Advice please, work in a school and they want to secure the fire doors that lead from the corridor to the dining hall,  there are alternative exits to outside from inside the hall, my thinking was the doors Could be secured but only by Push Bar / Push Pad / or Thumb turn which would allow immediate exit for anyone in the hall needing to use without a key, but would keep people out when not in use? 

If potential escape would only be needed through those doors from the hall to the corridor and not vice versa then yes.