In a perfect world all fire doors would be kept closed but, we don't live in a perfect world,
To get over the problem of fire doors being held open with fire extinguishers, rubbish bins, boots and the like there is an interesting piece of equipment on the market called "Dorgard".
Certainly no plumbing.
But it does need batteries.
The Dorgard is battery operated and designed to safely and legally hold open a fire door and automatically release the fire door when a fire alarm sounds.
It takes approximately 5 minutes to install by fixing to a fire door with four screws. Dorgard can be used to hold a fire door open 24 hours a day.
However, it is recommended that fire doors are closed at night so Dorgard can be set to release at a pre-set time.
When Dorgard is used to hold open a fire door, after approximately 14 seconds of the continuous sound of a fire alarm over 65 decibels, it will release, allowing the door to close under pressure from the overhead door closure.
And it comes in different finishes.
DorGard Fire Door Retainers