Hydrogen and Fuel Cell Operations and Related Hazards

Hydrogen and Fuel Cell Operations and Related Hazards

Loading
Loading Social Plug-ins...
Language: English
Save to myLibrary Download PDF
Go to Page # Page of 72

Description: Fuel Cells’ Intro:- An electrochemical cell that converts a source fuel into an electrical current. The fuel cell generates electricity through reactions between a fuel and an oxidant. Hydrogen Fuel Cells: A hydrogen fuel cell uses hydrogen as its fuel and oxygen as its oxidant.

It's very similar to a battery but it has its differences. Discovered by Christian Friedrich Schönbien in 1838.

 
Author: Ioanni Koliousis  | Visits: 270 | Page Views: 533
Domain:  Green Tech Category: Battery & Fuel Cell 
Upload Date:
Link Back:
Short URL: https://www.wesrch.com/energy/pdfTR1YL6000OQMP
Loading
Loading...



px *        px *

* Default width and height in pixels. Change it to your required dimensions.

 
Contents:
Methods of hydrogen and
fuel cells operations and
related hazards.

Koliousis, Ioannis
Department of Maritime Studies
University of Piraeus

Today’s agenda
 Introduction
 Safety Issues (high Level)
 Hydrogen Related Safety practical issues
 Q+A

FUEL CELLS’ INTRO
• Definition: electrochemical cell that converts a
source fuel into an electrical current.
• The fuel cell generates electricity through reactions
between a fuel and an oxidant.

Source: “HYDROGEN FUEL CELLS & ENERGY EFFICIENCY”, by Claudio Bolzoni, David Carlos Echeverria, Andres Segura, Dari Seo

Hydrogen Fuel Cells
• A hydrogen fuel cell uses hydrogen as its fuel and
oxygen as its oxidant.
• Its very similar to a battery but it has its differences.

• Discovered by Christian Firedrich Schönbien in 1838

Source: “HYDROGEN FUEL CELLS &
ENERGY EFFICIENCY”, by Claudio
Bolzoni, David Carlos Echeverria,
Andres Segura, Dari Seo

• https://www.youtube.com/watch?v=tajigZ2e6tQ

Benefits

•Reduction in burning of
fuel cells
•Improvement of air
quality especially in
urban areas
•Reduction of
greenhouse gases
(global warming)
•Low noise and high
power

•Reduction in energy
consumption (saving
energy)

Problems
•Cost

•Durability
•Hydration
•Delivery
•Infrastructure
•Storage
•Safety

Examples
•Vehicles
•Bicycles
•Rockets

•Airplanes
•Buses

•Motorcycles
•Scooters

Stationary fuel cells






Fuel cells generate water from a fuel (such as hydrogen or natural gas) and from oxygen in
the air, while producing electricity and heat.
This reaction is carried out in each of the basic cells of the fuel cell.
Each fuel cell consists of an anode, a cathode, and an electrolyte allowing the charges to
move from one side to the other side of the fuel cell.
Εlectrons move from the anode to the cathode through an external circuit, producing an
electrical current - and thus powering the load.
Such cells are placed in series, to reach an adequate voltage output. When assembled
together, the cells constitute an energy module of the required power known as the stack.

http://www.renewableenergyworld.com/content/dam/rew/migrated/assets/images/story/2014/7/1/body-0-1404243657205.jpg

Fuel cells types (I/II)
1. Proton Exchange Membrane Fuel Cells (PEMFC),
2. Solid Oxide Fuel Cells (SOFC) and
3. Molten Carbonate Fuel Cells (MCFC).
These fuel cells are classified according to the type of electrolyte they use.
In Proton Exchange Membrane Fuel Cells, a proton-conducting membrane is used as
an electrolyte.
In pure hydrogen PEMFC, hydrogen is dissociated into protons H+ and electrons on
the anode. Protons are conducted through the proton-conducting membrane to the
cathode. As the membrane is electrically insulated, electrons move from the anode to
the cathode through an external circuit, producing an electrical current. On the
cathode, oxygen reacts with the electrons and protons to form water.
Such fuel cells operate at temperatures between 50 and 220°C, typically 80°C.
Other types of PEMFC also exist: some are fed with a mixture of CO2 and H2.
Proton Exchange Membrane Fuel Cells are preferred for mobile
applications.

Fuel cells types (II/II)


In Solid Oxide Fuel Cells, a ceramic material called yttria-stabilized zirconia (YSZ) is most
commonly used as an electrolyte. In SOFC, oxygen gas reacts on the cathode with electrons, to
form negatively charged oxygen ions. These oxygen ions move through the electrolyte from the
cathode to the anode, where they react with hydrogen gas, producing electricity and water.
SOFC operates at high temperatures (between 800 and 1000°C). They can be fed with fuels
other than hydrogen gas, such as natural gas for instance. Natural gas is then reformed (i.e.
converted to hydrogen) internally.



In Molten Carbonate Fuel Cells, lithium potassium carbonate salt is used as an electrolyte.
At high temperatures (about 650°C), this salt melts and allows for the movement of the
negative carbonate ions from the electrolyte. On the anode, hydrogen reacts with carbonate
ions to produce mainly water, carbon dioxide and electrons. The electrons move from the anode
to the cathode, producing an electrical current. On the cathode, carbon dioxide (from the
anode) and oxygen react with the electrons to form carbonate ions.

MCFC can be fed with fuels other than hydrogen gas, such as natural gas for instance. As in SOFC,
natural gas is reformed (i.e. converted to hydrogen) internally.
Because of their high operating temperatures, Molten Carbonate Fuel Cells and Solid Oxide Fuel
Cells have slow start-up times. Therefore, they are not suitable for mobile applications and are
limited to stationary applications.

Hazards and safety measures
• Fuel cells are low-pressure systems: upstream the fuel cell, the hydrogen feed
pressure is reduced down to low pressures (e.g. 250 mbar at the cells’ inlet of
Axane’s fuel cell Comm PacTM). Therefore, stationary fuel cell systems are free
from hazards related with the handling of pressurized hydrogen.
• But, since fuel cells consist of a stack of basic cells in which chemical reactions
involving hydrogen are carried out, there is a risk of leaks.
• In order to avoid the formation of flammable mixtures, sensors able to detect
hydrogen leaks are used. Once sensors have detected the presence of hydrogen at
a concentration higher than a threshold value, isolation measures are taken.

Stationary applications: standards

IEC/TS 62282-1:2010 Fuel cell technologies Part 1 Terminology, Edition 2
IEC 62282-2:2007 Fuel cell technologies Part 2: Fuel cell modules, Edition 1.1
Provides the minimum requirements for safety and performance of fuel cell
modules.
Applies to fuel cell modules with the following electrolyte chemistry: alkaline;
proton exchange membrane (including direct methanol fuel cells); phosphoric
acid; molten carbonate; solid oxide fuel cell modules.

Stationary applications: standards
IEC 62282-3-100 Fuel cell technologies
Part 3-100: Stationary fuel cell power systems – Safety
Edition 1 (Revision of IEC 62282-3-1)
Applies to stationary packaged, self-contained fuel cell power systems or fuel cell power
systems comprised of factory matched packages of integrated systems which generate
electricity through electrochemical reactions. Is a product safety standard suitable for
conformity assessment.
IEC 62282-4 Fuel cell technologies – Part 4-100: Fuel cell systems for forklift applications
Safety requirements, environmental aspects and test procedures, Edition 1
will cover safety, performance, construction, marking and test requirements and
interchangeability of fuel cell systems onboard specialty vehicles other than road
vehicles and
auxiliary power units (APUs). However, the first edition of this document will include
items
applicable to forklifts. The future editions of this document will include items applicable
to onboard vehicles other than road vehicles and APUs
Ad hoc group no.2 Safety aspects with respect to explosion

Stationary applications: standards
IEC 62282-3-150 Fuel cell technologies
Part 3-150: Stationary fuel cell power systems - Small stationary fuel cell power system
serving as a heating appliance providing both electrical power and useful heat with or
without a peak load heating device. This standard applies to fuel cell power systems
that are intended to be permanently connected to the electrical system of the customer
(end user). Connection to the mains directly (parallel operation) is also within the scope
of this standard
IEC 62282-3-3 Fuel cell technologies
Part 3-3: Stationary fuel cell power systems – Installation, Edition 2
Provides minimum safety requirements for the installation of indoor and outdoor
stationary fuel cell power systems in compliance with IEC 62282-3-1; applies to the
installation of systems intended for electrical connection to mains directly or with a
transfer switch, or intended for a stand-alone power distribution system, or intended to
provide AC or DC power.

Stationary applications: standards
IEC 62282-4 will cover safety, performance, construction, marking and test requirements
and interchangeability of fuel cell systems onboard specialty vehicles other than road
vehicles and auxiliary power units (APUs). However, the first edition of this document will
include items applicable to forklifts. The future editions of this document will include items
applicable to onboard vehicles other than road vehicles and APUs Ad hoc group no.2
Safety aspects with respect to explosion
IEC 62282-3-1:2007 Fuel cell technologies Part 3-1: Stationary fuel cell power systems –
Safety Edition 1

Indoor use of hydrogen: standards
Partially covered by ISO 62282-3-3 (Fuel Cell Technologies: Installation)
ISO/TR 15916:2004 (Basic considerations for the safety of hydrogen systems)
provides guidelines for the use of hydrogen in its gaseous and liquid forms. It
identifies the
basic safety concerns and risks, and describes the properties of hydrogen that are
relevant
to safety. Detailed safety requirements associated with specific hydrogen
applications are
treated in separate International Standards.
ISO 26142 (for hydrogen detectors)

Indoor use of hydrogen: standards
IEC 60079-1, Explosive atmospheres
Part 1: Equipment protection by flameproof enclosures “d”
Part 2: Equipment protection by pressurized enclosures “p”
Part 7: Equipment protection by increased safety “e”
Part 11: Equipment protection by intrinsic safety “i”
Part 15: Equipment protection by type of protection “n”
Part 18: Equipment protection by encapsulation “m”

IEC/TR 60079-20-1, Explosive atmospheres
Part 20-1: Material characteristics for gas and vapour classification — Test methods and
data
IEC 60079-29-1, Explosive atmospheres
Part 29-1: Gas detectors — Performance requirements of detectors for flammable gases

Case Study: USA DoD
Source: Cost Effectiveness Analysis of Defense Department
Deployment of Fuel Cell Forklifts at Large Distribution Centers,
by Michael E. Canes, 2013

Project sites

Hydrogen tank at DDSP
Refueling station at DDJC

Fuel dispensers at DDSP

Mobile refueler at DDWG

Approach
• Gather detailed cost data at each site from
participating manufacturers, onsite staff, open source
literature
• Compare costs of fuel cells going forward with
pertinent alternatives
• Include capital and operating costs
• Analysis to cover about 10 years, real costs, no
discounting

Cost Categories – Hydrogen
Production





Infrastructure depreciation
Infrastructure O&M
Infrastructure space
Fuel source
• Natural gas
• Water

• Power (in)

In each case, comparison made to cost of delivered H2

24

Cost Categories - Fuel Cells








Forklift depreciation
Forklift O&M
Fuel cell O&M (including spares)
Fuel cell refueling labor time
Hydrogen infrastructure O&M
Infrastructure space cost
Hydrogen (either produced or delivered)

25

Cost categories – Batteries &
Propane
• Batteries








Forklift depreciation
Forklift O&M
Battery depreciation
Battery O&M
Charger depreciation
Charger O&M
Power to recharge
batteries
• Battery change labor
• Infrastructure O&M
• Infrastructure space

• Propane





Forklift depreciation
Forklift O&M
Fuel
Infrastructure
depreciation
• Infrastructure O&M
• Infrastructure space
• Refueling labor

26

Non-economic Factors





Reduction in hydrocarbon emissions
Reduction in greenhouse gas emissions
Enhanced work productivity with fuel cells
DoD leadership in national energy effort by creating a
market opportunity for fuel cell technology
• Development of a transport option that might have
value to DoD & others in the future

Results - Comparative Costs of Hydrogen
Cost of Produced H2

Cost of delivered H2*

DDSP

N/A

$6/kg (liquid)

DDWG (steam
methane reformer)

$22.41/kg

$22.50/kg (gaseous)

JBLM (waste gas
digester)

**

$8/kg (liquid)

DDJC (electrolyzer)

$22.20/kg

$35/kg (gaseous)

*Not counting system losses.
**Insufficient information with which to estimate H2 production cost
Source: Cost Effectiveness Analysis of Defense Department Deployment of Fuel Cell Forklifts at Large Distribution Centers,
by Michael E. Canes, 2013

Conclusions from Hydrogen
Production Analysis
• Going in, production of H2 from natural gas thought to be the least expensive
option, but ongoing technical problems with reformer reduced the
attractiveness of this option
• Producing hydrogen from waste gas is a great concept but proved difficult to
implement in practice
• Production via electrolysis turned out to be economic vis a vis the cost of
importing gaseous H2
• The electrolyzer ran a high percentage of the time
• Expensive to import gaseous H2 because of the high cost of transport
• Experiment associated with solar voltaic
production of electricity, but that
was treated as a separate investment

Results – Comparative Cost of Fuel Cell &
Battery Forklift sample site
Fuel Cell Forklift

40 forklifts

Fuel Cell Forklift with Cost
Reduction Program

Battery forklift

$155,104

$119,825

$68,643

Conclusions:

• Cost of hydrogen infrastructure plus fuel cell upkeep too high for fuel
cells to be economically competitive
• Cost reductions feasible but still leave fuel cells higher cost than
battery option
• Expansion of the fuel cell powered fleet would render this option
more competitive with batteries

Results – Comparative Cost of Fuel Cell and
Propane Forklift at JBLM
Fuel Cell Forklift

19 Forklifts

Propane Forklift

$129,470

$76,166

Conclusions:





Fuel cells are not competitive with propane at JBLM
Propane is relatively inexpensive because it requires little onsite infrastructure
Forklifts used too little at JBLM to justify investment in hydrogen infrastructure
Adding the bus improves forklift economics but does not make the overall project cost
effective

Overall Conclusions
• Fuel cells were not economically competitive in any of DoD’s 4
experimental projects
• However, their relative attractiveness could be increased by:







Raising the intensity of their use
Increasing the number of forklifts utilizing fuel cells at each given site
Downsizing H2 infrastructures to more closely accord with demand
Accepting more of the risk of infrastructure failure
Longer term contracts
Taking advantage of tax breaks accorded fuel cells via appropriate
leasing arrangements

Source: Cost Effectiveness Analysis of Defense Department Deployment of Fuel Cell Forklifts at Large Distribution Centers, by Michael E. Canes,
2013

32

Hydrogen Related Safety
practical issues
• Source: Millennium Reign University first
respondents handbook, www.mreh2.com

Safety Introduction
• Sizing up the scene
• Identifying hydrogen
• Taking initial protective actions

• Detecting gaseous or a liquid hydrogen release
• Detecting a hydrogen flame
• Fire and combustion response

Hy – Safety






Securing the equipment
Rescuing passengers
Personal protective equipment
The importance of emergency response diagrams
Recognize probable causes to hydrogen-related incidents

Personal Protective Equipment (PPE)
• Personal protection equipment is needed for non-injury
accidents, catastrophic accidents including vehicle fires, and
accidents involving fuel cell vehicles
• Thermal imaging equipment to detect a hydrogen flame is
recommended, as are insulated hand tools to avoid igniting any
hydrogen gas.
• Standard firefighter turn-outs and respiratory protection are
necessary when working an incident where a hydrogen leak or
fire may occur.
• If the incident involves liquid hydrogen, wear thermal protective
clothing.

Personal Protective Equipment (PPE)
• Non-static equipment and tools are required, as are
fire extinguishers, a fire blanket, and broom
• Wearing jewelry, rings, necklaces, or watches is
strongly discouraged
• Equipment also provides firefighters with the
essential protection necessary from the potential of
electric shock, flammable/explosive gas, and
hazardous fumes

Personal Protective Equipment (PPE)










Self-contained breathing apparatus
Coveralls, turnout pants, turnout coat
Fire resistant gloves
High-voltage rubber gloves
Boots, steel toe and shank
Helmet
Face shield
In case of hazmat:
Hooded chemical-resistant clothing (two-piece
chemical splash suit, disposable chemical
resistant overalls, disposable chemical resistant
boot-covers)

Hydrogen Safety Facts
Safe Handling
• Safety Glasses –
Well ventilated area

Emergency – Eye/
Skin
• Not a factor

Inhalation
• Hydrogen is not
poisonous, but is
an asphyxiate.
Accidental
inhalation of
sufficient
hydrogen to
cause breathing
problems is
unlikely, Move to
a well ventilated
area. Use CPR if
breathing has
stopped.

General Hazards and Risks Hydrogen
Storage
• Hydrogen is capable of migrating through small openings
• The main concerns for emergency responders are electrical
shocks and flammability of fuel
• Other concerns include cryogenic burns and asphyxiation
• Venting of stored hydrogen may be the best means of
mitigating a situation as long as the area is free from ignition
sources
• Hydrogen will dissipate very quickly

• Hydrogen will combine with oxygen to form water.

How tos:
• Eliminate ignition sources
• No smoking or open flames
• Keep tools and equipment in good condition and use only nonsparking tools; use the correct size tool for loosening and
tightening hardware.
• No synthetic clothing (nylon, etc.), silk, or wool. Ordinary
cotton, flame retardant cotton, or Nomex ® clothing is
preferred
• Electrical equipment must be explosion proof and intrinsically
safe or purged

General Hazards and Risks for Tanks /
Cylinders
• Liquid hydrogen tanks always emit small quantities of hydrogen if
the hydrogen is not oxidized or burned off in a controlled manner
• All hydrogen-containing fuel systems have great propensity for at
least small leaks due to the pressure of the gaseous hydrogen
and the small size of the molecules
• Because of the high dispersion rate of hydrogen, small leaks
would likely pose a problem in rare instances such as unvented,
very tight, small individual garages
• Safety concerns in larger unvented private or public parking
garages will be more of an issue

General Hazards and Risks Cylinders
• Never crack open a hydrogen cylinder to clear the valve of dust as
the escape hydrogen may ignite
• Never drop, drag, roll, or slide cylinders
• Wrenches - never be used to open or close a valve equipped
cylinder.
• Use only a strap-wrench to remove over-tightened or rusted caps
• Group of cylinders is burning - fire fighters keep their distance.
Aware of fragments or shrapnel if an explosion occurs

General Hazards and Risks Valves, Leaks,
and PRDs

• Hydrogen systems include high-and low-pressure fuel lines

• They are equipped with pressure relief devices for safety location of the pressure relief device depends on the type
of system; there is no standard location.
• Hydrogen leaks generally originate from valves, flanges,
diaphragms, gaskets, and various types of seals and fittings
• For leaks that are relatively small and controllable, use the
shut-off valve; for leaks that are uncontrollable, shut off
the supply source and evacuate area

General Hazards and Risks Valves, Leaks,
and PRDs

• Indicators:
• For compressed hydrogen – a loud hissing or high-pitched shrill
sound with PRD release and/or concentrated flame stream
• For liquid hydrogen – a fog or cloud formed around the
cryogenic hydrogen storage tank; ice crystals formed around
the storage tank
• Liquid hydrogen poses greater risks than compressed hydrogen
due to its cryogenic capabilities
• Hydrogen is stored as a liquid at -423°F (-253o C), can cause
cryogenic burns or lung damage
• Detection sensors and personal protective equipment are critical
when handling liquid hydrogen
• Properly-working ventilation equipment can minimize potential
hazards.

General Hazards and Risks Valves, Leaks,
and PRDs
• Precautions:
• Eliminate source of ignition, and if possible,
remove cylinder to remote outdoor location away
from possible sources of ignition
• Ventilate area
• Avoid skin contact, with liquid or cold boil-off gas
• Do not enter area containing flammable mixtures
• Avoid spraying water on pressure relief devices or
gas vents

General Hazards and Risks Venting and
Asphyxiation
• Hydrogen is an asphyxiate. In rare instance and in closed
spaces it can displace oxygen, causing an oxygen deficient
atmosphere.
• Precautions:
• Always open a compressed gas cylinder valve slowly to
avoid rapid system pressurization.
• Indicators:
• Some signs and symptoms of overexposure include
headache, drowsiness, dizziness, excitation, excess
salvation, vomiting, and unconsciousness

General Hazards and Risks for Hydrogen
Vehicles
• The two prime dangers from fuel cell and hydrogen-powered
vehicles are the danger of:
(1) Electrical shock
(2) Flammability of the fuel

General Hazards and Risks Hydrogen
Vehicles
• Precaution: The danger of electrical shock is present
• The voltage needed to power the electric motors is
much higher in the new vehicles than can be
accommodated by the current standard voltage of a
14V system; the automobile industry is in the process
of moving to a new standard of a 42V system.
• The 42 volt system was chosen as an industry
standard in part for safety reasons; anything greater
than 50V can stop a human heart.
• Some fuel cell vehicle motors run on voltages
between 200-400V.

General Hazards and Risks Hydrogen
Vehicles
• Precaution: Hydrogen’s flammability range is very
wide compared to other fuels
• Other fuels used to power fuel cells include
methanol, ethanol, and methane
• Fuel used to power a vehicle does not necessarily
have to be stored on the equipement as hydrogen
• Reforming different hydrogen sources, such as
alcohols, methane, propane, and even regular
gasoline, can create gaseous hydrogen in the vehicle
itself

Emergency Procedures











Sizing up the scene
Identifying hydrogen in commercial transport or
stationary facilities
Identifying hydrogen vehicles (in the case of a
hydrogen vehicle accident)
Taking initial protective actions
Detecting gaseous or a liquid hydrogen release
Detecting a hydrogen flame
Securing the vehicle (in the case of a hydrogen
vehicle accident)
Fire and combustion response
Extrication of passengers from vehicles (in the
case of a hydrogen vehicle accident)

Sizing Up the Scene
• Do not rush in
• Position responding units (fire trucks, police cruisers, and
ambulances) upwind and away from leaking hydrogen or PRD
vents
• Regarding hydrogen fuel cell vehicles, in case of spill from the
high-voltage battery pack, contact hazmat immediately

Identifying Hydrogen in Commercial
Transport
• Placards and/or other markings are required on bulk
shipments
• Markings help emergency responders recognize the
material and respond appropriately in the event of an
emergency.

Identifying Hydrogen Fueling Stations (USA)
• The National Fire Protection Association also has a standard
for hazard placards to identify hydrogen used at stationary
facilities.
• The NFPA 704 hazard placards used for gaseous and liquid
hydrogen are shown here – the “4” shown in both the
gaseous and liquid hydrogen placards indicates
flammability, and the “3” on the liquid placard denotes the
health issue related to a cryogenic substance.

Initial Protective Actions
• When approaching an incident:
• Keep unauthorized personnel away
• Isolate the area,
• Stay upwind
• Listen for venting gas and watch for thermal waves that could
signal hydrogen flames
• Follow standard operating procedure
• Eliminate all potential ignition sources
• Hydrogen fire is detected, allow it to burn if safe to do so, and
protect adjacent structures

Detecting a Gaseous Hydrogen Release
• Hydrogen gas is colorless and odorless - human senses cannot
detect it
• Recommended that the responder listen for the sound of
high-pressure gas escaping from the vent or a breech in the
container
• Use commercially available thermal conductivity sensors,
catalytic combustion sensors, or electrochemical sensors
• Gas and flame detectors may be permanently installed in
storage facilities and fueling stations - where leaks may occur.
Listen and watch for alarms.
• Regarding vehicles, when it is safe to do so, listen for the
sound of hydrogen escaping, look for frost around the PRD
vent.

Detecting a Liquid Hydrogen Release
• A leaking liquid hydrogen container may have frost or ice
crystals on the outside.
• Small spills of hydrogen disperse quickly - any spill should be
considered a potential fire hazard.
• Large spills cause ground freezing; hydrogen will not vaporize
quickly.
• Evacuate area until spill has dissipated.
• Use water spray to reduce fog and diffuse vapors.
• Clouds of gas can quickly become huge fire balls with tragic
results.

Detecting a Liquid Hydrogen Release
• Even in dry climates, a liquid hydrogen spill will create
a white cloud of condensed water vapor.
• As the hydrogen warms, it will dissipate and quickly
rise

Source: Millennium Reign University first respondents handbook,
www.mreh2.com

Detecting Hydrogen Flame
• Hydrogen burns with a pale blue flame that is nearly
invisible in daylight.
• The flame may appear yellow if there are impurities
in the air like dust, sodium from the ocean spray, etc.
• A pure hydrogen flame will not produce smoke.
• Hydrogen flames have low radiant heat – unlike a
hydrocarbon fire, you may not feel heat until you are
very close to the flame.

Securing Hydrogen Vehicles
• When approaching a hydrogen vehicle that has been
involved in an incident, immobilize, stabilize, and
disable.
• Approach hydrogen vehicle at a 45° angle when
possible to help avoid direct exposure to a pressure
relief device release

Securing Hydrogen Vehicles
• It is essential that the location of the PRD vent be
identified before beginning any operation on a
hydrogen vehicle.

• Listen for venting hydrogen, and watch for thermal
waves that could signal a hydrogen flame.

Source: Millennium Reign University first
respondents handbook, www.mreh2.com

Securing Hydrogen Vehicles
• If safe to do so, isolate the high-pressure hydrogen
and high-voltage systems by turning the ignition key
off or by cutting the negative cable of the 12-volt
auxiliary battery.
• It may take a couple of minutes for the electrical
system to completely discharge.

Securing Hydrogen Vehicles
• Once the vehicle is turned off, the high-pressure
systems are isolated.
• Simply turning off the key closes the high-pressure
hydrogen gas tank.
• However, the hydrogen fuel lines from the tank to the
engine will still contain a small amount of hydrogen
(approximately 2 teaspoons of gasoline equivalent).

Securing Hydrogen Vehicles
• Regarding hydrogen fuel cell vehicles, it is essential to identify
both the 12-volt auxiliary electrical system and the 200-500
volt, 200-300 amp electrical system.
• Refer to vehicle emergency response guides to identify highand low-voltage systems.

Securing Hydrogen Vehicles
• The high-voltage Ni-MH battery pack must be disconnected
from the electrical system.
• To do this, simply remove the high-voltage service disconnect
switch. To remove this switch, turn it counterclockwise and lift
it out.
• Refer to vehicle emergency response guides to determine the
specific location of this switch.

Fire and Combustion Response
• The best way to handle a hydrogen fire is to let it
burn under control until the hydrogen flow can be
stopped or the fire is burned off.
• Small fires can be extinguished with carbon dioxide
or water spray; larger fires may be controlled with
steam and/or nitrogen.
• if fire is extinguished before all the gas burns off,
watch for pockets which may suddenly re-ignite.

Fire and Combustion Response
• A hydrogen flame is invisible under many conditions;
therefore, burns may result from unknowingly
walking into a hydrogen fire.
• Hydrogen flames cause little damage from radiation.
• Hydrogen flames can burn in a strong wind and be
stretched out away from their source by a number a
feet.
• Tanks containing hydrogen should be cooled with
water if near a fire.

Fire and Combustion Response
• Pipeline fires, where shutoff is possible and with flame
characteristics of a jet or torch, can be effectively controlled as
follows:
• Slowly reduce the flow of hydrogen feeding the fire.
• When the jet is small enough to be approached, put out the
flame with carbon dioxide or dry powder extinguisher.
• Close off the supply of hydrogen completely.
• Ventilate the area thoroughly.
• Unusual fire or explosion hazard: Potential explosion hazard
from re-ignition if fire is extinguished without shutting off
hydrogen.

Fire and Combustion Response
• For hydrogen vehicles, if the hydrogen system can be
isolated, put out the fire with traditional means.
• However, if the hydrogen system cannot be isolated,
let the fire burn.
• Concentrate on keeping the fire from spreading into
other areas or neighboring objects.

Extrication
• Never cut into the hydrogen fuel lines, the hydrogen storage
tank, or the PRD vent line.
• For hydrogen fuel cell vehicles, do not cut the orange electric
cables, the high-voltage Ni-MH battery pack, or the fuel cell
stack.

How a Hy-system looks like?

End of Session
Thank you for your attention!
Q&A
More info?
igk@unipi.gr