Flame Retardant Vs Fire Resistance
In cable terminology it is very important to distinguish flame retardant & fire retardant cable as many of people not understand what they actually want flame retardant or fire resistance cable. Flame retardant cables are designed to resist the spread of fire after a specific length, in these cables fire is not spread throughout the length it is self extinguish after a certain length. Fire resistance cables are designed to maintain circuit integrity & continue the working of cable under fire condition for a specific period of time.
|
Description |
Flame retardant Cables |
Fire resistance cable |
|
Outer Sheath |
Generally outer sheath have minimum “FR / FRLS” properties. |
Halogen Free & flame retardant Outer sheath material having minimum halogen free & flame retardant properties. |
|
Performance |
Fire performance limited to not to propagate further |
Signal transmission continues under the fire condition for a specific period |
|
Testing standard |
IEC 60332-1, IEC 60332-3, IEE-383 |
IEC 60331 & BS 6387 (Circuit Integrity test) |
The Fire Resistant cables are categorized by a letter symbol (e.g. A) or series of symbols (e.g. CWZ) according to the requirements for fire resistance characteristics which they meet, the test temperature selected and the duration of the test for resistance to fire alone in according to BS 6387 as below :
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Requirement |
Symbol |
|
( 1 ) Resistance to fire alone 650°C for 3 hours 750°C for 3 hours 950°C for 3 hours 950°C for 20 minutes (short duration) |
A B C S |
|
( 2 ) Resistance to fire with water |
W |
|
(3) Resistance to fire mechanical shock 650°C 750°C 950°C |
X Y Z |
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|
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Flame retardant tests
|
IEC 60332-1 |
Test for vertical flame propagation for a single insulated wire or cable |
|
IEC 60332-3 |
Test for vertical flame spread of vertical mounted bunched wire or cable |
|
IEC 60332-3-22(Cat A) |
7 liter of combustible material per meter, flame application: 40 minutes |
|
IEC 60332-3-23(Cat B) |
3.5 liter of combustible material per meter, flame application: 40 minutes |
|
IEC 60332-3-24(Cat C) |
1.5 liter of combustible material per meter, flame application: 20 minutes (Cable dia > 12 mm) |
|
IEC 60332-3-25(Cat D) |
0.5 liter of combustible material per meter, flame application: 20 minutes (Cable dia < 12 mm) |