What type of devices must all door assemblies requiring a fire-protection rating have?

All door assemblies requiring a fire-protection rating must have self-closing devices. This requirement is crucial because self-closing doors help ensure that doors close automatically after being opened, which is vital for maintaining the integrity of fire-rated partitions. By automatically closing, these doors inhibit the spread of smoke and flames between compartments, which is essential for occupant safety and for maintaining a fire-resistance-rated barrier during an emergency.

Self-closing devices are designed to conform with building and fire codes, as they play a critical role in preventing smoke from traveling from one area to another and ensuring that the doors function correctly in the event of a fire. They are also equipped to engage the latch, thereby sealing the door completely when shut, further enhancing the level of protection they provide.

The other types of devices listed, such as manual locking systems, electronic access control systems, and magnetic locking devices, do not fulfill the primary purpose of maintaining a fire-rated assembly's effectiveness during a fire emergency. In some cases, these devices may even impede the door's ability to close automatically, compromising the fire barrier they are supposed to protect. Therefore, self-closing devices are the specific requirement for fire-rated door assemblies to ensure safety and compliance with fire protection standards.