Hose Stream or Smoke Screen?
What door manufacturers really need to know about fire-rated glass?
This article reviews the uncertainty and division in the fire-rated glazing community regarding the hose stream test. Does the hose stream test provide an accurate representation of a real life fire situation? Does the hose stream test truly assess the structural strength of the glazing? And how are the codes affecting door and hardware manufactures?
In an article titled Strength Under Fire, the author draws an analogy between a pilots flight test and the code required hose stream test. This analogy suggest that the hose stream test replicates reality. Yet, many industry leaders have doubts that this is true. A paper on thermal shock analysis by the Schrimer Engineering Corporation (SEC) challenges the aforementioned article on 3 key terms of the hose stream test: impact, erosion, and cooling.
The paper by the SEC states a clear definition of the word impact, and how the properties of water skew the results. A “collision between two bodies, where relatively large forces result over a comparatively short amount of time… by definition an impact does not involve the creation of a temperature gradient, which causes thermal stresses.” This paper affirmed the skepticism by hose stream doubters preaching the introduction of the cooling effects of water skewed the entire nature of the impact.
The reality is that the hose stream test is not widely accepted. British test standards dropped the hose stream test in 1953 stating that it did not reproduce conditions in an actual fire. ISO test standards in Europe and elsewhere quickly followed suit.
Why Should Door Manufacturers Care About the Glass?
Approximately 75% of the U.S. Fire-rated door market is comprised of 20-minute product, which is exempt from the hose stream test requirement. The most common used glazing for 20-minute applications is polished wired glass. Though, after the adoption of International Building Code (IBC) 2003 and IBC 2006 in the United States, Consumer Product Safety Commission safety-rated glazing requirements are raising the cost of wired glass.
Until recently, most door manufactures left the glass up to either their fabricators/distributors or the glazier in the field. Now with the Door Manufactures Association (WDMA) NFPA code change submittal, glass is required to be “installed in accordance with the manufactures inspection service procedure and under label service.” Mr. Dan Hibbs, Chairperson of WDMA’s Interior Products Code Committee, exhorted that it’s not enough to simply call out the glazing to be installed per the manufactures glazing instructions. And that leaving procedure and elements contractors are unfamiliar with often lead to incomplete or improper installation.
If the WDMA’s code change is passed, door manufactures are going to be compelled to become far more interest in the finer points of fire-rated glass. Knowing your fire-rated glazing options will be essential to reaming competitive.
There’s More at Stake Than Just the Door
Without providing any engineering data to support the change, IBC 2000 parted ways with the NFPA standards of sidelites and transoms in 20-minute door assemblies. Requiring them to meet the standards of 45-minute rating requirements, including the hose stream test. As a result, sales of specialty tempered 20-minute glass took a nose dive and sales of more expensive ceramic glass products got a welcomed boost.
The code change affected many limited construction budgets of public entities such as schools, universities, hospitals, and government, along with the R&D budgets of door manufactures. Architects and Construction managers were forced to rethink the use of wire-free glass in sidelites and transoms given the increase in cost by the newly imposed criteria. The separate fire testing of doors and sidelites also affected the bottom-line of manufactures.
Despite being a distributor of ceramic and wired glass products, SAFTI FIRST continues to submit IBC code change proposals intended to reverse the IBC fire-rating distinction within the door assembly. SAFTI FIRST president, Mr. Bill O’Keeffe, expresses his disapproval in the code change, stating that “there was no technical or fire case history to show that products tested without hose stream pose a fire safety threat.” SAFTI FIRST has offered a patented and listed heat-reflective specialty tempered glass without hose stream testing since the mid-1990s. A product that is continuously specified by architects and approved by local authorities having jurisdiction in accordance with IBC guidelines.
So, what are the real issues that door manufactures need to keep in mind when it comes to fire-rated glazing? Know the product and the glass supplier’s vested interest. Keep tabs on fire-rated glazing and code changes affecting your market. And take responsibility for every aspect of your fire-rated product because your label ultimately confirms code compliance and product safety.