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Fläkt Woods publishes new guide

Fläkt Woods has published a guide on how to calculate the effect of jet fans on air and smoke flow rates in enclosed car parks.

Fläkt Woods has published a guide on how to calculate the effect of jet fans on air and smoke flow rates in enclosed car parks.

Entitled ‘A Practical Guide to Smoke Control for Enclosed Car Parks’, the technical white paper aims to help designers draw up the correct jet fan solution so that in the event of a fire, smoke can be efficiently removed, rather than accumulating in or spreading to other parts of a car park.

Author of the guide and senior fire safety and CFD design engineer at Fläkt Woods James Allen (pictured) said: “Many enclosed car parks throughout the world employ jet fans to help clear smoke in the event of a fire with good effect. However, current practice relies heavily on air change rates when designing such systems.

“Although this approach goes some way in assisting designers to meet the minimum ventilation requirements in car parks, it doesn’t provide all the answers to ensure that a proposed jet fan system will not cause smoke to spread.”

The white paper pulls together existing academic research and sets out formulae for how to calculate the rate of air flow according to the type and quantity of jet fans used, smoke flow rate from the fire origin, and how quickly the combination of smoke and air moves when pushed by jet fans. These calculations take into account the size of a fire to determine the extraction rate required at an exhaust point for removing smoke, and can be used in conjunction with CFD modelling. The guide also outlines the steps to consider when designing smoke control solutions.

Mr Allen continued: “Currently, no single definitive guide exists to show how to calculate air and smoke flow rates when jet fans are in operation. As a company at the forefront of developing ventilation solutions for fire safety, we want to plug this knowledge gap and provide a foundation for further work and research to be carried out. This will in turn improve the design process and help designers to more accurately identify how much ventilation plant space a car park needs.”

The guide can be downloaded free of charge from Fläkt Woods’ website:


26 January 2017


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