Hold-open device
A hold-open device is a mechanism that enables doors to be held open electronically.
The can be fitted to fire doors under certain circumstances. Fire doors are important in terms of providing proper fire separation, and preventing the spread of fire and smoke, but in some situations it may be inconvenient or undesirable for fire doors to be closed all the time. Closed doors can negatively impact upon the inhabitants, such as in a care home or school, or can present hazards where there is busy traffic circulation.
A hold-open device can be installed to hold the door leaves in the open position until they are released, either manually or in the event of a fire, at which point the door closes automatically.
A hold-open device comprises:
- A trigger mechanism which processes the signals issued by the fire alarm.
- A fire alarm.
- A hold-open mechanism – typically a door closer with electro-magnetic hold-open.
- A power supply.
In the event of a fire, the electro-magnetic hold-open de-energises, allowing the door to close.
The device can either be an attachment to the door or can be incorporated into the door closer. In the case of ‘delayed-action closers’, they are often installed as separate wall-mounted devices.
Fire risk assessment and guidance restricts the use of hold-open devices to applications where there is an automatic fire detection and warning system which incorporates smoke detectors, and which is designed to protect the building’s escape routes. The door must close in the event of:
- Activation of a smoke detector.
- Manual activation of a fire alarm.
- Any failure of the alarm system.
- Any electrical power failure.
A manual release push-button must also be provided so that the doors can be manually closed if necessary. It should typically be coloured red, with ‘Close door’ visibly displayed, and positioned in the immediate vicinity of the door, i.e. not concealed when the door is in the hold-open position.
[edit] Find out more
[edit] Related articles on Designing Buildings Wiki
- Automatic fire detection and alarm systems, an introductory guide to components and systems BR 510.
- Automatic release mechanism.
- Door closer.
- Doors.
- Fire detection and alarm systems.
- Fire door.
- Fire Door Inspection Scheme.
- Fire safety design.
- Fire stopping.
- Free-swing door closer.
- Installing fire doors and doorsets (GG 86).
- Means of escape.
- Self-closing device.
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