In the series of BRAVENT projects, the goal is to generate documentation and answers  to issues related to ventilation and fire by investigating these experimentally.  

In ventilation systems where the smoke will be extracted through the ventilation system in the event of a fire, it is common practice to install so-called bypass solutions to send the smoke past the ventilation filter in the event of a fire. This is done to avoid clogging the filters with smoke particulates and maintain the airflow through the ventilation ducts. If the airflow in the ventilation system stops, smoke can spread freely in the ventilation ducts between different fire cells. For ventilation systems that will be stopped and sealed by fire rated dampers, this challenge is not relevant. 

Even though this is a common solution, it has been difficult to find documentation that ventilation filters can be clogged by smoke from a fire. As part of BRAVENT, RISE Fire Research has conducted two test series to investigate this problem by drawing fire smoke through a ventilation filter and measuring how quickly the filter clogs. 

In most experiments that were carried out, it took about an hour before the filter was clogged, but there were also experiments where the filter was clogged within a few minutes. This shows that there can be a big difference in how efficiently fire smoke can clog a ventilation filter, but that under certain conditions this can happen very quickly. For example, an experiment where a small amount of polyether foam was burned in addition to wood showed that the filter was clogged quickly. This shows that the clogging rate is highly dependent on the type of fuel. However, in another test where only wood was burned, the filter was clogged in a similar time frame, indicating that also other factors than the fuel are important. It is thus necessary to secure the smoke an alternative route outside the filter if it is necessary to maintain a certain amount of air in the ventilation system in the event of a fire since the ventilation filter can become clogged within a few minutes.