What is the difference between the needle flame test and the scorching wire test?

The needle flame test and the glow wire test are two different methods used to evaluate the flammability and fire resistance of materials. Here are the main differences between these tests:

1. Purpose:

   • Needle Flame Test: The needle flame test, also known as the vertical flame test, is primarily used to assess the flammability characteristics of small components or materials such as textiles, films, and electrical insulating materials.
   • Glow Wire Test: The glow wire test is designed to simulate the effects of thermal stresses caused by overheating electrical equipment or household appliances. It evaluates the fire hazard potential of electrical contacts, connectors, and other similar components.

2. Test Setup:

   • Needle Flame Test: In this test, a small, defined flame produced by a needle-shaped burner is applied vertically to the specimen surface for a specified duration.
   • Glow Wire Test: The test involves applying a heated glow wire, usually made of nichrome, to a sample under controlled conditions. The glow wire is heated to a specified temperature, and the sample is brought into contact with the wire for a specific duration.

3. Flame Characteristics:

   • Needle Flame Test: The needle flame used in this test has specific dimensions and characteristics. It provides a standardized ignition source and measures parameters such as ignition time, flame spread, burning rate, and any signs of flaming particles.
   • Glow Wire Test: The glow wire simulates a hot wire or an overheated component in electrical devices. It evaluates the ignition resistance and flame-retardant properties of materials when subjected to high temperatures.

4. Application Standards:

   • Needle Flame Test: This test is commonly conducted according to standards such as IEC 60695-11-5 and UL 94 for assessing the flammability of electrical insulating materials.
   • Glow Wire Test: The glow wire test is performed according to standards such as IEC 60695-2-10 and IEC 60335-1 for assessing the fire hazard potential of electrical products and appliances.

In summary, the needle flame test is used to evaluate the flammability of small materials or components, while the glow wire test assesses the fire resistance of electrical contacts and appliances subjected to thermal stress. Each test has its own specific setup, flame characteristics, and applicable standards.