P&K KFA (VDI 3781 Part 4)

Discharge Devices (Chimneys)


In this form the discharge devices are declared These can also be conveniently added or modified via Add Discharge Device "Add Discharge Device" in the 2D View.


The names of the flue gas discharge devices are shown in the reports.


Inactive exhaust discharge devices are ignored in calculations and illustrations.

Emission Type

Select one of:

  • Oil and gas firing within the scope of the 1st BImSchV
  • Firing with solid fuel within the scope of the 1st BImSchV
  • Solvent according to 31. BImSchV


For combustion plants: nominal heat output in kW
For solvents: Percentage of the 31st BImSchV threshold.


Reference to the building with the discharge device.


Position on the building in longitudinal direction in m.


Position on the building in transverse direction in m.

Emission of solvents

For calculations within the scope of the 31st BImSchV, the directive requires the following provisions:

  • Section 5.2: For the additive term (HÜ) a height of 3 m
  • Section 6.3.2: For the exposure area (R) a radius of 50 m
  • Section 6.3.4: For the reference level (HB) a height of 5 m
  • Section A minimum height over terrain of 10 m

This definition applies to all parameters with the remark: For other than combustion plants outside the scope of application of the 31st BImSchV, the value may be graded in the same way as for the combustion plants accompanied.

Installations outside the 31st BImSchV fall below the emission threshold defined in this Ordinance.
P&K KFA integrates such systems by recording a percentage of the threshold value of the 31st BImSchV when emitting at such discharge devices. With this value, the relevant parameters are graded as follows:

  • Additive Term (HÜ)
    < 40%: 0,4 m
    < 100%: 1 m
    else 3 m

  • Exposure Area (R)
    Share/2 m
    maximal 50 m

  • Reference Level (HB)
    ≤ 21%: 1 m
    ≤ 26%: 2 m
    ≤ 36%: 3 m
    ≤ 55%: 4 m
    else 5 m

  • Minimum Height (Equation 21)
    ≤ 21%: 2 m
    ≤ 26%: 4 m
    ≤ 36%: 6 m
    ≤ 55%: 8 m
    else 10 m


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