Report of Committee on Fire Tests

Sanford Davis, Chairman NBS, Center for Fire Research

John A. Blair, Secretary E. I. Dupont De Nemours & Co.

(Rep. Society of Plastics Industry)

Jesse J. Beitel, Southwest Research Institute Irwin A. Benjamin, Benjamin/Clarke Assoc. Inc. David Brackett, Gypsum Assn. B. J. Callahan, Factory Mutual Research Corp. William J. Christian, Underwriters Laboratories Inc. Wells Denyes, Eastman Chemical Products Inc.

Rep. Man-Made Fiber Producers Assn. Gerard R. Dufresne, US Testing Co. Inc.

(Vote limited to text i le materials and related products) Buell B. Dutton, Building and Zoning Consultants Richard G. Gewain, American Iron & Steel Inst. Peter Higginson, Underwriters Labs of Canada Alfred J. Hogan, Cypress Gardens, FL

Rep. Fire Marshals Assn. of North America Joan Koonce, Cone Mills Corp.

Rep. American Textile Mfrs. Inst. Inc. (Vote limited to texti le materials and related products)

Gerald E. Lingenfelter, American Ins. Services Group Inc. George E. Meyer, Warnock Hersey In t ' l Inc. James A. Milke, University of Maryland E. E. Miller, Industrial Risk Insurers Shirley C. Reznikoff, Arizona State University John Ed Ryan, Natl Forest Products Assn. Herman H. Spaeth, Novato, CA K. Sumi, Natl Research Council of Canada Richard P. Thornberry, The Code Consortium Lewis W. Vaughn, Canadian Steel Const. Council

Alternates

J. S. Barritt, Industrial Risk Insurers (Alternate to E. E. Miller)

J. R. Beyreis, Underwriters Laboratories Inc. (Alternate to W. J. Christian)

Delbert F. Boring, American Iron & Steel Inst. (Alternate to R. G. Gewain)

J. P. Carroll, Society of the Plastics Industry (Alternate to J. A. Blair)

Philip J. DiNenno, Benjamin/Clarke Assoc. (Alternate to I. A. Benjamin)

Robert W. Glowinski, Nat'l Forest ProductS Assn. (Alternate to J. E. Ryan)

Thomas E. Kuhta, American Ins. Services Group Inc. (Alternate to G. Lingenfelter)

Norman S. Pearce, Underwriters Labs of Canada (Alternate to P. Higginson)

Nonvoting

A. J. Bartosic, Rohm & Haas Co.

This l i s t represents the membership at the time the Committee was balloted on the text of this edition. Since that time, changes in the membership may have occurred.

The Report of the Committee on Fire Tests is presented in 2 parts.

Part I , prepared by the Technical Committee on Fire Tests proposes for adoption its Report on amendments to NFPA 260A-IB83, Standard Methods of Tests and Classification System for Cigarette Ignition Resistance of Components of Upholstered Furniture. NFPA 260A-IB83 is published in Volume 5 of the 1984 National Fire Codes and in separate pamphlet form.

Part I has been submitted to letter ballot of the Technical Committee on Fire Tests which consists of 24 voting members; of whom all 24 voted affirmatively.

Part I I , prepared by the Technical Committee on Fire Tests proposes for adoption i ts Report on a new document NFPA 263-1985, Standard Method of Test for Heat and Visible Smoke Release Rates for Materials and ProductS.

Part I I has been submitted to letter ballot of the Technical Committee on Fire Tests which consists of 22 voting members eligible to vote on this document; of whom 19 voted affirmatively, 1 negatively (Mr. Ryan), and 2 members were recorded as not voting (Messrs. Callahan and Davis).

Mr. Ryan voted negatively with the reason that although the significance statement points out that the test should not be used for ranking materials, as does the commentary, that statement should be noted in the scope statement.

76

PART I

260A- I - ( i-2.2 and I -2.3) : Accept SUBMITTER: Technical Committee on Fire Tests ~ A T I O N : Add " in ter ior fabrics" to the components l isted in the f i r s t sentence of I-2.2 and I -2.3. In 1-2.2, position the insert so as to appear after "covering fabrics". In i -2.3, insert the term after "decking materials". SUBSTANTIATION: To add new requirement for al l in ter ior fabrics (used under cover fabrics). COMMITTEE ACTION: Accept.

260A- 2 - ( I -4 .2) : Accept SUBMITTER: Technical Committee on Fire Tests ~ A T I O N : Add new section i-4.2 to read:

I-4.2 All inter ior fabrics used in intimate contact with outer fabrics shall be subjected to the inter ior fabrics test.

Renumber sections 1-4.2 through i-4.5 as I-4.3 through I-4.6. SUBSTANTIATION: To add new requirement for al l in ter ior fabrics {used under cover fabrics). COMMITTEE ACTION: Accept.

260A- 9 - (1-4.3): Accept SUBMITTER: Technical Committee on Fire Tests RECOMMENDATION: Add "in seats or" after "cover fabric". SUBSTANTIATION: Clarif ies requirement that al l material used under the cover in seats (as well as vert ical walls) should be tested. COMMITTEE ACTION: Accept.

260A- 10 - (1-5): Accept SUBMITTER: Technical Committee on Fire Tests RECOMMENDATION: Add "cord or piping sewn into" after the words Welt. The . . . . . ' and before the word "seam".

SUBSTANTIATION: Editorial c lar i f i ca t ion. COMMITTEE ACTION: Accept.

260A- 11 - ( i -5) : Accept SUBMITTER: Technical Committee on Fire Tests RECOMMENDATION: Add Definit ions:

Igni t ion. Continuous, self-sustaining smoldering combustion of upholstered furniture substrates after exposure to burning cigarettes.

Obvious Ignit ion. Pronounced continuous and self-sustaining combustion of the test system. I t is a matter of operator judgement based upon experience in this type of operation.

Sample. Material being tested. Specimen. Individual pieces of sample used in one test assembly.

SUBSTANTIATION: Editorial c lar i f i ca t ion. COMMITTEE ACTION: Accept.

260A- 6 - (2-4 and 2-5): Accept SUBMITTER: Technical Committee on Fire Tests ~ A T I O N : Delete present 2-4 and 2-5 and replace with new 2-4 and 2-5 to read:

2-4 Standard Type I Cover Fabric. The standard Type I cover fabric shall be I00 percent cotton mattress t icking conforming to Federal Specification CCC-C-436D, cloth, t icking, tw i l l , cotton; Type I . I t shall be laundered and tumble-dried once before using.

2-5 Standard Type I I Cover Fabric. The standard Type I I cover fabric sha~l be UFAC standard Type I I , 100 percent cotton, velvet, 14.5 oz/yd ~ + 0.5 oz/yd% undyed, containing no flame retardant finishes or backcoating. SUBSTANTIATION: To c la r i f y the requirements for the standard "Type I Cover Fabric" used for the new Inter ior Fabrics Test and to c la r i f y requirements for the "Type I I Cover Fabric" used in the Welt Cord Test, Filling/Padding Component Test, Decking Materials Test and Barrier Materials Tests. "Type I Cover Fabric" was previously called "mattress t icking" and "Type I I Cover Fabric" was previously called "Class I I Cover Fabric". COMMITTEE ACTION: Accept.

260A- 12 - (2-6): Accept SUBMITTER: Technical Committee o n f i r e Tests

I RECOMMENDATION: Delete "or polyester/cotton". SUBSTANTIATION: Alternate material is deleted so that test is standardized to only one sheeting material. COMMITTEE ACTION: Accept.

260A- 13 - (2-12 (New)): Accept SUBMITTER: Technical Committee on Fire Tests ~ A T I O N : Add new 2-12:

2-12 Draft Enclosure. An open draft preventive enclosure shall be provided and used to rest r ic t air flow to convection only.

i~ 4B" " ] r -I

Figure 2-12 Draft Enclosure.

SUBSTANTIATION: Add requirements for draft preventive enclosure. COMMITTEE ACTION: Accept.

260A- 3 - (3-3): Accept SUBMITTER: Technical Committee on Fire Tests ~ A T I O N : Add new section 3-3 to read:

3-3 Inter ior Fabric Test. 3-3.1 From the material to be tested shall be cut three

specimens each 203 x 203 mm (8 x 8 in . ) . 3-3.2 From the standard cover fabric shall be cut three

203 x 203 mm (8 x 8 in.) and three specimens 305 x 305 mm (12 x 12 in . ) .

Renumber sections 3-3 through 3-6 as 3-4 through 3-7. SUBSTANTIATION: To add new requirement for al l in ter ior fabrics (used under cover fabrics). COMMITTEE ACTION: Accept.

260A- 4 - (4-2): Accept SUBMITTER: Technical Co~nittee on Fire Tests RECOMMENDATION: Add new section 4-2 to read:

4-2 Inter ior Fabric Test. 4-2.1 For horizontal panels, the 203 x 203 mm (8 x 8 in.) piece

of inter ior fabric and a 203 x 203 mm (8 x 8 in.) piece of standard Type I cover fabric shall be placed with the in ter ior fabric against the polyurethane substrate as shown in Figure 4- i , placing pins in the ends of the fabric specimen to hold i t in place.

4-2.2 For vert ical panels, 305 x 305 mm (12 x 12 in.) standard Type I cover fabric shall be placed on a 203 x 203 x 51 mm (8 x 8 x 2 in.) polyurethane substrate as shown in Figure 4-1. The fabric shall overlap the top and bottom of the substrate and be pinned into place on the corners.

4-2.3 Each assembled vert ical and horizontal panel shall be placed in a mini-mock-up tester as shown in Figure 4- i .

4-2.4 Three cigarettes shall be lighted and one of the lighted cigarettes placed on each of the three test assemblies such that the cigarette lies in the crevice and against the vert ical panel with equal distance of cigarette ends from either side of the assembly.

4-2.5 A piece of sheeting material shall be placed over each cigarette, smoothing i t over the cigarette, to ensure intimate contact.

NOTE: A finger run over the covered cigarette ensures a good fabric-to-cigarette contact.

4-2.6 The cigarettes shall be allowed to burn their f u l l lengths unless an obvious ignit ion of the polyurethane substrate occurs. I f a cigarette extinguishes before burning i ts entire length, a fresh cigarette shall be placed on a fresh area of the test assembly and covered with sheeting fabric unt i l either: ( I ) three cigarettes have burned their entire length on three individual test specimens, or (2) three cigarettes have self-extinguished on the sample.

4-2.7 I f an obvious ignit ion occurs on any of the three specimens, the smoldering materials shall be extinguished and the results of the test recorded as a determination that the fabric is a Type I I cover fabric.

4-2.8 I f no ignit ion occurs, the vert ical char on the vert ical panel from the original crevice position to the highest part of the destroyed or degraded cover fabric shall be measured. The original crevice position may be determined by marking the crevice on the sides of the vert ical panel with a pen or marking device and laying a straightedge or ruler between the two marks. The

77

highest point of destroyed or degraded fabric is defined as the highest point at which the entire fabric from face to back is charred.

Change t i t l e of Figure 4-I to read: Figure 4-I Interior Fabric Classification Test Method. Renu~rl)er 4-2 through 4-5 as 4-3 through 4-6.

SUBSTANTIATION: To add new requirement for all interior fabrics (used under cover fabrics). COt~41TTEE ACTION: Accept.

260A- 7 - (4-2): Accept SUBMITTER: Technical Committee on Fire Tests ~ A T I O N : Change words "ticking materials" and "ticking" to "Type I I cover fabric". SUBSTANTIATION: To clar i fy fabric types. See Proposal 260A-6 (2-4 and 2-5). COMMITTEE ACTION: Accept.

260A- 8 - (4-3): Accept SUBMITTER: Technical Committee on Fire Tests RECOMMENDATION: Change words "ticking fabric", "ticking materials" and "ticking" to "Type I cover fabric". SUBSTANTIATION: To clar i fy fabric types. See Proposal 260A-6 (2-4 amd 2-5). COMMITTEE ACTION: Accept.

260A- 14 - (4-4 and 4-5): Accept SUBMITTER: Technical Committee on Fire Tests

I ~ A T I O N : Change "Class I I " to "Type I I " fabric. SUBSTANTIATION: To clar i fy cover fabrics. See Substantiation for Proposal 260A-6 (2-4 and 2-5). COMMITTEE ACTION: Accept.

260A- 5 - (5-2): Accept SUBMITTER: Technical Committee on Fire Tests ~ A T I O N : Add new section 5-2 to read:

5-2 Interior Fabric Classification. 5-2.1 Type I interior fabric shall meet the cr i ter ia of 5-2.1.1

and 5-2.1.2. 5-2.1.1 When subjected to the interior fabric test, a specimen

shall allow no ignition. 5-2.1.2 The vertical char or any of the three test specimens

shall not exceed 38 n~n (1.5 in.) . 5-2.2 Interior fabrics that do not meet Type I cr i ter ia shall

be designated Type I I . Renumber 5-2 through 5-5 as 5-3 through 5-6.

SUBSTANTIATION: To add new requirement for al l interior fabrics (used under cover fabrics). COMMITTEE ACTION: Accept.

260A- 16 - (Chapter 8 (New)): Accept SUBMITTER: Technical Committee on Fire Tests ~ A T I O N : Move the current Appendix B so as to become a new Chapter 8 t i t led, Mandatory Referenced Publications% SUBSTANTIATION: Compliance with the Standards Councll directive to have all mandatory referenced publications reside within the body of the document. COMMITTEE ACTION: Accept.

260A- 15 - (Entire Standard): Accept SUBMITTER: Technical Committee on Fire Tests RECOMMENDATION: Throughout the Standard (except for 2-5) replace the words "Class I" or Class I I " by "Type I" or "Type I I " , respectively. For example, see I-4.5, 2-4, 4-1.7, 4-4.1, 4-4.2, 4-4.3, 4-5.1, all of Chapter 5, A-1-2 and A-2-2. SUBSTANTIATION: Standardization and consistency. COMMITTEE ACTION: Accept.

78

NFPA 263 PART II

263- 1 - (Entire Standard): Accept SUBMITTER: Technical Committee on Fire Tests RECOMMENDATION: The Technical Committee on Fire Tests recommends adoption of the new standard, NFPA 263, S~andard Method of Test for Heat and Visible Smoke Release Rates for Materials and Products. SUBSTANTIATION: 1. ASTMEg06, "Test Method for.Heat and Visible Smoke Release Rates for Materials and Products", American Society for Testing and Materials, Philadelphia, PA, 1984

2. Smith, E.E., "Release Rates and Their Application", Journal of Fire and Flammability, Vol. 8, (July 1977), p. 309

3. Smith, E.E., "Heat Release Rate of Building Materials", "Ignition, Heat Release and Noncombustibility of Materials", ASTM STP 302, American Society for Testing and Materials, Philadelphia, 1972, p. 119

4. Smith, E.E., "Measuring Rate of Heat, Smoke and Toxic Gas Release", "Fire Technology", Vol. 8, No. 3 (1972), p. 237

.5. Smith, E.E., Satija, S., "Release Rate Model for Developing Fires" presented at the 2Oth Joint ASME/AIChE National Heat Transfer Conference, Milwaukee,'Wisconsin, August 2-5, 1981

6. Smith, E. E., "Model for Evaluating Fire Hazard", "Journal of Fire and Flammability", Vol. 5, p. 179 (1974)

7. Smith E.E., "An Experimental Determination of Combustibility", "Fire Technology," Vol. 7, No. 2, p. 109-119 (May 19Zl)

8. Smith, E.E., "An Experimental Method for Evaluating Fire Hazard", Proc. 4th Int. Fire Protection Seminar, I I , Zurich, 1973, pp. 133-146

9. Smith, E.E., "Application of Release Rate Data to Hazard Load Calculations", "Fire Technology," 10, No. 3, 181-186 (1974) 10. Smith, E.E., "Application of the Ohio State Release Rate

Apparatus to Combustion Gas Studies", "Journal of Fire and Flammability/Combustion Toxicology Supplement," Vol. 1 (May 1974), pp. 95-103 11. Smith, E.E., "Product Fire Hazard Evaluation", "Journal of

Fire and Flammability/Combustion Toxicology Supplement," Vol. 2, (march 1975), pp. 58-69. COMMITTEE ACTION: Accept.

NFPA 263

Standard Method of Test for Heat and Visible Smoke* Release Rates for Materials and Products

1986 Edition

Chapter 1 General

1-i Scope.

1-1.1 This test method can be used to determine the release rates of heat and visible smoke* from materials and products when exposed to different levels of radiant heat using the test apparatus, specimen cohfiguration, and procedures described by this test method.

I-1.2 The method provides for radiant thermal exposure of a specimen both with and without a pi lot. Piloted ignition may be effected by direct flame-impingement On the specimen (piloted, point ignition) or by placing the pi lot to ignite gases evolved by pyrolysis of the specimen.

1-1.3 Heat and smoke release are measured from the moment the specimen is injected into a controlled exposure chamber. The measurements are continued during the period of ignition (and progressive flame involvement of the surface in the case of point ignit ion), and to such a time that the test is terminated.

I-1.4 The method tests materialsand products' under a constant, imposed, external heat f lux that may be varied from zero to 100 kW/m~. . ""

1-1.5 This standard is intended to measure and describe the propertiesof materials, prodOcts, or assemblies in response to heat and flame unde~ controlled laboratory conditions and shall not be used to describe or appraise the f i re hazard'6r f i re risk of materials, products, or assemblies under actual fi~e conditions. However, results of this test may be used as elements of a f ire risk assessment'which takes into account all of the factors which are pertinent to an assessment of the f i re hazard of a particular end use:

*Visible smoke is described in terms of the obscuration of transmitted light caused by combustion products released during the tests. The description is given in 6-2.2.

NFPA 263 I-2 Significance.

I-2.1" The test method provides a description of the behavior of material and product specimens under a specified f i re exposure, in terms of the release rate of heat and visible smoke. The change in behavior of materials and products with change in heat-flux exposure can be determined by testing specimens in a series of exposures which cover a range of heat fluxes.

1-2.2 The data obtained for a specific test describe the rate of heat and smoke release of the specimen when exposed to the specific environmental conditions and procedures used in performing that test.

1-2.3 The entire exposed surface of the specimen will not be burning during the progressive involvement phase when piloted, point-ignition (impingement) procedures are used. During the period of progressiv~ surface involvement, release rates of heat and smoke are "per m ~ of original exposed surface area," not "per m L of flame involved surface."

1-2.4 The rate of both heat and smoke release are calculated per m 2 of original surface area exposed. I f a specimen swells, sags, delaminates or otherwise deforms so that the exposed surface area changes, calculated release rates correspond to the original area, not to the new surface area.

1-2.5 Heat-release values depend on the mode of ignition. Gas phase ignition gives a more dimensionally consistent measure of release rate when very rapid or immediate flame involvement of the specimen's surface occurs. However, piloted, point ignition allows release-rate information to be obtained at external heat f lux from zero up to that requirRd for satisfactory gas-phase ignition -- usually over 20 kW/m ~ external exposure. No correlation between the two modes of piloted ignition has been established.

1-2.6 Release rites depend on many factors, some of which cannot be controlled. Samples that produce a surface char, a layer of adherent ash, or those that are composites or laminates may not attain a steady-state release rate. Thermally thin specimens, i .e . , specimens whose unexposed surface changes temperature during period of test, will not attain a steady-state release rate. Therefore, release rates for a given material will depend on how the material is used, i ts thickness, and method of mounting, for example.

i-2.7 Heat release values are for the specific specimen size (exposed area) tested. Results are not directly scaleable to different exposed surface areas for some products.

1-2.8 The method is limited to specimen sizes of materials described in 4~1.1 and to products from which a test specimen can be taken that is representative of the product in actual use. The test is limited to exposure of one surface; the exposed surface can be either vertical or horizontal. A heat release rate of 8 kW which is equivalent to~355 kW/m for 150- by 150-mm vertical specimens, or 533 kW/m ~ for 100- by 150-mm horizontal specimens shall not be exceeded. Combustion may occur above the stack at burning rates greater than these.

1-2.9 No general relationship between release rate values • obtained from horizontally and vert ical ly oriented specimens has been established. Specimens should be tested in the orientation of the material in its end use condition. To provide additional information, specimens which melt and drip in vertical orientation should also be tested horizontally.

1-2.10 Reiease rate measurements provide useful information for product development by giving a quantitative measure of specific changes in f i re performance caused by product modifications.

i-3 Summary of Method. The specimen to be tested is injected into an environmental chamber through which a constant flow of air passes. The specimen's exposure is determined by a radiant heat source adjusted to Produce the desired total heat f lux on the specimen. The specimen may be tested so that the exposed surface is horizontal or vertical. Combustion may be initiated by non-piloted ignition, piloted ignition of evolved gases, or by point ignition of the surface. The changes in temperature and optical density of the gas leaving the chamber are monitored from which data the release rates of heat and visible smoke, as defined in 6-2.2, are calculated.

1-4 Definitions and Terms.

I-4.1 SMOKE Unit. The cohcentration of smoke particulates in a cubicmeter of a i r which reduced the percent transmission of l ight through a one'meter path of 10 percent. SMOKE = Standard Metric Optical Kinetic Emniission.

I-4.2 Gas Phase Ignition. Ignition of pyrolysis products leaving a heated surface by a pi lot flame or other ~gnition source that does not impinge on, nor significantly affect (e.g., by re-radiation), the heated surface.

79

NFPA 263 Chapter 2 Test Apparatus

2-1 Test Apparatus. A Release Rate Apparatus used to determine release rates of heat and smoke by this test method is shown in Figure 2-1. All exterior surfaces of the apparatus, except the holding chamber, shall be insulated with 25 mm thick, low density,

NFPA 263 high-temperature, fiberglass board insulation.* A gasketed door through which the sample injection rod slides forms an airt ight closure on the specimen hold chamber.

*Owens-Corning Flat Duct Board,~Ty~e 475-FR; Density, 65 kg/m3; Thermal Conductivity, 0.033 W/m ~, UK; Thickness, 25 mm; or its equivalent is satisfactory.

0 =

Smoke Monitor - - ~

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Lsample holder

Air distributor plates '~

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Figure 2-i Release Rate Apparatus. 8 0

NFPA 263

2-2 Thermopile. The temperature difference between the air entering the environmental chamber and that leaving is monitored by a thermopile having 3 hot and 3 cold, 24 ga, Chromel-Alumel, Junctions. The hot junctions are spaced across the top of the exhaust stack. Two hot junctions are located 25 nml from each side on diagonally opposite corners, and the third in the center of the chimney's cross-section 10 mm below the top of'the chimney. The cold Junctions are located in the pan below the lower air distribution plate.

2-3 Thermal Inertia Compensator.

2-3.1 A Compensator Tab is made from 0.55 mm stainless steel sheet, 10 by 20 mm. An 800 mm length of 24 ga. Chromel-Alumel glass-insulated duplex thermocouple wire shall be welded or silver soldered to the tab as shown in Figure 2-3.1, and the wire bent back so that i t is flush agaiKst the metal surface.

~,,f 24 g Chromel-Alumel Gloss Insulated

~,~ Duplex TG. Wire

, i

u ' )

c 'J

,_L '~r-Weld cf Silver Solder

Bend W~re Back Agoinst Metal Surface

~'-0.55( 22 rail) Stainless Sleel

Ther rnopile

Compensolor TC.

NFPA 263

To Recorder

f

Figure 2-3.2B Wiring Diagram.

2-3.3 Adjust washers and varible resistor (R 1) so that 90 percent ful l scale response is obtained in 8 to 10 seconds. There shall be no overshoot as shown in Figure 2-3.3A. I f an insufficient number of washers is added, or R1 is too small, the output with square wave input will look like Figure 2-3.3B; i f too many washers are added and R I is too large, the output will look like Figure 2.3.3A.

Figure 2-3.1 Compensator Tab.

2-3.2 The Compensator Tab shall be mounted, on the exhaust stack as shown in Figure 2-3.2A using a 6-32 round head machine screw, 12 mm long. Add small (approximately 4.5 mm I.D., 9 mm O.D.) washers between the head of the machine screw and the Compensator Tab to give the best response to a square wave input. One or two washers should be adequate. The "sharpness" of the square wave can be increased by changing the ratio of the output from the tfiermopile and compensator thermocouple which is fed to the recorder. The ratio is changed by adjusting the 1-K ohm variable resistor (R1) of the thermopile bleeder shown in Figure 2-3.2B. When adjustTng compensation, keep R 1 as small as possible. Adjustment of compensator shall be made during calibration at a heat release rate of 7.0 + 0.5 kW.

LL

~E bJ LU

Time ~ Time

A B

Figures 2-3.3A and 2-3.3B Square Wave ResPonses.

2-3.4 Subtract the output of the compensator from the thermopile. The junctions enclosed in the dotted c~rcle of Figure 2-3.2B are kept at the same constant temperature by electr ical ly insulating the junctions and placing them on the pipe carrying air to the manifold, then covering them and the pipe with thermal insulation.

2-4 Smoke Monitor.

2-4.1 A photometer (Figure 2-4.1A) measures the percent of l ight transmitted through the gases leaving the apparatus. A photocell* and circuitry shown in Figure 2-4.1B shall'be used and calibrated as described in Section 3-2. The light source shall be No. 82 miniature incandescent lamp operated at its recommended current, 1.0 (one) ampere.

Figure 2-3.2A Compensator.Tab Mount. *NOTE: A "Clairex" CL 505 photocell or one having a similar color response is satisfactory.

81

NFPA 263 NFPA 263

S ' C l o i r e x " C L S 0 5 Photoce l l

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, , 5 - :FT-55--

/Vote." ,411 Inside Surfoces ond h~h/ "Gh/e/d Pointed Dull Block

~ - - - - A~r L ines,6.35 Tubing

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Stancon P-3357

1A

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j ~ ~ Mounted on wakefield model NC-A03A heatsink

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Photo cell

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1220 K

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All resistors ½ watt unless otherwise specified.

i Constant current lamp supply & photo cell bridge circuit

Figure 2-4.1B Constrant Current Lamp Supply and Photocell Bridge Circuit,

82

NFPA 263 2-4.2 The smoke monitor apparatus shall be mounted with the center line 25 mm above the exhaust stack and centered parallel to the length of the opening. The two parts of the optical system shall be 130 mm apart. A ~ontinuous flow of constant temperature air, approximately 0.004 m~/min, shall be maintained to the air lines to prevent smoke from entering the smoke monitor.

2-5 Radiation Source. A radiant heat source for generating a f lux up to 100 kW/m ~, using four, silicon carbide elements* Type LL, 20 x 12 x 5/8, nominal resistance 1.4 ohms, is shown in Figures 2-5A and 2-5B. The silicon carbide elements are mounted in the stainless steel panel box by inserting them through 15.9 mm holes in O.Smm thick ceramic fiber or asbestos board. Location of the holes in the pads and stainless steel cover plates are shown in Figure 2-5B. The diamond shaped mask of 24-g. stainless steel is added to provide uniform heat f lux over the area occupied by the 150- by 150-mm vertical sample. A power supply of 12.5 kVA, adjustable from 0 to 270,** volts is required.

* NOTE: Available from the Carborundum Co., "Globar" Division, Niagara Falls, New York.

**NOTE: I f a heat flux of up to 100 kW/m 2 is desired, a separate power supply for each pair of elements can be used where maximum voltage is less than 270 volts.

Top

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NFPA 263

39

[4- 2 5 - ~ I

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I15 ]~- 78,- tz ~22_~2_=_6._._:]

l

~-Reflector, odjusl slope, top and bottom, for uniform heo/ fiux on somple

~l~W '- I-''" 20 Mochine Screw, 4 75 Ig

\

Figure 2-5 A "Globar" Radiant Panel. Figure 2-5 B "Globar" Radiant Panel.

2-6 Air Distribution System.

2-6.1 The air entering the environmental chamber is distributed by a 6.3-mm thick aluminum plate having 8, No. 4 d r i l l holes, 51 mm from sides on 102 mm centers, mounted at the base of the environmental chamber. A second plate of 18 ga. steel having 120, evenly spaced, No. 28 dr i l l holes is mounted 150 mm above the aluminum plate. A well-regulated air supply is required.

2-6.2 The air supply manifold at thebase of the pyramidal section has 48, evenly spaced, No. 26 dr i l l holes lOmm from the inner edge of the manifold so that 0.03 ~ /s of air flows between the pyramidal sections and O.01mJ/s flows through the environmental chambe~ when total air flow to apparatus is controlled at 0.04 m~/s.

2-7 Exhaust Stack. An exhaust stack, 133 by 70 mm in cross section, and 254 mm long, fabricated from 28 ga. stainless steel is mounted on the outlet of the pyramidal section. A 25- by 76-mm plate of 31 ga. stainless steel is centered inside the stack, perpendicular to the air flow, 75 mm above the base of the stack.

83

NFPA 263 2-8 Specimen Holder.

2-8.1 Vertical specimen holders shall be attached to the injection rod using the vertical support shown in Figure 2-8.1A. Two different types of specimens holders shall be provided, one for 150-mm by 150-mm specimens to be tested in vertical orientation (Figure 2-8.1B) and the other for 110- by 150-~ specimens in horizontal orientation (Figure 2-8.1C). Each holder is provided with a "V" shaped spring pressure plate and 12.7 mm

NFPA 263 backing.plate of r i g i d insulat ion board* having a densi ty of 320 + 80 kg/m ~ and thermal conduct iv i ty of 0.08 + 0.01W/m,°K. The - posi t ion of the spring pressure plate may ~e changed to accon~nodate d i f f e ren t specimen thickness by inser t ing a re ta in ing rod in d i f fe ren t holes of the specimen holder frame.

* "Kaowool" M-Board, Surface Rigidized, Babcock/Wilcox Refractories, Augusta, GA, or its equivalent is satisfactory.

I

I ~ d, 920 Lg. ,Welded

I

li IO 8 ~l I

/ - 3 3 Steel

VERTICAL SUPPORT

I

f Center of Sp.eclrnen Holder

45 - - - q i

f i - 'No . I0 Drdl

I0 Drill

TEMPLATE FOR MOUNTING BOLTS VERTICAL MOUNT

Figure 2-8.1A Vert ical Holder Mount.

84

NFPA 263 NFPA 253

f

~,~ I

o ! E ~

J / / / j J

S

@

~24 Ga steel

415~ ___.Y

T ' - r -

( . _ ~ 45-------,, ,~

t 10-24 Machine screw |

25 long [ I

168

2 Radius, 5 flange

MOUNTING BRACKET

F .J

r ,

L.

e~

i

Figure 2-8.1B Vertical Specimen Holder.

,oo

÷ +

It ' i I [ i i I ) , l

___m_%

i i I i

~f t l

tl

SPECIMEN IFT L I I

o

L i t I i t , - J 4

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L o

2-8.2 The unexposed surfaces of the specimen shall be covered with two thicknesses of 0.025 mm aluminum fo i l pressed t ight ly to sides and back. This foi l shall be carried out and over the l ip on the horizontal holder to form a 8 + 3 mm high shield from radiant heat immediately to the side Tsee Figure 2-8.1C).

2-8,3 Pans or plates for supporting specimens that cannot be mounted in the holders of 2-8.1 or are to be tested in an unrestrained condition shall be constructed so that the weight of the holder is minimized to reduce heat capacity of the supporting structure. For horizontal specimens which melt, and for thermally thin specimens, the aluminum fo i l "boat" of 2-8.2 shall be set on, or backed by, the 12-mm rigid insulation board decribed in 2-8.1.

2-8.4 The adjustable radiation shield (Figure 2-1) on the vertical specimen holder, which covers the opening made when the radiation doors are in their open position and the specimen is inserted, is adjusted to position the front surface of the specimen 100 mm from the entrance to the environmental chamber.

2-8.5 The frame for the horizontal radiation reflector is shown in Figure 2-8.5A, and the horizontal assembly in the burn position is shown in Figure 2-8.5B.

o

_L

~_~ ~Alum. foil .--:--~ ,'~. ~'~'~- _ _ ~ _ _ . , ~ ~.. ~ 2 r o go, Stai~les~

~ : ~ ~ E C I M E N ~ ~ ' '" ~ " Steel

"-----Spring Suppor I 160 10ng

Figure 2-8.1C Horizontal Specimen Holder 8 5

NFPA 263

110

or Silver Solder

'1 Nut

,--6-32 Thd, 15rnm Ig

\

3.2 (~) rod

Ref/eclor From@ use ~" Rod Top Mounhn 0 Studs IBmrn Below

Top Edge of Bock Ptote of Honzontol Holder

"--- 6-32 Thd, lSmm Ig /---6-32 Nut

for Posihomng to Bock Plote Use Two Nuts to Secure to Piote.

Figure 2-8.5A Reflector Frame.

2-9 Radiation Reflector for Horizontally Mounted Specimens. A new 320- by 225-mm sheet of O.025-mm aluminum fo i l shall be placed over the rod supports before each test with bright side toward the panel. The foi l shall be supported by crimping around all edges with a 25-nm overlap.

2-10 Radiometers. Total-flux meters* (calorimeters) shall be used to measure the total heat f lux for both horizontal and vertical specimens at the point where the center of the specimen's surface is located at the start of the test. The total- f lux meters shall have view angles of 180 degrees and be calibrated for incident f lux. When positioned to measure f lux, the sensing surface of the flux meter for vertical specimens shall extend beyond any solid supporting device so that air heated by such a support does not contact the sensing surface of the flux meter.

2-11 Lower Pilot Burner. Pilot-flame tubing shall be 6.3 mm O.D., 0.8 mm wall, stainless steel tubing. Fuel shall be methane or natural gas )aving go percent or more methane. A methane-air mixture, 120 cm /min gas and 850 cm3/min air, shall be the fuel mixture fed to the lower pi lot flame burner. For the pi lot flame described in 2-12.4, no air is used.

2~12 Pilot-Flame Positions.

2~12.1 In addition to piloted and non-piloted mode of operation, pi lot ignition of a specimen may be accomplished by locating the pilot flame at different positions relative to the sample surface so that the flame may or may not impinge on the specimen's

* A model R-8015-C radiometer for vertical specimens, and a model P-8400-J pyroheliometer for horizontal specimens, available from "Hy-Cal" Engineering, Santa Fe Springs, CA, or their equivalents, shall be used with water cooling and without quartz window.

NFPA 263

24 go. S.S. I

12.6 Rod .900 Lg

'

Steel Plate 3x75 ~ 260 - ~ r , I -<i)-

+

SIC Rods

F . . . . I ~SiC ~od

Pm to, Sp . . . . en Holder. ! ~ l

i i Shield" 15xl5 Angle 24go S, Stee( ~ I " L ~

L------J

~RodionI Panel Port

Figure 2-8.5B Horizontal Configuration.

surface. The location chosen depends on the nature of ignition to be simulated by the test. In all piloted ignitions, the lower pilot flame size shall be that described in 2-i1. Pilot positions are described in 2-12.2 to 2-12.4. Pilot ignition by an impinging flame is required when release rate information is wanted at a heat flux below that at which the pyrolysis rate of the specimen can maintain a combustible gas phase. At heat fluxes above that producing a combustible gas mixture over the surface of the sample, either piloted, point-ignition or gas phase ignition may be used. In gas-phase ignition, surface involvement is usually very rapid, eliminating the progressive-involvement-phase of the release rate curve. I f the rate of surface involvement at a given flux is to be observed, piloted-point-ignition shall be used.

2-12.2 Pilot Ignition -- Vertical Specimen with Impinging Flame. Normal position of the end of the pi lot burner tubing is 10 mm from and perpendicular to the exposed vertical surface of the specimen. The centerline at the outlet of the burner tubing shall intersect the vertical centerline of the sample, 5 mm above the lower edge of the specimen. An upper, non-impinging pi lot burner shall also be used. The burner and its location are described in 2-12.4.

2-12.3 Piloted Ignition -- Horizontal Specimen with Impinging Flame. Normal position of the end of the burner tubing is 10 mm above and perpendicular to the exposed horizontal surface of the specimen. The centerline at the outlet of the burner intersects the center of the specimen.

2-12.4 Piloted Ignition -- Vertical Specimen without Impinging Flame. The pilot burner shall be a straight length of 6.3 mm-O.D., O.8-mm wall, stainless steel tubing 360 mm long. One end of the tubing shall be closed, and three, No. 40 dr i l l holes, 60 mm apart dril led into the tubing for gas ports, al l radiating in the same direction. The f i r s t hole shall be 5 m from the closed end of the tubing. The tube is inserted into the environmental chamber through a 6.6-mm hole dri l led 10 mm above

86

NFPA 263

the upper edge of the window frame. The tube is supported and positioned by an adjustable "Z" shaped support mounted outside the environmental chamber, above the viewing window. The tube is positioned above and 20 mm behind the exposed upper edge of the specimen. The middle hole shall be in the vertical plane perpendicular to the exposed surface of the specimen which passes through its vertical centerline and shall be pointed toward the radiation source. Fuel gas to the burner shall be methane or natural gas with at least 90 percent methane. Flow of fuel gas shall be adjusted to produce flame lengths of 25 mm. An air-gas mixture shall not be used for this pilot burner.

Chaper 3 Calibration of Equipment

3-1 Heat Release Rate.

3-1.1 A burner as shown in Figure 3-1.1 shall be placed over the end of the pilot flame tubing using a gas t ight connection. The gas to the calibration burner shall be accurately metered, e.g., by a wet test meter, and set at a low flow rate. The calibration is conducted without power to the radiation source. The gas shall be at least go percent methane and have an accurately known net heating value. The output of the recorder is "zeroed." Then the gas flow to the burner shall be increased to a higher, preset value and allowed to burn at this steady rate for an accurately measured time interval of 4.0 minutes. The flow of gas shall be changed abruptly to its in i t ia l low flow, or "zero," rate and continued for 4.0 minutes. At the end of 4.0 minutes, the base line shall be adjusted to zero i f necessary and the gas flow again increased to the higher preset value and allowed to burn for 4.0 minutes, after which the gas flow is again returned to its low flow rate. The sequence is repeated until a constant increase and consistent return to the "zero" base line is achieved.

3-1.2 The difference in flow between the low and high settings for gas flow, multiplied by its net heating value, shall be used as the rate of heat release. The output of the differential temperatur e recorder after reaching a steady state value is the output corresponding to that heat release rate. At least three levels of heat release shall be used. The heat release rate shall not exceed 7.75 kW, nor be less than 1.5 kW when calibrating.

3-2 Smoke Photometer.

3-2.1 Four neutral-density f i l te rs having accurately known optical densities of approximately 0.1, 0.2, 0.4, and 1.0 shall be used to calibrate the smoke photometer. The output of the photometer circuit is "zeroed" with no f i l t e r or smoke in the light path (zero absorbance), Then each of the f.ilters described above is alternately placed in the light p&th, and f ina l ly the light path is completely obscured (0 percent transmission). A plot of percent Transmission (% T) vs. Recorder Output is made. For the photometer of 6.3, this will not be a straight line. Using the relationship, Optical Density = log (100/% T), a curve of values of Optical Density (Absorbance) vs. Recorder Output is constructed.

3-2.2 The optical density of the neutral density f i l te rs shall be determined at a wave length of 580 mm.

3-2.3 After the Optical Density vs. Recorder Output relationship has been determined, minor variations due to aging of the light source, or its replacement, shall be compensated for by adjusting the 50 ohm, 2 watt resistor to produce the same chart reading for a given neutral density f i l t e r .

• 25

15 No ~2

2 5 / . .

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9.5 Tub,ng t _!"'I I J- l~Le°k-F~ee Seo, on63S

J Pilot Tubing

NFPA 263 • 3-2.4 The recorder's sensit ivity shall be adjusted so that a

full-scale chart reading is produced by a change in percent Transmission of (approximately) 100 percent to 30 percent.

3-3 Flux Uniformity. Uniformity of f lux over the specimen shall be periodically checked and also checked after each heating element change to determine i f i t is within acceptable limits of 5 percent.

Chapter 4 Test Specimens

4-i Specimen Preparation. The standard size for vert ical ly mounted specimens is 150- by 150-mm exposed surface with thickness up to lO0-mm. The standard size for horizontally mounted specimens is 100 by 150-mm exposed surface, up to 45 mm thick. Thin specimens such as wall or floor coverings shall be mounted in the same manner as used. For example, a wall covering to be glued to gypsum wall board shall be tested when glued to a section of gyPsum board using the same type of adhesive. The assembly shall be considered the specimen to be tested.

4-2 Specimen Conditioning. Specimens shall be conditioned in Standard Laboration Atmosphere (23°C and 50 percent relative humidity) as described by Procedure A, ASTM D 618, "Standard Methods of Conditioning Plastics and Electrical Insulating Materials for Testing."

4-3 Specimen Mounting. Only one surface of a specimen shall be exposed during a test. Specimens having a slab geometry shall be insulated on five sides. A double layer of O.025-mm aluminum foi l wrapped t ight ly on sides and back is satisfactory. For products whose exposed surface is not a plane, mounting and method of calculating surface area exposed must be described when reporting results.

Chapter 5 Test Procedure

5-i I f piloted ignition is to be used, the pilot flame is lighted and its position as described in Section 2-11 is checked.

5-2 The power supply to the radiant panel is set to produce the desired radiant f lux. The flux is measured at the same point as the surface at the center of the specimen will occupy when positioned for test. The radiant f lux is measured with the lower pilot flame displaced to the side of the environmental chamber and after air flow through the equipment is adjusted to the desired rate.

5-3 The air flow to the equipment is set* at 0.04 m3/s + 0.001 (at atmospheric pressure and 23°C). The stop on the vertical specimen holder rod Is adjusted so that the exposed surface of the specimen shall be positioned 100 mm from the entrance when injected into the environmental chamber.

5-4 Steady state conditi£ns, such that the radiant f lux does not change more than 0.5 kW/m c over a ten-minute period, shall be maintained before the specimen is inserted.

5-5 The specimen is placed in the hold chamber with the radiation shield doors closed. The air-t ight outer door is secured, recording devices started, and output of the. thermopile and smoke particle detector set to "zero" on the recorder. "Zero" conditions are those existing at the time immediately before the specimen is injected. The specimen shall be retained in the hold chamber 60 seconds ~ 10 seconds before injection.

5-6 When the specimen is to be inserted, the radiation doors are opened, and the specimen is inserted into the environmental chamber.

5-7 Unless immediate ignition occurs, a negative heat release will occur at elevated exposures due to heat absorption by the cold specimen holder. Data-acquisition devices shall have the capability of following these negative outputs. Correction for heat absorption by the holder is made by a blank run (Section 5-10).

6=8 InjectiOn of the specimen marks time zero. A continuous record of the output from the photometer circuit and thermopile shall be made during the time the specimen is in the environmental chamber.

5-9 Normal test duration time is 10 minutes. For specimens which are tota l ly consumed in less than 10 minutes, the test may be terminated when heat and smoke-particu!ate-release have ceased.

*Proper air flow may be set and monitored by 1) an orif ice meter designed to produce a pressure drop of at least 200 mm of the manometric f lu id, or 2) a rotometer (variable orif ice meter) with a scale capable of being read to ~ 0.0004 m~/s.

Figure 3-1.1 Calibration Burner. 8 7

NFPA 263 5-10 A blank run (base line) test shall be performed during which the specimen holder, without specimen, shall be injected and heat release vs. time data taken. At low heat fluxes, corrections for heat absorbed by the specimen holder should be negligible, hut at a heat flux over 10 kW/m ~, a correction due to the specimen holder may be necessary. (See 6-1.2.)

5-11 At least three determinations shall be made. I f the release rate value of values being compared for a given specimen are outside the range described in Section A-3, a greater number of replicate determinations is required as given in Section A-4. (See Appendix A.)

Chapter 6 Calculations

6-1 Heat Release Rate.

6-1.1 Heat release rates are calculated from the chart reading of the thermopile output, the exposed surface area of the specimen, and the constant "kH" which is obtained from calibration runs:

k H = Heat Release Rate (kW) Chart Reading

Then: Heat Release Rate per unit area (kW/m2) '= k h (Chart Rdg.)/A

where: A = exposed surface area of specimen (m2).

6-1.2 Heat release rates are determined from chart readings as a function of time. Sufficient points should be taken along the time axis to fa i th fu l ly reproduce 0.10 cycle/second fluctuations. Smoothed values every f ive seconds are adequate, and may be taken less frequently when heat release rates change slowly. When blank run corrections (see Section 5-10) are greater than 3 percent of the maximum heat release rates, blank run corrections shall be applied to the observed values.

6-2 Smoke Release Rate.

6-2.1 Using the Optical Density vs. Chart-Reading plot described in Section 3-2, values of optical density (D) are calculated at the same elapsed time selected for calculating heat release rates.

6-2.2 AS described, air having a concentration of one SMOKE (S)andard Metric Optical Kinetic Emission) Unit per cubic meter (m j ) reduced the percent Transmission (% T) of l ight through one meter of this air to 10 percent, i .e . , Optical Density (Absorbance) = 1.0.

6~2.3 SMOKE release rate expressed in SMOKE units per minute per m z of specimen's exposed surface area, shall be calculated as follows:

SMOKE Release Rate = SRR = O V_a kLA t

WHERE: k = Absorption Coefficient = 1.0 m2/SMOKE D = Optical Density (absorbance) = lo 9 (100/% T) L Light Path = 0.134 m (Stack width) 2, A Exposed surface area of specimen tm J

~o Flow rate of air (mJ/min) leaving apparatUs

tV_~ = Vi x t t

~ i = Flow rate of air entering apparatus (m31min)

T i , T O = Absolute Temperature* of air in and out of apparatus, respectively.

6-3 Cumulative Heat and Smoke Release. Heat and visible • smoke-particles released between any two points in time are given

by the'area under the respective curves for Release Rate vs. Time between those points.

Chapter 7 Report

7-1 The report shall include the following:

(a) Description of specimen.

(b) Orientation of specimen and detailed description of mounting.

(c) Radiant heat flux to specimen, expressed in kW/m 2.

*Note: Major temperature correction, i .e . , maximum difference in T i and T O occurs when operating at a high heat f lux and high heat release rates. At conditions of low heat release, an average temperature of effluent air (and therefore constant volumetric flow rate) can be assumed without significant error.

NFPA 263 (d) Piloted or nonpiloted ignition and location of pi lot flame,

and type of pi lot i f not standard.

(e) Data giving.release rates of heat (in kW/m 2) and visible smoke (in SMOKE/m L, min) as a a function of time, either graphically or tabulated at intervals no greater than 10 seconds.

(f) I f piloted, point ignition is used, time at which total involvement is reached shall be noted.

(g) I f melting, sagging, delaminating, or other behavior that affects exposed surface area or mode of burning occur, these behaviors shall be reported, together with the time at which such behaviors were observed.

Appendix A Precision and Accuracy

This Appendix is not part of this NFPA standard, but is included for information purposes only.

A-1 The precision of the test method is s t i l l being established, althoug h preliminary round-robin tests indicate the following:

A-2 Due to base line "noise," sensit ivity of sensors, and repeatability of base line setting, absolute values are no better than + 0.03 kW for heat release and 0.025 SMOKE/min. for smoke release rate. With permissible base line d r i f t and variation in setting, permissible base line differences for 3, 5, and 10 minutes heat and smoke release are + 0.01, 0.018, and 0.03 MJ, and + 0.10, 0~17, and 0.33 SMOKE, respeTtively. Note that2the surface area for~vertical and horizontal specimens is 0.0225 m and 0.0150 m L respectively. Therefore, the repeatability for a hea~ release base line setting for a horizontal specimen is 2.0 kW/m ~.

A-3 For samples that burn from a constant surface area, the precision of the method can be expressed by the general equation:

Sti= AX i + B

where: S t = Overall precision as standard deviation i for parameter " i "

&Xi B = value of parameter " i " A constants given in the table below.

Parameter Units of Single Laboratory; St i and XX i

Max. RHR kW/m~ 10 min HR MJ/m ~ Max. SRR SMOKE/m~n. m 2 10 min. SR SMOKE/m ~

Multilaboratory:

Max. RHR kW/m~ i0 min. HR MJ/m ~ Max. SRR SMOKE/m~n. m 2 10 min. SR SMOKE/m:

B B

A (Vertical) (Horiz.)

0.07 1.3 2.0 0.04 1.3 2.0 0.13 4.5 6.8 0.05 15. 22.

0.11 1.3 2.0 0.16 1.3 2.0 0.31 4.5 6.8 0.23 15. 22.

A-4 Additional round-robin tests are being conducted to get a better measure of reproducibility.

A-5 For materials or products that burn from a non-uniform surface due to warping, slumping, or melting, single laboratory standard deviation values for heat and smoke release may be 50 percent greater than those described in Section A-3. For such samples, at least f ive specimens shall be tested. I f two or more test values are greater by more than 50 percent of the standard deviation values in Section A-3, the test conditions or sample shall be judged inappropriate for test by this method.

A-6 For materials whose self-propagating f lux is greater than 0.0, repeatability of tests conducted at an incident f lux close to (e.g., + kW/m L) the specimen's self-propagating f lux may be poor because small differences in operating conditions may result in a large change in release rates.

Appendix B Release Rate Calibration

This Appendix is not a part of the requirements of this NFPA document...but is included for information purposes only.

B-1 The calibration data for heat release rate shows a linear relationship between rate of heat release and mi l l ivo l t output from the thermopi!e compensator thermocouples up to the recommended maximum of 8 kW. At heat release rates over 10 kW produced by a gas flame from a vertical 6.2-mm tube (not the calibration burner), flames can be seen above the chimney. Above this level of heat release, thermocouple output is no longer proportional to rate of gas flow. While flame height is lower for flames from a more diffuse source such as from a specimen or the calibration burner, the recommended upper l imit of heat release is 8 kW.

88

r

NFPA263 B-2 Methane is a convenient fuel for calibrating the apparatus for rate of heat release. Flow rates and therefore rates of heat release can be easily and accurately controlled for calibration. For this gas, complete combustion can be assumed when calibration is conducted with radiant panel off. Solidmaterials can also be used to checkcalibration in terms of total heat release. Samples" of polymethyl-methacrylate were burned and the cumulative heat release calculated from the area under the Rate-of-Heat-Release vs. Time curve. When specimens of 58.0 grams were burned, the total heat released from three determinations were: 1390, 1421, and 1290 kJ, giving an average heat release of 1367 kJ. Cumulative heat released per unit mass, based on the average, is 23.5 MJ/kg. The theoretical net heat of combustion for thls material is 21.1 MJ/kg. Based on these, combustion efficiency is 93 percent, a reasonable value for polymethyl methacrylate under normal burning conditions.

NFPA 263

B-3 A typical calibration curve of Chart Reading vs Percentage Transmission for the smoke monitor is shown in Figure B-3A. Points shown were experimentally'determined using neutral density f i l te rs described in 3-2. A smooth curve Is drawn through the points, and values of optical density calculated from selected points on the Percentage Transmission axis. Then a working curve of Optical Density vs. Chart Reading is prepared as shown in Figure B-3B. I f data reduction is computer assisted, the relationship shown in Figure B-3B may be converted to equation form using a power series:

Y = Ax + Bx 2 + Cx 3 where: Y = Optical Density

x = mi l l ivo l t output A, B, and C = constants

t-" q , w

"O

n r

t~ ¢o

c.)

10 20 30 40 50 60

% Transmission

70 BU ~u ~ uO

Figure B-3A Percentage Transmission vs Chart Reading.

89

NFPA 263 NFPA 263

I A

t - ° ~

" O

t~r

t -

(~

V 0.1 0.2 0.3 0.4 0.5 0.6 0,7 0.8 0.9 1.0 Opticaldensity(D)

Figure B-3B Optical Density vs Chart Reading.

B-4 The smoke monitor requires a 10 to 15 minute warm-up period to obtain a stable baseline. The condition of the detector should then be checked by inserting the O.4-O.D. f i l t e r in the l ight path and, i f necessary, adjust the current flow to the lamp to give the same output as given during calibration. Normally no adjustment is necessary.

B-5 Temperature of the effluent gases from the stack has no significant effect on the adjustment of the smoke monitor. No parts of the monitor are in contact with the effluent gases, and the elements of the monitor closest to the chimney, which may be subjected to low level radiant heat from the plume, are cooled by the purge air used to keep smoke from entering the monitor's openings.

Appendix C Flux Distribution

This Appendix is not a part of the requirements of this NFPA document but is included for information purposes only.

C-1 The distribution of radiant heat flux across the specimen's surface for both horizontal and vertical samples has been measured. Uniformity is achieved by the size and shape of the diamond-shaped mask (Section 2-5 and Figure 2-5A), the bend on top and bottom of the reflector behind the silicon carbide heating elements (Figure 2-5A and 2-5B), and a properly matched set of heating elements^ When properly adjusted, a maximum difference of less than 4 kW/m ~ is found over the~area occupied by a 150- by 150-Bin vertical specimen at 80 kW/m ~ incident f lux. Non-uniformity of flux over the area occupied by horizontal specimens is less than 5 percent of the average incident f lux. Flux measurements over the vertical surface were made using a plate with nine, covered holes sl ightly larger than the radiometer. The holes could be individually opened to admit and locate the radiometer at points correspond'ing to corners, center, and edge of the specimen's surface. The plate f i ts over the

opening covered by the radiation'doors when closed. Flux measurements on a horizontal plane were made by placing the pyroheliometer (Section 2-10) at different positions on the horizontal specimen holder with the radiometer's surface in the same plane a specimen's surface would occupy. When checking the flux distribution, the 8-mm aluminum fo i l shield as specified in 2-8.2 should be used on the front and back edge of the specimen holder.

Appendix D Radiation Reflector for Horizontal Specimens

This Appendix is not a part of the requirements of this NFPA document but is included for information purposes only.

D-I The best, general purpose radiation reflector is that prepared from aluminum fo i l . Although i t becomes coated with soot and, for some high heat release materials, melts during the course of a test, i t provides a uniform, inexpensively renewable reflector that performs the task for which i t was designed. The primary purpose of the reflector is to provide the desired incident f lux to a horizontal specimen until the specimen is fire-involved. When'a specimen which burns at such a rate of heat and smoke release that the quality of the reflector is impaired, the influence of external radiation on release rates is small; the specimen "sees" the radiation from its own flame, not the externally applied flux, The only portion of the release rate curve that may be influenced by the change in quality of the reflector is the cool-down portion when flaming decreases to zero, a comparatively unimportant period of a release rate test.

90

NFPA 263 Appendix E Commentary

This Appendix is not a part of the requirements of this NFPA document...but is included for information purposes only.

E-1 Release rate is not a "property" of a sample in the same sense as is calorif ic value, density, etc. Except for liquids (or solids which melt and burn as a l iquid), release rates are not constant values even when all external variables are constant; they are often discontinuous functions of exposure and, in practice and theory, are influenced by numerous external variables. There is no one value which uniquely describes the heat release of most items. In general, a dynamic characteristic is not a property of a material, but a reflection of external driving forces and internal resistances to these forces.

E-2 Release rate data are obtained at a constant mass flow rate of air and constant externally applied f lux for a specific test. The incident, or externally applied, f lux is that f lux to the gas phase boundary generated by the specimen, not to the solid (or liquid) surface of the specimen.

E-3 A release rate test is not designed to simulate an actual f i re . While i t is theoretically possible to predict a sample's performance in a real f i re given adequate release rate data, a single release rate test simply measures certan characteristics at one, controlled, external exposure. For this reason a single characteristic measured during a release rate test (e.g., maximum rate of heat release), taken by i tse l f , may have l i t t l e significance as a measure of general f i re performance. Fire performance tests using conditions intended to simulate an actual f i re usually measure the resultant of the individual characteristics that are individually measured by release rate tests. Therefore, use of release rate tests to describe performance in actual fires requires that all f i re performance characteristics be considered and evaluated over a range of exposure conditions. While measurement of individual f i re performance characteristics make direct interpretation of release rate data more complex, such data provide the advantage of giving some insight into what f ire performance characteristics of a sample need improvement to upgrade its overall f i re performance.

E-4 Using release rate tests, specimens can be examined at different exposure levels and their performance determined as a function of exposure level. This is a basically different approach to evaluating f i re performance compared to the conventional performance tests. Using the conventional test, performance is determined at one set of exposure conditions and comparisons or ratings made on the basis of results at this test exposure. Extrapolatien of data from single exposure tests is not advisable because performance does not change with temperature in the same way for different materials and products. Release rate tests provide a convenient means of getting information on performance at various exposure levels.

E-5 Release rate of visible smoke obtained using this test method is calculated from the optical density of the effluent gas stream. Smoke release is expressed using an arbi t rar i ly defined unit, "SMOKE," (6-2.2). The SMOKE unit is used to give a quantitative description of visible smoke "concentration" which is a direct function of optical density. By assuming an optical density value, e.g., 0.82 (or 15 percent Transmission), as limiting v i s ib i l i t y , the maximum light path (1) for v i s ib i l i t y can be calculated:

1 = D/kc where D = Optical Density

k = Absorption Coefficient~ (m2/SMOKE) = 1.0 m2/SMOKE c Concentration, SMOKE/m a

The v is ib i l i t y calculated in terms of " I " is based only on the optical properties of the smoke. The effect of eye irr i tants on v i s i b i l i t y is not considered in this calculation.

E-6 Reliable results are dependent upon obtaining reproducible specimens. Rate of heat release is sensitive to slight differences in surface characteristics as well as physical and chemical properties on a micro as well as macro scale.

E-7 This test method describes a standard procedure by which different parameters comprising combustibility can be separately evaluated.

E-8 A variety of materials and products can be tested by this procedure. The test has been applied to wall linings, ceiling t i l e , packaging materials, carpeting aid other floor coverings, communication and electrical cable, plastic pipe and conduit, upholstery systems and furniture, foamed plastics and composities, and laminates of many types and uses.

The test is normally performed using the product in its end use configuration and orientation (vertical and horizontal). For example, a wall covering should be tested in a vertical orientation applied to the wall, e.g., gypsum wallboard with the adhesive to be used in the f ie ld. For such nonthermally thick samples the heat sink properties of the substrate or backing of the sample may have a large effect on its release rate characteristics.

NFPA 263 E-9 Combustion characteristics whose change would be most effective in improving overall f i re performance are apparent from release rate test results.

E-IO All materials and products are evaluated using results from the same basic test, regardless of item's composition or use. Thus, a direct comparison of combustibility and the relative impact on a f i re system can be made between any product (e.g., floor covering, ceiling t i l e , upholstery, drapery, etc.).

E-11 Release rate data can also be used as the basis for specifying the minimum f i re performance levels of products at one (or several) exposure levels representative of that to which the product may be exposed in an actual f i re . Maximum "loading," i .e . , allowable exposed surface area of combustible materials, can be calculated from release rate data so that total heat or visible smoke release within a f i re system will not exceed some predetermined level, a useful concept in reducing the possibil i ty of catastrophic f i re in high risk situations.

E-12 One of the problems in using release rate test data is the large amount of information obtained from one or a series of release rate tests. Because the potential f i re hazard of an item depends both on its f i re performance and on the system in which i t is found, the relative importance of individual values wil l change, depending on where and how the item is used. For example, the maximum rate of heat release values for two items may bear l i t t l e relationship to the items' f i re hazard. The maximum RHR for a foamed plastic panel may be less than 50 kW, while that for a treated wood panel may be over 100 kW when both are exposed to a f lux of 30.0 kW/m L. But when the foam is tested, the maximum RHR is reached in f ive seconds, while in the case of the treated wood, an exposure of over f ive minutes is required before the material starts to release heat, and over nine minutes before the maximum RHR is reached.

E-13 Guidance for the Selection of Test Parameters. In order to use this test method the following variables must be selected.

i . Configuration.

(a) Horizontal.

(b) Vertical.

2. Ignition Source.

(a) Nonpiloted.

(b) Piloted ignition, vertical specimen with impinging flame.

(c) Piloted ignition, horizontal specimen with impinging flame.

(d) Piloted ignition, vertical specimen without impinging flame.

(e) Piloted ignition, horizontal specimen without impinging flame.

3. Radiant Heat Flux Level.

(a) 0-100 kW/m 2.

The selection of the test parameters should be related to the application of the test results (of the material). This selection discusses some of the factors relating to the application of the test results.

1. Configuration.

The test method is capable of being run with a vertical or horizontal s~mple orientation. Data from particle board exposed at 20.0 kW/m~indicates that the vertical configuration (piloted impinging) wil l provide a more rapid increase in rate of heat release; the maximum rate of heat release is similar in both situations.

Max RHR Heat Release (Btu/ft 2) (Btu/min-ft 2)

Orientation 3 min 5 min 10 min Vert. 630 690 2600 2950 Horiz. 605 290 1310 3350

Note that the total heat released in 10 minutes is higher for the horizontal sample, but the maximum rate is sl ight ly higher for the vertical orientation, at an exposure of 20.0 kW/m~. * Similar comparisons on rates of smoke release indicate a much higher smoke production rate for the vertical sample but a higher total smoke production for the horizontal sample.

*This is ~rue at 20.0 kW/m 2 exposure -- the opposite occurs at 60.0 kW/m ~.

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NFPA 263 Further guidance on selecting sample orientation may be obtained

by examining the effects of orientation on measured quantities for a variety of materials, as given in Table E-11a. These data for Just a few pol)meric materials indicates several important features, relative to orientation.

(1) Dripping may be a problem with vertically mounted samples.

(2) For a given material, the cumulative heat released is not a strong function of the orientation; on the other hand, the maximum heat release rate may vary widely with sample orientation.

Guidance to users relative to orientation would be to test the sample under both orientations, and examine judiciously which data to use for the end result application. For materials which drip excessively, i t is probably conservative to use the horizontal orientation when assessing the total cumulative heat released by the sample.

2. Type of Ignition.

Selecting the most applicable type of ignition source is a slightly more complex problem. The basic guidance relative to selecting ignition type is embodied in the following:

(1) The impinging piloted ignition source introduces an additional exposure to the material, and hence st r ic t ly speaking does not permit "pure" heat release measurement. I t does, however, represent a realistic case for hazard evaluation purposes.

(2) The nonimpinging ignition source wi l l , in general, require higher exposure levels to ignite the material, and ignition of the material will be delayed relative to the impinging piloted ignition case.

The use of a pilot ignition source impinging on the surface poses three potential problem areas:

a. Uneven heating of the sample, i .e . , the pilot flame locally heats the sample at a higher level than the remainder.

b. The maximum rate of heat release may be lower for the impinging case, because the nonimpinging case generally results in instantaneous surface involvement. However, extrapolation of release rate vs. time data during the period of progressive involvement in order to find the maximum rate of heat release of total in i t ia l surface involvement is possible.

c. The impinging flame may, when applied to very thin materials, give substantially different results.

I t appears that the uneven heating problem and the "nonsimultaneous involvement" limitation have no real impact on the u t i l i t y of heat release data except in the use of detailed mathematical models. The third problem has been compensated for by using a distributed piloted ignition source, such as a ribbon burner.

The main advantages of the impinging piloted ignition flame are:

(1) An impinging flame and subsequent ignition form an appropriate scenario for many applications.

(2) The high heat flux levels required to obtain ignition of the surface under the nonimpinging or nonpilot case are representative of post flashover f i re conditions. Much of the i l lustrative data obtained from rate of heat release testing occurs below those high flux 'levels. Further, a major application of heat release testing has been relative to the contribution of materials leading to flashever, or in the preflashover interval, where a material's combustibility properties are the most important.

Another important point is that, while the nonimpinging flame may yield slightly higher maximum rate of heat release levels, i t is entirely possible for a material to burn at a substantial heat release rate under the impinging p~lot flame case, and never ignite at relatively low (2.0 w/cm L) flux levels.

I t is recommended that for general hazard assessment purposes the impinging pilot source be used, bearing in mind the problems of verythin samples and the possibility of slightly reduced maximum rate of heat release values.

3. External Radiant Heat Flux Levels.

Perhaps one of the most useful aspects of this test method is the abi l i ty to vary flux levels over a wide variety of exposure conditions. This capability gives the test method great f lex ib i l i t y relative to assessing hazard for a wide variety of use conditions. The level or levels chosen to run the test should reflect the purpose of the application of the results as well as the expected exposure level of the material in the installation being examined. Dr. Smith, the originator of this apparatus, has applied the test results to a number of applications and has proposed several ways of integrating the exposure level into the analysis.

NFPA 263 Useful generic guidance for users or specifiers of this test

method is to test all samples under.a range of exposure conditions, from no externally applied heat flux to the maximum expected value. Notice from the table presented previously that, for many materials, the higher external heat flux has no significant impact on either the cumulative heat released or the maximum heat release rate above a certain exposure level. However, in some cases the effects are substantial.

As a general rule i t is recommended that each material be tested under external flux conditions of 0.0, 10.0, 20.0, 30.0, 40.0 and 60.0 kW/m ~, unless available test data indicates otherwise. This range of flux levels will cover the exposure to most materials in a room f i re up to and through flashover. I f the material heat release rate properties after flashover are required, the range of exposure levels should be increased.

As an example, E. E. Smith has recommended various exposure levels and subsequent generic product specifications for typical exposure and acceptability comditions in room fires. The exposure level is a function of the expected type of f i re (which may be related to occupancy) and the location of~he material in the room. For example, the recommended flux level for testing materials that are located on a floor is less than the test flux level for materials located on a ceiling.

A high hazard occupancy class would dictate a higher exposure level under which the product would be required to suitably perform. Similarly, a high "fuel load" class would pose a higher level of exposure to materials.

Acceptance Criteria

I t is generally inappropriate to specify a single acceptance criterion, for example, maximum rate of heat release. The required performance of a material should be specified by several test results. For example, a combination of maximum rate of heat release and total heat release at 3 and 10 minutes. Additional criteria which might be used include the slope "E" which is the slope of the line from the origin tangent to the heat release rate line. "E" is a surrogate measure of ign i t ib i l i ty ; high heat release rate over a short period of time yields a high value of "E". Other criteria might be maximum heat release rate over any one minute interval, etc. A sample of such a collection of acceptance criteria is given below.

Characteristics Maximum Permissible Value

Slope E kW/s~c - m 2 Maximum heat release rate kW/m~ 3 minute heat release rate kW/m~ 10 minute heat release rate kW/m ~

Users and specifiers of this test method must be cautioned that i t is not possible to specify either test conditions or acceptance cr i ter ia unless a clear understanding of the purpose of applying the test, as well as experimental and analytical data are available from which to derive both the test and acceptance conditions. There are no readily available pass/fail or nominal grading cri teria for all situation.

References

(1) Hilado, C. J. and Murphy, R. M., "Fire Response of Organic Polymeric Materials (Organic Materials in Fire: Combistibility), "Design of Buildings for Fire Safety, ASTM STP 685," E. E. Smith and T. Z. Harmathy, Eds, American Society for Testing and Materials, 1979, pp. 76-105.

(2) "Fire Property Data-Cellular Plastics," H. A. Nadear et al, eds., Technomic Publishing Company, Inc., Westport, CT., 1980.

(See next page for Tables E-11a and E-11b.)

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HFPA 263 NFPA 283

Table E-11a Selec~e~ T~st ~eKhod Results (Plloteu, implnglng)

App I i ed Max I mum Orientation Heat Heat Release

H = Horizontal Flu~ Rate Material V = Vertical w/cm c Btu/ft 2 min

GM 21/22 V 1.0 1200 (Flexible FU Foam) 3.0 1345

H 1.0" 1115 3.0 1230

GM23/24 V 1.0 1050 Flexible FU Foam 3.0 805

H 1.0 940 3.0 1900

GM47/48 V 1.0 500 Polystyrene Expanded 3.0 440

H 1.0 610 3.0 875

GM 51/52 V 1.0 0 3,0 720

H 1.0 O 3.0 1370

* = Dripping occured

Cumulatlve. Heat Release 8tu/f t 2

i mln 3 min 5 min 10 min

505 1660 1920 1920 715 *(drip) . . . .

225 1835 2195 2195 1230 1830 1830 1830

350 1350 1500 1500 445 1110" 1245 --

285 1400 1500 1500 900 1555 1555 1555

325 850 1110 1110 175" 705* 860 --

305 1005 ii00 1100 560 900 1050 1050

0 0 0 0 0 625 950 --

0 O' 0 0 10 1500 1770 1770

Material

Oak, 1 in.

Pine, I in.

Red Oak, Flooring

• Exterior Plywood, .5 in.

Polyviny! Chloride, go mil sheet

Polystyrene, Light: Diffuser

Particle Board i .5 in.

Particle Board, .5 in. Fire

Table E-11b Typical RHR Data from OSU Test Method (1} (Piloted, Impinging)

External Maximum Heat Heat Release Total Heat Release Flux Ra~e 8tu/ft 2

Orientation w/cm 2 Btu/ft L mln 3 min 10 min

V 1.0 300 250 750 2.0 420 800 3500 2.5 550 I000 4000

V 1.5 600 900 6000 2.5 800 1200 8000

H 1.0 300 500 800 2.0 450 go0 3500 2.75 600 1200 4500

V 1.0 400 700 1200 2.0 600 1000 3000

V 1.0 300 500 2000 2.0 500 1000 2000

H 0 500 75 2400 1.0 750 250 2500

V 1.0 400 70 1800 • 2.5 800 1800 5000

V 1.5 2G 0 50 2.5 350 200 1200

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