fire doors / escape routes

Hi

I am new to this world and am just starting to go out and carry out fire risk assessments with a mentor.

However, the big thing that confuses me is when does a door need to be a fire door??  I understand that you need fire doors to compartment hazard areas such as kitchens, plant rooms, etc.  But also escape routes... when does a corridor or passage way officially become an escape route?

We went to a small health care building today.  A small passageway / corridor [no more than 12m] had a mixture of fire doors and non-fire doors!  All store cupboards along the passageway had fire doors.  There were escape options at each end of the passageway / corridor - one was a 60min fire door-set and the other was an escape to fresh air.

Why would some doors be fire doors and others not?!

I thought that if there were 2 means of escape in different directions, and the travel distances were no greater than 25m/40m/60m [depending on hazard rating of building/area] then there was no need for a fire door.  The maximum travel distance in today's example would have been 15m max!

Any guides / tips on helping me work out when a door needs to be a fire door would be appreciated.