Fire dampers

[Meady]

Please can someone give me some guidance regarding fire dampers?

Do the bathroom extraction ducts which travel into the protected corridors need fire & smoke dampers?

ADB Vol 2 - 10.22 suggests that they do and they must be linked to the fire alarm. 

But I have been to a hotel (approx. 20 years old) where there is no fire damper fitted to the ducts coming from the bathrooms.

Someone suggested they may be 'shunt ducts' but I cannot seem to understand how these work?!  And whether they are acceptable?

Any advice would be greatly appreciated.

[AnthonyB]

If they are shunt ducts they are designed to reduce fire and smoke spread - if not and are directly ducted it's not considered practicable to retrofit new ducting or dampers but for bathrooms a more simpler intumescent grille is considered adequate, this would be more so in a hotel that simultaneously evacuates unlike flats.