Fire rated door hardware selection - Lock Set

To ensure optimal performance and fire resistance of fire-rated doors, selecting appropriate hardware to match the door is critical. The door and its hardware must work together to achieve the expected fire protection level. In previous articles, we discussed door closer and hinges. This article will provide guidance on selecting suitable locks for fire-rated doors.

Types of Lock Set

Common locks used on fire-rated doors include Lever Handle Lock, Mortise Lock, Handle Lock, Dead Bolt, and Smart Lock (hotel type). Additionally, Panic Devices are among the most common lock types for fire-rated doors. While panic devices have locking capabilities, they are typically left unlocked to facilitate rapid evacuation.

When hardware is used on fire-rated doors, it must be fire-rated and comply with relevant fire safety standards. Otherwise, the fire resistance of the entire door assembly cannot be guaranteed.

In the U. S. market, locks installed on fire-rated doors must comply with standards such as UL 10C, NFPA 80, or BS EN 12209 to ensure they can withstand high temperatures and maintain functionality during a fire. Lock and handle materials must be fire-resistant (e. g. , stainless steel or brass) to prevent deformation or failure.

Lever Handle Lock

A Lever Handle Lock is operated by a lever-style handle, typically paired with a spring latch or deadbolt. It is commonly used on interior and exterior doors, providing convenient access.

Advantages:

Ease of Operation: The lever design is more suitable for emergencies than knobs, especially for the elderly, children, or individuals with disabilities.

ADA Compliance: Lever handles meet the requirements of the Americans with Disabilities Act (ADA), making them accessible to all users.

Aesthetic and Functional: Available in various designs and finishes to suit different decorative styles.

Disadvantages:

Lower Security: Standalone lever handle locks (without a deadbolt) may not be suitable for high-security exterior doors, as they can be easily pried open or bypassed with tools (e. g. , a credit card).

Mortise Lock

A Mortise Lock is embedded within the door, incorporating a lock body, latch, and/or deadbolt, typically operated by a lever or knob. Mortise locks are commonly used on fire-rated doors in scenarios requiring high security and versatility.

Advantages:

High Security: The complex design, often with a five-lever mechanism, makes it difficult to pick or force open, meeting insurance requirements.

Versatility: Supports multiple operating modes (e. g. , passage, privacy, or locked modes) by combining latch and deadbolt functions.

Durability: Embedded within the door, mortise locks are robust and ideal for high-traffic areas.

Fire Performance: UL-certified mortise locks effectively withstand high temperatures, maintaining the fire door's integrity.

Dead Bolt

A Dead Bolt is an independent lock with a square metal bolt operated by a key or thumb turn, requiring full extension or retraction to lock or unlock the door. It is typically used as a secondary lock alongside simpler locking mechanisms.

Dead bolts should extend at least 1 inch into the door frame to ensure security. Single-cylinder dead bolts (key outside, thumb turn inside) are suitable for residential use, facilitating easy egress. Double-cylinder dead bolts (key required on both sides) offer higher security but may delay evacuation in a fire, so they should be used cautiously. Installation requires a reinforced strike plate secured with 3–4-inch screws to enhance impact resistance.

Advantages:

High Security: The dead bolt is difficult to pry open, providing robust anti-theft protection.

Simple and Durable: Its straightforward design results in low maintenance costs and long-term reliability.

Fire Performance: UL certified dead bolts withstand high temperatures, preserving the fire door's integrity.

Flexibility: Can be used alone or in combination with handle locks, adaptable to various scenarios.

Disadvantages:

Inconvenient Operation: Dead bolts require manual locking/unlocking and do not auto-latch like spring latches, that may cause people forget to lock.

Double-Cylinder Risks: In a fire, requiring a key to unlock from the inside may delay evacuation, and fire departments recommend cautious use.

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