Any fire alarm engineers on here…..????? British standard 5839-1:2002+A2: 2008 is the code of practice for the design of fire detection systems In section 22, the standard talks about what they call ‘perforated’ ceilings. These are mesh type ceilings, which are hung below the true ceiling. Such ceilings obviously create issues when it comes to spacing smoke detection. Section 22.3 specifically mentions where detector heads are mounted on such perforated ceilings where ‘air is FORCED (my capitals) through the perforated ceiling’. It goes on to mention the effect of this airflow and how to counter it’s effects on smoke travel. The code requires a 1200mm diameter part of the perforated ceiling around each head to be sealed to create a solid ceiling. A job I am working on involves a ‘chilled beam air conditioning system’. In effect, this is a chilled cold radiator located in the ceiling void, which cools the air in the void above a perforated ceiling. The cooled air drops by convection and chills the room. There are no fans or rotors of any description ‘forcing’ the air down. However, if we apply the code and 1200 mm sections of the perforated ceiling around detector heads is blocked, it will effectively block the cool air falling to the space below and create overheating of the room. So my question is: As the cool air is falling naturally by convection, I would argue that it is not being forced. Therefore section 22.3 does not apply (relating to blocking the perforations) Would you agree or disagree with my statement? If you disagree, please provide a brief rationale Thanks