# Presentation: 756945

## AC 20-135 / ISO 2685

**« Fire Safety Department »**

**AC 20-135 / ISO 2685**
**Fire tests on components used in fire zones. Comparison of gas burner to oil burner.**

**Serge LE NEVE**
**E-mail : Serge.le-neve@dga.defense.gouv.fr**

## Various test methods, standards or guides are used to assess the fire behaviour of various components used in fire zones

**Various test methods, standards or guides are used to assess the fire behaviour of various components used in fire zones**
** **_**Aircraft Material Fire Test Handbook :**_
- _Chapter 12_ is used to determine the capability of components & constructions to control the passage of fire or its effects in powerplant compartments,
** **_**AC 20.135 :**_** **
- Guidance to demonstrate the compliance with the powerplant fire protection requirements of the FAR (materials & components used in engines & APU installations and in areas adjacent to fire zones).
** **_**ISO 2685 :**_** **
- Test procedure for airborne equipments to assess the fire resistance of components, equipments & structures located in “fire zones”.

** ****The ISO standard is often asked / used by airplane suppliers to show the compliance with the FAR / CS requirements**

##      requirement : > 10.6 W/cm2 (9.3 Btu/ft2.s) or > 4500 Btu/hr

**Various methods of Heat Flux calibration are specified to set the burners**
** **_**Aircraft Material Fire Test Handbook **__Chapters 11 & 12_ **: **
**     ****requirement : > 10.6 W/cm2 (9.3 Btu/ft2.s) **_**or**_** > 4500 Btu/hr**
- Heat Flux density is measured by  a water-cooled calorimeter
- Power is measured by the heat transfer device
** **_**AC 20.135 :**_** ****requirement : > 10.6 W/cm2 (9.3 Btu/ft2.s) **_**or**_ **> 4500 Btu/hr**
- Parameters are measured by the heat transfer device or calorimeter. AC 20.135 does not clearly specify if the heat flux density must be measured from a water-cooled calorimeter or if it can be calculated from the power measured by the heat transfer device.
** **_**ISO 2685 :**_** ****requirement : 11.6 W/cm2 (+/- 1 W/cm2)**
- The Heat Flux density is calculated from the heat transfer device (the total heat recorded by the heat transfer device is supposed to come from the surface of the tube in front of the burner exit).

** ****Requirements : The choice is open (power **_**or**_** heat flux density)**
** ****Heat Flux density : The choice is open for the device to use (water-cooled calorimeter **_**or**_** heat transfer device)**

## Various burners are described and/or approved

**Various burners are described and/or approved**
** **_**Aircraft Material Fire Test Handbook **_**: **
-  Oil burner (such as Park PDL 3400) is described,
-  Gas burner (SAE AS401B Propane Burner) is also acceptable (chapt 12).
** **_**AC 20.135 :**_
-  Oil burner is described,
-  Gas burner is also acceptable.
** **_**ISO 2685 :**_
-  Oil burner or gas burner
- Can be used depending of the size of the critical part to be tested.

- Photo fluxmetr

## Various test configurations

|  | Oil Burner | Gas Burner |
| --- | --- | --- |
| FAR / CS         (Handbook / AC 20-135) | 4′′ (101,6 mm) | 2′′ (50,8 mm)
 |
| ISO 2685 | Env 100 mm (4′′) | Env 75 mm (3′′) |

**Various test configurations**
**(depending of the standard and the type of burner)**

** ****4 inches**

** ****2 inches**

** ****3 inches**

**AC 20-135 / ISO 2685 ****	****	****Comparison of gas burner to oil burner**

## SUMMARY OF THE SITUATION

** ****Several standards or guidance providing :**
** ****2 different methods of heat flux calibration,**
** ****2 different burners,**
** ****Various test configuration (positions of the burner)**
** **
** ****But same acceptance criteria :**

**AC 20-135 / ISO 2685 ****	****	****Comparison of gas burner to oil burner**

**SUMMARY OF THE SITUATION**

**To test the same kind of components used in the same area (fire zones) :**

** ****Fire resistant : 5 mn**
** ****Fireproof : 15 mn**

## What about the test results with 2 so different burners used in accordance with various standards ?

**Experiences with the Park burner has shown the difficulty to obtain the same test results using only one type of burner**

**What about the test results with 2 so different burners used in accordance with various standards ?**

** ****AS401B gas burner**

** ****Park oil burner**

**AC 20-135 / ISO 2685 ****	****	****Comparison of gas burner to oil burner**

## Some recent tests performed on real components according to ISO 2685 :

**Some recent tests performed on real components according to ISO 2685 :**
**	******** ****failed  when performed with oil burners,**
**	******** ****passed when performed with gas burner.****	****	**

**CEAT ran a short preliminary study on simple test specimens to compare these various test configurations.**

**AC 20-135 / ISO 2685 ****	****	****Comparison of gas burner to oil burner**

## Test Program

** ****Tested configurations (position of the burner) :**
** ****Oil Burner / d = 4 inches (ISO, FAA : Handbook, AC)**
** ****Gas burner / d = 3 inches (ISO)**
** ****Gas burner / d = 2 inches (FAA : Handbook, AC)**

**AC 20-135 / ISO 2685 ****	****	****Comparison of gas burner to oil burner**

**Test Program**

**Tested samples**
**Simulating critical areas to be tested**
**Sizes of the samples / critical areas were in accordance with all test methods (< 2xS****burner****)**

##  T° Oil Burner

** ****T° Oil Burner**

** ****T° Gas Burner**

** ****Gas Burner : av. flame T° = 1065°C**
** ****Oil Burner : av. flame T° =** **1038°C**

**ISO requirement : 1100°C +/- 80°C**

**Flame calibrations**

**dist. Burner = 3 inches**

**dist. Burner = 4 inches**

**AC 20-135 / ISO 2685 ****	****	****Comparison of gas burner to oil burner**

##  Heat Flux – Gas Burner

** ****Heat Flux – Gas Burner**

** ****Heat Flux – Oil Burner**

** ****Gas Burner : av. heat flux = 11.65 W/cm2**
** ****Oil Burner : av. heat flux = 12.43 W/cm2**

**ISO requirement : 11.6 W/cm2 +/- 1 W/cm2 **

**Recorded power : ****2284**** ****Btu/h**** **

**Calculated heat flux density ****(/ exposed surface of the tube)**
**(L=152.4mm)**

**Recorded power : ****4478**** ****Btu/h**** **

**Calculated heat flux density ****(/ exposed surface of the tube)**
**(L=280mm)**** **

**Flame calibrations**

**dist. Burner = 3 inches**

**dist. Burner = 4 inches**

**AC 20-135 / ISO 2685 ****	****	****Comparison of gas burner to oil burner**

## Tests on small 2024 aluminium plate

**dist. Burner = 3 inches**

**dist. Burner = 4 inches**

**Tests on small 2024 aluminium plate**

**A 1.2mm aluminium plate is fitted behind a 3mm steel plate, simulating a critical area to be tested**

**Gas Burner**

**Oil Burner**

**Alumina sheet**

**AC 20-135 / ISO 2685 ****	****	****Comparison of gas burner to oil burner**

## Tests on small 2024 aluminium plate

**Tests on small 2024 aluminium plate**

**Gas Burner**

**Oil Burner**

**Melted areas**

**Fail**

**Pass**

**Melting time (s)**

**Fail : 2 samples **

**Pass : 3 samples **

**AC 20-135 / ISO 2685 ****	****	****Comparison of gas burner to oil burner**

## Tests on aluminium tube – ISO 2685 standard

**Tests on aluminium tube – ISO 2685 standard**

** **_**Failure time :**_
**1mn 10 s**

**Nut & bolt simulating a critical part**

** **_**failure time :**_
**1mn 42 s**
**(+45 %)**

**L=30 cm / ****Ø=10 cm / th.=1.2mm**
**Failure time : burnthrough / fall of the bolt**

**dist. Burner = 3 inches**

**dist. Burner = 4 inches**

**AC 20-135 / ISO 2685 ****	****	****Comparison of gas burner to oil burner**

## Essai sur cadre Alu 2024 (ép. 5mm)

**Essai sur cadre Alu 2024 (ép. 5mm)**

** **_**Failure time :**_
**> 15 mn**
**Fire resistant (5mn) :**
**Pass**
**Fire proof (15mn) : ****Pass**

** **_**Failure time :**_
**4 mn 45 s**
**Fire resistant (5mn) :**
**Fail**
**Fire proof (15mn) : ****Fail**

**Tests on 2024 aluminium former – ISO 2685 standard**

**dist. Burner = 3 inches**

**dist. Burner = 4 inches**

**Nut & bolt simulating a critical part**

**thickness=5 mm**
**Failure time : fall of the bolt**

**AC 20-135 / ISO 2685 ****	****	****Comparison of gas burner to oil burner**

## Essai sur cadre Alu 2024 (ép. 5mm)

**Comparaison des brûleurs gaz / kérosène – ISO 2685**

**Essai sur cadre Alu 2024 (ép. 5mm)**

**Comparison of failure times**

**+ 15 %**

**+ 46 %**

**> + 200 %**

**Fire resistant**

** ****In all cases, the gas burner is less severe**

**> + 87 %**

**AC 20-135 / ISO 2685 ****	****	****Comparison of gas burner to oil burner**

**> 900s**

**> 600s**

## (d = 2 inches) 

**Heat flux Mapping (gas burner)**
**(horizontal centre line)**

-  Power : 2698 Btu/h (+20%)
- ISO calculated heat flux : 13.76 W\cm2

**Burner setting according to the ISO specification **
**Flame measurement according to AC 20.135**
**(**_**d = 2 inches)**_

** ****Maximum ****Heat-Flux : 10.76 W/cm2**
*Handbook/AC requirements : *_*>*_* 10.6 W/cm2*

**Comparison of the ISO gas burner flame**
**To**
**FAA Handbook / AC 20.135 requirements**

**AC 20-135 / ISO 2685 ****	****	****Comparison of gas burner to oil burner**

## (d = 2 inches) 

**Comparaison des brûleurs gaz / kérosène – ISO 2685**

** **_**Failure Time :**_
**> 15 mn**
**Fire resistant (5mn) : ****Pass**
**Fireproof (15mn) : ****Pass**

** **_**Failure Time :**_
**4 mn 45 s**
**Fire resistant (5mn) : ****Fail**
**Fireproof (15mn) : ****Fail**

**ISO flame settings + AC 20.135 test configuration**
**(**_**d = 2 inches**_**)**

** **_**Failure Time :**_
**5 mn 13 s**
**Fire resistant (5mn) : ****Fail**
**Fireproof (15mn) : ****Pass**

**ISO 2685 standard configuration**

**ISO & AC 20.135 configuration (Oil Burner)**

**Comparison of the ISO gas burner flame**
**To**
**FAA Handbook / AC 20.135 requirements**

**AC 20-135 / ISO 2685 ****	****	****Comparison of gas burner to oil burner**

## Essai sur cadre Alu 2024 (ép. 5mm)

**Comparaison des brûleurs gaz / kérosène – ISO 2685**

**Essai sur cadre Alu 2024 (ép. 5mm)**

**Comparison of failure times**

**+ 15 %**

**+ 46 %**

**> + 200 %**

**Fire resistant**

**> + 87 %**

**AC 20-135 / ISO 2685 ****	****	****Comparison of gas burner to oil burner**

** ****ISO gas burner at d = 3 inches**

** ****ISO gas burner at d = 2 inches**

**> 900s**

**> 600s**

**If used at d= 2 inches from the test sample**
** ****ISO gas burner is in accordance with AC/Handbook requirements**
** ****Gas burner & Oil burner test results are very close **

## Essai sur cadre Alu 2024 (ép. 5mm)

**Essai sur cadre Alu 2024 (ép. 5mm)**

**Comparison of the ISO gas burner flame**
**To**
**FAA Handbook / AC 20.135 requirements**

**(ISO 2685 is often used by suppliers to demonstrate the compliance with the FAA / EASA requirements)**

**Heat flux Mapping**
**(centre line (vertical impact position))**

** ****max : 10.3 W/cm2 **

**Handbook/AC requirements : **_**>**_** 10.6 W/cm2 **
**(using a Heat Flux Transducer) **

** ****Maximum ****Heat-Flux (gas burner) : ****10.3 W/cm2**

**Continuous movement of the HF meter above the burner**

** ****Av. above the burner :**** ****7.17**** ****W/cm2**** **

**AC 20-135 / ISO 2685 ****	****	****Comparison of gas burner to oil burner**

## Essai sur cadre Alu 2024 (ép. 5mm)

**Essai sur cadre Alu 2024 (ép. 5mm)**

**Comparison of the oil burner flame (set according to ISO 2685)**
**To**
**FAA Handbook / AC 20.135 requirements**

**Heat flux Mapping**

** ****max : 9.8 W/cm2 **

**Handbook/AC requirements : **_**>**_** 10.6 W/cm2**** **
**(using a Heat Flux Meter) **

** ****Maximum ****Heat-Flux : ****9.8 W/cm2**

**AC 20-135 / ISO 2685 ****	****	****Comparison of gas burner to oil burner**

## T° (steel plate - 3mm 500x500 mm)

**T° ****(steel plate - 3mm 500x500 mm)**

** ****Gas Burner**

** ****Oil Burner**

**AC 20-135 / ISO 2685 ****	****	****Comparison of gas burner to oil burner**

## IR mapping (steel plate - 3mm 500x500 mm)

**IR mapping (steel plate - 3mm 500x500 mm)**

**Oil Burner 1 mn**

**Gas Burner 1 mn**

**Oil Burner 3 mn**

**Gas Burner 3 mn**

**Oil Burner 5 mn**

**Gas Burner 5 mn**

** **_**Estimated area >520°C :**_
** ****Oil Burner : 189 cm2**
**    ****(**_**~**_** ****14cm x 14cm)**
**Gas Burner :  49 cm2**
**    ****(**_**~**_ **7cm x 7cm)**

**AC 20-135 / ISO 2685 ****	****	****Comparison of gas burner to oil burner**

## Conclusion 1

**These tests show that :**
**Within the ISO 2685 standard, the gas burner flame is always less severe than the oil burner flame,**
**Heat flux methods of measurement are not equivalent and the values of heat flux calibrations must not be compared,**
**When the gas burner and oil burner are calibrated according to the ISO standard, their flames are not in accordance with the Handbook / AC 20-135 requirements,**

**AC 20-135 / ISO 2685 ****	****	****Comparison of gas burner to oil burner**

## Conclusion 2

**Gas burner and oil burner are not equivalent**** **
**Gas burner :**
**Could be used within the Handbook/AC on small items.**
**Practical aspect : Should not be used on medium size items under the Handbook test configuration (d=2 inches) (too close to the burner => possible burner damages (heat concentration – radiation from the sample)**
**When this burner is used, as specified in the various standards it **_**should be used only on small critical parts**_
**Because of thermal diffusion effect, it should be allowed only on small **_**items**_** ****	****	****	****	****(****gas burner should not be allowed to test large items with a small critical part****, even if the critical part is at the centre line of the burner)**

**AC 20-135 / ISO 2685 ****	****	****Comparison of gas burner to oil burner**

## Conclusion 3

**As the ISO standard is often used in substitution with the FAA guidances and as the gas burner can be less severe than the oil burner :**
****** ****The ISO 2685 standard and (or) the Handbook / AC should be revised**** to fix all these « anomalies »**
****** ****As the ISO 2685 is currently under discussion within the TC20 ISO committee, ****the french mirror committee will probably ask for a complete review**

**AC 20-135 / ISO 2685 ****	****	****Comparison of gas burner to oil burner**

## AC 20-135 / ISO 2685

**Serge LE NEVE**

**E-mail : Serge.le-neve@dga.defense.gouv.fr**

**AC 20-135 / ISO 2685**
**Fire tests on components used in fire zones. Comparison of gas burner to oil burner.**

**Toulouse Aeronautical Test Center (CEAT)**

**« Fire Safety Department »**