Fire prevention and detection

Measuring the Airflow of a Firefighting Blower Fan

Why the ISO 5801 european standard is not the most suitable method for measuring the airflow of a firefighting blower fan?

The efficiency of a positive pressure ventilation (PPV) fan is based on its performance at a given distance from an opening.

This efficiency is linked to the following characteristics:

  • the nominal air flow: this is the amount of air that passes through the propeller,
  • the air speeds within the jet: the higher the speeds, the greater the air entrainment effect. The entrained air will be added to the nominal flow of the fan to create the total air flow generated by it,
  • the shape of the jet: this last criterion is very important because a very wide jet in the face of the narrowing of an opening will lose a large part of its effectiveness. An ovalised jet (Neo type) will optimize performances.
Measuring the Airflow of a Firefighting Blower Fan

A flow rate according to the ISO 5801 standard (reference used by some manufacturers for their PPV) is limited to the flow rate passing through the propeller. It does not take into account the air velocities or the shape of the jet. The air flow according to the ISO 5801 therefore does not allow to estimate the effective performance of a fire fighting fan during a disaster.

It would be like estimating the effectiveness of a firefighting nozzle solely on the basis of its flow, without considering either the range or the quality of the jet.

In addition, the scope of ISO 5801 is as follows: ” ISO 5801 specifies procedures for the determination of the performance of fans of all types except those designed solely for air circulation, e.g. ceiling fans and table”

It is clear that a PPV fan corresponds to a fan designed for the circulation of air and not to an industrial fan installed on a pipe network. This ISO 5801 standard should therefore not be taken as a reference in the field of positive pressure ventilation (PPV).

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