FAQ

With the increasing public awareness of fire safety and the issuance of relevant national standards, the domestic combustion testing industry is experiencing an upward trend. Many newcomers to the combustion testing industry are unfamiliar with horizontal and vertical burning ratings. Today, I will provide an introduction.

The UL94 standard, being consistent with China’s national standard GB/T 2408-2008. has become the most common test method for flame retardancy ratings. UL94 comprises 12 fire protection classes:

HB, V-0. V-1. V-2. 5VA, 5VB, VTM-0. VTM-1. VTM-2. HBF, HF-1. HF-2.

Among these, VTM-0. VTM-1. and VTM-2 are applicable to plastic films.

HBF, HF-1. and HF-2 are applicable to foamed materials.

UL94 HB: Horizontal Burning. This type of plastic can burn slowly but cannot self-extinguish. This is the lowest UL rating and is often used when achieving a vertical V0. V1. or V2 rating is not feasible.

UL94 V0. V1. V2. 5V: Vertical Burning.

UL94 V0: After ignition and flame removal, the specimen self-extinguishes rapidly within 10 seconds, with no burning drips falling (i.e., burning drips must not ignite a cotton pad placed one foot below the specimen).

UL94 V1: The assessment method is similar to V0. but it allows for a longer self-extinguishing time. This test allows molten drips to fall onto the cotton pad but they must not ignite it.

UL94 V2: After two 10-second flame applications, the flame must extinguish within 60 seconds. Burning drips are permitted and may ignite cotton located 12 inches (approx. 30 cm) below.

UL94 5V is the most stringent test method, involving the actual endurance of the plastic product in a flame. The test requires a 5-inch flame applied five times to the specimen. No flaming drips are allowed, the specimen must not exhibit significant distortion, and it must not develop any burn-through holes.

Based on the standard test flames, tests are categorized as:

• 500W Test Flame: Used for horizontal and vertical burning tests where materials are classified as 5VA or 5VB.
• 50W Test Flame: Used for horizontal burning tests (classifying materials as HB, HB40. HB75) and vertical burning tests (classifying materials as V-0. V-1. V-2).

Filaman R&D and production of horizontal and vertical burning test equipment can meet the requirements for both UL94 V vertical burning tests and UL94 HB horizontal burning tests.