How does the ul94 contribute in horizontal and vertical flame tests

UL94

UL 94is one of the most used flammability tests for determining the relative flammability of plastic materials (Underwriters Laboratories test standard UL 94). Under carefully controlled laboratory circumstances, it evaluates a plastic part’s capacity to put out a flame after it has started, as well as how it will leak in response to a little open flame or radiant heat source.

UL94 is a standard sample-based method for measuring burning rate and characteristics. The sample measures 12.7 mm by 127 mm, with thicknesses ranging from 0.8 mm to 3.2 mm. When a rating is given, the thickness must be reported. These are the ratings: HB, V-2, V-1, V-0, and 5V. “HB” denotes that the sample will burn at a controlled rate if ignited. The intensity of the requirements increases up to the “5V” rating. When increased protection from combustion is necessary, the most typical rating observed on IBM parts is “V-0” V-0 must meet the following requirements:

1. After each of the two ten second flame applications, none of the five samples may have blazing combustion for longer than 10 seconds.
2. A total blazing combustion period of greater than 50 seconds for the ten ten second flame applications (5 samples, 2 applications each).
3. None of the five samples may burn up to the clamp used for holding them with flame or glowing combustion.
4. None of the five samples may drip flame particles that burn 305 mm below the sample dry absorbent cotton.
5. After the second flame removal, none of the five samples may have luminous combustion that lasts for longer than 30 seconds.

HVR-LS Horizontal Vertical Flame Tester

Alternate rating systems

The format of the other ratings is comparable. The samples’ ability to promote blazing or glowing combustion is what causes the ratings to differ most noticeably. Except for the 5V rating, which necessitates five applications lasting five seconds each, the flame application duration is the same. These tests offer useful comparison information, but they may not accurately reflect how the materials will behave in a real fire.

One way to enhance the UL94 data is to assess actual parts and establish a flame exposure limit on the minimum wall section. Additionally, there are standards that apply to types of components, such as UL 478, “Electronic Data-Processing Units and Systems” The findings of the tests are meant to provide a preliminary assessment of the material’s flammability appropriateness for a particular application, such as plastic polymers used for parts in electronic appliances and devices.

Purpose

To evaluate the flame and glow propagation resistance of plastic materials utilized as parts in appliances and gadgets.
In terms of flammability, UL aims for this standard to function as a preliminary indication of a plastic’s suitability for use as a component of a device or appliance. It is not meant to represent how dangerous a substance would be in a real fire.

A layer of dry cotton is 300 mm above each of the five specimens. For 10 seconds, a calibrated flame is applied to the bottom edge of the test bar that is supported vertically, and any after flame time is recorded. The flame is reapplied for a further 10 seconds after the after flaring stops, and the after-flame time and afterglow time are recorded.

The following factors, among others, have an impact on flammability:

• Ease of ignition refers to how quickly a substance ignites. 
• Ease of ignition refers to how quickly a substance ignites. 
• Flame spread refers to fire spreads how quickly across a polymer surface. 
• Fire endurance refers to how quickly fire penetrates a wall or barrier. 
• Rate of heat release refers to how soon and how much heat is produced.
• Ease of extinction-the speed with which the flame chemistry causes extinction
• smoke evolution
• Toxic gas production.

The initial step toward receiving plastic recognition and a subsequent listing in the “Plastics Recognized Component Directory” is UL 94 flammability testing (former known as “Yellow Cards”). The 94HB, 94V, 94VTM, 94-5V, 94HBF, 94HF, and Radiant Panel tests are all part of UL 94.

Horizontal flame test

The Horizontal flame test is described in the 94HB test. Vertical flame test is a more exact and precise test than 94HB and is conducted using methods 94V and 94VTM. The 94-5V test is used for product enclosures that are attached to a conduit system or cannot be moved easily. For nonstructural foam materials, such as acoustical foam, the 94HBF and HF are utilized. An ASTM (E162) test known as the “radiant panel test” is used to estimate how quickly a material will burn when exposed to fire.

The rating methodology and three tests that are applicable to stock-shaped items (sheet, rod, tube, and film) are briefly described below. This is not intended to be a test-running technique or a way to judge whether a material is suitable for a given application.

Test for Horizontal Burning in 94HB

Materials that pass any of the V or VTM tests will typically be recognized by UL for applications that require 94HB, even though this test is widely seen to be the simplest to pass. Consult the UL representative assigned to the equipment the film will be used in to be certain. The 94HB rating is normally appropriate for decorative elements or portable, attended, intermittent-duty, domestic appliance enclosures (such as hair dryers).

A ½” x 5″ specimen with markers at 1″ and 5″ from the free end is used for the test, which is held at one end in a horizontal posture. The free end is heated for 30 seconds, or until the flame front touches the first “mark (see Fig. 2.1). The duration is timed between the 1″ mark and the 5” mark if combustion persists.

if burning ceases before to the five “The damaged length between the two markings, the combustion duration, and the mark are all noted. Three samples are tested as a set. If the burning rate is less than 3″ per minute or the burning stops before the 5″ point, a substance with a thickness of less than 0.118” will be labelled 94HB. A second set of three specimens are tested if one out of the initial three fails to pass muster. This second group of three all require compliance.

Vertical Burning Test at 94V

Three classes of this test-94V-0, 94V-1, and 94V-2-are commonly suitable for portable, unsupervised, intermittent-duty, domestic equipment (i.e., coffee makers). Which classification fits a given application relies on a variety of elements, including:

• Dimensions and part thickness.
• separation from live, uninsulated sections.
• Hot wire starting.
• lightning-fast arc ignition
• high rate of arc tracking.

In this test, a 12″ x 5″ specimen is held vertically at one end. Two 10-second bursts of burner flame are applied to the free end of the specimen, separated by the time it takes for flaring combustion to stop following the first application. Five samples each from two sets are evaluated. For each specimen, the following information is noted:

• After the initial application of burner flame, the length of the blazing combustion.
• length of the blazing combustion following the application of the second burner flame.
• Following the application of a second burner flame, the duration of glowing combustion
• whether or not cotton placed beneath the specimen is ignited by flame drops.
• Whether or not the specimen burns through the clamping force.

94V Thin Material Vertical Burning Test

Three classes are available for this test: 94V-0, 94V-1, and 94V-2. Thin gauge (usually £ 10 mil) or extremely flexible materials may deform, shrink, or stretch during the 94V test. The vertical burning test for thin materials, known as 94VTM, can be used to assess these materials. The 94V test is different from this in a number of ways:

The specimen measures 8″ x 2″.

The specimen is taped on one end and rolled longitudinally around a ½” dia. mandrel. The specimen takes on a cone shape when the mandrel is removed, adding rigidity to its length. The two flame applications last for three seconds as opposed to ten. Although this test was created for materials with thinner gauges, any material that can be produced around a ½” mandrel can be assessed using the 94VTM method.

The test is conducted in the same way as 94V, with the exceptions noted above. The Material Classification criteria are the same as those for 94V, with the exception that no specimens are allowed to have combustion that is burning or glowing up to a mark that is 5″ from the specimen’s bottom (free end).

If the material can be bent around the ½” mandrel, it is typically desirable to evaluate materials using 94VTM rather than 94V because it is typically simpler to pass or achieve a better rating. For example, 94VTM-0 = 94V-0, 94VTM-1 = 94V-1, etc.; UL will typically accept a 94VTM rating of a similar level when a 94V material is required. However, UL does reserve the authority to decide which rating a material need based on the application.

Industry use of the test

• Shipyards
• Vehicle Equipment
• Chemical processing equipment 
• agricultural machinery
• Welding Tools 
• Equipment for Woodworking

50W and 500W Horizontal Vertical Flame Fire Tester According to ANSI UL94, IEC60695

FAQs

What does UL94 standard mean?

Underwriters Laboratories released the plastics flammability standard known as UL94. (USA). According to the standard, plastics are divided into six separate classes based on how well they resist flame spread in varied part thicknesses and orientations.

A vertical flame test: what is it?

A test sample is exposed for a predetermined amount of time while being held vertically over a controlled flame. The flame source is eliminated after being exposed. The duration of the specimen’s flame as well as the afterglow’s persistence after the flame source has been extinguished are measured.

What does a horizontal flammability test involve?

The horizontal burning test calculates a specimen’s burning rate in mm/min while accounting for thickness. Two sets of three specimens having nominal measurements of 125 mm x 13 mm and a thickness of no more than 13 mm are considered a specimen.

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