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    • Flammability

     

    In many applications the potted part must display self-extinguishing properties in the event of fire. Since fire protection should also take into consideration installation conditions, the layer thickness of the tested material plays an important role. In other words, the thinner the actual layer in the component, the higher the demands on the material’s flame-retardant properties to ensure compliance with a classification such as UL94 V-0.

    Representative products

    WEVOPUR 552 FL / WEVONAT 300

    • Flame-retardant properties in accordance with UL 94 V-0 for a thin layer (1.5 mm)
    • Universal application and reliability
    • Shore hardness D 70
    • Optimised versions for railway applications

     

    WEVOPOX 36001 FL / WEVODUR 5001

    • Flame-retardant properties in accordance with UL 94 V-0
    • Insulation class H (180 °C)
    • Good impregnation characteristics
    • Cold curing

     

    WEVOSIL 22002 FL

    • Flame-retardant properties in accordance with UL 94 V-0
    • Thermal conductivity 1.0 W/m·K
    • Can be used for insulation class H applications
    • Very elastic with damping properties
    • UL approval

    Fire tests according to UL 94 V-0 / V-2

    Test specimen: 127 mm x 12,7 mm x 1–12 mm
    Test method of vertical test: 2x flame treatment of 10s

    Burning period after each flame treatment:
    V-0: ≤ 10s / V-2: ≤ 30s

    Total burning period 10 specimens:
    V-0: ≤ 50s / V-2: ≤ 250s

    Annealing time after the second flame treatment:
    V-0: ≤ 30s / V-2: ≤ 60s

    Ignition of cotton batting by dripping:
    V-0: no / V-2: yes

    Horizontal Burning (HB)-Test: test specimens horizontally
    Flame extinguishes after 100 seconds or
    Burning rate max. 38 mm/min – specimen thickness 3–12 mm
    Burning rate max. 76 mm/min – specimen thickness < 3 mm

    The thinner the layer, the higher the flame retardancy required.

    Fire safety standards and specifications

     Among numerous other fire safety standards, the self-extinguishing properties of potted parts are often classified by the UL 94 standard in the electrical and electronics sector. The corresponding resins meet this fire safety standard in various classifications, which depend on the afterburn time and the drip characteristics of the encapsulant after a defined fire exposure time (2 x 10 s). The classifications range from V-2 to V-0 but may also be according to HB (Horizontal Burning), which is a measure of the distance burnt over time. Besides UL 94 there are other fire safety standards, such as those relating to the railway or construction sector (e.g. EN 45545).