UL94 Flammability of Plastic Materials-Scope：
These requirements cover tests for flammability of plastic materials used for parts in devices and appliances. They are intended to serve as a preliminary indication of their acceptability with respect to flammability for a particular application.
The methods described in this Standard involve standard size specimens and are intended to be used solely to measure and describe the flammability properties of materials, used in devices and appliances, in response to heat and flame under controlled laboratory conditions. The actual response to heat and flame of materials depends upon the size and form, and also on the end-use of the product using the material. Assessment of other important characteristics in the end-use application includes, but is not limited to, factors such as ease of ignition, burning rate, flame spread, fuel contribution, intensity of burning, and products of combustion.
The final acceptance of the material is dependent upon its use in complete equipment that conforms with the standards applicable to such equipment. The flammability classification required of a material is dependent upon the equipment or device involved and the particular use of the material. The performance level of a material determined by these methods shall not be assumed to correlate with its performance in end-use application.
If found to be appropriate, the requirements are applied to other nonmetallic materials.
These requirements do not cover plastics when used as materials for building construction or finishing.
A product that contains features, characteristics, components, materials, or systems new or different from those covered by the requirements in this Standard, and that involves a risk of fire, electric shock, or injury to persons shall be evaluated using the appropriate additional component and end-product requirements as determined necessary to maintain the acceptable level of safety as originally anticipated by the intent of this Standard. A product whose features, characteristics, components, materials, or systems conflict with specific requirements or provisions of this Standard cannot be judged to comply with this Standard. Where considered appropriate, revision of requirements shall be proposed and adopted in conformance with the methods employed for development, revision, and implementation of this Standard.
UL94 classification：
1) HB Class: Horizontal Burning Test
A material classed HB shall:
a) Not have a burning rate exceeding 40 mm per minute over a 75 mm span for specimens having a thickness of 3.0 – 13 mm
b) Not have a burning rate exceeding 75 mm per minute over a 75 mm for specimens having a thickness less than 3.0 mm
c) Cease to burn before the 100 mm reference mark.
2) V0－V2 Class: Vertical Burning Test
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Criteria
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V0
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V1
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V2
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Afterflame time for each individual specimen t1 or t2
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≤10S
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≤30S
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≤30S
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Total afterflame time for any condition set (t1 plus t2 for the 5 specimens)
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≤50S
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≤250S
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≤250S
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Afterflame plus afterglow time for each individual specimen after the second flame application (t2+t3)
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≤30S
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≤60S
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≤60S
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Afterflame or afterglow of any specimen up to the holding clamp
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No
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No
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No
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Cotton indicator ignited by flaming particles or drops
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No
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No
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Yes
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3) 5VA/5VB Class: 500w (125 mm) Vertical Burning Test
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Criteria
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5VA
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5VB
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Afterflame time plus afterglow time after fifth flame application for each individual bar specimen
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≤60S
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≤60S
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Cotton indicator ignited by flaming particles or drops from any bar specimen
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No
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No
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Burn-through (hole) of any plaque specimen
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No
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Yes
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4) RP Class: Radiant Panel Flame Spread Test
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Average flame spread of four specimens
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Flame spread class
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15 maximum
25 maximum
50 maximum
75 maximum
100 maximum
150 maximum
200 maximum
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RP15
RP25
RP50
RP75
RP100
RP150
RP200
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5) VTM0-VTM2 Class: Thin Material Vertical Burning Test
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Criteria
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V0
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V1
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V2
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Afterflame time for each individual specimen t1 or t2
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≤10S
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≤30S
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≤30S
|
|
Total afterflame time for any condition set (t1 plus t2 for the 5 specimens)
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≤50S
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≤250S
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≤250S
|
|
Afterflame plus afterglow time for each individual specimen after the second flame application (t2+t3)
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≤30S
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≤60S
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≤60S
|
|
Afterflame or afterglow of any specimen up to the holding clamp
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No
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No
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No
|
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Cotton indicator ignited by flaming particles or drops
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No
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No
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Yes
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6) HBF,HF1-HF2: Horizontal Burning Foamed Material Test
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Criteria Conditions
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HF-1
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HF-2
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Afterflame time
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4/5 is·2s
1/5 is·10s
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4/5 is·2s
1/5 is·10s
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Afterglow time for each individual specimen
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30s
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30s
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Cotton indicator ignited by flaming particles or drops
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No
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Yes
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Damaged length for each individual specimen
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< 60mm
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< 60mm
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Notes: 4/5 – Four out of a set of five specimens.
1/5 – One out of a set of five specimens
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UL 94 Referenced standards：
> ASTM D 618, Method for Conditioning Plastics and Electrical Insulating Materials for Testing (ISO 291: Plastics – Standard Atmospheres for Conditioning and Testing)
> ASTM D 789, Test Method for Determination of Relative Viscosity, Melting Point, and Moisture Content of Polyamide (PA)
> ASTM E 162, Test Method for Surface Flammability of Materials Using a Radiant Heat Energy Source
> ASTM D 3195, Practice of Rotameter Calibration
> ASTM D 5025, Specification for a Laboratory Burner Used for Small-Scale Burning Tests on Plastic Materials
> ASTM D 5207, Standard Practice for Calibration of 20 mm and 125 mm Test Flames for Small-Scale Burning Tests on Plastic Materials
> ASTM E 437, Specification for Industrial Wire Cloth and Screens (Square Opening Series), Appendix X3
> 94HB: ASTM D 635, Test Method for Rate of Burning and/or Extent and Time of Burning of Self-Supporting Plastics in a Horizontal Position (IEC 707, Methods of Test for the Determination of the Flammability of Solid Electrical Insulating Materials When Exposed to an Igniting Source, ISO 1210, Plastics – Determination of the Burning Behavior of Horizontal and Vertical Specimens in Contact with a Small Flame Ignition Source)
> 94V: ASTM D 3801, Method for Measuring the Comparative Extinguishing Characteristics of Solid Plastics in a Vertical Position (IEC 707, ISO 1210)
> 94VTM: ASTM D 4804, Test Method for Determining the Flammability Characteristics of Nonrigid Solid Plastics (ISO 9773, Plastics – Determination of Burning Behavior of Flexible Vertical Specimens in Contact with a Small Flame Ignition Source)
> 94-5V: ASTM D 5048, Standard Test Method for Measuring the Comparative Burning Characteristics and Resistance to Burn-Through of Solid Plastics Using a 125 mm Flame (ISO 10351, Plastics – Method of Test for the Determination of Combustibility of Specimens Using a 125 mm Flame Source)
> 94HBF: ASTM D 4986, Standard Test Method for Horizontal Burning Characteristics of Cellular Polymeric Materials (ISO/DIS 9772.3, Cellular Plastics – Determination of Horizontal Burning Characteristics of Small Specimens Subjected to a Small Flame)
For more detailed information about UL 94 flammability test