Flammability Test Equipment UL-94

Flammability UL-94 test equipment

Fundamental assessment of Plastics for Fire Performance

UL 94 (Underwriters Laboratories test standard UL 94) is one of the most used flammability tests for determining comparative flammability for plastic materials. It measures the ability of sample to extinguish the flame after ignition and its dripping behavior in response to a mini flame or radiant heat source under controlled environmental conditions.

The tests results are intended to serve as a primary assessment of the material’s suitability with respect to flammability for a particular application, such as plastic materials used for parts in electronic devices and appliances.

The flammability is influenced by several factors such as:

Ignition time – time for a sample to take flames
Flame propagation – how far flame propagates
Fire resistance – how long the material can resist the flame from penetration
Rate of heat release – heat energy released per second

Ease of extinction – how rapidly the flame chemistry leads to extinction
Smoke release &
Toxic gas generation

Hence, plastic burning behavioral study is a major area of research to industry:

The behavior of the burning process in plastics
Various methods to reduce plastics flammability, and
Methods to test flammability
Main Types of Testing & Flammability Ratings to Classify Plastics

The UL standard classifies plastics according to the minimum thickness at which it stops burning when tested in a horizontal or vertical orientation.

Types of testing/flammability ratings covered in the UL 94 standard for flammability of plastic materials include:

• Vertical burning tests (V-0, V-1, V-2, 5V, 5VA, 5VB, VTM-0, VTM-1, VTM-2)
• Horizontal burning tests (HB, HBF, HF-1, HF-2)

The UL test methods are aligned with IEC 60707, IEC 60695-11- 10, IEC 60695-11-20, ISO 9772 and ISO 9773 standards used to determine fire properties.

UL 94 VTM Rating: VTM-0, VTM-1 and VTM-2 – Thin Material Vertical Burning Testing

This test method is used for thin specimen or materials that are too flexible or may distort, shrink or flex during the traditional vertical testing (failure to pass the UL 94 V test is a precondition of all VTM ratings). This test is similar to the vertical burning test except that the material is wrapped around a mandrel before clamping to the stand and the flame application is reduced. In this test, the flame is applied only for 3 seconds.

UL 94 5V Rating: 5V, 5VA, 5VB – Vertical Testing is done on both bar and plaque samples

For any Plastic material to achieve 5V classification, the test samples must not burn with flaming and/or glowing combustion for more than 60 sec after the fifth flame. Also, the test samples must not drip.

Horizontal Burning Test for Classifying Plastic material

Samples molded from the Plastic material are oriented in either a horizontal depending on the specifications of the relevant test method, and they are subjected to a defined flame ignition source for a specified period of time.

UL 94 HB Rating

A Plastic material having a thickness between 3 and 13mm will be classified as a HB Plastic material if it does not have a burning rate exceeding 40mm per minute. For Plastic material with thickness less than 3mm the burning rate should not exceed 75mm per minute. The Plastic material will also be rated as HB if it ceases to burn before the 100mm mark independent of thickness.

UL 94 HBF: HBF, HF-1 and HF-2 – Horizontal Burning Foamed Plastic material

This test grants three different types of ratings depending on burning rates and or afterflame times. A Plastic material will be classified as a HBF Plastic material if it does not have a burning rate exceeding 40mm per minute over a 100 mm span or if ceases to burn before flaming or glowing reach the 125mm mark.

Flammability UL-94 test equipment

Flammability test equipment for flammability Test with the below characteristics:

• Burner: in accordance with ASTM D 5025 part 94
• Burner assembly for angles of 20 Deg. 45 Deg. and 90 Deg.
• Sample holding mechanism: can hold the sample vertically or horizontally both
• Mass flow meter: Digital mass flow meter with graph and OLED display for methane/propane gas.
• Pressure controller
• Flammability test equipment Pressure monitor
• Motorized burner mechanism control and move with HMI touch Screen control. other economical
• Options available for customization and different designs such as motorized exhaust system, Manual control instead of HMI, etc.
• Dual flow meter console for Methane (CH4) range 300 ml/min and 1.7 L/min as per standard requirement
• Manometer: Not required, provided with the standard model with rotameters only.

Flammability UL-94 test equipment

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