Panic devices for glass entrances: overcoming design and specification challenges

by Sarah Said | September 11, 2018 10:08 am

by Al Eini, CDT

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Life safety is perhaps the most important consideration in building design, and emergency egress systems play a critical role. In particular, panic devices allow occupants to quickly and safely exit a building during emergency scenarios.

Glass entrance systems have been steadily growing in popularity because of their ability to improve daylighting, provide unobstructed views, and present a contemporary aesthetic. Although there are several panic device styles available for various door types, tubular panic devices are currently in demand, in part because their slim, minimalist design offers an ideal visual complement to glass entrances.

Apple Park, the headquarters for Apple in Cupertino, California, incorporates more than 1000 custom panic handles with custom finishes. This facility also employs custom electric strikes with lock indicators.

For full-frame glass doors, a variety of panic devices exist. For all-glass doors (frameless), the tubular style is used in most cases. Tubular panic devices present unique challenges requiring careful evaluation. For example, all the mechanics of a standard panic must be concealed in a low-profile design and still meet rigorous safety and performance standards. Due to their highly customized nature, compatibility issues with glass templates and sizes can arise.

Key hardware and specification criteria must be taken into account to ensure that tubular panic and glass door designs comply with life safety codes. Addressing and overcoming the challenges associated with tubular panics will produce safe and secure glass entrances that also meet the aesthetic intent.

Understanding applicable codes
The International Building Code (IBC) and National Fire Protection Association (NFPA) 101, Life Safety Code, require panic devices to be listed in accordance with Underwriters Laboratories (UL) 305, Standard for Panic Hardware. The Builders Hardware Manufacturers Association (BHMA) also has its own standard for panic hardware: American National Standards Institute (ANSI)/BHMA A156.3, Exit Devices.

Most jurisdictions have adopted IBC and NFPA 101 panic device requirements. It should be noted, each standard defines occupancy loads differently. According to IBC, panic devices are required on doors where:

• assembly occupancies have a load of 50 or more people;
• educational occupancies have a load of 50 or more people; and
• high hazard occupancies have a load of any amount.

NFPA 101 requires panic devices on doors where:

• assembly occupancies have a load of 100 or more people;
• educational occupancies have a load of 100 or more people;
• day care occupancies have a load of 100 or more people; and
• high hazard occupancies have a load of five or more people.

Additional safety requirements for panic devices are set forth in IBC and NFPA 101. They are as follows.

• The actuating portion of the panic device must be at least half the width of the door. On balanced doors, the actuating portion cannot extend past half the width of the door (measured from the latch side).
• The crossbar or crash bar must
  be mounted between 864 mm
  (34 in.) and 1219 mm (48 in.)
  above the floor.
• Panic hardware must be operable with less than 67 N (15 lb) of force.
• No additional locking devices are permitted on doors requiring panic hardware.
• Fire doors have their own unique set of requirements for panic devices.

Local jurisdictions sometimes adopt specific code requirements for emergency egress systems. It is important to consult the authority having jurisdiction (AHJ) early on in the project for clarification. Not doing so can lead to compliance issues, which may result in costly and time-consuming reworks and requests for interpretation (RFI).

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Glass entrance design and operational safety considerations
The types of door systems being manufactured today reflect the desire to create unique and appealing entrances while meeting code requirements for safety and performance.

First and foremost, panic devices are engineered to save lives; therefore, close attention must be placed on the design of the entrance system itself to ensure compatibility and safety. Nearly every glass entrance is custom designed, comprising an iteration of the thousands of possible glass and panic hardware configurations available. For this reason, critical considerations must be addressed early in the design phase before the hardware specifications are written.

While seemingly obvious, many fundamental questions are often overlooked. For example, what are the sidelite conditions? What is above the door? Answering these types of questions will clarify what hardware is required to maintain safety and performance. Another consideration is door and opening sizes; these will dictate the glass thickness, support system, and hardware required to mitigate deflection and ensure proper performance. The doorframe depth will dictate the panic handle location.

For best practices in glass entrance system and tubular panic design, follow the guidelines set forth in the Glass Association of North America (GANA) Fully Tempered Heavy Glass Door and Entrance System Design Guide. It specifies important parameters regarding door sizes, glass thicknesses, hardware required, etc.

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In the author’s experience, the main issues encountered with tubular panic and glass door quotes are: glass template errors, doors that are out of spec, and hardware incompatibility. Working with an experienced manufacturer will often prevent these issues. Some designers use proprietary design software capable of providing automatic alerts if any component of the emergency egress system is out of spec.

Certified glass fabricators and temperers are also a valuable resource to help ensure glass door and tubular panic designs are functionally sound and meet safety standards. They typically have a direct working relationship with the panic device manufacturer, which allows them to deliver single-source glass entrance system solutions.

Although glass is a specialized material, glass fabricators are experts in the field and will prevent detrimental outcomes, such as hardware compatibility issues, glass breakage, compromised safety, violations of GANA guidelines, and voided manufacturer warranties. Working with a local glass fabricator provides additional benefits in terms of logistics and experience with regional codes.

Achieving the desired aesthetic
The original tubular panic was patented more than 50 years ago. Since then, architects, specifiers, and end-users have come to value the style’s slim and elegant design.

When paired with glass doors, tubular panics maintain clean, unobstructed views and do not impede daylight from flowing through building interiors.

A principal objective for architects is designing for quick and easy egress during emergency scenarios. The challenge is specifying exit systems that do not interfere with an all-glass aesthetic intent. Access control devices that maximize safety and security without compromising visual appeal are therefore preferred.

Fortunately, manufacturers have been paying attention and the industry is beginning to see much-needed innovations in panic device design. For example, a panic device featuring an independent, ultra-narrow crash bar is now available. The crash bar is engineered to easily and securely attach to the vertical tubular panic component. This two-piece system allows architects to specify a panic device with back-to-back ladder pulls. The panic device can be mounted onto both monolithic heavy glass and double-glazed insulating glass. This is particularly important in light of increasingly stringent energy codes—the future of glass entrances might very well be thermally broken systems incorporating insulating glass units (IGU).

In many regions, evolving energy codes have already essentially mandated exterior entrances with thermally broken doors and insulating glass. To meet thermal performance requirements without compromising aesthetics, specify an all-glass entrance system that can accommodate tubular panics on standard 25.4-mm (1-in.) insulating glass. Be aware the tubular panics must be able to handle the loads imposed by the emergency exit test required by UL.

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Close attention should be placed on crossbar ends as they can have an impact on safety and aesthetics. UL 305 4.3 states:

The ends of the crossbar or push pad shall be curved, guarded, or otherwise designed to prevent catching of the clothing of persons during exit.

Curved crossbar ends are a key feature to look for in tubular panic devices for glass doors. The benefits are twofold. First, they produce a smooth, continuous flow of hardware through the glass, creating streamlined visuals. Second, they improve safety by preventing clothing and carrying bags from getting caught on crossbar ends in case of emergency egress.

Working with an established architectural hardware manufacturer can significantly reduce the risk of specification errors. The manufacturer can help overcome the unique challenges tubular panics and glass doors present by providing design and engineering services, as well as UL-tested products.

While thousands of possible configurations exist, an experienced manufacturer will be able to provide a panic device for nearly every type of door and application, including monolithic heavy glass doors, laminated tempered glass doors, insulating glass, aluminum rail and stile doors, hollow metal doors, wood doors, and balanced doors. Manufacturers should also be able to supply compatible manual strikes, electric strikes, or electric strikes with bolt position sensors.

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Conclusion
The appeal of glass entrances is evident. They offer contemporary aesthetics, daylight diffusion, transparency, and unobstructed views. A well-designed and thoughtfully specified glass entrance system can serve as a captivating introduction to a building’s visual theme, while providing the safety features required in emergency exit situations.

As the popularity of tubular panic devices continues to grow, architects and specifiers must recognize the unique design challenges they present. When it comes to life safety, diligence is imperative.

Understanding IBC, NFPA 101, and UL requirements for panic devices, and identifying critical glass entrance design considerations is vital. Working with a certified glass temperer and/or reputable full-service manufacturer will ensure the emergency egress system effectively combines safety, aesthetics, and function for the life of the building.

Al Eini, CDT, is brand manager of architectural hardware with C.R. Laurence Co. Eini has decades of experience in the hardware and metals industries. He was the owner of Tajima Corporation, a premium manufacture of hardware. Eini holds a Bachelor’s degree in economics and an MBA. He can be reached at Al_Eini@crlaurence.com[6].

Source URL: https://www.constructionspecifier.com/panic-devices-for-glass-entrances-overcoming-design-and-specification-challenges/

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