Determining the Effect of Fire 

Barriers on the Combustion Behavior 

of Cored Composite Products using a 

Cone Calorimeter

Mauro Zammarano

Fire Research Division, NIST, USA

Some of the data in this presentation hasn’t been through the NIST review process and 

should be considered experimental / draft results.
Product including two main components:

- CORE (acts as main fuel load of the item)

- SKIN (acts as Fire Barrier, FB)

Cored Composites Product?

Examples

Upholstered Furniture: padding material 

(core), upholstery fabrics (skin)

Cored Laminate: honeycomb (core),

glass reinforced epoxy (skin)
Case Study: Chair Mock-ups

1000

25

1000 150

FRONT VIEW Back cushion (polyester fibers)

Armrest padding (TB117-2013 foam)

Seat cushion (TB117-2013 foam)

Armrest support (5 mm plywood)

950 

300

SIDE VIEW

7 chair types (C0 to C6):

C0: cover fabric (B0) only

C1 to C6: cover (B0) +1 fire barrier (B1 to B6)

7 chair types in triplicate tests: tot. of 21 chairs

All chair components protected by FB

3

Seams (Metal Staples) 

Dimensions in mm

B0 to B6 are expected to be compliant with 

California Bill AB 2998
Ignition Source

• Square Burner (18 kW for 80s) 

Flux Gauge

4
5

Effect of Fire Barriers

Fire barriers allows to:

• increase time to peak from 3 min (C0) to 22 min (C1 and C6)

• decrease PHRR from about 3 MW to about 1 MW

C0 C4 C1

Playback speed: 73x
Barrier Failure

6

Bottom Ignition (BI): persistent burning under the seat cushion due 

to the ignition of liquid product of pyrolysis
y = 1.0578x + 1.208

R2 = 0.9994

0

5

10

15

20

25

30

0 5 10 15 20 25

TTP 

- Time to PHRR (min)

TTBI - Time to Bottom Ignition (min)

Bottom Ignition (BI) and PHRR

Bottom Ignition leads to PHRR within (2 ± 1) min

7
Burning of Upholstered Furniture

TTBI and HRRBI used to characterize Stage I burning

0

200

400

600

800

1000

1200

0 5 10 15 20 25 30 35 40

HRR (kW)

Time (min)

TTBI

Time to BI 

Plateau Duration HRRBI

HRR at Bottom 

Ignition

8

Bottom Ignition

STAGE I:

gaseous pyrolyzates

STAGE II:

gaseous/liquid pyrolyzates
Polymeric Material

Idealized cross-section of a Cored Product

Two-fold mechanisms of action of Fire Barriers:

(1) Limiting generation rate of flammable pyrolyzate (Heat Transfer)

(2) Limiting or controlling the rate and location at which pyrolyzates 

are released and able to burn (Mass Transfer)

9

Schematic Combustion Process

mሶ bottom

mሶ top

Fire Barrier

qሶtop

qሶbottom

POLYMER → Gaseous products + Liquid products 

POLYMER PYROLYSIS

(gaseous pyrolyzates) 

(gaseous & liquid pyrolyzates) 
NIST Cube Test (ASTM WK65005) 

10

qሶ mሶ

One-Dimensional 

Heat/Mass Transfer

The sample is intended 

to be a representative 

cross-section of an item

Sample dimensions:

100 mm × 100 mm ×

product thickness

Polymeric

Core

Material

Insulation

Fire Barrier

Fire Barrier

Metal 

Frame

Substrate

Cone Heater

What is it? Tool for the Cone Calorimeter to capture Mass Transfer and Heat Transfer 

phenomena through the top and bottom of the sample.

What is used for? Characterize the combustion behavior of a flammable core material in 

presence of fire barriers. 
Schematic Drawing

11

F

F
Cube Test Set-up (Schematics) 

12

Insulation

4.25 in

FOAM

CUBE

Fire Barrier

Metal 

Frame

Fire Barrier

Cover Fabric

Catch pan

Cone heater:

75 kW/m2

TOP VIEW

BOTTOM 

VIEW

WIDE 

VIEW
Example of a Typical Cube Test

“Wetting”: appearance of visible liquid pyrolyzates on the bottom barrier 

Playback speed: 30x

Mass Transfer:

liquid pyrolyzates

13
Example of HRR Curve in Cube Test

14

0

1

2

3

4

5

6

0

200400600800

10001200

Time (s)

HRR (kW)

Wetting Point

HRR at Wetting

HRR

w

TTW

Time to Wetting


Heat transfer through Barriers

Normalized HRR =

HRRw,BF

HRRw,No BF

Calculate effectiveness 

of barrier by calculating 

normalized HRR
Case Study: Upholstered Furniture (UF) 

• 1 Polyurethane Foam (TB117-2013)

• 1 Cover Fabric (Polypropylene)

• 6 Fire Barriers compliant with 

California Assembly Bill No 2998

Reduced Scale Test 

(Cube Test)

Full-scale Test

(Chair Mock-ups)

C

o

r

r

e

l

a

t

i

o

n

Materials
Cube to Full-Scale Correlation?

19

Correlation:

-TTBI to TTW?

-HRRBI to HRRw?
y = 0.1299x - 9.8593

R2 = 0.9872

0

5

10

15

20

25

50 100 150 200 250 300

TTW - Cube (s)

TTBI 

- Full Scale (min)

C3

Prediction of TTBI (and TTP) by Cube

ASTM D2261-13 (2017) 

Paper B1 B2 B3 B4 B5 B6

0

20

40

60

80

100

120

140 Tear Strength (N)

20
Prediction of Plateau Value 

y = 310.03x - 108.59

R2 = 0.9313

0

100

200

300

400

500

600

700

800

900

1000

0.0 0.5 1.0 1.5 2.0 2.5 3.0

HRRBI

- Full Scale (kW)

HRRW - Cube (kW)

21

C3
• The Cube Test is a tool developed to capture mass/heat transfer 

mechanisms through fire barriers

• The Cube test has been successfully used to predict Stage I burning 

(within the limited data set available) in Upholstered Furniture and 

properly rank the effectiveness of Fire Barriers

• Other cored systems (honeycombs+ fiber reinforced epoxy, insulation 

foam + aluminum foil, etc.) are currently under investigation

22

Conclusions
23

THANK YOU!

Acknowledgements:

Contact Information:

Mauro Zammarano

Phone: 301-975-5244

e-mail: mauro.zammarano@nist.gov

Fire Research Division, NIST:

J. Randy Shields, Ickchan Kim, 

Isaac Leventon, Andre Thompson, 

Ronald Lankone, Anthony Hamins, 

Matt Bundy, Arthur Chernovsky