Air conditioing condenser units inside a building

[Fire Monkey]

Hello,

Would air conditioning condenser units inside a building be considered a risk?

What if they were in a room where by occupants of another room had to pass by them to escape the building in case of a fire (dead end situation)?

What rating should such units be given in terms of room risk - low medium or high?

What detection would be best for early warning in a condenser room - heat may not give early enough warning to those using thhe adjacent room but smoke may result in false alarms due to air movement and dust.

Cheers,

[kurnal]

Hi Fire Monkey

Sorry to answer a question with more questions!

What are the possible ignition sources? Motors, compressors, heating elements? What are the fuels associated with the condensers eg refrigerant, paper filters?

When you refer to a dead end are we talking about a corridor with doors off or passing a machine as we pass through one room into another? How close would a person have to pass to the condenser if it were considered to be a hazard?

The chances are that if this was a plant room with an inner room leading off, and if the condenser were considered to be a hazard (it probably is not if for example it's just a motor compressor and uses non combustible refrigerant) then Building Regulations ADB would as a default recommend a high risk rating and for a new building a maximum travel distance of 9m from the inner room though this may be extended by providing AFD.  The FSO guides would suggest a maximum of 15-18m firm the inner room plus smoke detection in the access room. Heat detectors are of little use if the room is well ventilated for cooling purposes. I think multi sensor detection including optical smoke or aspirating detection carefully sited may be the best bet.

[wee brian]

An aircon unit is just a big fridge.

I expect no more or less likely to ignite

[kurnal]

I agree. But it would be remiss of a fire risk assessor not to ask the basic questions.

And there's been a number of serious fires involving fridges that use LPG as a refrigerant though as far as I know these have been all domestic appliances rather than commercial.

[wee brian]

All fires are serious 

As you say, you need to look at the detail and take a view. Back in the day, we used to put photocopiers in special rooms.

[Fire Monkey]

Hi,

The distance of travel to a final exit is around 9m - I would want detection of some sort. It is not clear how close the compressors would be to a person as they tired to escape - but I think it would be more than 1m. The route would be - meeting room - compressor room - exit.

I can put in place any additional maintenance requirements - such as cleaning of filters.

There would be no other fuel sources in the room.

What about flame detection sensors - costly?

The ventilation in the room would be grills - I don't think any mechanical extraction/supply is currently being considered.

I can certainly check on the refrigerant type.

An additional extinguisher will be required.

Cheers,

[kurnal]

Would you describe the compressor room as a plant room or is it just a room with a single a/c unit within? if it is just a single unit then the risk probably justifies no more than a smoke detector in the access room. Flame detectors have their place but I would say was overkill here especially due to the lack of combustible materials. Recycling and compactor areas are where they come into their own.