Fire behaviour

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

  • 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 8260 FL/60  / WEVODUR 1018/25

  • Flame-retardant properties in accordance with UL 94 V-0
  • Insulation class H (155 °C)
  • Good impregnation characteristics
  • Thermosetting

 

WEVOPUR 20018 FL

  • Flame-retardant properties in accordance with UL 94 V-0
  • Thermal conductivity 1.8 W/m·K
  • Can be used for insulation class H applications
  • Very elastic with damping properties

Fire tests according to UL94 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).

Information
Contact

WEVO-CHEMIE GmbH
Schönbergstrasse 14
73760 Ostfildern-Kemnat
Germany
Phone +49 711 167 61-0
Fax +49 711 167 61-44
info@wevo-chemie.de