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Temperature curves

Following temperature curves are used for the description of the gas temperature according to EN 1991-1-2.

Standard temperature curve

The fundamental nominal curve, the temperature of gas in the fire compartment is given by the expression

Where is:

θg

  • The gas temperature in the fire compartment in °C

t

  • The time in minutes

Parametric temperature curve

This curve is valid for fire compartments up to 500m2, without openings in the roof and for a maximum compartment height of 4m. The curve consists of two phases: heating phase and cooling phase. Following parameters describe the geometry of the curve:

  • The time tlim for maximum gas temperature in case of fuel controlled fire
  • The thermal absorptivity for the total enclosure b given by the expression

Where is:

ρ

  • The density of boundary of enclosure in kg/m3

c

  • The specific heat of boundary of enclosure in J/(kg K)

λ

  • thermal conductivity of boundary of enclosure in W/(m K)
  • The opening factor O given by the expression

Where is:

Av

  • The total area of vertical openings on all walls in m2

heq

  • The weighted average of window heights on all walls in m

At

  • The total area of enclosure (walls, ceiling and floor, including openings) in m2
  • The design value of the fire load density qt,d related to the total surface area At of the enclosure.

This curve may be used only for "500°C isotherm method".

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