Plastic combustion testing is critical for product safety, especially in electronics, construction, and automotive industries. This guide explains key UL 94 flammability ratings, test methods, and standards—using BONAD testing equipment—to help you select compliant materials.
What is UL 94 Plastic Flammability Testing?
The UL 94 standard evaluates plastic materials’ reaction to fire under controlled conditions. It classifies materials into 12 flame ratings based on:
- Flame spread speed
- Self-extinguishing time
- Dripping behavior
- Resistance to ignition
These tests align with global standards like IEC 60695-11-10, ISO 9772/9773, and IEC 60112.
UL 94 Flame Rating Classifications
1. Enclosure & Structural Materials
For electronics housings and insulators:
- 5VA/5VB: Most stringent (500W flame). No dripping allowed.
- V-0/V-1/V-2: Vertical tests. V-0 = fastest self-extinguishing (<10 sec).
- HB: Slow-burning in horizontal orientation.
2. Foam Materials (HF)
For speaker grilles and acoustic dampers:
- HF-1, HF-2, HBF (Horizontal Burning Foam).
3. Thin Films (VTM)
For flexible circuits (e.g., VTM-0, VTM-1):
- *Note: VTM-0 ≠ V-0 due to different test methods.*
Key Plastic Combustion Tests
Horizontal Burning (UL 94 HB)
- Purpose: Measures burn rate of horizontally mounted plastics.
- Standards: UL 94, IEC 60695-11-10A.
- BONAD Equipment: Flammability test chamber with controlled ignition.
Vertical Burning (UL 94 V-0/V-1/V-2)
- Purpose: Evaluates self-extinguishing time and flaming drips.
- Test: 50W flame applied twice.
- Standards: UL 94, IEC 60695-11-10B.
Severe Fire Exposure (UL 94 5VA/5VB)
- Purpose: Tests resistance to intense 500W flames.
- Key: 5x stricter than V-0. Specimens must not drip or form holes.
- Standards: UL 94, IEC 60695-11-20.
Why Testing Methodology Matters
- HB vs. V Tests: Horizontal tests measure burn rate; vertical tests evaluate self-extinguishing capability.
- 5VA vs. V-0: 5VA uses a 500W flame (vs. 50W for V-0) and prohibits dripping.
- VTM Tests: Require failed UL 94 V-test as a precondition.
BONAD Flammability Test Solutions
BONAD testing equipment performs all UL 94-compliant combustion tests, including:
- UL 94 HB, V, 5V, VTM, and HBF ratings
- IEC/ISO equivalent standards
- Customizable chambers for foams, thin films, and rigid plastics
