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|Bridging Installation Standards and Fire Protection Engineering|
Bridging Installation Standards and Fire Protection Engineering:
Recent Research at the Fire Protection Research Foundation
By | Fire Protection Engineering
In June of 2011 the University of Edinburgh's Center for Fire Safety Engineering convened a seminar on the topic of fire safety engineering education. One of the agenda items for that seminar was the role of codes and standards in the future education of a fire safety (or fire protection) engineer. How does a legacy of fire safety principles inherent in prescriptive codes and standards enable and complement an increasingly capable fire safety engineering profession?
In considering a response to that question, it is useful to review the research carried out at the Fire Protection Research Foundation, the National Fire Protection Association's (NFPA's) independent research affiliate. Each year, NFPA technical committees come to the Foundation seeking technical information on fire safety issues. In the research conducted at the Foundation over the past several years, many of the questions asked and answers provided contribute to the emergence of engineering in its various forms in code development. The most frequently asked question by far is:
"What is the basis for that number?"
NFPA standards are full of numbers! This legacy of prescriptive codes and standards requirements embodies the basic fire safety principles embedded in the modern codes and standards framework. So, when the Foundation is asked to determine the technical basis for these numbers, it is in effect being asked to articulate the engineering design principles embodied in them. Here are some examples of the "numbers”: a spacing requirement for fire protection equipment; a required minimum distance from a hazard; the minimum performance criteria for a fire protection technology; a hazard classification; and many others.
The Foundation has answered this question for various technical committees on various fire protection topics. Although
all Foundation work relies on engineering and scientific principles, from the perspective of further enabling the use of engineering methods, projects may be labeled "ok, ” "better, ” and "best.” The examples below illustrate each of these categories.
The Foundation has conducted a number of projects to provide a better technical basis for performance criteria for equipment specified in NFPA codes and standards. This is a particularly common type of project in support of the National Fire Alarm Code®, NFPA 72,1 where new detection and signaling technologies are rapidly entering the marketplace and code provisions must adapt from a prescriptive basis that relates to older forms of the technology.
A current example is a project to develop performance criteria for emerging light sources for emergency notification appliances.2 The goal of this project is to adapt requirements based on traditional strobe light characteristics to the different visual qualities of other sources such as Light Emitting Diodes (LEDs). With a quantified understanding of performance, engineers can more easily integrate these systems into fire safety design for egress. This project, and others like it, uses engineering analysis to develop new prescriptive code provisions; this will more easily enable further changes once the technical basis for requirements is clearly understood. This is the most common of Foundation research projects.
A second example involves friction loss characteristics for modern fire hose.3 The calculation of friction loss in fire hose is a common task for firefighters responsible for operating fire apparatus pumps. This is required to deliver water at the proper flow rate and pressure to firefighters controlling the fire hose nozzle. Pressures and flow rates too low will be insufficient for fire control, while pressures and flow rates too high will create dangerous conditions with handling the nozzle, burst hose and other hazards.
Baseline friction loss coefficients used by today’s firefighters for calculating fire hose pressure loss were derived using hose design technology from upwards of 50 years ago. A need exists to update these coefficients for use with today’s fire hose. The focus of this study has been to develop baseline friction loss coefficients for the types of fire hose commonly used by today’s fire service, and identify any additional performance characteristics that should be considered for friction loss calculations.The methodology developed in this study can be used to evaluate future updates to this technology.
Another example of an "OK" project investigated combustion air requirements for power burner appliances.4
The National Fuel Gas Code® 5 combustion air requirements in section 9.3 were developed primarily for residential-sized non-power burner appliances. The code contains no separate requirements for power-burner type appliances often having large volume inputs. Therefore, when the code’s current combustion air requirements are applied to these high-volume input power burner appliances, they usually result in excessively-sized outdoor combustion air openings. The objective of this project was to provide the technical justification to establish new combustion air provisions for high-volume input power burner appliances.
A second typical project type is hazard assessment: the Foundation has conducted several projects to understand the storage hazard associated with emerging hazards. This type of project conducts a thorough engineering hazard assessment to identify storage configurations, ignition scenarios, and often includes laboratory research to characterize fire hazard parameters.
A recent example of a Foundation project in this category is the assessment of the hazards associated with the storage of lithium ion batteries6 so that engineers can develop appropriate protection strategies for the growing proliferation of this hazard in storage warehouses. By quantifying the hazard scenarios upon which protection criteria in the code are based, fire protection engineers can design alternative strategies in real facility scenarios.
Another example is in the area of detection in warehouses.7 Recent large-loss warehouse fires have caused the community to explore the application of fire detection for early fire warning, fire location identification and monitoring with perceived benefits of quicker response of suppression systems, reducing water supply requirements, and minimizing the involvement of fire departments. However, currently there is little research available or guidance on the utilization of fire detection technologies of various types in warehouse environments. In the recently-completed first phase of this project, a hazard assessment of warehouse fires, based on incident data and potential fire scenarios, was conducted to form the basis for developing performance criteria for detection systems in this environment.
A third example of a "better" project analyzed the hazards involved with fire safety in consumer fireworks storage and retail facilities.8
This study reviewed the fire incident literature and fundamentals of the hazards associated with this commodity in order to identify research gaps for the basis of facility fire protection criteria.
From the fire protection engineering perspective, perhaps the ultimate installation standard would simply refer the user to engineering analysis and design methods, removing "prescribed numbers” altogether from the standard.
The Foundation is currently embarking on a project to develop a reliability-based engineering template to determine required inspection and testing frequencies for fire protection equipment. These types of requirements have a long history in many NFPA standards and are often the subject of frequent technical committee debate, as they have strong implications for the maintenance costs.
The proposed template will identify the required reliability-based calculation methods, review the data needs, and address means to accommodate limitations in those data. Individual technical committees (and engineers tasked with developing specific maintenance plans for fire protection equipment) can then adapt this template using the data resources available to them.
A second project in the category of "best" evaluated health care operating rooms as wet/dry locations.9
This study defines and analyzes the hazards associated with hospital operating rooms to clarify the classification type (i.e., wet location versus dry location) of their electrical environment.
This included a review of the existing literature on fluid spills and electrical hazards in the operating room, a gap analysis for missing information, and a proposed risk assessment method for hospitals to use to evaluate the proper classification of an operating room.
A third project in this category evaluated entrainment fractions for dust layers.10
NFPA 65411 includes long-standing prescriptive criteria that have been used for determining whether an explosion hazard exists in a building compartment. The objective of this project was to establish the technical basis for quantitative criteria for determining that a compartment is a "dust explosion hazard” that can be incorporated into NFPA 654 and other relevant safety codes and standards. This report presents the results of the Phase I portion of the study, which is the development of a straw man method to assess the dust hazard.
Another type of Foundation project that falls in the "best”category from the perspective of integrating engineering methods into codes and standards are projects that evaluate computer modeling applications. Here, the goal is to build confidence in models that predict performance in a given application, enabling the most flexible tool for the profession. Two projects of this type are underway at the moment: a project focused on validating models to predict smoke detector actuation in high air flow environments (for NFPA standards 7512 and 7613 on Protection of Information Technology Equipment and Telecommunications Facilities) and a project on evacuation modeling as applied to mixed evacuation from high-rise structures.
The Data Challenge
Each of these projects at various stages has faced the same challenge that every fire protection engineer faces in every project: access to quality, relevant data to inform engineering methods. Each Foundation project that involves the collection of data contributes to the larger body of information upon which the tools of our profession are based. As codes and standards move towards further enabling engineering design, the profession needs to work together to strengthen this database.
For more information on Foundation projects, visit http://www.nfpa.org/foundation.
Kathleen Almand is with the Fire Protection Research Foundation.