Engineering ToolBox - Resources, Tools and Basic Information for Engineering and Design of Technical Applications!

Exhaust Hoods

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

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

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

before they "escapes" to from the surrounding air.

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 before design.

Capture velocity - v1 - for an exhaust hood can be estimated with the empirical equation

v1 = q / 2 y2 c                                     (1)

where

v1 = capturing 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 air volume flow

q = 2 v1 y2 c                                    (1a)

Example - Kitchen Exhaust Hood

Required air volume flow for a exhaust hood with circumference 3 m located 1.2 m above a stove can be calculated  as

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

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 an internal 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

    Design of systems for ventilation and air handling - air change rates, ducts and pressure drops, charts and diagrams and more.

Related Documents

Search

Search is the most efficient way to navigate the Engineering ToolBox.

Engineering ToolBox - SketchUp Extension - Online 3D modeling!

3D Engineering ToolBox Extension to SketchUp - add parametric components to your SketchUp model

Add standard and customized parametric components - like flange beams, lumbers, piping, stairs and more - to your Sketchup model with the Engineering ToolBox - SketchUp Extension - enabled for use with older versions of the amazing SketchUp Make and the newer "up to date" SketchUp Pro . Add the Engineering ToolBox extension to your SketchUp Make/Pro from the Extension Warehouse !

Translate this Page

Translate this page to Your Own Language .

About the Engineering ToolBox!

Privacy Policy

We don't collect information from our users. More about

We use a third-party to provide monetization technologies for our site. You can review their privacy and cookie policy here.

You can change your privacy settings by clicking the following button: .

Citation

This page can be cited as

  • The Engineering ToolBox (2008). Exhaust Hoods. [online] Available at: https://www.engineeringtoolbox.com/exhaust-hoods-d_1036.html [Accessed Day Month Year].

Modify the access date according your visit.

3D Engineering ToolBox - draw and model technical applications! 2D Engineering ToolBox - create and share online diagram drawing templates! Engineering ToolBox Apps - mobile online and offline engineering applications!

Unit Converter

















































5.16.12

.