The double leaf fire doors to the services cupboard in the communal corridor of a residential block of flats displays the mandatory blue "Fire door keep locked".
Both door leaves are fitted with concealed door closers. One leaf is secured using a top and bottom door bolt fitted inside the cupboard, and the other leaf is secured to its mate with a FB mortice lock.
Residents need to access the cupboard to read their gas meter and access the water stopcocks. The FB key to unlock the door is made available in an unsecured lockbox located adjacent to the services cupboard.