Keys and fire doors meet at two very different places. On an escape route, the rule is that a person must be able to open the door easily and immediately without a key. On a riser, cupboard or plant room door, being locked shut is how the door does its job. The same building normally has both, and the failure is applying the second reasoning to the first.
The escape route rule
Emergency routes and exits must be capable of being opened easily and immediately by any person who may require to use them in an emergency. A key changes that into a search. This holds regardless of how well managed the key is, because the person who needs the door may not be the person who knows where the key is kept.
Where locked shut is correct
Service risers, electrical intake cupboards, plant rooms and stores are fire doors that nobody escapes through. Keeping them locked achieves the closed condition better than a closer does, because there is no mechanism to fail and nobody has a reason to prop them. These doors carry a keep locked shut sign rather than a keep shut one.
Break glass and key boxes
Where a door must be secure and is on an escape route, the arrangement has to release without a key. A break glass key box beside a door is sometimes proposed and is a poor answer, because it adds a step and depends on the glass being intact and the key being present. Electromagnetic locks that fail safe on alarm and on power loss, with a local green break glass release, are the engineered solution.
Key control as a management issue
Buildings accumulate locks. A door that was locked shut correctly becomes a problem when a route changes and it is now on the escape path, or when a store becomes an occupied room. The fire risk assessment review is where that is caught, which is another reason review is triggered by change of use rather than by the calendar.
Questions people ask about fire door key
Can an escape door ever need a key?
Not from the escape side while anybody is in the building. Doors can be secured when the premises are empty, provided the management arrangements guarantee that.
What sign goes on a locked fire door?
Fire door keep locked shut, where the door is locked as its normal condition. Using the keep shut sign on a locked door is a mismatch that confuses the routine check.
Are digital locks acceptable on escape routes?
Only where the door releases and opens in a single action from the escape side without entering a code, and fails safe on alarm and power loss.