Development of a Database ofContemporary Material Propertiesfor Fire Investigation Analysis -Materials and Methods

Mark McKinnonDaniel MadrzykowskiCraig Weinschenk

UL Firefighter Safety Research InstituteColumbia, MD 21045

TM

UNDERWRITERS

LABORATORIES

©Underwriters Laboratories Inc. All rights reserved. UL and the UL logo are trademarks of UL LLC

Development of a Database ofContemporary Material Propertiesfor Fire Investigation Analysis -Technical Panel Update

Mark McKinnonDaniel MadrzykowskiCraig Weinschenk

UL Firefighter Safety Research InstituteColumbia, MD 21045

August 11, 2021

TM

UNDERWRITERS

LABORATORIES

Underwriters Laboratories Inc.Terrence Brady, President

UL Firefighter Safety Research InstituteStephen Kerber, Director

©Underwriters Laboratories Inc. All rights reserved. UL and the UL logo are trademarks of UL LLC

In no event shall UL be responsible to anyone for whatever use or non-use is made of theinformation contained in this Report, and in no event shall UL, its employees, or its agentsincur any obligation or liability for damages including, but not limited to, consequentialdamage arising out of or in connection with the use or inability to use the informationcontained in this Report. Information conveyed by this Report applies only to the specimensactually involved in these tests. UL has not established a factory Follow-Up Service Programto determine the conformance of subsequently produced material, nor has any provision beenmade to apply any registered mark of UL to such material. The issuance of this Report in noway implies Listing, Classification or Recognition by UL, and does not authorize the use ofUL Listing, Classification or Recognition Marks or other reference to UL on or in connectionwith the product or system.

Contents

1 Summary 1

2 Materials and Methods 2

3 Tools for Analysis of Collected Data 8

4 Future Work 9

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Acknowledgments

This project was supported by Award No. 2019-DU-BX-0018, awarded by the National Instituteof Justice, Office of Justice Programs, U.S. Department of Justice. The opinions, findings, andconclusions or recommendations expressed in this publication/program/exhibition are those of theauthor(s) and do not necessarily reflect those of the Department of Justice.

To ensure the database is of the most use to the fire investigation, fire protection, and general firemodeling communities, UL FSRI assembled a technical panel comprised of representatives frompublic, private, academic, and research sectors. The individuals below provided direction for theproject.

Project Technical Panel

Name Affiliation

Vyto Babrauskas Fire Science and Technology IncErnest Barile Philadelphia Fire DepartmentNicole Brewer Portland Fire & RescueMorgan Bruns Virginia Military InstituteSteve Carman Carman & Associates Fire Investigation, IncPaul Claflin Bureau of ATF, Fire Investigation & Arson Enforcement DivisionJason Dress Bureau of ATF, Fire Research LaboratoryAdam Friedman Jensen Hughes, Inc., ATF Fire Research Laboratory ContractorBrian Geraci Maryland State Fire MarshalBarry Grimm International Association of Arson InvestigatorsBrian Lattimer Virginia Polytechnic Institute and State UniversityKevin McGrattan National Institute of Standards and TechnologyTom Sabella Fire Department City of New YorkStanislav Stoliarov University of Maryland

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1 Summary

Meetings with the majority of the Technical Panel were held on June 29 and June 30, 2020. Themajor subjects of discussion included the list of proposed materials to be tested and character-ized, the properties for the database, and the experimental and analytical methods to determine theproperties for the database. A list of 101 materials divided into 11 categories were identified forinclusion in the database. The topics of variability in materials and aging of products and furnitureitems was discussed and it was concluded that investigating these variations is outside the scope ofthe project in this phase.

The list of properties to be stored in the database for each material as well as proposed experimentalmethods to determine each property were discussed in the Technical Panel meetings. The discus-sion emphasized that the priorities for the properties represented in the database are dependent onthe expected users for the database. Three potential user groups and the sets of properties thateach group would likely require were identified. To ensure that the data contained in the databaseis useful for modeling, it was determined that prioritization would be given to complete sets ofproperties to be measured and stored in the database.

Over the course of the two meetings, several tools were proposed to make the database easier formodel practitioners to use. Once such tool included functionality to output lines of code for themodels or entire model input files to simplify the process of inserting the properties into computa-tional fire models. Another tool that was discussed would involve automatically extracting derivedproperties from data sets or translating between complex and simple representations of burning.

The next phase of the project includes conducting research to finalize the structure of the databaseand finalizing experimental procedures and protocols to populate the database.

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2 Materials and Methods

The list of materials and products to be characterized for the database is provided as Table 2.1. Thislist includes the materials and products that were proposed prior to the meeting as well as additionalmaterials that were suggested during the Technical Panel meetings. During the meetings, theimportance of the properties of non-combustible materials was discussed and it was determined thatknowledge of these properties may be important to fire models, and that they should be included inthe list. The final list of materials to be characterized includes several non-combustible materialsthat were mentioned in the Technical Panel discussions.

All of the 11 material categories were deemed important, and several methods were proposed toidentify the materials that should be characterized during the initial period of performance forthis project. It was proposed that to prioritize the materials, all of the materials should be rankedin order of fire load within the built environment. Determination of the fire load would requireknowledge of the total mass of the material or item in the built environment as well as the total massof pyrolyzate produced during burning. Because of the extensive effort required to determine thefire load and the relative lack of available data about the majority of these materials and products,the fire load was not calculated for the materials and products. Furthermore, the consensus amongthe Technical Panel was that all of the materials and products were important and specific prioritiescould not be identified.

Table 2.1: Initial Proposed Materials for the Database

Number Category Material/Product1 Roofing EPDM Membrane on XPS Rigid Foam2 Roofing Roof Felt Underlayment3 Roofing Cedar Shake4 Roofing Asphalt5 Roofing Fiberglass Asphalt6 Exterior Siding Composite Decking7 Exterior Siding Exterior Insulation and Finish Systems8 Exterior Siding Tent Systems9 Exterior Siding Vinyl Siding with EPS Foam10 Exterior Siding Vinyl siding11 Exterior Siding Window Systems12 Exterior Siding Pine lap siding (Painted)13 Exterior Siding Window Screen Material (Vinyl-Laminated)14 Exterior Siding Fiber Cement siding15 Exterior Siding Stucco16 Structural Exterior Plywood/CLT17 Structural Oriented Strand Board18 Structural SPF Wood Joist/Stud

Continued on next page

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Table 2.1 – continued from previous pageNumber Category Material/Product19 Structural Particle Board20 Structural Medium Density Fiberboard21 Structural Cinder Block22 Structural Concrete23 Insulation Extruded Polystyrene Rigid Foam (XPS)24 Insulation House Wrap25 Insulation Polyisocyanurate Rigid Foam26 Insulation Polyurethane Spray Foam27 Insulation Wool28 Insulation Cellulose29 Insulation Fiberglass30 Interior Finish Rebond foam carpet padding31 Interior Finish Memory foam padding with moisture barrier32 Interior Finish Nylon carpeting high pile33 Interior Finish Nylon carpeting (low pile)34 Interior Finish Wool35 Interior Finish Fiber Reinforced plastic panel36 Interior Finish Laminate flooring37 Interior Finish Polyester carpet (high pile)38 Interior Finish Polyester (low pile)39 Interior Finish Triexta40 Interior Finish Vinyl plank flooring41 Interior Finish Vinyl tile42 Interior Finish Rayon (Rug)43 Interior Finish Cotton (Rug)44 Interior Finish Pine board paneling45 Interior Finish Rubber carpet padding46 Interior Finish Luan Paneling47 Interior Finish Solid Oak Hardwood flooring48 Interior Finish Basswood bead board49 Interior Finish Engineered hardwood flooring50 Interior Finish Eucalyptus Hardboard paneling51 Interior Finish Ultralite Gypsum Board (2 Coats of Latex Paint)52 Interior Finish Standard Gypsum53 Interior Finish Plaster54 Plumbing Foam insulation55 Plumbing Heat-tape Materials56 Plumbing Cross linked polyethylene (PEX)57 Plumbing Polyvinyl chloride (PVC)58 Plumbing Chlorinated Polyvinyl chloride (CPVC)

Continued on next page

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Table 2.1 – continued from previous pageNumber Category Material/Product59 Cable Solid Romex NM-B (PVC jacket)60 Cable Coaxial Cable (PVC Conduit)61 Engineered Wood Counter top, Solid acrylic polymer62 Engineered Wood Engineered wood cabinets/furniture vinyl over particle board63 Engineered Wood Counter top, Plastic Laminate over particle board64 Engineered Wood Engineered wood cabinets/furniture vinyl over MDF65 Upholstered Furniture Bean Bag Furniture66-68 Upholstered Furniture Polyester Microfiber/PUF/ Polystyrene69-71 Upholstered Furniture Vinyl/Polyester batting/PUF72 Upholstered Furniture Cotton Upholstery73 Upholstered Furniture Hemp74-76 Upholstered Furniture Polyester Microfiber/Polyester batting/PUF77 Sleeping Products Mattress Topper, Latex Foam78 Sleeping Products Polyester Sheets79 Sleeping Products Microfiber Sheets80 Sleeping Products Mattress Topper, Polyurethane Foam81 Sleeping Products Mattress Topper, High Density Polyurethane Foam82-84 Sleeping Products Innerspring Mattress85-87 Sleeping Products High Density Polyurethane Foam Mattress88 Sleeping Products Cotton sheets89 Sleeping Products Feather Pillow90 Sleeping Products Bamboo Sheets91 General Polymers High-Density Polyethylene (HDPE)92 General Polymers Low-Density Polyethylene (LDPE)93 General Polymers Polypropylene (PP)94 General Polymers Polystyrene (PS)95 General Polymers Polyethylene Terephthalate (PET)96 General Polymers Polycarbonate (PC)97 General Polymers Polyamide (PA) (Nylon)98 General Polymers Acrylonitrile butadiene styrene (ABS)99 General Polymers Acrylic (PMMA)100 General Polymers Polylactic Acid (PLA)101 General Polymers Polyvinyl chloride (PVC)

The history of materials, and particularly aging of upholstered furniture items, was acknowledgedas a potentially important factor. Aging or contamination of furniture items may affect the thermo-physical properties and flammability characteristics of the component materials. Because there is aplan to support development and hosting of this database in perpetuity, the sensitivity of propertiesand the fire response of the materials to these factors is an important consideration to study, but itis outside the scope of the initial period of performance.

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There may be significant differences in the components, properties, and reaction-to-fire betweenmaterials that are sold under the same trade name due to variations in manufacturing processes,standards, and intended end use. A detailed investigation into all of the scatter in properties andreaction-to-fire or variation in composition for all of the proposed materials is unfeasible for thisperiod of performance. Material from a single manufacturer/production method will be investi-gated during this period of performance with a structure in place to update the entry in the futurewith data collected from different manufacturers/production methods. Descriptions of the materi-als and products that appear in the database will provide as much detail as possible to specify thematerial or product that was characterized.

One specific variation in preparation that may be investigated during this period of performanceis gypsum wallboard with the surface painted and unpainted. Additionally, many of the purematerials from the General Polymers category have been characterized in previous studies and theproperties and test data measured during this project may provide a representation of the variabilityin the properties due to different formulations, manufacturers, and processes. The list of materialspresented here should be considered a baseline and starting point, with a structure in place toexpand the number of materials and variables investigated after the initial period of performance.

A discussion was held in each Technical Panel meeting to determine the relative importance of eachproperty in order to rank the priority of each. These discussion were intended to allow UL FSRI tofocus on the high priority proposed properties in the event that all of the proposed properties couldnot be determined during this period of performance. It was noted that the most important experi-mental data and properties for each material and product in the database will vary with the variousstakeholder groups. Representation of all groups that may use the database and incorporation oftheir data needs into planning will be essential to maximize the utility of the database.

The discussions during the Technical Panel meetings identified three major groups that are ex-pected to use the database: fire investigators, fire protection engineers, and fire researchers. It isimportant to identify how these groups will use the data in the database to ensure a full set of datais provided to fulfill the needs of each of these groups. Table 2.2 identifies the sets of propertiesthat must be complete to ensure each user group can effectively use the database. The propertydenoted as ‘HRR’ in Table 2.2 includes all heat release related properties, including HRR, totalheat released, and heat release rate per unit area (HRRPUA). In the table, an ‘X’ symbol denotesa property that is expected to be required by that user group as an input to a model, a ‘V’ symbolindicates data that is expected to be useful for validation of a modeling methodology or modelingresults, and no symbol indicates a property that is not expected to be heavily used by that usergroup.

The Fire Investigators user group is expected to use the database as a reference for ignition tem-peratures and melting temperatures as well as for inputs to models used to test hypotheses aboutpotential fire scenarios. The models that fire investigators use are generally related to fire spread,ignition, and burning rates. To model these phenomena, investigators may require HRRPUA, HRR,total heat released, time to ignition, ignition temperature, heat of combustion, and the thermo-physical properties.

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The Fire Protection Engineers user group is expected to use the database for inputs to fire protectionanalyses and models that predict fire growth and spread and smoke movement in the built environ-ment. These methods generally require the same inputs as those used by the Fire Investigators usergroup, with the addition of product yields and the radiative fraction of the fuel.

The Fire Researchers user group are expected to use the properties in the database for modeldevelopment and modeling fire phenomena from first principles. The Fire Researchers user groupis expected to use all of the properties in the database because of the breadth of inputs required todescribe burning using the most complex model representations. This means that Fire Researchersuser group is expected to need the pyrolysis reaction kinetics, heats of reaction/gasification, andthe optical properties in addition to the expected requirements for the Fire Protection Engineersuser group. The HRRPUA, time to ignition, ignition temperature, and full scale HRR data areexpected to be used by Fire Researchers to validate models and modeling methodologies.

Table 2.2: Expected Property Requirements for Each User Group

User Group HR

R

Igni

tion

Tem

pera

ture

Tim

eto

Igni

tion

Soot

Yie

ld

CO

Yie

ld

Rea

ctio

nK

inet

ics

Hea

tofR

eact

ion

Hea

tofC

ombu

stio

n

Den

sity

The

rmal

Con

duct

ivity

Spec

ific

Hea

tCap

acity

Em

issi

vity

Abs

orpt

ion

Coe

ffici

ent

Rad

iativ

eFr

actio

n

Fire Investigators X X X X X X XFire Protection Engineers X X X X X X X X X X

Fire Researchers V V V X X X X X X X X X X X

Although this database has been conceptualized to serve many sectors of the fire protection com-munity, the initial funding for the database comes from the National Institute of Justice (NIJ),which has a vested interest in fire investigations. To ensure the database is effective for the fireinvestigation community, the properties that correspond to the Fire Investigators user group inTable 2.2 will hold the highest priority.

Some of the properties that are listed in Table 2.2 must be determined from raw data through ananalytical method, and the resulting property may be dependent on the method used to determinethe property value. Compounding this issue is the fact that several of the properties lack a con-sensus on the definition of the property or the accepted methods to determine the property. Tocombat confusion and misuse of the derived properties provided in the database, the definitionsof the properties and the equations used to derive the properties will be clearly indicated in thedatabase.

The experimental methods and standard tests that were proposed to measure each of the propertieswere discussed in the meetings. The proposed experimental methods are presented in Table 2.3 in

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order of descending priority. The property denoted as ‘HRR’ in Table 2.3 includes all heat releaserelated properties, including HRR, total heat released, and HRRPUA. The proposed methods weregenerally accepted by the Technical Panel with a few points of conversation.

The use of the Controlled Atmosphere Pyrolysis Apparatus (CAPA) to measure thermal conductiv-ity was initially proposed. Determination of the thermal conductivity using the CAPA is dependenton a pyrolysis model to conduct an inverse analysis, which also makes the measured thermal con-ductivity dependent on the assumptions and inputs to the model. Because of the model-dependentnature of determination of thermal conductivity using the CAPA, the other well-established meth-ods for measuring thermal conductivity that are also listed, and the relatively recent emergence ofthe CAPA to the fire protection community, the CAPA was identified as a lower priority measure-ment method and was removed for the initial period of performance for this project.

A discussion about the typical range of emissivity values for the proposed materials raised thequestion of the importance of measuring emissivity and the sensitivity of the model results tothe definition of emissivity. The prediction of the time to ignition is particularly sensitive to theemissivity, but it is true that most practical materials have average emissivity values in the range ofapproximately 0.7 to 0.95. Additionally, there is currently no computational fire model in which thespectral emissivity of a material may be defined. For these reasons, the measurement of emissivityusing an integrating sphere was deemed a low priority measurement relative to the other listedmeasurement methods.

Table 2.3: Initial Proposed Properties and Methods for Database

Property Method

HRR Oxygen Consumption CalorimetryHeat of Combustion Oxygen Consumption CalorimetryIgnition Temperature Cone CalorimeterDensity Balance and Direct Volume MeasurementThermal Conductivity Heat Flow MeterSpecific Heat Capacity/Heat of Reaction DSCThermal Diffusivity Transient Plane SourceRadiative Fraction CalorimeterEmissivity/Absorption Coefficient Integrating SphereReaction Kinetics TGA

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3 Tools for Analysis of Collected Data

The data that will be stored in the proposed database will include comma-separated values (CSV)files of experimental data, as well as photographic and video data of the specimens and pertinenttests. The database will provide as much information as possible to identify the material or productto minimize misuse of the data. Uncertainty is an important consideration in fire protection andpredictive modeling, and the uncertainty in the experimental method and in each measured quantityfor each material will be clearly presented. As the database becomes populated with data collectedon high priority materials and products and the ability to test material samples produced withdifferent formulations and through different processes becomes available, the uncertainty of eachproperty for a material with a specific trade name will also be quantified.

The raw data that will be stored in the database is expected to be useful to a subset of the potentialusers and various tools that interface with the database will be essential to ensure the entire set ofpotential users is able to benefit from the data. Ideas for tools and functionality were mentionedthroughout the Technical Panel meetings.

As previously mentioned, it is expected that there will be several user groups that will requiredifferent data and properties from the database. One of the tools that was suggested is a methodto translate between more complex representations of burning to less complex representations ofburning to ensure all user groups extract their specific required properties from the same set ofdata. Such a method should guarantee that the same general results and conclusions are achievedregardless of the complexity of the model. This type of tool may also help to minimize the effortrequired to extract derived properties from the raw experimental data. As an example, an auto-mated tool may be capable of extracting the melting temperature from TGA data according to thedefinition of the melting temperature, and automatically populate that property to the database.

Because computational fire modeling requires many property values as inputs and the intention isto make this database easy for fire model practitioners to use, a tool was recommended that willoutput the lines of code required for common fire models using the selected properties from thedatabase. Such a tool will bring the database closer to a state where it is seamlessly integrated withcommon publicly-available computational fire models. To validate this type of tool and the set ofproperties that are stored in the database, it will also be important to demonstrate that commonfire models parameterized with the collected properties adequately describe realistic fire scenarios.Through these validation exercises, the most accurate representation of burning that uses the mea-sured properties will be explored to improve the utility of the tool that generates input lines for thefire model.

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4 Future Work

The meetings with the Technical Panel and the valuable suggestions provided in the discussionshave helped develop a roadmap for future work on this project. The next major phase of thisproject involves conducting additional research to finalize the structure and type of database aswell as the format of the experimental data to be stored in the database. It is expected that thetools and functionality that have been proposed will factor into the structure of the database, andthat ideas for additional tools and functions will result from the database research. Concurrently,the experimental procedures and protocols proposed to measure each property will be finalizedto ensure consistency between experiments conducted on different materials. The procedures forsecuring and storing data and the format of the raw data will also be finalized to facilitate transferof the data and properties from the laboratory to the database.

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