What is the needle flame test?

The needle flame tester is an important tool for evaluating combustion performance. It simulates the small flame produced by a product under fault conditions, using simulation technology to assess fire hazard. This equipment is widely used in a variety of industries, including electronics, building materials, textiles, automotive interiors, and aerospace materials, to evaluate material combustion properties, such as flame retardancy, burning rate, and toxicity of combustion products.

The IEC60695 needle flame tester is designed according to the international standard IEC 60695 series specifications. Its core function is to evaluate the flame retardancy and fire hazard of materials by simulating the small flame generated by internal equipment failures.

Operating Principle

The needle flame tester uses a fine needle of a specific length and diameter to ignite the test material under certain conditions, including temperature, oxygen concentration, and wind speed. The material's combustion performance is evaluated by recording parameters such as the needle's temperature change during combustion and the mass of the residual material after combustion. Specifically, a needle is inserted into a combustion hole of a specific length and depth on the surface of the test material, igniting the hole and causing combustion. During the combustion process, the needle's temperature increases continuously, forming a specific time-temperature curve.

Procedure

The procedure is as follows: First, prepare the sample. Select appropriate samples according to relevant standards and test requirements and perform pre-treatment, such as cleaning and cutting to the specified size. Next, calibrate the needle flame tester before each test to ensure that parameters such as the burner's flame size, temperature, and application time meet standard requirements. This can be done by measuring flame height and adjusting the needle valve and pressure gauge. The prepared sample is then securely mounted on the sample holder, ensuring that its position and angle meet test specifications to prevent movement during the test. Parameters such as the flame application time and observation time are set based on the test standard and sample characteristics. The test is then conducted by starting the equipment, generating a flame from the burner and applying it to the sample. A timing device is also activated. During the test, the sample's combustion behavior, including ignition, flame spread, and the presence of dripping, is closely observed and recorded. Finally, when the set flame application time or observation time has expired, the test is terminated, the burner is turned off, the sample is removed, and the test results are analyzed and evaluated to determine whether the sample meets the relevant safety standards.

Factors Affecting Test Results

1. Flame Parameters: Flame parameters such as size, temperature, and shape significantly influence test results. For example, an overly large flame may make the sample more susceptible to ignition, while unstable flame temperature may bias test results. Therefore, precise control of flame parameters is crucial to ensuring test accuracy.

2. Sample Characteristics: Sample characteristics such as material, thickness, shape, and surface treatment affect its combustion performance. Different materials have different flammability properties, so thicker samples may be more difficult to ignite or have a slower flame spread than thinner ones. Furthermore, surface coatings or treatments may alter the sample's combustion behavior.

3. Test Environment: Ambient temperature, humidity, and ventilation conditions can influence test results. Higher ambient temperatures may make the sample more susceptible to ignition, while higher humidity may inhibit combustion. Ventilation conditions affect oxygen supply and combustion product emissions, thereby affecting flame stability and the combustion process.

4. Operating Procedures: Operator proficiency and adherence to procedures also significantly influence test results. For example, loose sample mounting, inaccurate flame application positioning, and inaccurate timing can all lead to unreliable test results.

Calibration Methods

The calibration method primarily involves the following: First, flame size calibration. Using specialized measuring tools, such as a flame height gauge, the burner flame's height, width, and other dimensions are measured and compared to standard requirements. Adjustments are made to components such as the needle valve and pressure gauge to bring the flame size within the specified range. Second, temperature calibration involves using temperature measuring devices such as thermocouples to measure the flame temperature at specific locations to ensure it falls within the standard's temperature range. If the temperature deviation is significant, the burner's gas flow rate, combustion conditions, and other factors must be checked and adjusted accordingly. Finally, time calibration involves calibrating the needle flame tester's automatic timing mechanism using high-precision timing equipment to ensure the accuracy of the flame application and observation times. The reliability of the timing can be verified through repeated measurements and comparisons.

Applications

Evaluating the Flame Retardancy of Materials

It simulates the behavior of materials under fire conditions by applying a burning flame to the surface of a material and observing the flame's combustion behavior and the extent of the material's combustion. Parameters such as the flame's extinction time, the burned area, and the duration of post-burning combustion are used to assess the material's flame retardancy—that is, its ability to resist the spread of flame. This is crucial for improving the fire safety of products, particularly in areas such as building materials, electrical appliances, furniture, and automobiles.

Evaluating the Combustion Performance of Materials

In addition to flame retardancy, the needle flame tester can also assess the combustion performance of a material—that is, its combustion behavior under the influence of a flame. By observing indicators such as the flame's duration, height, and dripping, the material's flammability and flame spread can be assessed. This information is crucial for selecting and designing materials with lower flammability, thereby improving product safety and fire resistance.

Guiding Material Selection and Design

Needle flame tester test results can be used to compare the flame retardancy and combustion performance of different materials, thereby guiding material selection and design. By selecting materials with superior flame retardancy, the risk of fire in products can be reduced, protecting people and property. These test results provide engineers with important references during product design and material selection.

Promoting Material Improvement and Optimization

Analyzing needle flame tester test results can guide material improvement and optimization. By adjusting material formulations, modifying material structure, or adding flame retardants, flame retardancy can be enhanced and combustion performance reduced. This is crucial for improving a product's overall fire performance and meeting market and regulatory requirements.

Simulating Actual Fire Scenarios

The needle flame tester simulates the smoke, flame, and other characteristics of a real fire scenario, conducting combustion tests on materials using high-temperature flames. This simulation technology helps to realistically replicate actual conditions and assess the fire hazard of products. This is crucial for evaluating product performance under abnormal conditions and identifying potential fire risks in advance.

In summary, the needle flame tester, with its scientific operating principles, standardized operating procedures, precise control of multiple influencing factors, and rigorous calibration methods, plays a vital role in safety assessments in a wide range of fields, including electrical products, building materials, and automotive parts. Through practical application cases, we have demonstrated its significant effectiveness in ensuring product fire safety and preventing fire hazards. In the future, as various industries continue to increase their requirements for safety standards, the needle flame tester will continue to be optimized and upgraded to provide stronger support for the accurate evaluation of the safety performance of various products, further strengthening the line of defense for the safety of people's lives and property.