermostats are a typical representative, widely used in industry, households, and vehicles. This heading also includes parts and accessories thereof, but attention must be paid to distinguishing them from other headings, for example, instruments that only measure without regulating are classified under 9031, etc. The first 2 digits 90: indicate Chapter 90, i.e., optical, photographic, measuring, checking, medical, and other precision instruments and apparatus. The 3rd-4th digits 32: indicate heading 9032, specifically automatic regulating or controlling instruments and apparatus. The 5th-6th digits 10: indicate subheading 903210, further limited to thermostats. Therefore, the complete meaning of 903210 is thermostats within automatic regulating or controlling instruments and apparatus. Under this subheading, further subdivisions may be made according to specific types, but the international HS code only goes to 6 digits, and countries may add additional digits on their own. Vehicle thermostats, as a type of thermostat, are classified under this code. Vehicle thermostats are used to automatically regulate engine coolant temperature and maintain the engine at the optimal operating temperature, so they belong to automatic regulating or controlling instruments and apparatus. They are not classified under 9031 (measuring or checking instruments) because their main function is regulation rather than mere measurement; nor under 8481 (valves, etc.) because although a thermostat contains a valve, its core is automatic temperature control. Therefore, according to the functional principle, classification under 903210 is most appropriate.

Product Name: The standard name of the declared commodity should accurately reflect the product attributes, such as "vehicle thermostat" or "automotive thermostat". Use: Explain the application scenario of the commodity, such as used in an automobile engine cooling system to control coolant temperature. Working Principle: Briefly describe how the thermostat works, such as using paraffin wax that expands when heated to push the valve open and closed, thereby achieving automatic temperature regulation. Brand: Fill in the commodity brand; if there is no brand, fill in "no brand". Model: Fill in the commodity model, such as "TH-001", to facilitate identification of specific specifications. Material: Main materials, such as the valve body being copper or aluminum, and the temperature-sensing element being paraffin wax, etc. Electric: Indicate whether it relies on electricity to work; for mechanical type fill in "no", for electronic type fill in "yes". Product Name: Vehicle Thermostat; Use: Used in automobile engine cooling system to automatically regulate coolant temperature; Working Principle: Wax-type temperature sensing, paraffin wax expands when heated to push the valve; Brand: No Brand; Model: TH-001; Material: Valve body brass, temperature-sensing element paraffin wax; Electric: No. Mistakenly classifying the thermostat under 9031 (measuring instruments), ignoring its automatic regulating function. Failure to distinguish between mechanical and electronic types during declaration, which may affect subheading subdivision. Ignoring the declaration of brand and model, leading to customs review doubts.

The core basis for classification is the function of the commodity: whether it is used for automatic regulation or control of temperature. Vehicle thermostats automatically regulate coolant flow through a temperature-sensing element to maintain engine temperature, which conforms to the definition of heading 9032 "automatic regulating or controlling instruments and apparatus". According to the Explanatory Notes to the Harmonized System, thermostats are explicitly classified under 9032, and subheading 903210 specifically refers to thermostats. Therefore, vehicle thermostats should be classified under 903210. 903289 Other automatic regulating or controlling instruments and apparatus: 903289 covers other automatic regulating apparatus under 9032 other than specifically named ones such as thermostats and pressure regulators, while vehicle thermostats are already specifically named, so they are classified under 903210. 903190 Parts and accessories of other measuring or checking instruments and apparatus: If a thermostat only measures temperature and outputs a signal without regulating function, it might be classified under 9031, but the core of a vehicle thermostat is regulation, so it is classified under 9032. 848180 Other valves and similar devices: Although a thermostat contains a valve, its main function is automatic temperature control rather than mere fluid control, so it is classified under 9032 according to function. 870899 Other parts and accessories for vehicles: If the thermostat were not specifically named, it might be classified under Chapter 87 as a vehicle part, but because its function is clear and Chapter 90 has a specific heading, it is preferentially classified under 903210. Is the commodity used for automatic temperature regulation? Does it contain a temperature-sensing element and a valve mechanism? Does it work independently rather than only measuring? Is it specifically used for automobile engines? Is it explicitly listed as a thermostat in the HS Explanatory Notes?

Why is a vehicle thermostat classified under 903210 instead of 8708? Because Chapter 90 has a specific heading, and the function of a thermostat is automatic temperature regulation, which conforms to the definition of 9032. Chapter 87 covers vehicle parts, but if Chapter 90 has a specific heading, Chapter 90 should take precedence. How can one determine whether a thermostat is mechanical or electronic? Mechanical types usually use paraffin wax or a bimetallic strip for temperature sensing and have no electrical connection; electronic types contain a temperature sensor and circuit and require power supply. The declaration should be based on the actual structure. What is the difference in classification between a thermostat and a temperature sensor? A temperature sensor only measures temperature and outputs a signal, and is classified under 9031; a thermostat automatically regulates according to temperature and is classified under 9032. Is it necessary to provide a description of the working principle when declaring? Yes, the working principle is key to determining classification, and a brief description should be provided during declaration, such as "wax-type temperature sensing, automatically regulating coolant flow". Must the brand and model of a thermostat be declared? According to customs regulations, brand and model are important declaration elements and must be truthfully declared. If there is no brand, fill in "no brand"; the model should be accurately filled in. If the thermostat is used in a non-automotive field, is the code different? It is still classified under 903210, because this subheading covers all thermostats, not limited to automobiles. However, if used for specific equipment, proof of use may be required. How can one check the tax rate when importing thermostats? Tax rates change, so it is recommended to check the latest tax rate through the official website of the General Administration of Customs or the China International Trade Single Window, or consult a professional customs broker. After a thermostat is classified under 903210, what are the regulatory conditions? Regulatory conditions vary by country. Generally, there are no special regulations, but import licenses for mechanical and electrical products may be involved. Specifics should be checked in the current year's Customs Import and Export Tariff.