Virginia Clean Cities Webinar
June 30, 2011
Hydrogen and First
Peter B. Sunderland
Dept. of Fire Protection Engineering
University of Maryland
V. Molkov and the Hydrogen
Safety and Research Centre at
the University of Ulster.
NIST, under the technical
management of J. Yang.
Fire Protection Research
Foundation, under the technical
management of K.H. Almand.
R.L. Axelbaum (Washington
Univ.) and B.H. Chao (Univ. of
Students: M.S. Butler, C.W.
Moran, N.R. Morton, V.R.
DOE first responder training resources
U.S. hydrogen vehicles
Unique fire hazards
Pressure relief devices
Codes and standards
DOE First Responder Training
DOE First Responder Training
In 2003, President Bush announced an initiative to
develop hydrogen vehicles and infrastructure.
In 2003, Calif. Gov. Schwarzenegger announced plans
for a “hydrogen highway” with 150 – 250 fueling
stations by 2010.
Annual U.S. production of hydrogen is 11 million metric
tons, valued at $30 billion.
The safety record is good.
There are about 400 – 500 hydrogen vehicles in U.S.
Most are in California.
Average cost of a hydrogen fueling station is $1.5 million.
There are 1100 km of hydrogen pipeline in U.S.
U.S. DOE is researching the conversion of CNG pipelines
for hydrogen service.
Hydrogen Fuel Cell
Toyota FCHV Emergency
Response Guide, 2006
Current Hydrogen Filling Stations
77 total, 15 public (versus 170,000 gasoline stations)
U.S. NRC Report (2008)
Hydrogen vehicles can dramatically reduce U.S.
consumption of oil.
Challenges include high vehicle costs and lacking
The predicted maximum numbers of vehicles are:
- 2 million by 2020
- 60 million in 2035
- 200 million in 2050
By 2023, fuel cell vehicles will be cost competitive.
Required funding by 2023 is US$ 55 billion by U.S.
government and US$ 145 billion by industry.
Vehicle Fire Statistics
• USFA’s National Fire Incident Reporting System
– Fire cause and origin
– Voluntary, but 42 states participate
• DOT’s Fatal Accident Reporting System (FARS)
– Fatal accidents only
– Fire cause and origin not reported
– Fuel type not reported
• NFPA annual fire department survey
• NFPA overviews (Ahrens, 2005)
Unique Fire Hazards of Hydrogen
Lightest fuel, thus requiring the highest storage pressure.
Highest volumetric leak propensity of any fuel.
Smallest ignition energy of any fuel in air (28 J).
Lowest autoignition temperature of any fuel ignited by a heated air jet
Wide flammability limits in air (4 – 75% by volume).
Highest laminar burning velocity of any fuel in air (2.91 m/s).
Smallest quenching distance of any fuel premixed with air (0.51 mm).
Highest heat of combustion (120 kJ/g).
Dimmest flames of any fuel in air.
Fuel Flash Point, °C AIT, °C LFL, % UFL, %
Gasoline -40 468 1.4 7.6
Methane -180 632 3.8 17
Propane -104 504 2.3 9.5
Hydrogen - 571 4 75
Ethanol 15 392 3.3 19
Methanol 30 470 6.7 36
Biodeisel 130 240 0.6 5.6
• In U.S. there are 30,000 fire departments and 1M firefighters, 75% of
whom are volunteers.
Microflame Fire Scenario
A small leak develops in a H2 system, e.g., a H2 vehicle.
The leak could arise from H2 embrittlement, H2
permeation, impact, equipment failure, or improper
The leak ignites from static discharge or heat.
The leak burns undetected for a long period, damaging
the containment system and providing an ignition source
for a subsequent large release.
SAE J2579 Leak Limits
Localized leaks must not be capable of supporting a
The maximum localized leak rate is 5 μg/s (i.e., 3.6 sccm).
This equates to about 33 bubbles/s under water.
Total system leakage is limited to 150 sccm.
SAE J2579, Technical Information Report for Fuel systems in Fuel Cell and Other
Hydrogen Vehicles (2009)
Pressure Relief Devices
CNG and Hydrogen vehicle containers require
PRDs, primarily to protect against impinging fires.
Modern composite tanks are good thermal
insulators that weaken at high temperatures.
Fuel pressure may not increase significantly during
an impinging fire. A container may not be filled with
fuel at the time of the fire.
PRDs can be activated by pressure, temperature,
or a combination.
Most hydrogen, CNG, and propane containers are
protected by temperature activated PRDs.
Mirada Bayonet PRD
Rolander et al. (2003) 18/28
SAE J2579 Bonfire Test
Performed at initially NWP.
Involves hydrogen system, not entire vehicle.
Fire source must be 1.65 m long, with flames that
impinge entire diameter.
Container is to be centered 100 mm above fire and in
Metal shields should prevent flame impingement onto the
Thermocouple on container exterior must reach 590 C
within 5 min of ignition.
TPRD must activate and prevent rupture.
Container cannot rupture before venting below 10 bar.
SAE J2579 (2009) 19/28
CNG Vehicle PRD Case Studies
Two CNG bus fires resulted in safe venting by
A CNG Ford Crown Victoria in a fire
experienced a container rupture in 2003.
A CNG Honda Civic ruptured in 2007 (below).
Seattle FD (2007).
Hydrogen Vehicle PRD Test
Swain (2001) tests comparing hydrogen and
gasoline vehicle fires (above).
SAE2578 Limits on Normal Hydrogen Discharges
Scheffler (2008) 22/28
Hydrogen Vehicle Labeling
SAE J2578 (2009) 23/28
There are at least 30 codes and standards applicable to
NFPA 2, “Hydrogen Technologies Code” (2011).
NFPA 2 extracted and updated material from about 10 other
NFPA hydrogen codes.
NFPA 2 includes hydrogen generation devices.
NFPA 2 covers dispensing systems for gaseous and liquid
hydrogen from NFPA 52.
Also under preparation is SAE J2919, Technical Information
Report for Compressed Hydrogen Fuel Systems in Fuel Cell
Powered Industrial Trucks.
The traditional way to detect H2 flames is with
a straw broom. H2Scan Corp.
H2 gas detectors can detect down to 15 ppm Hy-Alerta Model 500
These require gas sampling and will not alert
if flames consume the H2.
H2 flame detectors can detect a H2 flame of
50 mm from 30 m (UV/IR).
Thermal imaging firefighting cameras are Det-Tronics (UTC)
effective. Model X3302
Listen for leaking gas.
Look for white clouds near liquid hydrogen spills.
Watch for heat shimmering.
Use outstretched brooms, hydrogen detectors, and
thermal imaging cameras.
Prevent ignition sources (sparks, heat).
Stop the flow of hydrogen if possible.
Otherwise, allow flame to consume the entire gas
supply when this can be done safely.
Protect nearby objects and fuels.
Extinguishing flames without stopping leaks can result
in explosive mixtures.
Use a dry powder extinguisher or water.
The U.S. continues to invest in hydrogen
vehicles and infrastructure.
Codes and standards are being revised
to ensure hydrogen vehicle safety.
Hydrogen is not inherently hazardous,
but requires specialized knowledge.
Extensive training materials are available
for hydrogen first responders.