Exhaust Hoods

Sizing exhaust hoods - air volume flow and capture velocities - online exhaust hood calculator

Exhaust hoods are essential in kitchens, laboratories and many industrial application for removing

  • fumes
  • mists
  • vapors
  • aerosols
  • particulates
  • hazardous substances
  • polluting contaminants

Exhaust Hoods

In general, for an exhaust hood to be efficient

  • the height - y - should not exceed 1.20 m (4 ft)
  • the distance - x - should not be less than 1/3 y
  • the capture velocity - v1 - should not be less than 0.15 - 0.20 m/s (30 - 40 ft/min)

Note! Potential hazardous and polluting applications requires special solutions. Always check local regulations.

The capture velocity - v1 - of the exhaust hood can be estimated with the empirical equation

v1 = q / 2 y2 c         (1)

where

v1 = capture velocity (m/s)

q = air volume flow (m3/s)

y = distance between table and exhaust hood (m)

c = circumference of the hood (m)

(1) can be modified to calculate required air volume

q = 2 v1 y2 c         (1a)

Example - Kitchen Exhaust Hood

Required air volume in a exhaust hood with circumference 3 m, 1.2 m above the stove, can be calculated like

q = 2  (0.2 m/s) (1.2 m2)2 (3 m)

    = 1.7 m3/s

Note! The units don't match since the equation is empirical (a result of experiments).

Exhaust Hood Calculator

The air flow volume in the exhaust hood can be calculated below

capture velocity - v1 - (m/s)

vertical distance from table to hood - y - (m)

circumference exhaust hood - c - (m)

Exhaust Hood with internal Plate

The efficiency of an exhaust hood can be improved by adding an internal plate.

exhaust hood with internal plate

The required air volume for an exhaust hood with a plate can in general be reduced to approximately 80% compared to an exhaust hood without a plate.

Exhaust Hood with Side Walls

The exhaust hood efficiency can be further improved by adding side walls.

exhaust hood with side wall

Related Topics

  • Ventilation - Systems for ventilation and air handling - air change rates, ducts and pressure drops, charts and diagrams and more

Related Documents

Tag Search

  • en: exhaust hoods velocity air volume
  • es: campanas de extracción de volumen de aire de velocidad
  • de: Dunstabzugshauben Geschwindigkeitsluftvolumen

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