FireComp WP6 Task6.3 Current-fire-approach-cylinders Public · CGH2 Compressed Hydrogen Gas SCM...

Modellingthethermo‐mechanicalbehaviourofhighpressurevesselincompositematerialswhenexposedtofireconditions

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DELIVERABLE ID D6.6 Deliverable name Current fire approach for cylinders Lead beneficiary HEX Contributors AL

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consortium.

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Document information

Document type Deliverable Document name FireComp_D6.6.doc Related task according to the DoW (Annex I)

Task 6.3

Document title Current fire approach for cylinders, RCS mapping and project expected outcomes

Revision Draft | Final Due date DoW (Annex I) M12 Author Patrick Breuer, HEX Dissemination level PU Public X

RE Restricted to a group specified by the consortium (including the Commission Services)

CO Confidential, only for members of the consortium (including the Commission Services)

Document approval

Name Position in project Beneficiary Date Visa Lucas Bustamante Valencia Coordinator AL DD/MM/YYYY

Document history

Revision Date Modification Author V0.1 03/09/2013 Creation (D2.1) Breuer, HEX V1.3 19/11/2013 Release (D2.1) Breuer, HEX V2.0 01/06/2014 Creation D6.6 Valérie Nauder, Lucas

Bustamante Valencia, AL

.



Content

1. Executive summary ........................................................................................... 4

1.1. Description of the deliverable content and purpose ............................................. 4 1.2. Deviation from objectives, corrective action ...................................................... 4 1.3. Technical progress ................................................................................... 4 1.4. Impact of the results ................................................................................. 4 1.5. Dissemination activities .............................................................................. 4

2. Abbreviations .................................................................................................. 5

3. List of tables ................................................................................................... 7

4. List of figures .................................................................................................. 8

5. Deliverable report ........................................................................................... 10

5.1. Description of different applications and storage integrations ............................... 10 5.1.1. Automotive application ....................................................................... 10

5.1.2. Tube Trailers (Bulk hauling) ................................................................. 15

5.1.3. Transportable cylinders, bundles ........................................................... 21

5.1.4. HyPulsion fuel cell systems for forklifts .................................................... 22

5.1.5. Stationary application ........................................................................ 24

5.1.5.1. Hydrogen refueling station for Fuel Cell Vehicles ........................................ 24

5.1.5.2. HRS for Fuel Cell Forklifts ................................................................... 26

5.2. Description of existing fire protection designs .................................................. 29 5.2.1. Automotive application ....................................................................... 29

5.2.2. Tube Trailers (Bulk hauling) ................................................................. 36

5.2.3. Transportable cylinders, bundles ........................................................... 38

5.2.4. HyPulsion fuel cell systems for forklifts .................................................... 39

5.2.5. Stationary application ........................................................................ 40

5.3. Mapping of existing cylinder standards requirements ......................................... 42 5.3.1. Automotive application ....................................................................... 42

5.3.2. Transportable gas cylinders ................................................................. 51

5.4. Summary and Conclusion ......................................................................... 52

6. Definitions .................................................................................................... 53

7. References ................................................................................................... 54



1. Executive summary

1.1. Description of the deliverable content and purpose Air Liquide (AL) and Hexagon (HEX) have experience in designing high pressure systems in different applications. AL develops portable cylinders, bundles and stationary applications such as hydrogen fuelling station. HEX develops MEGC (Multi Element Gas Containers) and tube trailers, etc. They will review the literature in their application domain, and interview the engineers in charge of the development of the high pressure release systems for the applications concerned in order to perform the following tasks:

Description of different applications and storage integration (automotive application, stationary application, transportable cylinders, bundles, tube trailers)

Description of existing protection designs, detection strategies and consequence on detection time

Mapping of existing cylinder standards requirements and influence of cylinder integration (e.g. shield protection)

1.2. Deviation from objectives, corrective action N/A

1.3. Technical progress N/A

1.4. Impact of the results N/A

1.5. Dissemination activities N/A



2. Abbreviations MPa Mega Pascal

ICE Internal Combustion Engine

GM General Motors ().

FCEV Fuel Cell Electric Vehicle

WC water content

CNG Compressed Natural Gas

CH2, CGH2

Compressed Hydrogen Gas

SCM Standard cubic meter

SCF Standard cubic feet

ISO International Standard Organization

HRS Hydrogen Refueling Station

LH2 Liquide Hydrogen

TPRD Thermally-activated pressure relief devices

PRD Pressure relief devices

SMA Shape memory alloy

MEGC Multi-Element Gas Container

ADR Agreement Concerning the International Carriage of Dangerous Goods by Road

CE Communauté Européenne

MMI Man-machine interface

N2 Nitrogen

FMVSS Federal Motor Vehicle Safety Standard

TC Thermocouple

SwRI Southwest Research Institute

SAE Society of Automobile Engineers

NGV Natural Gas Vehicle

OEM Original Equipment Manufacturer



ANSI American National Standardization Institute

IAS International Accounting Standards

CHSS Compressed hydrogen storage system

LPG Liquefied Petroleum Gas

JARI Japan Automobile Research Institute

CSA Canadian Standards Association

GTR Global technical regulation

NHTSA National Highway Traffic Safety Administration

TGA Thermal gravimetric analysis



3. List of tables Table 1. Dimensions of TITAN™ tanks for gas transportation [16] ......................................... 17

Table 2. Dimensions of TITAN™ modules for gas transportation (CNG) [15] ............................ 18

Table 3. Dimensions of TITAN V™ trailers for gas transportation (CNG) [15] ............................ 18

Table 4. Dimensions SMARTSTORE™ modules for gas transportation (CNG) [15] .................... 20

Table 5: List of existing standards related to transportable gas cylinders. ................................ 51



4. List of figures Figure 1. GM Sequel Hydrogen fuel cell vehicle [2] .......................................................... 11

Figure 2. Ford Focus Fuel Cell Electric Vehicle (FCEV) [3] ................................................. 11

Figure 3. Mazda RX-8 Hydrogen Rotary Engine [4] .......................................................... 11

Figure 4. Mercedes Benz B-Class F-CELL [5] ................................................................ 12

Figure 5. Mercedes Benz B-Class F-CELL Assembly [6] .................................................... 12

Figure 6. Nissan X-Trail FCV 2003 Model (2003) [7] ......................................................... 12

Figure 7. Hyundai ix35 Fuel Cell vehicle [8] ................................................................... 13

Figure 8. Toyota's FCHV-adv Fuel Cell Vehicle [9] ........................................................... 13

Figure 9. GM Chevrolet Equinox Fuel Cell Vehicle Concept [10] ........................................... 13

Figure 10. Honda FCX Clarity Concept [11] ................................................................... 14

Figure 11. Honda FCX Clarity Assembly [12] ................................................................. 14

Figure 12. GM Chevrolet Volt Fuel Cell Vehicle Concept [13] .............................................. 15

Figure 13. Hexagon Lincoln TITAN™ Module [14] ........................................................... 16

Figure 14. Hexagon Lincoln SMARTSTORE™ Module [15] ................................................ 16

Figure 15. Hexagon Lincoln TITAN™ Trailer on the road ................................................... 16

Figure 16. Front view of a TITAN™ module plumbing system [15] ........................................ 17

Figure 17. SMARTSTORE™ module for gas transportation [15] ........................................... 19

Figure 18. Unloading a SMARTSTORE™ module [15] ...................................................... 19

Figure 19. Example of hydrogen composite cylinder trailer (view 1) ....................................... 20

Figure 20. Example of hydrogen composite trailer (view 2) ................................................. 20

Figure 21. Air Liquide first generations composite hydrogen storages .................................... 21

Figure 22. Air Liquide bundle prototype scheme and characteristics ...................................... 21

Figure 23. Air Liquide bundle with digital image .............................................................. 21

Figure 24. Air Liquide bundle prototype ............................... Error! Bookmark not defined.

Figure 25. View of a single type IV hydrogen cylinder. ....................................................... 22

Figure 26: Different elements integrated inside the HyPulsion fuel cell systems for forklifts ........... 22

Figure 27: Integrated box installed inside the HyPulsion fuel cell systems for forklifts. ................. 23

Figure 28: Example of flexible connection to the HyPulsion fuel cell systems for forklifts .............. 23

Figure 29: HRS distribution in Germany (May 2012) [17] .................................................... 24

Figure 30: Projected HRS coverage in Germany for 2020 [17] ............................................. 24

Figure 31: Typical design of a 3-Stage cascade HRS [17] .................................................. 25

Figure 32: HRS with Booster compressor [17] ................................................................ 25

Figure 33: HRS with onsite generation of CGH2 [17] ........................................................ 26

Figure 34: Liquide (LH2) - Supplied CGH2 Refueling station [17] .......................................... 26

Figure 35. HRS principles ........................................................................................ 27

Figure 36. Air Liquide 70 MPa HRS illustration ............................................................... 27

Figure 37. Warehouse view with human-machine interface and dispenser ............................... 27



Figure 38. HRS equipped with tube trailers as H2 source ................................................... 28

Figure 39. Layout of a HRS with tube trailers ................................................................. 28

Figure 40. TPRD with Eutectic alloy ring [20].................................................................. 29

Figure 41. TPRD with Eutectic alloy puck [21] ................................................................ 30

Figure 42. Glass bulb TPRD – End Plug [22] .................................................................. 30

Figure 43. Glass bulb TPRD for valve integration [23] ....................................................... 30

Figure 44. Concept with 1 TPRD on one side of the cylinder ............................................... 31

Figure 45. Concept with 2 TPRD on one side of the cylinder ............................................... 31

Figure 46. Intumescent paint on bottom of composite cylinder during exposure to fire test [17] ....... 32

Figure 47. Intumescent coating before (left) and after fire exposure (right) [17] .......................... 32

Figure 48. Composite cylinder wrapped in Flexible Ceramic Fibre Blankets [17] ........................ 32

Figure 49. Application of wet felt wrap to cylinder [17] ....................................................... 33

Figure 50. Heat damage to stainless steel shell after bon fire test [17] .................................... 33

Figure 51. Thermal encapsulated cylinder system [28] ...................................................... 34

Figure 52. Fuse wire and glass bulb on cylinder [17] ......................................................... 35

Figure 53. Fire test with composite cylinder protected by a mechanical activation tube [17] ........... 35

Figure 54. TITAN™ module component overview ............................................................ 36

Figure 55. TITAN™ module component overview ............................................................ 37

Figure 56: Picture of an Air Liquide cylinder trailer ........................................................... 37

Figure 57. Representation of the metallic structure of the hydrogen bundle .............................. 39

Figure 58: Virtual view of a hydrogen bundle with the venting grids and the TPRD and PRD vents .. 39

Figure 59: 35 MPa Hydrogen storage surrounded by an external envelop ............................... 40

Figure 60. Representation of safety distances around the dispenser and MMI .......................... 41

Figure 61. FMVSS 3O4 Bonfire Test for cylinder shorter than 1.65 m [24] ............................... 42

Figure 62. FMVSS 3O4 Bonfire Test for cylinder longer than 1.65 m [22] ................................ 43

Figure 63. Thermal Couple Layout of FMVSS 304 Bonfire test by SwRI [32] ............................ 43

Figure 64. FMVSS 304 Bonfire test temperature profile [32] ................................................ 44

Figure 65. Hydrogen Fuel System definition in SAE J2579 [24] ............................................ 45

Figure 66. CNG Cylinder In-Service Failures from 2000-2008 [34] ........................................ 45

Figure 67. Overview of Vehicle Fire Tests [34] ................................................................ 47

Figure 68. Time of Localized Degradation during Vehicle Lab Fire Tests [34] ........................... 48

Figure 69. Temperatures Measured During Localized Portion of Vehicle Lab Fire Test [34] ........... 48

Figure 70. Preliminary Minimum Temperature Profile for the Localized Fire Test [34] .................. 49

Figure 71. Temperature Profile for the Fire Test in the GTR [36] ........................................... 50



5. Deliverable report

5.1. Description of different applications and storage integrations

5.1.1. Automotive application

Within the automotive application, mainly high pressure composite cylinders (Type IV and Type III) are used for the on-board storage of the hydrogen fuel. The strength of these types of cylinders is fully (for Type IV) or mostly (for Type III) determined by composite material made of wrapped carbon fibre in an epoxy resin matrix. The hydrogen storage pressure is either 35 or 70 MPa; however most of the car makers focus their activities on the 70 MPa technology because of the major advantage with regard to higher storage density per required mass or volume.

The dimensions of automotive cylinders seem to have a large variety in the range of 20L to 150L. In the large end of the range, the cylinder might become either long and slim or short and fat depending on the orientation of the cylinder on-board. However, when evaluating the integration of hydrogen storage cylinders for Fuel Cell Vehicles, there are various aspects that need to be considered.

Many times, the discussion whether system weight or needed package volume for the hydrogen storage system packaging has the higher priority takes place [1]. Of course, both parameters are important, e.g. weight is important because added mass adversely affects vehicle performance, e.g. cuts fuel mileage causing the fuel system to grow for the same range or decreases the vehicle performance causing a more powerful power train system. On the other hand, the sprung mass increases which requires vehicle structure enhancement. In addition, these factures lead automatically also to an increase in cost. Therefore each kilogram of added weight has an amplifier effect, making the car weight and cost more and possibly perform worse.

Below listed are the negative effects with regard to additional volume:

Bigger fuel storage systems require vehicle grows to be able to provide enough package space

extra structural burden needed (and increasing weight) Aerodynamic drag can be increased More wheel suspension and brake capacity required Considerably degradation of handling performance

As a consequence, the key challenge for the integration of the hydrogen storage system is to package the storage in the vehicle in such a way that the vehicle does not have to "grow" respectively the modifications of the base ICE (Internal Combustion Engine) vehicle should be limited. In an ideal world, the petrol tank would be removed and replaced with a hydrogen storage system without changing the vehicle underbody, structural framing or trunk compartments.

Subsequently volume is probably the biggest concern whichever hydrogen system concept is selected (especially in the near term before advanced designs reduce the volume storage system). A solution might be that Fuel Cell Vehicles need to be designed from the ground up around the storage system (resp. the fuel cell system) rather than simply fitted into existing ICE vehicle.

This concept has been realized e.g. in a Fuel Cell Vehicle, developed by the US automaker General Motors (GM). The GM Sequel (see Fig. 1.) has packaged the hydrogen storage cylinder in the centre of the vehicle, longitudinal to the vehicle axes. Because of this unique integration concept, the engineers have been able to store 8 kg of hydrogen in three cylinders. This vehicle was not based on an existing ICE vehicle platform; it was especially designed around the storage system and the fuel cell system.



Figure 1. GM Sequel Hydrogen fuel cell vehicle [2]

But of course there are numerous ways in integrating the hydrogen storage system into the fuel cell car. The cylinders can be mounted into the trunk, like chosen for the Ford Focus Fuel Cell Electric Vehicle (FCEV) (see Fig. 2.) or the Mazda RX-8 Hydrogen Rotary Engine (see Fig. 3.).

Figure 2. Ford Focus Fuel Cell Electric Vehicle (FCEV) [3]

Figure 3. Mazda RX-8 Hydrogen Rotary Engine [4]

The advantage of this configuration is that the underbody needs only minor adjustments and the rear axle could be possibly a carry-over of the ICE vehicle. Major disadvantages are of course the elimination of the trunk space and the additional efforts need to handle the permeation of the cylinders itself.

Other integration concepts are able to incorporate the storage system in the underbody area in front of the rear axle, like realized in the Mercedes Benz B-Class F-CELL (see Fig. 4 and Fig. 5.), Nissan X-Trail FCV 2003 Model (see Fig. 6.) and Hyundai ix35 Fuel Cell vehicle (see Fig. 7.). The advantage of this concept is the possibility that the rear axle could be possibly a carry-over of the ICE as well, however the available volume/package



space for the cylinders is limited and the ground clearance will be a critical aspect of the safety evaluations for this concept.

Figure 4. Mercedes Benz B-Class F-CELL [5]

Figure 5. Mercedes Benz B-Class F-CELL Assembly [6]

Figure 6. Nissan X-Trail FCV 2003 Model (2003) [7]



Figure 7. Hyundai ix35 Fuel Cell vehicle [8]

The Toyota's FCHV-adv Fuel Cell Vehicle (see Fig. 8.) combines the integration of the cylinders before and after rear axle, which gives additional package volume respectively storage capacity but the area behind the rear axle is of course critical from the crash point of view, because it is normally used as energy absorbing structure of the vehicle during a rear crash scenario.

Figure 8. Toyota's FCHV-adv Fuel Cell Vehicle [9]

Figure 9. GM Chevrolet Equinox Fuel Cell Vehicle Concept [10]



Also the GM Chevrolet Equinox Fuel Cell Vehicle (see Fig. 9.) uses a slightly modified approach in integrating two hydrogen cylinders before and one above the rear axle, which had the advantage to avoid major modifications of the rear axle design of the ICE, however resulted in a slight reduction of the trunk volume.

The concept of the hydrogen storage system contains already an improved fire protection method where each cylinder is equipped with a fire protection cover in addition to the TPRD incorporated in the valve on one end of the cylinder. The protection shield is composed of a thin stainless steel shell and a ceramic blanket inside of it to act as a thermal isolation layer to shield the composite with regard to external thermal impacts. Further details of the concept and the performance evaluation will be discussed in the later section of this work package.

The Honda FCX Clarity (see Fig. 10. and Fig. 11.) and the concept vehicle GM Chevrolet Volt Fuel Cell Vehicle (see Fig. 12.) position the hydrogen cylinder above the rear axle, requiring of course new rear axle and wheel suspension concepts to be developed.

Figure 10. Honda FCX Clarity Concept [11]

Figure 11. Honda FCX Clarity Assembly [12]



Figure 12. GM Chevrolet Volt Fuel Cell Vehicle Concept [13]

With regards to the Chevrolet Volt (see Fig. 12.), another cylinder was planned in front of the rear axle in the underbody area of the vehicle, increasing the available storage volume but also the complexity of the system layout and package concept.

If we review the mentioned integration and system strategies, some automakers are using multi cylinder systems, some are choosing a single cylinder strategy which is of course reducing parts and therefore decreasing cost resulting in lean storage system. Multi cylinder systems are enabling the usage of the available package space in the most effective way, leading to a higher available storage volume, respectively stored hydrogen mass. This on the other hand increases the system complexity and cost.

5.1.2. Tube Trailers (Bulk hauling)

Traditional bulk hauling for transport of compressed gases employs heavy steel cylinders or tubes. But the increasing demand for gas and a focus on cost, efficiency and safety today requires larger payloads of gas transported per unit. Also, corrosion issues play a significant role in a modern safety concept for gas distribution. The costs related to hydraulic retesting are significant and critically important if using steel cylinders or tubes due to this corrosion risk.

The target to substantially reduce the weight of transportable storage solutions can be achieved by the use of composite cylinder technologies, which has the potential to reduce the fuel cost versus transport cylinders out of steel as well.

Transport of compressed gas (primarily CNG and Hydrogen) is today done in either:

1) Tube trailer with very long cylinders (tubes) at pressure levels of 20-30 MPa (e.g. see Fig. 13.) However, technology is available today for pressures up to 95 MPa in large composite cylinders and length equal to the longest trailer that can be used on roads in Europe. The low weight of composite will open up for a better utilization of available volume on a trailer giving a payload of more than 1 metric ton of hydrogen on each trailer. Nevertheless, currently available standards (e.g. ISO 11515:2013) cover only composite reinforced tubes up to 3000l water capacity. The European Standard for transportable gas cylinders (EN 12245) considers only composite gas cylinders with a water capacity up to and including 450 l for compressed, liquefied and dissolved gases.



Figure 13. Hexagon Lincoln TITAN™ Module [14]

2) Bundles of smaller (less than 100L) cylinders [(M)ulti-(E)lement (G)as (C)ontainer] at 20-30 MPa (e.g. see Fig. 14.). Weight and size has so far been the limitations, but with higher pressure and use of composite cylinders, the size of the cylinders can be increased, and the payload can be significantly increased compared to what is used today.

Figure 14. Hexagon Lincoln SMARTSTORE™ Module [15]

In the following, possible solution of each transport approach will be further described.

1) Tube trailer with very long cylinders:

As an example, the Company Hexagon Lincoln has developed the TITAN™ Module, which enables the gas transport of up to 44.000 l WC (water content ) in single operation (see Fig. 15.) or up to 88.000 l WC in tandem operation at 25 MPa service pressure.

Figure 15. Hexagon Lincoln TITAN™ Trailer on the road



These moveable gas transportation units can be used for the transport of CNG, hydrogen, helium and other non-oxidizing gases. The units consists of 4 to 5 large TITAN™ tanks (each up to 8500 l WC at 25 MPa service pressure) per module, which are mounted into a steel transportation frame, able to fit into 30` and 40` ISO container modules and trailers for transportation via rail, truck or ship. The TITAN™ tank is designed specifically for bulk-transportation and to be mounted in an ISO 1496 certified shipping container, withstanding the required mounting and transportation loads. The dimensions and capacities of the 40`variant can be found in Table 1. below.

Table 1. Dimensions of TITAN™ tanks for gas transportation [16]

A Stainless steel plumbing system interconnects the container within the module, including a thermally-activated pressure relief system for fire protection, which will be described in later sections of the report (see Fig. 16.).

Figure 16. Front view of a TITAN™ module plumbing system [15]



Totally, the module tare weight of is between 13,100 and 15,830 kg. The other dimensions of the four tanks TITAN™ Module can be found in the table below (see Fig. 18.).

Table 2. Dimensions of TITAN™ modules for gas transportation (CNG) [15]

In addition to the standard TITAN™ Module with four TITAN™ tanks, there is also other customized options available with e.g. 5 TITAN™ tanks and additional smaller storage tanks to fill up the free space within the transport frame. Dimensions of the TITAN V™ trailer can be found in the table below (see Fig. 19.).

Table 3. Dimensions of TITAN V™ trailers for gas transportation (CNG) [15]



2) Bundles of smaller cylinders (MEGC Units): One solution for the integration of a large number of small cylinders into a trailer for transportation is the SMARTSTORE™ Module (see Fig. 17. and 18.), developed by the Company Hexagon Lincoln.

Figure 17. SMARTSTORE™ module for gas transportation [15]

Figure 18. Unloading a SMARTSTORE™ module [15]

The SMARTSTORE™ Module is a multi-element gas system which can be used for the transport of up to 18.000 l WC CNG, hydrogen, helium and other non-oxidizing gases. The service pressure of the cylinders can vary between 25 to 95 MPa. It can contain 10`and 20` ISO container modules, with a horizontal arrangement of up to 40 cylinders with each 450 l WC.



Table 4. Dimensions SMARTSTORE™ modules for gas transportation (CNG) [15]

A 30 MPa 11,000 m3 cylinder trailer composed of type III (aluminium liner) composite cylinders is currently under development within Air Liquide (AL). Some illustrations (commercial representations) are given in Fig. 19. and 20.

Figure 19. Example of hydrogen composite cylinder trailer (view 1)

Figure 20. Example of hydrogen composite trailer (view 2)



5.1.3. Transportable cylinders, bundles

Remark from Air Liquide:

All AL applications are under development meaning that their description may change in the future. Only generic design patterns are presented in this report. The presence or not of a fusible plug to release the pressure before the cylinder burst in case of fire is not yet established as designs and risks analyses are still in progress.

A type IV hydrogen composite bundle is currently under development within Air Liquide. It is composed of four cylinders having a 100 l-150 l water capacity.

Figure 21. Air Liquide first generations composite hydrogen storages

Its average specifications and prototype scheme are given below:

H2 distribution system Ps 52,5 MPa (70 MPa target) Capacity at 52,5 MPa / 15°C,

- ~ 200 m3 - ~ 20 kg of H2

Total weight ~ 700 kg

Figure 22. Air Liquide bundle prototype scheme and characteristics

Figure 23. Air Liquide bundle with digital image



The characteristics of the composite hydrogen cylinder integrated in the bundle are given below:

Type IV Water capacity: 140 L Ps 52,5 MPa Capacity at 52,5 MPa 15°C (70 MPa

target): - ~ 50 m3 - ~5 kg of H2

Figure 24. View of a single type IV hydrogen cylinder.

Up to date, hydrogen cylinders are not used as a single element but integrated in bundles.

5.1.4. HyPulsion fuel cell systems for forklifts

All the elements that constitute the forklift driving system are integrated in a “box” (see Fig 26.).

Figure 25: Different elements integrated inside the HyPulsion fuel cell systems

for forklifts

The forklift integrated system contains:

o A fuel cell

o A 35 MPa hydrogen storage equipped with its pressure regulator

o A battery

o A water retention tank

The hydrogen content is between 1 kg and 1.5 kg in each forklift.



Figure 26: Integrated box installed inside the HyPulsion fuel cell systems for

forklifts.

Figure 27: Example of flexible connection to the HyPulsion fuel cell systems for

forklifts



5.1.5. Stationary application

5.1.5.1. Hydrogen refueling station for Fuel Cell Vehicles

One of the main future stationary applications for composite pressure vessels are hydrogen refueling stations (HRS) for Fuel Cell Vehicles. In Fig. 29, the situation of already operating and planned stations mid of 2012 is displayed:

• 17 HRS with 70 MPa, 13 are public accessible • 8 HRS with 35 MPa, 4 are public accessible

Figure 28: HRS distribution in Germany (May 2012) [17]

However, the number of installed HRS will increase significantly in the future due to various activities in national and international partnerships to support the expected launch of fuel cell vehicles by various vehicle manufactures starting in the 2015 time frame. A potential scenario for a nationwide coverage of H2 stations in Germany is shown in Fig. 30:

Figure 29: Projected HRS coverage in Germany for 2020 [17]



As an example, the automaker Daimler, the oil company Total, Shell and OMV and gas specialists Linde and Air Liquide are going to form a joint venture for the construction of HRS [18]. The companies had already jointed together in 2009 on the initiative "H2 Mobility", which has the structure of a hydrogen infrastructure to the target. Within the new agreement, a total of 400 stations for the supply of fuel cell vehicles will be built by 2023, the first 100 should be already created till 2017.

To enable the realization of those scenarios, different HRS concepts are feasible. All conceptions contain in one or the other way hydrogen storage capabilities, which can be provided by composite cylinders. Some major design principles are illustrated in the following sections:

1) Cascade Filling (multi-bank refuelling concept):

Figure 30: Typical design of a 3-Stage cascade HRS [17]

2) Booster refuelling concept:

Figure 31: HRS with Booster compressor [17]



3) Station with onsite generation of compressed hydrogen gas (CGH2):

Figure 32: HRS with onsite generation of CGH2 [17]

4) Liquide (LH2) - Supplied CGH2 HRS:

Figure 33: Liquide (LH2) - Supplied CGH2 Refueling station [17]

As seen in the examples 1) to 3) above, instead of using tube trailers as the hydrogen source, composite hydrogen cylinder/tubes or bundles could be installed at the refuelling station. Potential concepts for the location are e.g. the placement of the cylinder in in ground storage submerged in water. This has the advantage of a very good protection against external fire impacts. Another possibility is the storage on top of a container at the station or in a certain safety distance nearby the station to enable a good protection against external impacts and to ease the release of gas in case of a leak scenario.

The use of composite cylinders is possible for all desired pressure levels for the hydrogen storage at the stations ranging from low pressure high volume storage at 15 to 30 MPa up-to the highest pressure of 95 MPa, which is used for fast cascade filling without the need of an active compressor for the final top fill of the vehicle.

5.1.5.2. HRS for Fuel Cell Forklifts

Stationary filling stations are also necessary to provide fuel for Fuel Cell forklifts. The use of hydrogen as an energy carrier for logistic platforms has been developing in the U.S. and Canada, with over 3,000 forklift trucks currently running on hydrogen. Up to date around 10 forklift refuelling stations have been deployed.

As another example, Air Liquide is going to provide a HRS for a logistic platform in France. In the context of this project, the hydrogen filling station will supply around twenty forklift trucks powered by hydrogen fuel cells. Air Liquide's filling station will supply hydrogen at a pressure of 35 MPa, with refills in few minutes. Replacing electric batteries with fuel cells provides greater flexibility and productivity thanks to a longer operating range for users and a shorter down-time for refilling.



Figure 34. HRS principles

The HRS is composed of a hydrogen source, a compressor, buffer cylinders (type I, type III or type IV) and a dispenser. A general illustration is presented in Fig. 36.

Figure 35. Air Liquide 70 MPa HRS illustration

Figure 36. Warehouse view with human-machine interface and dispenser

dispensercompressor

200 bar 450 bar

outdoor

warehouse

dispensercompressor

200 bar 450 bar

outdoor

warehouse

compressorcompressor

200 bar 450 bar

outdoor

warehouse



Figure 37. HRS equipped with tube trailers as H2 source

Figure 38. Layout of a HRS with tube trailers



5.2. Description of existing fire protection designs


An overview about current and future fire protection concepts has been provided in [19]. Whether a high pressure composite cylinder will need a special fire protection will be evaluated, simulated, tested within and concluded as outcome of the FireComp Project. The following pages provide a summary about techniques currently available on the market and which might be promising future solution.

Currently, the most commonly used fire protection strategies rely on the use of thermally-activated pressure relief devices (TPRDs). Alternative methods for protecting a cylinder from fire effects include coating systems that shield from the heat and fire and heat detecting techniques that will remotely activate the attached pressure relief device.

Considerations of the cylinder installation/package in the vehicle can also significantly influence the chance of a cylinder being exposed to external fire effects. Nevertheless, integration methods will not be considered in this summary due to the reason that there is a wide variation of vehicle architectures and concept (as seen in section 5.1 of this report) and more important, there are several ways a vehicle fire can propagate itself, including:

Passenger compartment fire Vehicle cargo fire Tire fire Collision fire from spilled liquid fuel Engine compartment fire

Hence, an effective fire protection concept for the individual composite cylinder will anyway minimize the threat of each possible fire scenario.

Methods of protecting hydrogen cylinders from fire effects, other than the standard use of TPRDs, may be separated into 3 types of systems:

Coating systems that have intumescent properties Heat insulating wraps or shells Heat detection systems that activate remote pressure relief devices (PRDs)

In the following sections, some examples of the different kinds of fire protection concept are further described:

Thermally-activated pressure relief devices:

Within TPRDs designs, which are currently used for high pressure composite cylinders, we can find two main activation modes respectively trigger mechanism:

1) TPRD with a fusible material (see Fig. 40. and 41.), that melts and flows under the influence of heat.

2) TPRD with a glass bulb (see Fig. 42. and 43.), that breaks under influence of heat.

Figure 39. TPRD with Eutectic alloy ring [20]



Figure 40. TPRD with Eutectic alloy puck [21]

Figure 41. Glass bulb TPRD – End Plug [22]

Figure 42. Glass bulb TPRD for valve integration [23]

Both TPRD concepts induce the movement of a piston inside of the valve body after the activation, which allows gas venting from the container internal volume to the outside before the integrity of the pressure reservoir is impacted by the external thermal load. One major risk of the TPRD concept is that blockage of the gas vent path must be avoided in any case.

Relief devices activated by pressure cannot be used in composite cylinders as the required pressure increase during thermal heating is not pronounced enough (due to the low thermal conductivity of the composite) to reach the trigger pressure of the pressure-activated relief devices, as the values also needs to be high enough to not being triggered during the proof test of the cylinder (normally 1.5 times the nominal working pressure). In addition, the excessive pressures required for activation will not be achieved if the cylinder is only partially filled.

Therefore, most CNG and hydrogen cylinder standards specify that the device, relieving the pressure of the cylinder in case of a fire, shall only activate when exposed to heat.



Typically, TPRDs can be found attached to a valve at one end of a cylinder (see Fig. 44) and they will only function fast enough if they are directly exposed to the external thermal load. Therefore, a fire occurring on a cylinder remote from the TPRD will probably not activate that device fast enough to avoid a rupture of the cylinder.

Figure 43. Concept with 1 TPRD on one side of the cylinder

If the protection concept contains out of two TPRDs placed on both ends of the cylinder (see Fig. 45.), the area covered by the heat sensing devices is larger and only the cylindrical section of the cylinder might be without supervision.

Figure 44. Concept with 2 TPRD on one side of the cylinder

Anyway, high pressure system integrator (which designs the integration of a vessel in a HP system) needs to evaluate the time to opening, which may be highly dependent on the thermal flux and the actual flow rate.

Indeed, there are a lot incidents reported [24], in which the TPRDs failed to open either due to the lack of heat induced towards the trigger element or the slow venting behaviour which was not able to reduce the cylinder pressure fast enough to avoid the rupture.

As specified in various CNG and hydrogen cylinder standards, the bonfire test requirements of specify the length of the fire used to assess the performance of a TPRD as protection device for a specific cylinder design, is 1.65m [25, 26]. Therefore on cylinders exceeding this length, it is often required to add additional TPRDs (e.g. by using a high pressure piping with TPRDs along the cylinder) to ensure at least one TPRD is within the bonfire source and able to activate fast enough before the cylinder ruptures.

Due to the fact that the use of TPRDs (attached to an exposed high pressure tube) is only used on large tanks, this approach hasn’t been used in existing hydrogen vehicles. In addition, it introduces an additional risk due to high pressure lines external to the tank. This design approach introduces the risk of the uncontrolled release of high pressure hydrogen in a collision. Furthermore, additional TPRDs are only effective if their position on the cylinder happens to correspond to the location of a localized fire condition.

Coating systems with intumescent properties:

Paint coatings that shield the composite with regard to external fire effects could be a way to improve fire protection because they are able to be naturally thin, light, and potentially lower cost than other options. The nature of the fire resistant coatings is typically being intumescent, that means the material swells when exposed to heat, generating an insulating layer (see Fig. 46.). However test data provided in [17] showed that intumescent paint coatings will only offer limited protection from heat effects, especially where high flame temperatures might be encountered. In addition, some



intumescent paintings lose their mechanical properties with fire aggression. They can even fall during the exposition to fire (even without vibration of the system).

Figure 45. Intumescent paint on bottom of composite cylinder during exposure

to fire test [17]

Intumescent Epoxy Coatings (e.g. Pitt-Char XP”, by PPG Industries, see Fig. 46.) are alternative solutions and can be applied to any thickness to adopt the required protection performance for the application needs. When exposed to fire, the chemical composition transforms the surface of the coating into a ceramic-like, insulating char that provides thermal protection for the product even under high thermal loads. PITT-CHAR XP e.g. is typically applied in dry-film thicknesses from 5 – 20mm depending on the required protection performance. When fire strikes, it forms an insulating, ceramic-like layer of char, 5 – 6 times as thick as the original coating [27]. However, special spray application is necessary to apply the coating in a reliable and uniform distribution.

Figure 46. Intumescent coating before (left) and after fire exposure (right) [17]

Figure 47. Composite cylinder wrapped in Flexible Ceramic Fibre Blankets [17]

Intumescent coating after drop tests



Heat insulating wraps or shells:

Another fire protection option is the use of ceramic fibre blankets, which are wrapped around the cylinder (see Fig. 48.). As reported in [17], tests have shown that relatively thick fibrous ceramic blanket materials would provide the necessary fire protection to hydrogen cylinders. A challenge remains to find a ceramic material that can be easily conformed to the shape of a composite cylinder requiring only minor package space needs, for reasonable cost and without adding much weight. A major concern with the use of wrapped materials is that they must be held into place on the cylinder surface by some means of mechanical fixation, which of course is not an appropriate solution for the automotive application but might be able to be developed within this regard.

To overcome this problem, the use of more flexible and self-adhesive materials should be more beneficial, that will adopt the shape of the object as it is wrapped around. Supplied in a wet condition, once removed from its sealed package and wrapped around a cylinder, it dries into place (see Fig.49.).

Figure 48. Application of wet felt wrap to cylinder [17]

The performance of such kind of product has been already proven, but the used material was very brittle after drying, which would have the consequence to be not suitable for handling during cylinder installation into the vehicle fuel system [17]. Therefore, improved materials have been developed with increased surface hardness and resistance to erosion when applied to the surface of the felt wrap.

With regard to insulating shell concepts, an alternative approach was already mentioned in the former section of the report by using stainless steel heat shields out of metal (see Fig. 50.).

Figure 49. Heat damage to stainless steel shell after bon fire test [17]



The concept consists of an outer shell out of thin stainless steel sheets. On the inner surface of the casing, a ceramic blanket material below an aluminium foil is incorporated as isolating barrier for the composite shell with regard to external thermal loads. It has successfully demonstrated its performance during a 30 minute localized fire test with temperatures of at least 900ºC without a rupture of the carbon fibre cylinder at 70 MPa during the test [17].

A disadvantage of the concept is of course that the associated product costs are rather high. Furthermore, the inspection of the composite shell during regular inspection procedures is not possible without removing the heat shield which requires a disassembly of the complete system at the end. With regard to the system assembly, the handling of the heat shields add time during the installation process which is and requires mainly manual operation which is not favourable with regard to high volume production demands.

If the thermal encapsulation is driven to a higher extends, the complete storage system might be encapsulate with insulating and impact resistant foam, like shown in Fig. 51.

Figure 50. Thermal encapsulated cylinder system [28]

Heat detection systems that activate remote pressure relief devices (PRDs):

The current assumptions with regard to the application of remote sensing technology within the automotive industry is that they could not be an “active” system, i.e. rely on the electrical supply of the vehicle to function because the functions during e.g. a crash cannot be guaranteed. Whereas passive fire protection systems (coatings or thermal shields) are able to protect the container from localized fire without the need for a TPRD, all remote sensing technologies require a pressure relief device, typically of a design that is specific to the heat sensing technology as an integral component of the system.

Heat Transfer Liquid Tube:

One example could be a copper tube containing a “heat conduction” liquid, which is placed lengthways of the cylinder. It needs to be connected to a pressure relief device located at one end the cylinder.

Heat Transfer Metal Tube:

In a variation on the liquid tube concept, this concept is using a metal line with high heat conduction properties. The line is also placed along the length of the cylinder, connected to a pressure relief device located at one end as well.

Fuse Wire:

A system, which uses an ignition cord that ran the length of the cylinder, with connection to a PRD located at one end (See Fig. 52.).



Figure 51. Fuse wire and glass bulb on cylinder [17]

The fuse wire can be wound around the length of a cylinder. Once ignited due to elevated temperatures, it will burn to the PRD. The heat from the ignited cord will break the glass bulb and allow the release of gas through the TPRD. In comparison to metal tube concepts, the ignition cord concept could have some significant benefits:

- It does not ignite under external impacts e.g. cutting with a knife - It is resistant to moisture and will burn underwater because it is encapsulated in a

plastic cover - It does not require direct flame impingement to ignite – air temperatures over

150ºC are sufficient

Mechanical Activation Tube

This heat detection technology is using shape memory alloy (SMA) wire routed within a tube. Only a small portion of the tube (around 300mm) needs to be heated to cause a contraction of the SMA wire. This change in length pulls open a piston in the pressure relief device, releasing the cylinder pressure. One concept tested in [17] is using a SMA wire which shrinks roughly 5% when heated (from ambient) to 108ºC and can be placed in a tube up to 2.4m long.

An example for a fire test with a composite cylinder protected by a long SMA tube connected to a piston-activated PRD located outside of the fire can be seen in Fig. 53.

Figure 52. Fire test with composite cylinder protected by a mechanical

activation tube [17]



5.2.2. Tube Trailers (Bulk hauling)

The use of PRDs in the bulk transport of merchant gases is not universally applied or accepted in many of the world markets, e.g. in European countries, the use of PRDs on transport pressure vessels is either optional or explicitly prohibited by the regulations. This philosophy is based on both an understanding of the older metal technology and the practical fact that various PRDs used in the transport of merchant gases have questionable operational reliability.

Metal cylinders have shown over time an acceptable level of safety if the lading has been properly matched to the vessel. This perceived level of safety mated with a rigorous inspection infrastructure has led to many attempts to expand the prohibition of PRDs wherever possible by the gas supplier industry.

The reliability of a metal vessel can be projected to be many times better than the typical PRD and valves used in the merchant gas market. In many cases the addition of PRDs in metal transport cylinders can reduce the overall safety performance of the system, provided of course the vessel has been appropriately filled.

Composite pressure vessels have uniquely different performance from the metal cylinders they replace in the market. Because of the unique character of composite materials the use of PRD on composite cylinders must be considered.

The application of composite vessel technology to bulk transport makes it imperative that adequate fire protection needs to be provided at the system level. This protection must be provided without decreasing the containment reliability of the assembly. In dense pack installations the requirement to use PRDs to protect each individual cylinder is not practical as the high pressure lines, fittings and PRDs themselves work to reduce the overall safety of the MEGC.

This means it becomes necessary considering the module as a “single” containment vessel and not an assembly of individual vessels. As un-separable assembles, with single point shut-off valves and an integrated fire protection system they become standalone units specific to the bulk transfer of gas.

As an example, the fire protection system of a TITAN™ Module is further described in the following section (see Fig 54. and 55.).

Figure 53. TITAN™ module component overview



The TITAN™ Module is using a different and unique system in comparison to an automotive application because a storage cylinder in a vehicle has a relatively small volume and can simply vent through the PRDs itself. The Titan tanks have too much volume to vent through such a small orifice in a short time period. Therefore, this concept is using the heat sensing elements to activate pneumatic valves, connected to the inner tank volume, which have a much greater flow area and will allow the system to vent safely before failure occurs.

A plumbing system under pressure is connected to the pneumatic valves, which serve as the vent valves in case a fire is detected. The lower left tank constantly feeds the fire protection system with gas, which means it will keep pressure on the system if small leaks occur. This holds the normally open valves closed during daily operation. The heat sensing part of the system are shape memory alloy wires, routed on each corner of the container along the tanks. They are all connected to a second valve, which is connected to the pressurized piping system as well.

Figure 54. TITAN™ module component overview

In a fire, respectively when a temperature above 108°C is detected, the shape memory alloy wire changes shape and shrinks pulling a trigger that creates a flow path in the valve body that it is connected to. When this occurs, the fire protection system can no longer hold pressure. As a result, the pneumatic valves are opening and all Titans vent simultaneously. The entire system is interconnected so if there is only a fire under one small area, it will nevertheless vent all tanks at once. The tank valves will vent the content of the tanks in about 45 to 60 minutes.

Figure 55: Picture of an Air Liquide cylinder trailer



Many requirements, already existing for trailers composed of steel tubes or cylinders (e.g. Fig 56.) could be applied for the development of composite trailers. Most of them are required by the ADR regulation (Agreement Concerning the International Carriage of Dangerous Goods by Road).

o According to the ADR regulation, trailers in flammable gas service must be equipped with isolating valves. It helps to prevent the release of large amounts of product in case of rear impact.

o The use of TPRDs (instead of PRD) for composite cylinder trailers is not established and could be decided as a function of the cylinders maximum service pressure and the associated calculated safety distances. A TPRD would prevent the tube from rupturing. When it is actuated, the gas released must be safely vented, for example through a vent pipe, and the extremity of the vent pipe must be protected from water and other contaminant ingress.

o Rear protection from impact should be provided for the main valves if any, and the TPRDs when used.

o Trailer drivers should be protected from flammable gas leaking. Therefore, trailers transporting flammable gas could be equipped with a barrier. This barrier protects the driver compartment from leaking flammable gas which may ignite.

o Lateral protection (or other suitable protection) from external fire or tyre fires could also be installed.

o Bundles and their fastenings shall be able to resist to acceleration of 2 g in both directions for road transportation and 4 g for train transportation. Calculation of the fastening system resistance must be verified by a competent person.

Some additional requirements are:

o A grounding lug shall be provided.

o Fire extinguishers shall be available on the trailer or in the tractor (depending on local regulations).

5.2.3. Transportable cylinders, bundles

Type III and type IV cylinders would likely have their strength compromised by the fire before the pressure increased enough to vent through a pressure relief valve. Therefore, in case the induced fire effects are too important, they could be protected by a temperature sensitive pressure relief device. Within Air Liquide, the use of TPRDs is not systematic and depends on several parameters as the service pressure, the safety distance and the storage integration. As already underlined before, the use of a TPRD is not yet defined in AL.

In order to avoid consequences such as overpressure or fire ball effects, following safety barriers have been added:

o A steel wrapping composed of six plates all around the bundle structure as shown in Fig. 57. The thickness of the metallic shields is a few millimetres. The objective is to delay the thermal aggression of the cylinders.

o If required, the TPRD could be located at the top of the bundle, slightly at the back on the opposite side of the operator and collected into a vent (see figure 8). It consists of a thermal fuse composed with a eutectic that melts at about 110 °C.

o A calibrated orifice located before the TPRD in order to limit and control the released hydrogen flow in case of TPRD opening.

o A pressure relief device, PRD and more precisely a pressure relief valve, to protect the 1 MPa outlet piping, collected into a vent located beside the TPRD vent as shown in Fig 52. In operation, venting systems (TPRD and PRD) are collected to increase the release height.



o A mechanical protection against flammable leaks that could lead to flames and impact cylinders from cylinder fittings and manifold all located at the front (Fig. 57.). In order to avoid the formation of an explosive atmosphere in the space between the external steel plate and the mechanical protection, opposite venting grids are installed on the top and the bottom on the external structure of the bundle (Fig. 58.). The design of the grids is based on a conservative 0.1 mm leak diameter assumption on fittings.

o Figure 56. Representation of the metallic structure of the hydrogen bundle

Figure 57: Virtual view of a hydrogen bundle with the venting grids and the

TPRD and PRD vents

5.2.4. HyPulsion fuel cell systems for forklifts

Description of the protection device for HyPulsion fuel cell systems for forklifts, developed for the logistic station in France:

o Pressure regulator

o Isolating valves



o Flow rate limitation to avoid the temperature increase during the hydrogen filling operation and a continuous temperature measurement inside the hydrogen storage.

o Non-return valve could prevent the draining of the storage.

o The fuel cell and the forklift carry CE marking should be in conformity with European Directives.

o As shown on Fig. 59. , the hydrogen storage could be located inside a cast iron envelop (also called the “ballast”) to protect the container from shocks and thermal exposures.

o Fusible plug (TPRD).

Figure 58: 35 MPa Hydrogen storage surrounded by an external envelop

Accident experience on forklift comes from North America. The H2incidents.org database updated by the Department of Energy in the US contains only two accidents involving forklifts. For both the fuel cell was damaged but not the forklift.

5.2.5. Stationary application

The different measures cited below for fire safety are specific to the main hydrogen source of the refuelling station and the dispenser. The fire safety of the buffers is not detailed:

o The piping between the hydrogen source and the refuelling station

- is mainly outdoor

- tubes are welded

o Calibrated orifice at the warehouse entrance to limit the hydrogen flow rate at in case of flexible leak

o Man-machine interface (MMI) deported

o A safety distance from any combustible materials should be defined calculated from a 8 kWm-2 domino effects assumption for buildings (see Fig. 60.)

o Filling flexible manipulated without pressure

o Break away device on the flexible

o Isolation valves to limit the volume in case of fire inside the warehouse

o Control of all piping by pressure measurements

o Close control loop between the HRS to the warehouse one

o Hydrogen and flame detection near the dispenser in the ware house and near the compressor outside the building

o The wall near to which the dispenser is installed could have firebreak properties



Figure 59. Representation of safety distances around the dispenser and MMI

For the direct fire protection of the composite cylinder, it is possible to use rather simple method of winding a plastic hose around the cylinder, which is under nitrogen (N2) pressure and is additionally linked to a relieve valve. In case of an external fire impact, the plastic hose melts at a certain temperature with the consequence of losing the pressure before the composite structural strength is weakened too much. Subsequently, the connected valve opens and relieves the pressure of the storage cylinders.



5.3. Mapping of existing cylinder standards requirements


The following section provides a summary of the automotive cylinder standards and associated testing requirements for withstanding fire exposures.

FMVSS 304

U.S. federal requirements for CNG vehicle fuel cylinders integrity are described in FMVSS 304 [31]. The stated purpose of FMVSS 304 is “to reduce deaths and injuries occurring from fires that result from fuel leakage during and after motor vehicle crashes.” The FMVSS 304 requirements were developed based on the ANSI standard NGV2. Although it’s a CNG specific standard, it’s currently used as basis for the qualification of Hydrogen storage systems as long as no Fuel Cell Vehicle specific FMVSS is published. The bonfire test described in FMVSS 304 requires that two CNG cylinders be tested, with one filled to 98% of its service pressure and the second cylinder filled to 24% of its service pressure.

Remark:

The different pressure levels for the bon fire test are a unique requirement within the FMVSS 304. All other high pressure container standards or regulations require only one test at the nominal working pressure. Since most CNG cylinders are equipped with a thermally actuated Pressure Relief Device (PRD) next to the cylinder valve, the test has specific requirements for the cylinder and PRD location above the burner, as shown in Fig. 61. and 62. Cylinders shorter than 1.65 m are situated over the centreline of the burner, but cylinders longer than 1.65 m are situated such that the PRD(s) and valve are not directly exposed to the burner flame. The PRD on the short cylinder shown in Figure 61 is required to be shielded from the burner flame by surrounding it with a box made of steel plate. If the cylinder is protected with thermal insulation instead of a PRD, it is positioned symmetrically with its centre directly above the centre of the burner.

Although the burner fuel and flame heat release rate are not prescribed in FMVSS 304, there are prescriptions for the gas temperatures exposing the cylinder. Three thermocouples are installed 1 inch (2.54 cm) above the bottom of the cylinder, equally spaced along a line parallel to the cylinder longitudinal axis. The average gas temperature measured with these thermocouples must be at least 430 °C within five minutes from flame ignition. The CNG container must successfully withstand exposure to the bonfire flame for at least 20 minutes, or until the gas contents of the container are vented via the PRD to a pressure less than 100 psig (689 kPa), as measured with a pressure transducer.

Figure 60. FMVSS 3O4 Bonfire Test for cylinder shorter than 1.65 m [24]



Figure 61. FMVSS 3O4 Bonfire Test for cylinder longer than 1.65 m [22]

In [32], The Fire Technology Department of Southwest Research Institute (SwRI) performed a series of tests on compressed hydrogen cylinders in accordance with the FMVSS 304. Among other testing, six cylinders have been subjected to the bonfire test described before and they all successfully released their contents in less than 3 minutes after exposure had begun. The test setup was instrumented with 11 thermocouples (see Fig. 63.). Three thermocouples measured the flame temperatures 1 in. below the cylinder surface. Three thermocouples measured the lower cylinder surface temperature just above the flame temperature thermocouples. Three thermocouples measured the surface temperature at the front, rear, and zenith of the cylinder’s longitudinal center. One thermocouple measured the temperature on each the TPRD end (valve end) and the opposite end of the cylinder (non-valve end). The following figure outlines the thermocouple (TC) layout for the bonfire tests.

Figure 62. Thermal Couple Layout of FMVSS 304 Bonfire test by SwRI [32]

Typical bonfire test temperature profiles are shown in Fig. 64. It can be seen that the flame temperature reaches values up to 600°C already within 2-3 minutes after flame ignition. At the valve side, equipped with the TPRD, the temperature values measured on the surface are smaller, reaching temperatures of ~ 300°C also after 2-3 minutes. Still, the test conditions provide the TPRD rather high thermal loads already after a short period in time after test start.



Figure 63. FMVSS 304 Bonfire test temperature profile [32]

Therefore, a conclusion was that the test evaluates only whether the test setup can engulf a TPRD in flame. Although the procedure specifies for the TPRD to be shielded against direct flame impingement from below, in a fully engulfing fire scenario, the radiant heating effects from above will provide enough heat for activation. The bonfire test standards, as written in FMVSS 304, do not provide a safety measure small/localized fire/heating scenario that does not directly heat the pressure relief device.

EC79/2009 and EU406/2010

The EC79/2009 (resp. EU406/2010) [24 and 25] is using only carry-over bonfire test requirements from the FMVSS 304 approach. Whereas the FMVSS 304 requires testing of 2 different pressure levels (100% and 25%), the EC79/EU406 only requires testing @ 100% nominal working pressure. The only other difference is the higher target temperature of 590°C after 5 minutes of ignition.

SAE TIR J2579:

The latest, released version of the SAE TIR J2579 published Jan 2009 [33], is still referring to the same bonfire test concept, as described in the FMVSS 304. Nevertheless, one important difference between the approach in SAE J2579 and the NGV2, ISO/DIS 15869 and EC 79/406 approach is that SAE J2579 is intended as a vehicle fuel system standard for vehicle OEMs (Original Equipment Manufacturer), covering the whole hydrogen fuel system in its requirements, whereas i.e. the NGV2 is a cylinder standard developed primarily for the vehicle aftermarket, concentrating on the container and its performance testing itself.

Fig. 65. shows a schematic diagram of the compressed hydrogen storage system (CHSS) addressed in SAE J2579. The dashed line designates the boundary of the hydrogen storage system, which includes the PRD, the container isolation valve and the fill check valve.



Figure 64. Hydrogen Fuel System definition in SAE J2579 [24]

However, the SAE TIR J2579 document is currently under development mainly due to the inadequate fire test requirement.

To improve the fire test requirement, a study was conducted [34] to examine the CNG cylinder in-service failures during the past decade. Approximately 26 cylinder failures were identified in the 2000-2008 time period. Based on available information, the failures were categorized according to their root cause. As indicated in Fig. 66., the highest occurrence (~50%) for in-service failures is related to vehicle fires.

Figure 65. CNG Cylinder In-Service Failures from 2000-2008 [34]

Upon further review of these failures, the majority of these incidents occurred on storage systems that did not utilize properly certified PRDs. In 1998, a performance-based CNG PRD standard was developed (ANSI/IAS PRD 1-1998) which significantly reduced these types of failures.

There were only a few vehicle fires in cars and buses where PRDs did not respond to protect the container due to the lack of adequate heat exposure on the PRD during the localized fire. A summary of the incidents has been provide in [35]:

1) Ford Crown Victoria (Madison, WI)

A Type 2 (steel lined, glass fibre hoop wrapped) cylinder ruptured in a fire. The CNG vehicle was a 1996 Ford Crown Victoria. The incident investigation focused on the TPRD. The TPRD was removed from the failed cylinder and subjected to a yield temperature determination test. It was concluded that a directed flame from inside the vehicle onto the cylinder compromised the cylinder’s hoop strength, which allowed the cylinder to fail before the TPRD’s fuse could melt to release the gas.

2) Honda Civic (Seattle, WA)

A type 4 cylinder, with a TPRD installed in a Honda Civic CNG vehicle, exploded as a result of a vandalism fire set in the vehicle. The CNG cylinder exploded as fire-fighter



crew approached to a distance of 50-75 feet. There were no injuries, but 12 vehicles were damaged or destroyed in the explosion and subsequent fires. Debris from the explosion was thrown up to 100 feet in all directions including on the overpasses above the incident.

The Investigation determined that the cylinder ruptured before the TPRD activated to release the gas due to localized fire. It has been surmised that a plastic/rubber vent box covering the valve/TPRD may have shielded the TPRD during the fire.

In one test later, a Honda Civic CNG vehicle was set on fire to re-create a potential explosion resulting from an arson fire. A gasoline soaked rag was ignited and thrown into the rear seat of the passenger compartment. Although the TPRD activated and began venting the CNG cylinder contents after an elapsed time of 19 minutes, 49 seconds, the cylinder ruptured after 21 minutes, 34 seconds.

3) CNG Bus Fire – Bordeaux, France

A type 4 cylinder, installed in an OEM Bus, ruptured when vandals set fire to the bus (Molotov cocktail thrown into the passenger compartment). One of the roof mounted cylinders burst within 10 minutes after the fire broke out. Horizontal jet flames were witnessed, indicating the remaining TPRDs released the fuel in the other cylinders.

4) CNG Bus Fire – Monbeliard, France

A type 4 cylinder, installed in an OEM Bus, ruptured after a small fire started in the engine compartment due to a short circuit. The TPRD activated but system design restricted the vent rate, causing the cylinder closest to the fire to burst. The TPRDs were fitted with 1.5 mm flow limiters in order to comply with a French regulation that mandates a CNG release time of 25-35 minutes. The fire broke through a roof opening located 20 cm ahead of the ruptured cylinder, creating a localized thermal stress in the cylinder mid-section. In addition, it was postulated that the ignited CNG release from the adjacent cylinder’s TPRD impinged on the ruptured cylinder.

5) CNG Bus Fire – Saarbrucken, Germany

A type 3 cylinder installed in an OEM Bus ruptured approximately 9 minutes after a fire broke out in the bus’ engine compartment, which started because of an oil deposit close to the hot gearbox. 19 out of 20 CNG cylinders exposed to fire behaved as expected, with the two TPRDs per cylinder activating for a controlled release of the stored gas. After the fire was thought to be “in control” and 15 minutes after fire initially broke out, one of the cylinders burst.

After investigation it was determined that one of the 38 TPRDs did NOT activate because the eutectic fuse did not have time to melt completely (TPRD “freezing”). A fire-induced short circuit triggered the opening of a roof-mounted door which directed the flames to the cylinder sidewall. This localized fire resulted in the weakening of the cylinder in an area away from the TPRD.

Even though there were only a few incidents of localized vehicle fires (none with FCEVs or hydrogen vehicles), the severity of the events has prompted the respective SAE Working Groups to address this potential failure mode in the future by developing a localized fire test.

The first step was to determine the scope of the test article for the proposed test. It was clear that the test should be at least at the systems level so that the entire CHSS would be exposed to the fire and that the PRDs would have opportunity to protect the high pressure hydrogen containers from failure. Additionally, the working group foresaw that additional protective features, such as thermal shields, for example, should be allowed (if used on the vehicle) to provide protection during at least the localized portion of the fire.

As an alternative to a systems level test, the SAE Working Group considered expanding the test to the entire vehicle, with all fire protective features included, whether attached to the CHSS or part of the vehicle design, but concerns about the practicality of such



testing were raised. Therefore, it was decided to develop a compromise where the test would be conducted at the CHSS system level, but the test method would allow for options in conducting the test that could include protective features that were either attached to the CHSS itself or part of the vehicle depending on the test method option selected. By providing two options for the test method, the vehicle manufacturer or integrator is able to either define a CHSS with integral fire protection features that can be used on more than one vehicle, or to design and test a system that can only be used on vehicles with the specific protective features verified during the localized fire test.

The size for the generic localized fire test was defined to be 250mm ± 50mm longitudinally with a width covering the diameter of the container. Thermocouples must be located 25 mm ± 10mm from the outside surface of the test article are used to control the heat input and confirm that the required temperature profile is met. In order to improve the response and controllability of the fire during testing (as well as reproducibility of results), the use of Liquefied Petroleum Gas (LPG) and wind guards are specified. Experience indicates the controllability of the LPG fire will be approximately ±100°C in outdoor situations, producing peak temperatures that also agree favourably with test results.

If the vehicle manufacturer or integrator elects to use the specific vehicle test approach, the size of the localized fire would be specified and documented by identifying the localized fire exposure area in the vehicle-installed configuration. The localized fire exposure is defined as any hole or pathway within the vehicle that could allow the container in the CHSS to be exposed to localized fire. Hence, the specific vehicle test set-up can take advantage of a CHSS that is effectively integrated in the vehicle with reduced localized fire exposure. In addition, the size of the localized fire may have to be reduced from the size used in the generic test to capture the effect of the vehicle features.

Another important parameter is the establishment of the time/temperature conditions when performing the systems level test. The Japan Automobile Research Institute (JARI) and US manufacturers shared information with the SAE Working Group to support the definition of the test conditions. The data addressed fires in conventional passenger cars and vans and considered that the fires could originate in the passenger compartment, luggage/cargo compartments, or wheel wells. Specially-instrumented containers were installed transversally in typical locations within different vehicles configurations (see Fig. 67.) to assess the fire exposure on the container end bosses where PRDs are conventionally located and container side walls that could be compromised.

Figure 66. Overview of Vehicle Fire Tests [34]

Review of the vehicle laboratory test data revealed several interesting findings:

1) About 40% of the vehicle laboratory fires investigated resulted in conditions that could be categorized as a localized fire since the data indicates that a composite gas container could have been locally degraded before conventional PRDs on end bosses (away from the local fire exposure) would have activated.

2) While vehicle laboratory fires often lasted 30-60 minutes, the period of localized fire degradation on the storage containers lasted less than 10 minutes. See Fig. 68. for test results of specific cases that were investigated.



Figure 67. Time of Localized Degradation during Vehicle Lab Fire Tests [34]

3) The average of the maximum temperature during the localized fire period was less than 570°C with peak temperatures reaching approximately 600°C in 2 cases and 880°C in one case (see Fig. 69.).

Figure 68. Temperatures Measured During Localized Portion of Vehicle Lab Fire Test [34]

4) The rise in peak temperature near the end of the localized fire period often signalled the transition to an engulfing fire condition.

Based upon the above findings, the SAE Working Group has preliminarily adopted a 3 minute ramp to 600°C and then a 5 minute hold at a minimum of 600°C before increasing the minimum temperature to 800°C, over a 2 minute period, and advancing to an engulfing fire. An illustration of the minimum temperature profile for localized fire test is presented in Fig. 70.

The combination of temperature ramps with the 5-minute hold provides 8-10 minutes of localized fire exposure on the test article prior to the engulfing fire. The selection of 600°C as the minimum temperature for the localized fire hold period ensures that the average temperature and time of localized fire test exposure are greater than those experienced in the test data presented.

In the specific vehicle test approach, the localized fire is positioned at the fire exposure area that has been identified based on the assessment of the installation. The LPG



burner(s) in the localized fire region are lit and the minimum temperature profile in Fig. 70. is followed in the localized fire zone.

Figure 69. Preliminary Minimum Temperature Profile for the Localized Fire Test

[34]

The test continues until the system vents through the PRD and the pressure in the container falls to less than 1 MPa. If the test needs to progress to the larger, engulfing fire to demonstrate that the PRDs will activate and protect the system, the length of the engulfing fire is limited to a flame length of 1.65 m to retain consistency with previous Canadian Standards Association (CSA) and ISO fire tests.

If the test needs to progress to the larger, engulfing fire to demonstrate that the PRDs will activate and protect the system, additional LPG burners are lit to simulate the spread of fire; however, the length of the engulfing fire is limited to a flame length of 1.65 m to retain consistency with previous CSA and ISO fire tests. A burst during either the localized or engulfing period of the fire test constitutes a failure of the test.

Global technical regulation (GTR - No. 13)

The GTR for hydrogen and fuel cell vehicles [36] principally adopted the approach of the fire test developed under the SEA working Group for the SAE J 2579 standard.

The proposed localized fire test set-up is also based on the preliminary work done by Transport Canada and the National Highway Traffic Safety Administration (NHTSA) in the United States of America, with the allowance that the storage system can be qualified by either a generic installation test or a specific vehicle installation test as well.

There are only some modifications within the minimum temperature profile required during the bonfire test, which was proposed by the NHTSA (see Fig. 72.):

1) A temperature of 300°C was selected as the temperature where the localized fire condition could start (intermediate target after 1 minute in the test), because thermal gravimetric analysis (TGA) indicates that container materials begin to degrade rapidly at this temperature.

2) The time period, after the localized fire is extended to the engulfing fire, producing a uniform temperature along the entire length of the test article has been changed from 8 to 10 minutes after test start, creating a more severe test condition for the container in test.



Figure 70. Temperature Profile for the Fire Test in the GTR [36]

The global technical regulation requires that hydrogen is used as the test gas during the fire test. However, it also states that contracting parties under the 1998 Agreement may choose to use compressed air as an alternative test gas for certification of containers for use only within their countries or regions.



5.3.2. Transportable gas cylinders

Table 2 gathers the current standards dealing with transportable composite cylinders. It does not take into account the hydrogen storage integration in the whole system.

Table 5: List of existing standards related to transportable gas cylinders.

Reference NF EN 11623 ISO 12257 EN 12245 ISO 11119-3

Date September 2002 August 2008 March 2012 April 2013

Title Transportable gas cylinders — Periodic

inspection and testing of composite gas

cylinders

Transportable gas cylinders Seamless, hoop-wrapped

composite cylinders

Transportable gas cylinders — Fully wrapped composite cylinders

Gas Cylinders Refillable composite gas cylinders and

tubes. Part 3. Fully wrapped fibre reinforced composite gas cylinders

and tubes up to 450 L with non-load-sharing metallic liners.

Fire characteristics

NA Wood or kerosene fire. Capable of enveloping the entire length of the cylinder and valve but no direct flame on the valve.

Wood or petroleum lamp fire. The fire shall be capable of producing a temp. of at least 590°C, measured at 25 mm max below the cylinder, within 2 min.

Any fuel. 1.65 m length , temperature > 590°C within 2 min.

Procedure NA Two cylinders shall undergo this test (horizontal & vertical position)

The cylinders should be fitted either with a PRD (fusible plug) or bursting disc).

Two cylinders shall undergo this test (horizontal & vertical position)

The cylinders should be fitted either with a PRD (fusible plug) or bursting disc)

Test in both vertical & horizontal position.

Two cylinders shall undergo this test (horizontal & vertical position).

The cylinders should be fitted either with a PRD (fusible plug or bursting disc).

Criteria Decolouration, carbonisation or calcination of the composite envelop only. Resin should stay intact.

No burst within 2 min. Possibility of vent through the PRD or leak through the cylinder wall or other surfaces.

For cylinders equipped with a TPRD, vent through it.

Without TPRD, no burst within 2 min. Cylinder may leak through the wall or other surfaces.

For cylinders equipped with a TPRD, vent through it.

Without TPRD, no burst within 2 min. Cylinder may leak through the wall or other surfaces.



5.4. Summary and Conclusion In the first part of the report, several storage integration methods for the considered applications (automotive application, stationary application, transportable cylinders, bundles, tube trailers) have been described, which should give a good impression how much difference can be found in the various concepts. Consequently, also the specific fire protection method selection (described in the 2nd part of the document) will be very much depending on the application area and the preferred solution will perhaps differ from application type to application type.

In the automotive usage field, active pressure relief systems (mainly thermally activated TPRDs) are currently dominating as primary fire protection system. Depending on the safety strategy of the OEM, one or two TPRDs are connected to the cylinder.

In the area of transportable cylinders, bundles and tube trailers, the space which needs to be supervised and protected is normally much bigger in comparison to the vehicle usage, which favourites the selection of remote activated pressure relief devices or even passive fire protection systems like fire barriers which extends the time the cylinders and tubes are able to survive in thermal aggregation till either the fire is distinguished or the heat is reaching the pressure relief component. The utilization of several PRD distributed all over such the larger systems would automatically lead to higher risk with regard to potential leakage location or component mal functions and will be potentially not in favour.

Similar strategies are possible for the stationary application as well, because here the size of the storage system is likewise large leading to the same conclusion as described in the previous paragraph.

However, if we look into the latest development respectively changes in the fire test requirements with regard to lately published regulation, codes and standards (as also described in the last part of the deliverables), localized fire scenarios are playing more and more an important role at least with regard to the automotive application. This has the consequence that the user correspondingly designer of the composite cylinder or tube must have very detailed knowledge about the fire resistance performance of their product respectively carbon fibre and epoxy resin material selection and design. This needs to be considered in the overall system fire protection approach, which is normally in the responsibility of the system integrator, leading to a more or less sophisticated fire protection solution.

One method to gain data and knowledge about the fire performance of the product is to perform numerous tests under various heat aggregation conditions to determine e.g. the time to failure, which will be of course very time consuming and costly. Therefore, the approach of the FireComp project to develop a material and finally composite cylinder model to be able to predict the fire performance resp. thermal degradation of the composite over time (e.g. the point in time when the cylinder will burst) by virtual simulations will accelerate the design and development process a lot. This will enable the comparison of different materials and design variants in a much shorter time period.

Independent of the virtual assessments, a final fire test should be performed to finally validate the fire performance and protection concept of the product. A critical parameter of this evaluation is the thermal load over time profile during such a fire test. This thermal impact should be as realistic as possible and should reflect real world worst case scenarios. However, these scenarios might differ in between the different considered applications. This will be further evaluated in the next deliverable D2.2.



6. Definitions The following definitions are commonly used to specify a protection device with regard to its trigger mechanism (triggered by temperature, pressure or both)

Burst Disk: The operating part of a pressure relief device which, when installed in the device, is designed to burst at a predetermined pressure to permit the discharge of compressed gas.

Pressure Activated Relief Device: A pressure relief device activated by pressure.

Pressure Relief Device (PRD):

A device that, when activated under specified performance conditions, is used to vent the container contents. Reseating and resealing devices are not addressed by this temporary interim requirement.

Combination Relief Device:

A pressure relief device activated by pressure or temperature, either independently or together.

o Parallel Combination Relief Device:

A pressure relief device activated by pressure or temperature independently.

o Series Combination Relief Device:

A pressure relief device activated by pressure and temperature together.

Thermally Activated Relief Device (TPRD): A pressure relief device activated by temperature.



7. References 1. James, B.D., Baum, G.N., Lomax, F.D.Jr., Thomas, C.E., Kuhn, I.F.Jr.

“Comparison of Onboard Hydrogen Storage for Fuel Cell Vehicles, Task 4.2 Final Report“, May 1996

2. http://www.autoconcept-reviews.com/cars_reviews/gm/GM-sequel-concept-2005/cars_reviews-gm-sequel-concept-2005.html

3. http://www.motonews.pl/ford/news-518-challenge-bibendum-2002-focus-fcev-hybrid.html

4. http://www.autonews.com/apps/pbcs.dll/article?AID=/20071119/ANA03/711190309&te#axzz2brq7QPrP

5. http://www.mbusa.com/vcm/MB/DigitalAssets/pdfmb/fcell/248x168_b-klasse_f-cell_NP11_EN_DS_low2.pdf

6. http://blog.mercedes-benz-passion.com/2011/11/die-produktion-der-b-klasse-f-cell-in-sindelfingen-so-entsteht-das-elektrofahrzeug-mit-brennstoffzelle/

7. http://www.netinform.net/h2/h2mobility/Detail.aspx?ID=98 8. http://www.evwind.es/2013/02/26/hyundai-to-make-worlds-first-mass-

production-of-fuel-cell-cars/29921 9. http://www.autobizz.com.my/forum/forum/Toyota/3170-Toyotas-FCHV-adv-

hydrogen-fu 10. http://www.automotiveillustrations.com/illustrators/dp_gm_hydrogen-fuel-

cell_cutaway.html 11. http://www.sdcleanfuels.org/alliance-fuel-cell-technology/ 12. http://www.treehugger.com/cars/production-of-honda-fcx-clarity-hydrogen-car-

begins.html 13. http://www.hfcletter.com/issues/XXII_1/stories/809-1.html 14. http://hexagonlincoln.com/ 15. http://de.slideshare.net/vasisht123/bulk-trabnsportsept2012 16. http://de.slideshare.net/vasisht123/final-brochure-web 17. Webster, C., “Localized Fire Protection Assessment for Vehicle Compressed

Hydrogen Containers“, NHTSA Report - DOT HS 811 303, March 2010 18. http://www.h2-genehmigung.de/infos_h2/ 19. http://www.manager-magazin.de/unternehmen/autoindustrie/brennstoffzelle-

daimler-plant-400-wasserstoff-tankstellen-bis-2023-a-925347.html 20. http://www.circle-seal.com/alternative_fuels/alt-fuel_pdfs/8100_series.pdf 21. http://www.gficontrolsystems.com/pdf/GFI%20PDFs.pdf 22. http://www.ptec-gmbh.com/ 23. http://www.norbulb.de/_german/ueber_norbulb.htm 24. Zalosh, R. “CNG and Hydrogen Vehicle Fuel Tank Failure Incidents, Testing, and

Preventive Measures“ 25. DIRECTIVE 2009/79/EC OF THE EUROPEAN PARLIAMENT AND OF THE COUNCIL of

13 July 2009 26. Commission Regulation (EU) No 406/2010 of 26 April 2010 27. http://www.ppg.com/coatings/pmcglobal/Documents/PPG-PITT-CHAR-XP-

Product-Brochure-A4_26JUN2012_EN_LRSP.pdf 28. Gambone, L., Wong, J, “Fire Protection Strategy for Compressed Hydrogen

Powered Vehicles”, 2ndICHS –International Conference on Hydrogen Safety, San Sebastian, Spain, September, 2007

29. Duplantier, Les phénomènes d’explosion résultant de la combustion de gaz, de vapeur et de brouillard dans des appareils clos, Rapport scientifique et technique de l’Ineris, ref. RST 04.



30. Hord J., Is Hydrogen safe? NBS Technical note 690, 1976 31. http://www.nhtsa.gov/DOT/NHTSA/Vehicle%20Safety/Test%20Procedures/Associ

ated%20Files/TP304-03.pdf 32. Weyandt, N. et al “Compressed Hydrogen Cylinder Research and Testing In

Accordance With FMVSS 304”, NHTSA Report - DOT HS 811 150, June 2009 33. http://standards.sae.org/j2579_200901/ 34. Scheffler, McClory, Veenstra, Gambone, Sage ”Establishing Localized Fire Test

Methods and Progressing Safety Standards for FCVs and Hydrogen Vehicles”, SAE Technical Paper 2011-01-0251, Published 04/12/2011

35. Gambone, L., Wong, .J, Webster, C., “Hydrogen Vehicle Fuel Systems – Localized Fire Protection Considerations, Milestone 2 VEHICLE FIRE CONDITION REPORT, 2008

36. http://www.unece.org/trans/main/wp29/wp29wgs/wp29gen/wp29glob_registry.html

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