BS EN 60695-8-1-2001 pdf download.Fire hazard testing Part 8-1 : Heat release – General guidance ( IEC 60695-8-1 : 2001 ).
This part of IEC 60695 provides guidance in the assessment of heat release from electrotechnical products and materials from which they are constructed.
Heat release data can be used as part of fire hazard assessment and in fire safety engineering, as described In IEC 60695-1-1.
One of the responsibilities of a technical committee is, wherever applicable, to make use of basic safety publications in the preparation of its publications.
2 Normative references
The following normative documents contain provisions which, through reference in this text, constitute provisions of this part of IEC 60695. For dated references, subsequent amendments to, or revisions of, any of these publications do not apply. However, parties to agreements based on this part of fEC 60695 are encouraged to investigate the possibility of applying the most recent editions of the normative documents indicated below. For undated references, the latest edition of the normative document referred to applies. Members of lEG and ISO maintain registers of currently valid International Standards.
fEC 60695 (all parts), Fire hazard testing
lEG 60695-1-1:1999, Fire hazard testing — Part 1-1: Guidance for assessing the fire hazard of electrotechnical products — General guidelines
IEC 60695-8-2:2000, Fire hazard testing — Part 8-2: Heat release — Summary and relevance of test methods
lSO/IEC 13943:2000, Fire safety — Vocabulary
3 DefinitIons
For the purpose of this part of IEC 60695, definitions taken from ISO/lEG 13943, together with the following definitions, apply.
heat release
thermal energy which is released by the combustion of an item under specified conditions
NOTE It is expressed in joules.
3.4
gross heat of combustion
heat released per unit mass when a material or product burns completely and the combustion products are In their standard states
NOTE The standard heat of combustion of a substance is defined in thermochemical terms as the enthalpy change that occurs when one mole of a substance undergoes complete combustion under standard conditions. In the fire science community, heat of combustion is also referred to as gross calorific valu& or as gross heat of combustion. and the units used are energy per unit mass rather than energy per mole. The water formed as a product of combustion is considered to be in the liquid state. For a compound containing carbon and hydrogen, for example. complete combustion means the conversion of all the carbon to carbon dioxide gas, and conversion of all the hydrogen to liquid water.
Gross heat of combustion Is measured by oxygen bomb calorimetry. A small quantity of powdered material Is seated under pressure in pure oxygen and ignited by an electric spark. In this way all the sample is completely converted to fully oxidized products. Note that in real fires this is rarely the case. Some potentially combustible material is often left as char and products of combustion are often only partly oxidized, for example. soot particles in smoke and carbon monoxide.
3.5
net heat of combustion
heat released per unit mass when a substance burns completely and the combustion products are in their standard states with the exception of water which is considered to be in the vapour state
NOTE The net heat of combustion is always smaller than the gross heat of combustion because the heat released by the condensation of the water vapour is not included.
3.6
effective heat of combustion
calculated by dividing the heat released in a given time interval by the mass lost from the burning test specimen in the same time period
NOTE In most cases. it is not the same as the net heat of combustion of the test specimen. The only case where it is the same is when all the test specimen is consumed (i.e. all converted to volatile fuel) and when all the combustion products are fully oxidized.
The following examples illustrate the difference between net heat of combustion and effective heat of combustion.
EXAMPLE 1: Toluene
The net heat of combustion of toluene is 40,99 MJkg and is a measure of the thermal energy released by the chemical reaction
Cit (liquid) + 9 02 Igas) — 7 Co2 (gas) i 4 H0 (gas)
If toluene is burned in a cone calorimeter it burns inefficiently with the production of soot, carbon monoxide and other partially oxidized products. A typical value for the effective heat of combustion of toluene (without external heat flux) is about 36 MJ/kg reflecting the incomplete combustion. In this case, all of the test specimen volatilizes and, as a result. the effective heat of combustion of the volatile fuel is also the same as the effective heat of combustion of the test specimen.BS EN 60695-8-1-2001 pdf download.