People don't close and lock doors - door closers do!
On access-controlled doors - it is the door closer that ensures the door is closed properly so that it can re-lock after each use, preventing unwanted intrusions.
On emergency exit and fire escape doors, the door closer re-closes the door after exit or escape, to ensure that the door and frame form a proper air and smoke-seal.
This smoke-seal prevents the distribution of toxic smoke and prevents the flow of fresh air to the fire. Air would fan the fire, making it hotter - producing more smoke and driving the smoke around the building and into the fire escape routes.
By closing the door, the door closer will also assist in preventing opportunistic intrusions during an emergency, as well as saving energy costs in air conditioned buildings.
Contrary to popular belief - it is the SIZE of the door - rather than the weight - that should determine the model of door closer to be used. Read the article below to learn more about choosing the right door closer.