Federal AviationAdministrationRevised Rate of Heat

Release Test Method

2013 December Triennial ConferencePhiladelphia, PA USA

Michael Burns, FAA Tech Center

Agenda• Test Method• Background for Revision• Improvements• Prototype Data• Next

Heat Release Rate Test Method• Required by Federal Aviation Administration

• Qualify large surface area interior materials for use in commercial passenger aircrafto Ceilingso Stow binso Sidewalls

• Federal Register 14 CFR parts 25 and 121o Descriptiono Useo Calibrationo Pass / Fail criteria

Revised Heat Release Rate Test MethodGoal: Simplify and Streamline the Test Method

• Multi-laboratory studies in which the same material was tested at different locations indicate reproducibility of test results can be improved.

• Many factors can contribute to poor agreement between test laboratories.

• This presentation describes a detailed revision of the test apparatus conducted by the International Aircraft Materials Fire Test Working Group to better standardize components, procedures and calibration of equipment for this test method.

Categories Of Improvements

• Airflow (Dual Flow to Single Flow)• Standardized Construction• Procedures / Software• Calibration Equipment• Changes in Documentation (Chapter HR)

Airflow – Single Flow Design

OSU: Orifice Meter, Natural 3:1 Airflow Split HR2: Mass Flow Meter Controlled

Removal of Bypass Air and Components

• Chimney• Baffle Plate• Outer Pyramid• Bypass Air Manifold• Piping• Surplus Gasket Material and Hardware• Orifice Meter/Mercury Manometer

Removal of Bypass Air and ComponentsPROS

• Single air sourceo 1 MFM Req’do Smaller Compressed Air System Req’d

• Easier to clean, inspect, maintain• Fewer Components• Lower Manufacturing / Operating costs• Quieter system• Thermocouples operating in a better performance range• Higher gain in the Thermopile output signal• Lower Calibration Factor (Approx. 4.0 kW/m2/mV or 0.09 kW/mv)

CONS• Higher Exhaust Gas Temperatures (approx. 500 degrees F)

Airflow• Defined Air Quality

- “…free of oil mist, water and foreign particles”

• Airflow (MFM/MFC Controlled)- Calibrated To STP 0º C at 760 mmHg- Accuracy: 1% Reading, 0.2% Full Scale- Flow Rate: 20 ± 0.5 SCFM- Positioned within 24 inches of the inlet port to the

system- Provision for Flow Straightening Piping

¼ inch Aluminum Unchanged Holding Chamber DoorUnchanged Air Distribution Plate

     0.036 +/- 0.003 Alum. Not Specified Exhaust Stack Covering (New)     0.125 ± 0.005 Not Specified 1/8 inch Retaining Rod

0.048 ± 0.004 (0.049 ± 0.002) Main BodyNot Specified Globar PanNot Specified Holding ChamberNot Specified Second Stage PlateNot Specified Lower Air Plenum

• Insulation - Thermal Conductivity Criteria• Overlap Criteria• Component Metal Thickness & Tolerances Table

Standardized Construction

New Previous Component

0.042 ± 0.004 (0.042 ± 0.002) Diamond Mask

0.036 ± 0.003 (0.030 ± 0.008) Reflector Plate24-Gauge Steal Sample Holder Plate

0.030 ± 0.003 (0.031 ± 0.002) Outer Pyramid (Removed)Not Specified Radiation Doors (2)

0.018 ± 0.002 Unchanged Inner Pyramid (Modified)Unchanged Chimney (Removed)Unchanged Baffle Plate (Removed)Unchanged Sample HoldersUnchanged Holder SpringUnchanged Retaining Ring

Standardized Construction

New Previous Component

HR2 Exhaust Assembly

1” Stiffening Doubler

1” Flange

Standardized Construction Exhaust Stack Mounting

o #10-32 x ¾” Bolts / Washers / nuts (28)o Gasket o 0.036 +/- 0.003 Aluminum Coveringo No substitutions permitted

Main bodyo Dimensionso Observation windowo Inner radiation doorso Rear globar pano Reflector plateo Diamond plate shafto Upper Pilot/Calibration Burnero Second Stage Plate

Hole pattern (Centered in Chamber) Perimeter sealed Removable

Standardized Construction Holding Chamber

o Dimensionso Outer dooro Preheat sample position

Specimen Holder / Componentso Dimensionso Retaining Ringo Spring Plateo Retaining Rodo Drip Pan

HFG Mountingo Refractory Board (Thickness, HFG flush mount)o Corner HFG position

Standardized Thermopile / Globars • Thermopile mV Generating System

o New Thermocouples (9)o Detailed Wiring Diagramo 96 inch Overall Lengtho 24 Gauge, Solid Conductor, Thermocouple Grade Wireo Quick Disconnectso Cold Junctions Centrally Located in Lower Plenum: 1.5 inch

Spacingo Reference Junction: Closest To Air Inlet

• Globarso Construction: CHZ, Length, Diameter, Resistanceo Rheostat control of upper/lower pairs or individuallyo Advisory on final power adjustments / Uniformityo Voltage Fluctuation Tolerance (Globars)

New Procedures: CalibrationGoals:

• Achieve better stability at each step change in flow• Obtain largest mV rise possible for each step change in

flow (resulting in the low calibration factor)• Linear analysis to mV rise per step change in flow• Low % error (<5%)• Reduce time req’d to complete the calibration process• Reduced use of Methane Gas• Make it easier

New Procedures: Calibration• Replaced Wet Test Meter with Mass Flow Meter (MFM)

• Calibration Gas MFMo Thermal-basedo 0.25 inch inlet/outlet fittingso Calibrated annually with NIST traceabilityo Calibrated for Methane gaso Accuracy: 0.5% Reading, 0.1% Full Scale, 2-sigma level of

confidenceo STP 0ºC at 760 mmHgo Signal Output To Data Acquisition Systemo Flow deviation of < 0.2 SLPM

• Dual Purpose Burner (Upper)o Calibration Burner (Removed T-Burner)o Upper Pilot Burner during testing – 2 SLPM / Air (Approx. 50/50 Ratio)

New Procedures: Calibration• Calibration Method Changes

o Optimized flow settings from 1,4,6,8 L/min to 1,2,3,4 SLPMo Entire calibration sequence defined (Beginning to end)o 3 minute Preheat at 4 L/mino Step Change: 1-2, 1-3, 1-4 SLPM o Longer dwell – Increased from 2 to 3 minutes (last 10 second average) o Methane MFM/MFC output recorded with Thermopile outputo Only 3 step changes in flow (previously 5)o Exhaust ventilation system must be on

• Calibration Pass / Fail Criteriao Unchanged @ 5% STDEV error between the three calibration constants

derived during the calibration process (1-2, 1-3, 1-4 SLPM)

HR2 PrototypeCALIBRATION PARAMETERS

METHANE FLOW (SLPM) THERMOPILE OUTPUT (mV)

Low Range TARGET High Range Low Range TARGET High Range

0.98 1.0 1.02 60.0 61.0 62.0

1.96 2.0 2.04 67.0 68.0 69.0

2.94 3.0 3.06 73.0 75.0 77.0

3.92 4.0 4.08 78.0 80.0 82.0

CALIBRATION FACTOR RANGELow Range TARGET High Range

0.07 kW/mv 0.08 kW/mV 0.09 kW/mV

3.0 kW/m2/mV 3.5 kW/m2/mV 4.0 kW/m2/mV

New Procedures: Heat Flux

• HFG Type: Replaced Gardon with Schmidt-Boelter

• HFG Guidance: Paint / Care / Mounting

• New insitu method (Center)o 3.65 +/- 0.05

• New Uniformity Tolerance (4-Corners)o 3.65 +/- 0.10

Calibration Factor / HRR EquationOSU – FAA Fire Test Handbook

 Simplifying this gives…

 

Heat Release Rate = kW/m2

HR2 – Chapter HR

 Simplifying this gives…

 

Heat Release Rate = kW/m2

Deleted Sample Area Moved to HRR Calculation

HR2: Total Heat Release CalculationTotal Heat Release = kW · min/m²

 

Simplifying this gives…

 

Total Heat Release kW · min/m²

 Where:n = Total number of data collection points in 2 minutesx = Total number of data collection points in 1 minuteAverage thermopile millivolt reading at baseline (mV)Thermopile millivolt reading at any point during test (mV) Calibration factor Note: This formula uses the Riemann Left Hand Sum method of integration.

Chapter HF: Definitions• Calibration Factor (Kh) - Correlates the heat released by a

specimen when burned to the known heat content of Methane.• Thermopile• Mass Flow Meter (MFM)/Mass Flow Controller (MFC)• Methane Gas (CH4) - Minimum purity of 99%• Supply pressures – Methane @ 20 ± 2 psig, Air @ 30 ± 2 psig• NIST - The National Institute of Standards and Technology

(USA)• NIST Traceability - A calibration entity using NIST traceable

calibration instrumentation.o Heat flux gauges (Chapter HF)o Data acquisition / Display deviceso Flow meters (System Airflow and MFM for thermopile calibration)

• Stability Criteria - Heat flux, Chamber equilibrium

Chapter HF: Calibration Requirements and Frequency

• Equipmento Heat Flux gaugeso Data Acquisition System/Display Deviceso MFM / MFC (Air)o MFM / MFC (Methane)

• Procedureso System Heat Fluxo Heat Flux Uniformityo Thermopile (Gas Calibration)

Chapter HF: Misc.• General / Scope

• Drawingso System Overview Drawing (assembled)o Individual Components - 29 Detailed Drawings

• Test Procedureo Aluminum foil thickness criteriao Sample Insertion / Removal Time - Approximately 3 to

5 secondso Cleaning procedures

• Requirementso 65/65 (Peak HRR / Total HR) - Unchangedo < 80 % must pass

HR2 Prototype Testing

Materials (5 coupons each)

1. Schneller Panel (2012 RR)

2. Light Brown Panel (2012 RR)

A06B1

7A20B1

0B1

2B1

4A22A09A17A21A24A25A16B0

8A03B1

1B0

7B1

5B0

9A18A26A10A01B0

3A05B0

5A11A04A07A23B0

4A13A14A02A12B0

6

0

10

20

30

40

50

60

70

80

0%

2%

4%

6%

8%

10%

12%

14%

16%

18%

4043 43 44 45 46 46 46 47

48 49 49 49 50 50 51 52 53 53 54 54 55 55 5659 60 60

6163 64 65 66 66 67 68

73

3% 3%2%

4% 4%

10%

3% 2%

1% 1% 1%

17%

8%

1%

3%

4%

6%

5%

2%

14%

8%

5%

7%

3%

7%

3%

9%

5%

7%

2%2%

1%

10%

7%

Light Brown Honeycomb PanelPeak HRR vs. % STDEV

Avg = 54 kW/m2; 16% STDEV

Lab Code (A03 = Tech Center HR2 Prototype; A20 = Tech Center OSU)

Kw/m

2

Lab

Repe

atab

ility

(% S

TDEV

)

HR2: 53.5

A06A10B0

7A09B1

4A20B1

1B1

0B1

2B1

7B0

5A17A22A23A16B1

5B0

9A02A25A24A01A21A03B0

8A14A05A04B0

3A18A26B0

4A11A07A12B0

6A13

0

10

20

30

40

50

60

70

80

90

100

0%

1%

2%

3%

4%

5%

6%

7%

8%

9%

53 54

5961 62

64 6466 67 67 67 67 67 68 68 69 69 70 70 70 71 71 73

75 75 7780 80 81 81 82 82 82 83

89

95

1%

8%

8%

0%

4%

6%

9%

4%

7%

3%

4%

1%

7%

3%

8%

2%

4%

7%

3%

2%

1%

7%

1%

6%

5%

4%

2%

6%

2%

3%

7%

5%

1%

1%

Light Brown Honeycomb PanelTotal HR vs. % STDEV

Avg = 72 kW*min/m2; 13% STDEV

Lab Code (A03 = Tech Center HR2 Prototype; A20 = Tech Center OSU)

Kw*m

in/m

2

Lab

Repe

atab

ility

(% S

TDEV

)

HR2: 69.6

A10B1

4B1

1A12A20A06B0

3A21A03A16A01A25B0

8B1

7A26A04A24B1

2B0

7A22A14B1

0A02A17A09B0

5B0

4A18A23A13B1

5B0

9B0

6A11A07A05

0

10

20

30

40

50

60

70

0%

2%

4%

6%

8%

10%

12%

14%

16%

18%

20%

3639

4042 42

43 44 45 45 45 46 46 46 46 47 4749 49 50 50 50 51 51 51 51 52 52 52 52 53 54 54

58 59 59

65

3%3%

7%

14%

1%

2%

17%

4%

2%

9%

2%

1%

4%

9%

1%

9%

14%

2% 2% 2%

7%

5%

2%3%

4%

1%

6%

7%

6%

3%

5%

3% 2%

4%

Dark Brown Honeycomb PanelPeak HRR vs. % STDEV

Avg = 49 kW/m2; 12% STDEV

Lab Code (A03 = Tech Center HR2 Prototype; A20 = Tech Center OSU)

Kw/m

2

Lab

Repe

atab

ility

(% S

TDEV

)

HR2: 47.9

A10A16B0

5A06A01B1

1B1

4A02B0

3B0

7A12A23A17A24A25A21B1

2A20B1

5A22A09A04A14A03B1

7A18A26B0

4B1

0A07A11B0

9B0

8B0

6A13A05

0

5

10

15

20

25

30

35

40

45

50

0%

5%

10%

15%

20%

25%

30%

20

2628 28 28 28

33 33 33 33 34 34 34 35 35 35 35 36 36 37 37 37 37 37 3739 39 40

41 41 41 42 42

46 4647

20%

16%

9%

15%

19%

7%

5%

27%

18%

9%

13%

6%

13%

10%

3% 4%

14%

7%

9%

6%

2%3%

5%

14%

11%

2%1%

7% 7%

3% 3%

5%

13%

9%

Dark Brown Honeycomb PanelTotal HR vs. % STDEV

Avg = 36 kW*min/m2; 16% STDEV

Lab Code (A03 = Tech Center HR2 Prototype; A20 = Tech Center OSU)

Kw*m

in/m

2

Lab

Repe

atab

ility

(% S

TDEV

)

HR2: 36.9

Next

• Participation in 2013 Round Robin

• Conformance Documentation Development

• Additional Unit Buildups for Comparative Testing