Professional ethics and the fire dynamics simulator, Part 2

By Richard Schulte

Schulte & Associates, Evanston, Ill.

The International Code Council (ICC) Code Technology Committee (CTC) voted to study the provisions for smoke/heat vents in one-story buildings contained in the International Building Code and International Fire Code at its meeting in Kansas City in October 2006. After the study group appointed by the CTC was unable to make any progress with its assigned task, the CTC voted to hear 30-minute presentations on the subject by the proponent (Schulte & Associates) and by opponents of the code change proposal to delete the requirements for smoke/heat vents in buildings protected by sprinklers at its meeting in Cincinnati in June 2007.

The presentations were made at the CTC's meeting in Baltimore on the afternoon of May 22, 2008. Due to time constraints, an in-depth discussion of the presentations by the CTC had to be postponed until the CTC's meeting in Chicago on November 14, 2008.

Prior to discussing the presentations that supported the installation of smoke/heat vents in sprinklered buildings, a little background information is in order.

Background
A report on fire tests conducted at Underwriters Laboratories involving the interaction between sprinklers and smoke/heat vents conducted in 1997 and 1998 titled "Sprinkler, Smoke & Heat Vent, Draft Curtain Interaction - Large Scale Experiments and Model Development" was released in September 1998. The Executive Summary of this report (referred to as NISTIR 6196-1) contains the following excerpts:

"This study was the result of a coordinated public-private research effort to gain insight into the interaction of sprinklers, roof vents and draft curtains through fire experiments and numerical modeling. The work was conducted over a period of two years."

"Funding for the large scale tests, although substantial, permitted only five high rack storage commodity fire tests to be conducted. In order to best prepare for these tests and to add to the information available for model development and verification, 34 easily conducted and controlled heptane spray burner tests were also performed."

"In parallel with the large scale fire tests, a program was conducted at NIST to develop a numerical field model, Industrial Fire Simulator (IFS) that incorporated the physical phenomena of the experiments. ...There are plans to continue the development and evaluation of the IFS model beyond publication of this report."

Note: Section 2.2.3 of Volume 3 of the FDS Technical Reference Guide contains the following excerpt that explains the relationship between the Industrial Fire Simulator and the Fire Dynamics Simulator (FDS):

“At the time [1998], FDS had not been publicly released and was referred to as the Industrial Fire Simulator (IFS), but it was essentially the same as FDS version 1."

A paper titled "Interaction of Sprinklers with Smoke and Heat Vents," co-authored by Dr. Craig Beyler and Leonard Cooper (dated February 1999) was written roughly six months after the publication of NISTIR 6196-1. The following are excerpts from the Beyler/Cooper paper:

“This paper reviews 13 experimental studies that have some relevance to the claims posed for and against the combined use of sprinklers and smoke/heat vents. These studies are used to evaluate the positive and negative claims that have been made with regard to the combined use of sprinklers and smoke/heat vents." (Executive Summary)

"The experimental studies have shown that early vent activation has no detrimental effects on sprinkler performance and have also shown that current design practices are likely to limit the number of vents operated to one, and vents may, in fact, not operate at all in very successful sprinkler operations. Design practices should move to methods that assure early operation of vents, and vent operation should be ganged so that the benefit of roof vents is fully realized." (Executive Summary)

"However, there are ongoing controversies regarding the use of these two well established fire protection technologies together. The goal of this paper is to assess our current state of knowledge regarding the interactions of sprinklers and smoke/heat vents through a review of the experimental research that has been performed." (page 2)

"A notable result in the testing [referring to the testing program summarized in NISTIR 6196-1] was the small number of thermally activated vent operations. There were no tests in this program where more than one smoke vent operated thermally, and there were many tests where no vents operated thermally. The smoke vents used in the tests had a relatively slow response fusible link system. The rack fire tests series further demonstrates the previously recognized fact that individual tests cannot be relied upon due to the limited reproducibility of this type of test." (page 18)

"While there have been many attempts to model all or part of the interactions of sprinklers and vents, the issues are more complex than can be dealt with using even the most sophisticated modeling methods available today [1999]. The most clear indication of this is the recent NFPRF [National Fire Protection Research Foundation] research project [summarized in NISTIR 6196-1]. While modeling of the fluid mechanical aspects of the problem were quite successful in predicting aspects of sprinkler activation in the first heptane spray fire series, the model was unable to predict the corresponding results in the rack storage tests beyond first sprinkler activation." (page 18)

"The review of the studies relevant to venting sprinklered fires gives rise to two design issues for smoke and heat venting systems. First, it is clear that the current focus on assuring that vent operation is delayed has an adverse effect on [vent] system performance. It is important that design attention be paid to causing vents to operate more rapidly and in greater numbers. The data indicate that the European approach of ganged operation of vents based on early detection is a viable and desirable strategy." (page 23)

On February 18, 2008, Hughes Associates Inc. (HAI) issued a report on research into the concept of the "ganged" operation of smoke/heat vents in buildings protected by sprinklers. This report, titled "Analysis of the Performance of Ganged Operation of Smoke and Heat Vents with Sprinklers and Draft Curtains," contains the following excerpts:

"The objective of this study was to evaluate the performance of gang-operated smoke and heat vent systems in sprinklered facilities. The gang operation concept involves opening all the vents within the coverage area of the sprinkler system in which the fire originates one minute after the first sprinkler has operated." (page 11, Executive Summary)

"Comparison of sprinkler operations between vented and unvented cases clearly shows that the operation of sprinklers was not affected by smoke and heat vents or by smoke and heat vents with draft curtains. The time to first sprinkler operation, the number of sprinkler operations and the pattern of operation were not impacted by the venting system." (page 11, Executive Summary)

"CFD [computational fluid dynamics] was used to investigate the performance of the design. The employed model was a later version of that used in [McGrattan, Hamins, & Stroup, 1998] as well as in [Trelles & Beyler, 1999a; Trelles & Beyler, 1999b; Trelles & Beyler, 1999c; Beyler, 2006]. The goal is to follow [McGrattan, Hamins, & Stroup, 1998] whenever possible." (page 14)
Note: [McGrattan, Hamins, & Stroup, 1998] is a reference to NISTIR 6196-1.

"The Fire Dynamics Simulator, version 4 (FDS4), was used to perform the field calculations. FDS4 is a three-dimensional large eddy simulation CFD program developed at the National Institute of Standards and Technology's (NIST's) Building and Fire Research Laboratory (BFRL) [McGrattan & Forney, 2004; McGrattan, 2005]. FDS4 is a multidimensional, multiphysics simulation that solves the low Mach number equations of expandable flow [Rehm & Baum, 1978]. FDS was specifically written to address fire scenarios. It has over a twenty-year development history. Some of its antecedents include the Industrial Fire Simulator (IFS) and LES3D." (page 14)

"... and the recognition that control-mode sprinklers are not designed to extinguish fire." (page 22)

"The main concern of this investigation is the activation of sprinklers. Sprinkler activation typically occurs after the ceiling jet engulfs a sprinkler head. ... However, activating sprinklers will cool the ceiling jet." (page 26)

"As was indicated above, the reason for choosing the t2 growth rate of 1.78 kW/s2 (0.157 BTU/s/ft2) was to facilitate comparisons with the results of the tests reported in [McGrattan, Hamins, & Stroup, 1998]. ... The sprinkler performance results for the heptane tests from [McGrattan, Hamins, & Stroup, 1998] are reported in Table 6." (page 30)

"For a variety of reasons, comparisons with the commodity tests in [McGrattan, Hamins, & Stroup, 1998] are not appropriate. For example, in the current set of simulations, the heat release rate is well defined. It was not measured for the commodity tests in [McGrattan, Hamins, & Stroup, 1998]." (page 31)

"The simulations performed in this study were based upon the experimental work of McGrattan et al [1998]. The results with respect to sprinkler operation are consistent with that work both in terms of the time to first sprinkler operation and the total number of sprinklers operating. The simulations clearly span the range of performance that can be expected in practice with sprinkler operations numbering from four up to the number of sprinklers in the design area." (page 91)

Volume 3 of the FDS Technical Reference Guide provides data from fire tests and experiments that are intended to be used to validate the Fire Dynamics Simulator. The following are excerpts from Volume 3 of the FDS:

"A common question asked of any mathematical model is whether it is validated. To say that FDS is "validated" means that the model has been shown to be of a given level of accuracy for a given range of parameters for a given type of fire scenario. Although the FDS developers continuously perform validation studies, it is ultimately the end user of the model who decides if the model is adequate for the job at hand." (page 1)

"FDS was officially released in 2000. However, for two decades, various CFD codes using the basic FDS hydrodynamic framework were developed at NIST for different applications and for research. In the mid 1990s, many of these different codes were consolidated into what eventually became FDS. Before FDS, the various models were referred to as LES, NIST-LES, LES3D, IFS (Industrial Fire Simulator), and ALOFT (A Large Outdoor Fire Plume Trajectory)." (page 5)

"There is an on-going effort at NIST and elsewhere to validate FDS as new capabilities are added. To date, most of the validation work has evaluated the model's ability to predict the transport of heat and exhaust products from a fire through an enclosure. ... More recently, validation efforts have moved beyond just transport issues to consider fire growth, flame spread, suppression, sprinkler/detector activation and other fire-specific phenomena." (page 6)

"A significant validation effort for sprinkler activation and suppression was a project entitled the International Fire Sprinkler, Smoke and Heat Vent, Draft Curtain Fire Test Project organized by the National Fire Protection Research Foundation [60]. Thirty-nine large-scale fire tests were conducted at Underwriters Laboratories in Northbrook, IL. ... For the period of time prior to application of water, the simulated heat release rate was within 20 % of the experimental heat release rates." (page 10)

Chapter 6 in Volume 3 of the FDS Technical Reference Guide is titled "Ceiling Jets and Device Activation ." Excerpts from Chapter 6 include the following:

"The ceiling jet is an important fire phenomenon because of the presence of automatic fire protection devices at the ceiling, like sprinklers and smoke/heat vents. The results of the UL/NFPRF experiments provide useful data to assess the accuracy of FDS in predicting the velocity and temperature near the ceiling and, consequently, the resulting activation of sprinklers." (page 63)

"Figure 6.2 displays graphically the difference between predicted and measured sprinkler activation times as a function of burner position. Note that there are no experimental uncertainty bounds on the plot because it is difficult to estimate the combined uncertainty related to the various parameters that are input into the model. For example, changing the median volumetric droplet size from 1000 μm to 750 μm led to a reduction of approximately 50 % in the number of predicted sprinkler activations due to the increased cooling of the smaller droplets. Consequently, three replicate experiments are compared to show how much variation one can expect in sprinkler activation times in repeat experiments." (page 63)

In addition to these excerpts, Section 6.4 in Volume 3 of the FDS Technical Reference Guide also includes experimental data from 22 of the 39 tests in the UL/NFPRF tests series on the interaction between sprinklers and smoke/heat vents conducted in 1997/1998. This data provides a comparison between the activation time of the first sprinkler and total number of sprinklers activated recorded in the experiments and the predictions of these values by the FDS utilizing heptane spray fires.

Rather than reproduce the data contained in Section 6.4, the following is an analysis of the data regarding the activation time of the first sprinkler:

• In 17 of the 21 tests, the FDS underestimates the actual activation time of the first sprinkler and over-predicts the activation time in three of the tests.
  Note: One of the 22 tests was conducted with only a smoke/heat vent. Sprinklers were not provided in this test. Hence, only 21 of the 22 tests involved the activation of sprinklers.
• The errors in the underestimation of the activation times of the first sprinkler range from four seconds to 20 seconds.
• The errors in the underestimation of the activation times exceed 10 seconds in 10 (47.6%) of the 21 tests.
  The following is an analysis of the data regarding the total number of sprinklers activated:
• In six (28.6%) of the 21 tests, the FDS accurately predicted the number of sprinklers that would operate.
• In eight (38.1%) of the tests, the FDS over-predicted the number of sprinklers that would operate and in seven (33.3%) tests, the FDS under-predicted the number of sprinklers that would operate.
• In 12 (57.1%) of the tests, the FDS predicted the number of sprinklers that would operate in a range of ±1 sprinkler.
• The FDS predictions ranged from an under-prediction of six sprinkler activations to an over-prediction of eight sprinkler activations.

The CTC presentations
The presentations to the CTC in support of the use of smoke/heat vents in buildings protected by standard spray sprinklers were made by Dr. Craig Beyler of Hughes Associates Inc. (HAI). Dr. Beyler presented the results of HAI studies that utilized the Fire Dynamics Simulator to model a fire in a sprinklered building with individually activated smoke/heat vents and also various fires in a sprinklered building provided with "ganged" smoke/heat vents.

The case study with individually activated smoke/heat vents provided utilized a building that was 80,000 square feet in floor area, with the roof area divided into four equal sections by draft curtains. Beyler indicated that the entire building would become "smoke-logged" if the building was not provided with smoke/heat vents (or if no vents operated) and that unobstructed visibility would be maintained at the floor of the building if the building were provided with smoke/heat vents. Based upon a single case study, Beyler concluded that individually activated smoke/heat vents provided in sprinklered buildings "work ."

Beyler also presented HAI's research on the ganged operation of smoke/heat vents activated 60 seconds after the first sprinkler activation. Given that it was HAI's conclusion that individually activated smoke/heat vents would maintain visibility at the floor of a building in a fire, it was obvious that the ganged operation of multiple vents would do the same. Beyler further stated that the modeling studies using the FDS demonstrated that the ganged operation of vents would not have an adverse impact upon the capability of the sprinkler system to control the fire.

The portion of Beyler's presentation of the case study of a building with individually activated vents neglected to address a number of factors that would influence the results, including the following:

• the description of the fire that was assumed in the building
• the temperature rating and RTI of the sprinklers and vent fusible links
• the activating times of the smoke/heat vents
• the area of the vents activated

Interestingly enough, Beyler also neglected to indicate where the case study presented to the CTC was published. (To my knowledge, this case study has never been published, although HAI has mentioned it a number of times in ICC code development hearings.)

In the May portion of Beyler's presentation on ganged operation of smoke/heat vents, he neglected to discuss the validation of the FDS. Beyler addressed the issue of validation in his November presentation, however. He stated that the FDS was "validated" for purposes of predicting the activation times of multiple sprinklers, the number of sprinklers that would operate and the activation times of smoke/heat vents. He also emphatically stated that the FDS was even capable of predicting "sprinkler skipping ." With this statement, Beyler implied that there were no limitations on the capability of the FDS to accurately model sprinkler and smoke/heat vent activations.

Discussion
The series of tests on the interaction of standard spray sprinklers and smoke/heat vents conducted at Underwriters Laboratories in 1997/1998 conclusively demonstrated that the operation of sprinklers interferes with the activation of individually activated smoke/heat vents. This effect was so conclusively demonstrated that even Dr. Beyler could not deny this fact. The Beyler/Cooper paper released in February 1999, six months after the publication of NISTIR 6196-1, confirms that this is the case with the following statements:

"The experimental studies ... have also shown that current design practices are likely to limit the number of vents operated to one, and vents may, in fact, not operate at all in very successful sprinkler operations."

"There were no tests in this program where more than one smoke vent operated thermally, and there were many tests where no vents operated thermally."

Given these statements, it is interesting to note that in Beyler's presentation to the Code Technology Committee in both May and November 2008, he indicated that the FDS predicted that a total of four individually activated smoke/heat vents would open in a building protected by sprinklers. The obvious question is, Who is correct, Dr. Beyler (1999) or Dr. Beyler (2008)? Given Beyler's statements in other forums, such as those previously excerpted and including a proposal to amend NFPA 204 (204-26 Log #21, Report on Proposals F2006), it seems obvious that Beyler still agrees that his statements made in February 1999 are correct.

This, of course, brings us to another question: Can the FDS accurately predict the activation times of smoke/heat vents and the number of vents that operate in a building protected by a sprinkler system? Dr. Beyler's answer to this question at the November CTC meeting was that predicting the activation times of smoke/heat vents is the same as predicting the activation times of sprinklers or fusible links. Based upon this, Beyler indicated that the capability of predicting the activation time of smoke/heat vents was validated; however, a statement included in the Conclusions section (Section 8, page 101) of NISTIR 6196-1 seems to once again contradict Beyler's opinion. This statement reads as follows:

"The significant cooling effect of sprinkler sprays on the near-ceiling gas flow often prevented the automatic operation of vents. ... In one cartoned plastic commodity experiment, a vent did not open when the fire was ignited directly beneath it. The model [IFS] simulations could not predict this phenomenon."

As previously indicated, the IFS is actually Version 1 of the Fire Dynamics Simulator. Hence, this excerpt casts considerable doubt upon Beyler's conclusion that the FDS can accurately forecast the activation times of smoke/heat vents in buildings protected by standard spray sprinklers.

HAI's modeling study of the concept of the ganged operation of smoke/heat vents indicates that "the main concern of this investigation is the activation of sprinklers." Hence, the answer to the question of whether or not the Fire Dynamics Simulator has been validated for the purpose of predicting the activation times of multiple sprinklers is key to whether or not HAI's conclusions relative to the impact of the ganged operation of vents on the operation of a sprinkler system can be considered to be credible. In response to questions regarding the validation of the FDS at the November CTC presentation, Beyler unequivocally stated that the capability of the FDS to accurately predict the activation times of multiple sprinklers had been validated. Further, Beyler stated that the FDS is also capable of accurately predicting the phenomenon referred to as "sprinkler skipping ."

Beyler's statements regarding the validation of the FDS at the November CTC meeting are at odds with the statement addressing this issue in the 1999 Beyler/Cooper paper that reads as follows.

"While there have been many attempts to model all or part of the interactions of sprinklers and vents, the issues are more complex than can be dealt with using even the most sophisticated modeling methods available today. The most clear indication of this is the recent NFPRF research project. While modeling of the fluid mechanical aspects of the problem were quite successful in predicting aspects of sprinkler activation in the first heptane spray fire series, the model was unable to predict the corresponding results in the rack storage tests beyond first sprinkler activation."

Given Beyler's statement regarding the capabilities of the Industrial Fire Simulator (Version 1 of the FDS) in 1999, the question then becomes whether or not the capabilities of the FDS in regards to the prediction of activation times of multiple sprinklers has been substantially upgraded in the last 10 years and also whether or not this upgraded capability has been validated. It would seem that the answer to the question regarding validation of the capability of the FDS to predict sprinkler activation times can be answered simply by looking at Volume 3 of the FDS Technical Reference Guide published in August 2008.

Section 6.4 in Volume 3 provides experimental data on the test series conducted at Underwriters Laboratories in 1997/1998 (the sprinkler/vent interaction research). A summary of the experimental data versus the Version 5 FDS predictions has already been provided above. This summary indicates that the FDS under-predicts the activation time of the first operating sprinkler by four seconds or more 80 percent of the time and under-predicts the activation time by 10 seconds or more approximately 48 percent of the time.

Given that predicting the activation time of the first sprinkler to operate should be the most accurate prediction of the activating time of sprinklers (because there are no water spray droplets to influence the movement of heat), under-estimating the activation time by 10 seconds or more nearly one-half of the time should not be considered to be a particularly good performance when it is considered that this performance is in response to controlled heptane spray fires and in light of the following statement contained on page 93 in NIST 6196-1:

"Less clear, however, is why so many sprinklers activated in Test P-2. The simulation of Test P-1 with no manipulation of the sprinkler activation times produced only 4 activations. What was the difference between the simulation of Test P-1 and Test P-2? Only the presence of a 1.2 m by 2.4 m by 0.3 m deep (4 ft by 8 ft by 1 ft deep) cavity in the ceiling formed by the vent in Test P-2. This cavity led to a 14 s delay in the first sprinkler activation in the simulation of Test P-2. The significance of this delay is shown in Fig. 56, in which the heat release rate histories for the simulations of the two versions of Test P-2 are plotted on the same graph as the heat release rate curves for the 2 by 2 by 4 tier cartoned plastic calorimetry experiment and the simulation of Test P-1 with no second sprinkler delay. The growth of the fire during the time period 60 to 100 s after ignition was very fast, and it was demonstrated that even a 14 s delay in sprinkler activation could significantly alter the number of sprinkler activations."

The summary of the data on the prediction of the total number of sprinklers that will operate similarly only shows an average performance by the FDS. The summary indicates that the FDS predicted the number of operating sprinklers within a range of + 1 sprinkler only 57 percent of the time. Of more concern, however, is that the predictions ranged from an under-prediction of six operating sprinklers to an over-prediction of eight sprinklers. Obviously, if the FDS is not capable of predicting the activation times of sprinklers relatively accurately, then it would be expected that the performance of the FDS for purposes of predicting the total number of sprinklers that activate would also be expected to only be fair, at best.

Again, it should be noted that data provided in Section 6.4 of Volume 3 of the FDS Technical Reference Guide is based solely on sprinkler activations in response to controlled heptane spray fires. No data is provided in Volume 3 on sprinkler activations in response to fires that occur in ordinary combustibles and plastic, even though the UL/NFPRF test series included five full-scale fire tests utilizing storage racks 20 feet high. The reason why predictions on sprinkler activations in response to the fires in the storage racks was not included in this section of Volume 3 can be explained in the following excerpt from NISTIR 6196-1:

"In the [model] simulations of Test P-4 and Test P-1 without any imposed sprinkler delay, 4 sprinklers activated. ... In the actual Test P-1, 20 sprinklers activated, but over about 15 min."

With respect to the prediction of the number of sprinkler activations, it should also be noted that Section 6.4 in Volume 3 of the FDS Technical Reference Guide contains the following excerpt:

"For example, changing the median volumetric droplet size from 1000 μm to 750 μm led to a reduction of approximately 50 % in the number of predicted sprinkler activations due to the increased cooling of the smaller droplets."

One last issue that Beyler discussed in his presentation to the CTC in November and that deserves some attention is the capability of the standard spray (control mode) sprinklers not only to control a fire but also to extinguish a fire. Beyler emphatically stated that control mode sprinklers were not capable of extinguishing a fire. Beyler supported this assertion with the simple statement that that's why standard spray sprinklers are referred to as "control mode" sprinklers.

The fact that control mode sprinklers are capable of extinguishing a fire in light and ordinary hazard occupancies is well-known, although control mode sprinklers do not extinguish fires in these occupancies 100 percent of the time prior to the arrival of the fire department. The capability of control mode sprinklers to extinguish "high challenge" fires (fires in high-piled storage) is addressed in NFPA 13. The following excerpts from NFPA 13 address this issue.

"Sprinkler protection installed as required in this standard is expected to protect the building occupancy without supplemental fire department activity."

"During the testing program, the installed automatic extinguishing system was capable of controlling the fire and reducing all temperatures to ambient within 30 minutes of ignition. Ventilation operations and mop-up were not started until this point."

These statements in NFPA 13 are supported by an article on the operation of control mode sprinklers titled "Meeting the Challenges of an Ever-Changing Storage Industry," written by James Golinveaux and Joe Hankins of Tyco Fire Protection. The article appeared in the Winter 2006 issue of Fire Protection Engineering magazine. The following are excerpts from this article:

"Cooling takes place at the roof/ceiling, where relatively small drops are lifted by the fire plume and cool the gas layer at the ceiling. This has the positive effect of preventing collapse of the building structure and sprinkler piping but also can delay operation of adjacent sprinklers (commonly known as 'skipping')."

"Prewetting takes place away from the actual fire area, where discharge from sprinklers falls onto unburned combustibles, preventing ignition."

"Penetration of the fire plume by water is the only one of the three mechanisms that actually reduces the heat release rate (HRR) of a fire and, if sufficient, can completely extinguish a fire. Penetration is a function of the momentum of water discharge from sprinklers and drop size, as well as the intensity of the fire plume."

"Control mode (CM) [standard] sprinklers are designed to rely on cooling and prewetting, allowing the fire to continue to burn in the area of ignition while controlling roof/ceiling temperatures and preventing fire spread until firefighters arrive or until the fire burns itself out. Control mode sprinkler protection is characterized by a relatively large area of sprinkler operation (15 - 50 sprinklers) [in storage occupancies]."

Given adequate time (30 minutes), control mode sprinklers are most certainly capable of extinguishing a fire, even a high challenge fire. The problem for Beyler with acknowledging this fact is that the principal argument for providing smoke/heat vents in single-story buildings protected by sprinklers, the need to facilitate interior manual fire fighting in order to effect extinguishment of the fire, is obviated if he concedes this point.

Conclusions
The developer of the Fire Dynamics Simulator, the Building and Fire Research Laboratory (BFRL) at the National Institute of Standards and Technology (NIST), has clearly stated that users of the FDS are responsible for validating the FDS for the purpose for which it is being utilized. When the director of the BFRL was queried on June 10, 2008, as to whether or not the FDS has been validated for purposes of predicting the activation times of multiple sprinklers, Dr. Shyam Sunder responded as follows:

"Craig Beyler, in his study of roof vents, references NIST validation work, but it is he and his sponsors who have decided that the model is appropriate for their application, and that is an argument that he, and any other users of FDS, must make.

Organizations like the US NRC, NFPA Research Foundation and the SFPE have all cited NIST validation reports but also have done validation work on their own to determine if FDS and CFAST are appropriate for various applications of interest. They decide, not us, whether or not the model is appropriate for their application."

Merely stating that the FDS has been validated for purposes of predicting the activation times of multiple sprinklers does not mean that the FDS has actually been validated for this purpose. Although articles on the issue of the validation of the FDS for this purpose have appeared in this magazine a number of times, no one has yet written to say that they agree with Dr. Beyler's opinion on the validation of the FDS for the purpose utilized in the HAI study of the ganged operation of smoke/heat vents. One can hardly say that Dr. Sunder's comments excerpted above are a "glowing endorsement" of Dr. Beyler's position on validation, and it is a unanimous opinion among colleagues of mine (who have expressed an opinion) that the use of the FDS for this purpose has not been validated.

Given this, it would seem that demonstrating the capability of FDS to accurately predict the activation times of multiple sprinklers in response to typical fires in ordinary combustibles and in response to high challenge fires is in Beyler's court. Since Dr. Sunder's response to my query on the capabilities of the FDS on June 10, Dr. Beyler has yet to respond to the issue of validation with evidence that his position is correct.

Excerpts from the Canon of Ethics adopted by the Society of Fire Protection Engineers (SFPE) were reviewed in Part 1 of this series of articles. Once again, let's briefly review these excerpts:

"Preamble. ... Accordingly, the services provided by fire protection engineers require honesty, impartiality, fairness and equity, and must be dedicated to the protection and enhancement of the public safety, health and welfare; ..."

"Fundamental Principles. Fire protection engineers uphold and advance the honor and integrity of their profession by: ... Being honest and impartial, and serving with fidelity the public, their employers and clients. ..."

"Canon 6. Fire protection engineers shall be honest and truthful in presenting data and estimates, professional opinions and conclusions, and in their public statements dealing with professional matters ..."

"Canon 12. Fire protection engineers having knowledge of any alleged violation of this Code shall cooperate with the proper authorities in furnishing such information or assistance as may be required."

"Canon 15. Fire protection engineers shall perform professional services using only those engineering methods and tools that are appropriate for the specific application."

Did Dr. Beyler's representations to the ICC Code Technology Committee regarding the validated capabilities of the FDS comply with the ethical standards established by the SFPE outlined above? I'll leave that judgment to the readers of this column.

Richard Schulte is a 1976 graduate of the fire protection engineering program at the Illinois Institute of Technology. After working in various positions within the fire protection field, he formed Schulte & Associates in 1988. His consulting experience includes work on the Sears Tower and numerous other notable structures. He has also acted as an expert witness in the litigation involving the fire at the New Orleans Distribution Center. He can be contacted by sending e-mail to rschulte@plumbingengineer.com.