Fire Classification and Usage
Q: How do you know you are using the correct exit devices when it comes to fire classification?
A: With all these accessories available to the designer, the exit device truly represents one of the most highly integrated system devices used in security. Exit devices are classified as either Accident Hazard Devices or Fire Exit Hardware. Both are designed to provide unrestricted exit with a free path of egress. However, Fire Exit Hardware has additional design features intended to keep a fire door latched to prevent the spread of smoke and fire, thus maintaining the integrity of the fire assembly.
If the subject door is fire rated, then any hardware applied to the door shall be listed and approved for use on the door. A fire rated door is specified when fire containment is required. Using anything other than components specified for the particular fire door assembly, or, in many instances, modifying the door in any way will nullify the rating on the door.
If the subject door is an Emergency Exit, then the emergency exit device must be listed for this application. Emergency exit devices are specified on doors deemed to be essential for the safe egress of the building occupants.
In order to assure that Fire Exit Hardware will always latch, the devices are not permitted to have a mechanical "dogging" feature which normally is available with exit devices listed as Accident Hazard. Although mechanical dogging is not allowed on fire exit hardware, there are several manufacturers who have listed electrical dogging devices. These units may hold the latch retracted only if they are connected into the building's fire/smoke alarm system. When the alarm is activated, the latch is released and immediately provides the positive latching needed for a fire assembly.
Request To Exit Signaling: For applications where the access control system is monitoring the door for "Forced Entry" or "Door Ajar" conditions, it is necessary to provide the access controller with a REX signal when the door is opened for normal egress.
Electric Door Control: It may be necessary to electrically unlock a door equipped with an exit device. For some situations, it may be preferable for the latch to physically retract. If you are dealing with a vertical rod exit device, electric latch retraction is probably your best option.
Other applications may indicate that an electric strike be used for control of the door. For mortise type exit devices, a conventional electric strike may be installed in the doorjamb. For Rim type exit devices, a special type of door strike is available designed for this application.
Electrically Actuated Trim: "Outside Trim" refers to the handle that is mounted on the exterior surface of the door to permit entry into a door with an exit device. Electrically actuated trim provides a lever on the door which will only enable entry when the access control system approves it. Electrically actuated trim may be either Fail Safe or Fail Secure. An advantage of using the electrically actuated trim is that the installer may use a conventional exit device with its positive latching and life-safety characteristics, while still being able to implement electronic access control on an opening.