Thursday, January 1, 2009 - Vol. VIII Issue 1
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Fires and Explosions
fighters respond to propane incidents in the United States nearly once per day
on the average. According to the National Fire Incident Reporting System (the
data base of the U.S. Fire Administration), the number of propane incidents on
an annual basis was 301 in 2005 and 317 in 2006; as all states do not require
participation in this data base, the actual number of propane incidents
responded to by fire departments may be higher. Unfortunately, firefighters
and emergency responders have died responding to propane incidents. Many of
these incidents occurred in rural locations. There are about 17.5 million
propane installations in the United States. We will look at a couple of tragic
Farm, Albert City Iowa, 9 April 1998. Two fire fighters killed, seven injured
incident was investigated by the U.S. Chemical Safety and Hazard Investigation
Board (CSB); their findings are published as report no. 98-007-I-IA, and can be
downloaded from http://www.csb.gov/completed_investigations/docs/Final%20Herrig.pdf. The photos
used here were taken from this report. Only a few of the total number of
propane incidents are investigated by the CSB. NIOSH also investigated this
accident; their report is available at
photo of Herrig Brothers farm taken on 10 April 1998, one day later. Yellow
oval shows the location of propane tank prior to the blast (photo from CSB).
A 18,000-gallon propane tank similar to the one that exploded at the Herrig
Brothers Feather Creek Farm (the turkey farm) in Albert City, Iowa, from NIOSH
report. Note protective fencing around piping for this tank which was lacking
at the Iowa farm propane tank.
Herrig Bros. 42-foot long tank before explosion. The tank was out in the open
away from any buildings, and the tank and above ground piping had no protective
fence to keep intruders away. Right, large tank fragment, about half of the
tank, was propelled inside a turkey barn as a result of the explosion.
following is a sketch of 18,000-gallon propane tank and piping setup at the
farm, from the CSB report. The tank was estimated to contain 10,000 gallons of
propane at the time of the explosion, at approximately 11:28 pm, on April 9,
1998. Two firefighters responding to a fire which engulfed the propane tank,
were killed by tank fragments resulting from a BLEVE explosion (BLEVE= Boiling
Liquid Expanding Vapor Explosion). Seven other people were injured, and
several buildings were severely damaged by the blast. The firefighters assumed
if they stayed away from the ends of the tank they would be “safe”, but
exploding tank fragments were hurled in all directions.
Herrig Brothers Feather Creek farm raised turkeys, which were housed in seven
barns. Propane was used as fuel for space heaters and furnaces, which provided
heat for the turkey barns. On the evening of 9 April 1998, eight high-school teens
gathered at the farm for a party. The owners, which did not live at the farm,
said that they did not have knowledge or consent of the event although they
were aware of other social gatherings took place in the past. One of the
youths began driving an all-terrain vehicle (ATV), which struck two above
ground pipes which ran parallel to each other at the tank location and were
used to transport propane to vaporizers located 37 feet away. Liquid propane
leaked out of the ¾-inch pipe at the point of the break. An excess flow valve
protecting the liquid pipe line leaving the tank failed to function. Propane
may also have leaked from the second line struck by the ATV, but this was not
conclusively established. As the liquid propane sprayed from the line, it
quickly vaporized and ignited within a few minutes, presumably from one of the
direct-fired vaporizers located 37 feet away. The time of ignition was
estimated to be roughly 11:05 PM (based on later CSB interviews of the
teenagers). Two teens drove to a neighbor located ½ mile away, who called the
911 operator at 11:10 PM to report the fire.
members of the Albert City Volunteer Fire Department and two Buerna Vista
County Sheriff Deputies arrive at the farm at 11:21 PM. The firefighters
observed flames originating from the west end of the tank, and also from
pressure relief valve pipes located on top of the tank. One fire fighter said
that the propane tank was fully engulfed in flames and flames shot 70 to 100
yards into the air. Because of the fire, the firefighters did not attempt to
reach a manual shutoff valve on the broken pipe. The plan was to let the fire
burn itself out and to setup the fire trucks to spray water on nearby buildings
which were getting hot. One of the fire trucks was sent away to get more
approximately 11:28 PM, as fire-fighting equipment was being moved into
position, the tank exploded scattering tank fragments in all directions. One
large piece hurled to the northwest struck and killed two volunteer firemen
located 100 feet away from the tank. The same piece narrowly missed the Fire
Chief. Another large piece was propelled to the north narrowly missing two
firefighters. Seven firefighters were injured, including some with severe
burns. The largest piece was hurled to the east and came to rest inside one of
the turkey barns (shown in the photo). At least 36 pieces (possibly 40 pieces)
were later located by investigators, some in fields off the 14-acre property
site. Unfortunately, while the CSB report identified the fragments and
locations, there were no distances presented as to how far the fragments were
CSB report established that the propane explosion was a BLEVE, a Boiling Liquid
Expanding Vapor Explosion. Unpressurized propane is a gas (at room
temperature) with a normal boiling point of about -42oC (-43oF),
but it is normally stored in tanks as a liquid under pressure. At the
estimated 38oF ambient temperature before the incident, the vapor
pressure of the liquefied propane inside the tank would initially be at about
80 psi. When responders arrived at 11:21 PM, the tank was engulfed in flames,
and the safety release valves at the top of the tank designed to vent at 250
psi gauge were obviously working, based on firefighter reports that the noise
from the release valves was “like standing next to a jet plane with its engine
at full throttle”. It is not known at what pressure the propane tank failed,
but the CSB report estimated it to be somewhat less than 1000 psi. The sudden
release of pressure resulted in a rapidly expanding boiling liquid and vapor
photo, Aerial view of Incident scene showing locations of firefighters and
equipment at time of explosion, from NIOSH report at http://www.cdc.gov/niosh/fire/reports/face9814.html.
= position of propane tank
2 = location of firefighters killed by fragments from exploding propane tank
= position of other firefighters
= position of apparatus
1. The above ground
piping was not protected from potential damage by vehicles, as required by Iowa
law citing the 1979 edition of the National Fire Protection Association’s
“Standard for the Storage and Handling of Liquefied Petroleum Gases” (NRPA
58). The lack of piping protection allowed the ATV to crash into the pipes
that ran from the tank to the vaporizers.
2. The outlet
propane pipe diameter was improperly sized for the excess flow valve, which was
supposed to automatically shut off the flow in case of excess flow in the
propane pipe. The valve was designed to shut off at 200 gpm, which in no way
could occur with the ¾ inch diameter propane outlet pipe. Therefore the valve
did not shut off. Had the valve shut off, the BLEVE probably would not have
were too close to the propane tank. The firefighters assumed that if they kept
away from the ends of the propane tank they would be safe. The CSB report
cited that firefighters had receive inadequate training for responding to
propane tank fires.
Fire Service Training Association guidelines1 for responding to
propane tank fires:
1. Do not assume
that the venting of propane from relief valves will prevent over pressurization
and rupture of the tank.
2. Apply large
quantities of water to the tank. For large propane tanks, at least 500 gallons
per minute is needed.
3. If a flame is
impinging on the tank, water must be applied directly to the impinged area in
order to prevent a BLEVE.
4. Water should be
sprayed by use of an unmanned fire hose system.
5. If a continuous
supply of water is not available, withdraw and isolate the area for ½ mile in
1996 Emergency Response Guidebook(ERG), which was carried by the fire fighter
vehicles at this incident, under Guide Number 115 which addresses propane tank
fires, recommends that responders to a massive fire use “unmanned hose holders
or monitor nozzles”, or if this is not possible, to “withdraw from the area and
let the fire burn”. There was also a statement in the 1996 ERG to “withdraw
immediately in case of rising sound from venting safety devices…”. However the
1996 ERG also contained a possible misleading statement under Guide Number 115,
“ALWAYS stay away from the ends of tanks”, which could be interpreted by
firefighters to mean that by avoiding the ends of the tank the sides of the
tank would be safe. As the result of the Herrig Brothers propane explosion and
CSB report, later editions of ERG Guide Number 115 for responding to large
propane tank fires reads as follows (from 2008 ERG):
Explosion, 30 January 2007, Ghent WV, Four killed including two responders, six
incident was investigated by the U.S. Chemical Safety and Hazard Investigation
Board (CSB); their findings are published as report no. 2007-04-I-WV released
in September 2008, and can be downloaded from http://www.csb.gov/completed_investigations/docs/CSBFinalReportLittleGeneral.pdf. Information
including the illustrations used here were taken from this report.
case study was used as a basis for a CSB safety training video, which can be
30 January 2007 at 10:53 AM, a propane explosion at the Little General Store in
Ghent, West Virginia, killed four and injured six people. The dead included a
fire department captain and an emergency medical technician from the Ghent
Volunteer Fire Department and two propane service technicians. The injured
included two other Ghent Volunteer Fire Department emergency responders and
four store employees who were inside the store at the time of the explosion.
from West Virginia State Fire Marshall as used in CSB report
above photo, taken from CSB report no. 2007-04-I-WV, shows the demolished store
and ambulance caught in the propane explosion.
the Herrig Brothers Albert City explosion, this did not involve a tank BLEVE.
The cause was a propane leak which resulted in propane concentration in and
near the store to build up and exceed the lower explosive limit concentration
in the air (>2.1% by volume of propane in air).
propane leak occurred during transfer operations, when propane was being
transferred from an existing older tank owned by Ferrellgas to a newly
installed tank owned by Thompson Gas and Electric Services (called the
Thompson tank). The two tanks were located adjacent to The Little General
Store, as seen in the sketch to the left. The propane tanks were each 500
gallon capacity. The new Thompson tank was to be installed 10 feet from the
building but the older tank was right next to the building.
headquartered in Kansas, is the second largest propane marketer in the United
States, with customers in all 50 states. Thompson installs commercial and
residential systems and delivers propane in eastern and southeastern U.S. Late
in 2006, The Little General Store initiated a change in propane suppliers.
Appalachian Heating, a local family owned business, has a contract with
Thompson to install propane systems in the local area.
the morning of 30 January 2007, two propane service technicians from
Appalachian Heating arrived in separate vehicles at the Little General Store.
The plan was to transfer propane from the existing Ferrellgas tank (installed
in 1994) to the newly installed Thompson tank and place the new propane system
in service. At about 9:30 AM, the lead technician left the store to make a
delivery 31 miles away leaving a junior technician alone. The lead technician
had earlier completed his “Certified Employee Training Program” in September
2006 for installing propane systems and had also spent nearly a full year
working with experienced personnel, but the junior technician had no such
training. For the next hour the junior technician worked alone preparing to
transfer propane between the two tanks.
about 10:25 AM, the junior technician removed a plug from the liquid withdrawal
valve on the Ferrell tank, which resulted in liquid propane spraying from the
valve. The junior technician then called (10:28 AM) the lead technician who
was still off site. After the lead technician called Thompson technical
support, he tried to reach the junior technician, most likely to encourage him
to call “911”. A deliveryman in the store at about 10:30 AM told CSB
investigators that he had smelled a strong odor and noticed employee eyes were
watering. A Little Store cashier checked on the junior technician who was
standing outside within a dense vapor cloud near the tank, but the junior
technician said that he was OK. At 10:40 AM, the junior technician called 911
to summon aid, but continued to remain near the tank within the propane vapor
about 10:47 AM, a captain from the Ghent Volunteer Fire Department arrived on
scene and assumed role of incident commander. Shortly afterwards, two EMT’s
arrived in an ambulance. The captain ordered the business to close, and asked
the EMT’s to follow him to behind the building to treat the junior technician
who was still near the propane tanks and apparently had suffered frostbite from
the leaking propane. Shortly after 10:50 AM, the lead technician returned, and
walked back to the area of the propane tanks. The captain ordered one of the
EMT’s to the front of the store to check that the store was closed and that no
one was smoking or pumping gas; the store was locked, but the EMT spoke to
employees who were still inside the store. A firefighter then arrived in his
personal vehicle and could hear the escaping propane. The captain ordered the
firefighter to get all employees out of the store. As the firefighter
approached the front of the store, the propane ignited and exploded. The four
people near the propane tank were killed (the lead and junior service
technicians, the captain, and the EMT treating the junior service technician).
The four employees inside the store and two firemen were injured. The
explosion leveled the store, destroyed an ambulance, and damaged many parked
vehicles. The Ferrellgas tank was hurled about 80 feet due to the force of the
of a propane tank showing locations of Liquid Withdrawal Valve and Fill Valve
Liquid Withdrawal Valve
Removed Plug, with telltail circled
1. The Ferrellgas
Propane Tank, installed in 1994, was located right next to the building in
contrary to OSHA and National Fire Protection Association (NFPA) Standards
which state that a 500 gallon propane tank should be located at least 10 feet
from commercial or residential buildings. The OSHA standard, Storage and
Handling of Liquefied Petroleum Gases, and NFPA 54, National Fuel Gas
Code, and NFPA 58 Chapter 6, Liquefied Petroleum Gas Code, all
address the location of tanks. The open building overhang above the propane
tank, and the interior restroom exhaust ducts provided a direct pathway for
propane gas to enter the store. It was not clear to CSB why this shortcoming
was not recognized and corrected during the 12 or 13 years the tank was in
service, even though it was filled many times and inspected. Another propane
company prior to Ferrellgas had originally installed the tank. The new
Thompson tank was to be located 10 feet away from the store.
2. The junior
technician, who was hired 45 days earlier, did not undergo the “Certified
Employee Training Program” (CETP) put together by the propane industries.
Thompson requires its employees to be CETP-trained, and Appalachian Heating did
not notify Thompson of the new employee. This training program is developed by
the National Propane Gas Association (details at http://www.npga.org, go to
“Safety/Training Programs”). The junior technician apparently did not
recognize the hazard of a propane gas cloud. OSHA and DOT require employee
training, but do not elaborate on the requirement.
3. Technicians only
open liquid withdrawal valves when propane tanks are completely emptied of
liquid. The CSB investigation found that the liquid withdrawal valve was still
on the damaged tank after the accident, but the plug was removed. The
investigation found that the liquid withdrawal valve itself was defective
causing it to be in an “open position”, and assuming the valve was defective
before the accident, this means that the plug was the only thing preventing the
propane from escaping the tank. As an additional safety backup, the plug on
the withdrawal valve has a telltale drilled through the treaded portion which
should have released a small stream of propane once the plug was partially backed
out in the case of a defective valve in open position. This should have
alerted the junior technician that the valve was leaking and something was
wrong. This specific information was addressed in CETP training, which included
written instructions, and which included the statement, “WHEN IN DOUBT DO NOT
REMOVE THE PLUG”. The junior technician apparently did not recognize this and
continued to unscrew the plug.
4. The Incident
Commander (captain from the Ghent Volunteer Fire Department) while he initially
followed procedure on assessing the situation was slow to act on ordering a
complete evacuation. The Incident Commander apparently allowed the junior
technician to try to stop the leak. Had the Incident Commander had certain
critical pieces of information available (the technician did not have training;
propane gas was entering the building), he probably would have ordered everyone
to leave the area immediately. Only six minutes passed from the time the
Incident Commander arrived on scene until the explosion.
5. The Ghent
Volunteer Fire Department only had minimal information available (gas leak at
The Little General Store at Flat Top Lake) when they were contacted by the 911
dispatcher, and the 911 operator was not trained to ask the right questions.
The 911 caller said he had a propane leak, the 911 dispatcher said a gas leak.
There was also no prompt card available on propane to prompt the 911 caller to
ask the right questions, and the responders did not know the severity of the
situation. A citizen driving past called the response team to clarify that it
was a propane leak. The propane industry has prepared a script for use in
situations where customers report propane leaks, which could be part of a 911
* Where is the leak?
* Do you hear gas escaping?
* Is the leak near any building?
* Is there odor of gas in the
a fire department permit propane service technicians to stop a propane leak
from a valve or piping?
CSB reviewed another incident, a vapor release of propane from the Southshore
Mall in Aberdeen, Washington, which occurred on 23 October 2007. The
1,150-gallon propane tank was located in a utility yard approximately 25 feet
from mall restaurants. Shortly after 2 PM, a mall employee heard a “pop”, and
upon investigation discovered the leaking tank. The fire department was
called, they evacuated the mall, and secured the scene. The fire department
contacted the propane company that owned the tank for support. The propane
company sent a service technician. The service technician discovered that the
release was from the propane tank’s fill valve which was stuck in a partially
open position. The service technician installed a double check valve on the
leaking fill valve to stop the release. All this was done in less than one
hour. The evacuation order was lifted at 2:45 PM. The differences between
this incident and the Ghent explosion with respect to allowing a propane
service technician to work on the tank was as follows:
1. The fire
department first evacuated everyone and secured the area before permitting the
service technician to enter.
2. The fire
department already had a working relationship with the propane company and knew
that the service technician was CETP-certified, and the service technician had
previously worked with the fire department on propane incidents.
3. The vapor
release was minor compared with the Ghent release, and the service technician
knew how to correct the leak.
of 2007, only 14 states require training for propane service technicians, and
11 of the 14 states either require or accepts CETP certification for this
first duty of first responders is to evacuate and secure the area. There may
be also be injured that need attending; an important step is removal of injured
to a safer area if possible while evacuation takes place. The PEAC tool can
provide responders on safe evacuation distances for propane, which is linked to
Guide Number 115 in the Emergency Response Guidebook. In case of a large
spill, the recommended evacuation distance is at least ½ mile or 800 meters.
As an immediate precautionary measure, the spill or leak should be isolated for
at least 330 feet (100 meters) in all directions. Guide Number 115 also gives
guidance on how to fight fires and whether responders should evacuate. In the
case of tank fires, responders should evacuate immediately in case of rising
sound from a venting tank or a tank is engulfed in flames or becomes
discolored. If there is no flame, responders should also evacuate if they hear
escaping propane from a tank, or a strong tell-tale odor (rotten egg odor) is
noticed. Propane itself is odorless, but trace amounts of butyl mercaptan or
a similar odorous chemical is added as a warning if a leak occurs. Propane gas
is heavier than air and will tend to hug the ground.
PEAC tool does not give instructions on how to stop a leak. Only when the
situation is deemed “safe” (a vapor cloud explosion or a BLEVE is not likely)
should qualified technicians be allowed to approach the tank.
PEAC tool is designed to contain considerable technical information in a small
package useful for first responders. The tool is set up so the information can
be extracted quickly.
two examples show the complex situations involving response to emergency
situations and interaction between other people. First responders do not have
the benefit of hindsight when responding to an emergency situation. They must
act quickly under a stressful situation, and cannot take for granted that
propane or other chemical storage facilities are designed properly or people on
site know what they are doing. They must recognize quickly a potentially
dangerous situation and not be afraid to set priorities especially if an
immediate evacuation is required.
Fire Service Training Association. Hazardous Materials for First Responders
pages 276-280. Oklahoma State University, Stillwater OH, 1990.
the firefighters and their families who have died in the line of duty.
total number of firefighter deaths and injuries for all responses on an annual
basis is found at the website, http://www.usfa.dhs.gov/fireservice/fatalities/statistics/casualties.shtm.