Recommended Air Changes
Calculating the right fan
In order to provide sufficient ventilation it is essential that the correct fan is selected for the application.
1. Firstly calculate the volume of the room (length x width x height)
2. Multiply this by the recommended number of air changes per hour, the total will give the fan performance required, expressed in m3/hr
3. Find the fan that matches the performance and application
Recommended Air Changes per Hour
|Cinemas and theatres||8-12|
|Sheet metal shops||8-12|
|Stores and warehouses||3-6|
|* These rooms may require an explosion proof, flame proof or anticorrosive fans. Please ask for our technical team on 08456 44 6001 to discuss your specific requirements|
Alternatively, if your working with Litres per second then here is a simple example:
Imagine a room measuring 3 metres in all directions, with a single extractor fan for ventilation.
The volume of your room is 3m x 3m x 3m = 27m³. There are 1000 litres in a cubic metre, so another way to state the volume of your room is 27,000 Litres.
If this room requires one air change per hour, the fan will have to move 7.5 Litres of air a second. (27,000 / 60 / 60, or 27,000 Litres divided by 60 minutes in an hour, divided by 60 seconds in a minute)
If the room needed two air changes per hour, we'd need 15 Litres per second to pass through the fan. (27,000 x 2 / 60 / 60)
So when thinking of replacing or installing ventilation, you'll need your tape measure and a calculator handy. Remember if you're not shifting enough air, you're not going to solve that mould, smell or moisture problem.
The above information is offered as guidance only. Discuss your specific requirements with our technical team on 08456 44 6001.Back to all articles