Mechanical equipment and parts: Product fire and flame retardant level certification

Core Content of the Certification

The Fire Resistance and Flame Retardant Grade Certification for mechanical equipment and component products focuses on the combustion characteristics and ignition resistance of product materials, examining the following core dimensions:

• Material Combustion Grade Classification: Based on the GB/T 2408-2021 standard, the combustion performance of plastic and non-metallic materials is graded. The vertical burning test classifies materials into three grades: V-0, V-1, and V-2. V-0 is the highest flame retardant grade, requiring the total afterflame time not to exceed 30 seconds after two 10-second ignition tests, and dripping must not ignite the absorbent cotton. V-1 requires the total afterflame time not to exceed 60 seconds, and dripping must not ignite the absorbent cotton. V-2 has the same afterflame time requirement as V-1 but allows dripping to ignite the absorbent cotton. The horizontal burning test (HB grade) is the lowest flame retardant grade, requiring a burning rate of less than 40 mm per minute for samples 3 to 13 mm thick. According to the GB 8624-2012 standard, materials are classified into Grade A (non-combustible materials, such as metal, stone), Grade B1 (difficult-to-burn materials, such as flame-retardant plastics), Grade B2 (combustible materials), and Grade B3 (flammable materials).
• Glow-Wire Test: Based on the series of standards GB/T 5169.10 to GB/T 5169.13, this simulates the high-temperature effects caused by overheating or overload in electrical equipment under fault conditions. The glow-wire test evaluates the ignition characteristics of materials at specific temperatures. The Glow-Wire Flammability Index (GWFI) indicates the highest temperature at which a material does not ignite at a specified temperature. The Glow-Wire Ignition Temperature (GWIT) indicates the lowest temperature at which a material begins to ignite at a specified temperature. For finished equipment, the Glow-Wire Flammability Test (GWEPT) is conducted according to GB/T 5169.11 to verify safety under high-temperature conditions. Insulating materials for electrical equipment typically require passing a 750-degree glow-wire test.
• Needle-Flame Test: Based on the GB/T 5169.5 standard, this simulates the impact of small flame sources that may be generated inside equipment on the product. The needle-flame test uses a test flame with a height of 12 mm, applied for durations of 5, 10, 20, 30, 60, or 120 seconds, to observe whether the specimen ignites and the duration of burning after ignition. This test is suitable for detecting fire hazards caused by small flames that may arise from faults in electrical and electronic products.
• Specialized Tests for Material Categories: For rigid foam plastics, vertical burning tests are conducted according to GB/T 8333, recording the flame height, burning time, and percentage of residual mass of the specimen. For foam plastics with a density less than 250 kg per cubic meter, horizontal burning tests are conducted according to GB 8332. For enclosures, connectors, insulating materials, etc., of electrical and electronic products, 50W horizontal and vertical flame tests are conducted according to GB/T 5169.16 and GB/T 5169.17.
• Key Testing Equipment: Fire resistance and flame retardant grade testing requires specialized equipment, including horizontal and vertical burning testers (equipped with 20 mm and 125 mm standard flames), glow-wire testers (with adjustable temperature hot wires and thermocouples), needle-flame testers, oxygen index testers, etc. All instruments must be calibrated and certified by CNAS and undergo regular traceability.

Certification Process

The Fire Resistance and Flame Retardant Grade Certification for mechanical equipment and component products typically involves the following stages:

• Preliminary Evaluation and Material Selection: Clarify the product's usage environment and industry access requirements to determine the target flame retardant grade (e.g., V-0, V-1, 5VA). Optimize material selection from the source, prioritizing flame-retardant plastics that have already passed UL 94 V-0 grade certification to ensure stable flame-retardant performance. Design must consider the impact of wall thickness on combustion performance; typically, thicker walls make it easier to achieve higher flame retardant grades.
• Sample Preparation: Prepare test samples according to standard requirements. The GB/T 2408 vertical burning test requires sample dimensions of 125 mm in length, 13 mm in width, and up to 13 mm in thickness, with at least 5 specimens prepared for each test item. Specimens must be preconditioned at 23°C and 50% humidity for 48 hours, and the burning test must be completed within 1 hour.
• Application and Document Submission: Choose a third-party testing organization with CMA and CNAS qualifications. Submit documents such as the business license, product manual, material composition description, and product drawings. The certification body conducts a preliminary compliance review of the application materials.
• Product Sampling and Inspection: The laboratory conducts tests according to the target grade requirements. V-grade testing requires two 10-second ignitions, recording afterflame time, afterglow time, and whether dripping ignites the absorbent cotton. The 5V-grade test is more stringent, requiring five 5-second ignitions with a 125 mm test flame height. It requires afterflame time not to exceed 60 seconds (5VB) or 30 seconds (5VA), and block specimens must not be burned through (5VA). The test period is typically 3 to 7 working days.
• Functional Verification and Judgment: During the test, key parameters such as afterflame time, afterglow time, flame spread length, and dripping status after each ignition are recorded. All specimens must meet the judgment criteria for the corresponding grade. Failure of any single specimen results in non-compliance with that grade requirement.
• Rectification and Re-inspection: If non-conformities are found during testing, the enterprise must analyze the causes (e.g., insufficient flame retardant additive in the material, wall thickness too thin, structural design issues), rectify them, and resubmit samples for testing. The rectification process must retain complete records and evidence.
• Certification Decision and Issuance: After passing all tests, the certification body issues a formal test report. The report clearly states conclusions such as "Complies with GB/T 2408 V-0 grade requirements" or "Complies with GB 8624 B1 grade requirements" and is stamped with CMA or CNAS seals. The product can be marked with the corresponding flame retardant grade label. The certification report is valid indefinitely, but re-certification is required if product materials or structures change.
• Post-Certification Surveillance (Optional): Some certification bodies offer annual surveillance audit services to confirm the product's continued compliance with certification requirements. Enterprises should establish internal quality control mechanisms and conduct regular random inspections of raw material flame retardant performance.

Value of Certification

• Ensuring Equipment and Personnel Safety: Through scientific fire resistance and flame retardant grade certification, it is ensured that mechanical equipment and components will not rapidly burn or spread flames under abnormal operating conditions such as electrical faults or overload heating. V-0 grade materials have a total afterflame time not exceeding 30 seconds after two ignitions, effectively preventing the equipment from becoming a fire source and buying valuable time for evacuation and firefighting.
• Meeting Mandatory Industry Access Requirements: In project bidding for industries such as rail transit, power equipment, and construction machinery, fire resistance and flame retardant grade certification is a core access qualification. Rail transit interior materials need to meet the TB/T 3138 difficult-to-burn grade requirement, with a char length not exceeding 100 mm in the 45-degree burning test. Insulating materials for power equipment need to pass the IEC 60695 750-degree glow-wire test. Industrial machinery enclosures typically require UL94 V-0 or GB 8624 B1 grade.
• Enhancing Export Competitiveness: UL 94 flame retardant grade certification is widely recognized in the international market, with V-0 grade being a common requirement for entering European and American markets. Products certified to GB/T 2408 V-0 can equivalently meet the requirements of the IEC 60695-11-10 standard, facilitating the overcoming of foreign technical trade barriers.
• Reducing Fire Risk and Insurance Costs: Certified flame-retardant materials can significantly reduce the probability of equipment fires caused by electrical faults. Higher flame retardant grades indicate stronger self-extinguishing ability after flame removal, effectively controlling the spread of fire. Products with high flame retardant grades often qualify for more favorable fire insurance rates.
• Standardizing Production and Improving Quality: The certification process compels enterprises to establish standardized flame-retardant material procurement and quality control systems. Enterprises need to establish an incoming inspection system for flame-retardant materials, conducting random inspections of flame retardant performance for each batch to ensure the lasting stability of product flame retardant performance.

Applicable Product Scope

The Fire Resistance and Flame Retardant Grade Certification for mechanical equipment and component products is applicable to various types of industrial mechanical equipment and component products, mainly including:

• Industrial Machinery Enclosures: Control cabinets, distribution boxes, motor housings, servo drive housings, frequency converter housings, industrial robot housings
• Electrical Product Components: Low-voltage circuit breaker housings, relay housings, terminal blocks, insulating spacers, electrical insulating films, cable sheaths
• Rail Transit Equipment: Carriage interior panels, seat materials, wire and cable sheaths, connector housings, signaling equipment housings
• Power Equipment: Transformer insulating materials, switchgear insulating parts, capacitor housings, cable trays
• Electronic and Electrical Components: Power adapter housings, switch panels, socket housings, connector insulators, printed circuit board substrates
• Ventilation and Air Conditioning Equipment: Fan impellers, duct materials, insulation materials
• Automotive Components: Engine compartment plastic parts, battery pack housings, charging port housings, wiring harness sheaths