Laboratory Safety
Incidents: Fire
Chemical Based Fire (top)
Bleach and Methanol Mixed Waste Cause Lab Fire
(top)
Key Instruction Points
1. Clean up of small spills of hazardous waste should be bagged or
put into a suitable closed container and disposed of as hazardous waste.
2. Know the incompatibilities of chemicals mixed in each step of
your experiment, including waste disposal.
Mixing of incompatible chemicals was the likely cause of a laboratory
fire. Luckily, no one was injured, but extensive cleanup of
equipment in the room was required because eight extinguishers were
needed to put out the fire.
Paper towels had been thrown into a trash container after a
laboratory spill of Comassie blue dye. The researcher first wiped the
area with methanol, which Comassie blue is soluble in. A blue stain
remained on the floor, which was then removed with concentrated
bleach and wiped up. All paper towels were put into the same trash
container. The next day, as the bag was being lifted out the trash
container, a fire flashed up. Fortunately the researcher who was
removing the bag was uninjured. He notified fellow lab workers, and
the Fire Department was called. Eight extinguishers had to be used
because the fire would appear to be extinguished, but would then
flare up after each extinguisher was emptied. The room and equipment
were coated with a thick layer of dry extinguishing agent (probably
ammonium phosphate) by the end of the operation.
What is the likely cause of the fire?
Bleach (sodium hypochlorite) and methanol can form methyl
hypochlorite, which can be explosive and may have caused the fire to
flash several times. Bleach is a strong oxidizer even at the low
concentrations used (4-10%) for disinfection. It can react with other
chemicals to release toxic gases: chlorine gas is released when mixed
with acids, and chloramines are released when mixed with nitrogen
compounds (ammonia, urea, amines, isocyanurates).
Shelf
Collapse leads to a spill and a spill/explosion at separate institutions
(top)
Key Instruction Points
1. Do not procrastinate at getting broken equipment repaired.
2. Follow your institution's safety procedures.
3. Treat spill clean-up materials as hazardous waste.
The collapse of a shelf in a flammable
storage cabinet lead to an explosion and fire in a lab at X causing the destruction of two labs and damage ranging from
$200,000 to 300,000 in repairs. Spills due to
the unstable shelf had occurred previously but no one had tried to repair or replace the
defective shelf. In this instance,12
containers of hexane were being unpacked into a flammable storage cabinet when one of the
shelves collapsed. The resulting three-alarm blaze took about 20 fire trucks and 84
firefighters from several area fire stations more than an hour to extinguish.
Flammable liquids ignite when there is
enough fuel and oxygen in the air to support a flame, as well as an ignition source. Common ignition sources in labs are Bunsen
burners and stirrers with brush-type motors. Plugged-in electrical equipment could also be
an ignition source. In this case it was never
determined what the ignition source was.
There were about 50 gallons of
flammables in the lab which lead firefighters to switch from water to dry powder
extinguisher, and finally to chemical foam, which eventually put out the blaze.
In a completely separate incident at
another institution, a spill occurred when a shelf located in a flammable storage cabinet
under a chemical hood, collapsed. A gallon
bottle of glycerol and a gallon bottle of isopropyl alcohol broke and spilled.
Additionally, a gallon bottle of acetone had fallen off the shelf and was leaking. Rather than vacating the room and contacting the
safety office to clean-up the spill lab personnel cleaned up the spill themselves which
took about 30 minutes. The personnel recently
attended training where emergency procedures were reviewed.
They used a broom, a dustpan, and brush to pick up the broken glass and the
liquid. They placed the entire contents of the spill, including the liquid, in a box
designed for broken glass on the floor of the lab where it continued to evaporate over the
weekend.
It is believed that improperly
installed shelving clips caused the shelf to collapse.
This was a new lab and the solvent cabinet was being used for the first
time. An inspection of all the shelves in the
area found other clips that were also not installed properly.
The personnel involved in incident did
not follow the institution’s emergency procedures which had been reviewed during
training and which are listed in a emergency flip chart which is posted in the lab. Lab personnel are responsible for cleaning up minor
chemical spills, only. A minor chemical spill
is defined as = 1 liter of any chemical that is NOT a carcinogen, acutely toxic or a
reproductive hazard. The safety office and other emergency response personnel handle all
other chemical spills. Everybody should have
left the room and someone should have called for help from a location where the safety
office could call back to get information about the spill.
Besides posing a fire hazard (vapors
from flammable liquids catch on fire, not the liquids themselves), they violated their
institutions policies as well as EPA regulations regarding hazardous waste. It is against federal environmental regulations to
evaporate chemical waste into the atmosphere.
_______________________________________________________
Fire From Diethyl Ether Spill (top)
Key Instruction Points
1. Wear long pants and shoes in the lab.
2. Work at least 6" inside the chemical hood.
A graduate student was injured by flash fire due to a reaction product that contained about 1 liter of ether. The ether was to be filtered through a cup shaped device containing the desiccant sodium sulfate. The filter apparatus was placed in a 2 liter round bottom flask and connected to house vacuum. The round bottom flask was attached to a ring stand.
The 2-liter Erlenmeyer flask that containing the diethyl ether and reaction product broke and spilled into the hood and onto the floor in front of the hood. The whole assembly was situated at the front of the fume hood on the sill adjacent to the fume hood airfoil so when the container broke the flammable mixture was not contained in the hood. In addition, the sash on the hood was fully open.
Seconds later, a fire rising from the floor in front of the fume hood engulfed the student. The source of ignition was most likely a drying oven that was situated under the hood. Unfortunately the student was wearing shorts and sandals. The student moved away from the fume hood and rolled on the floor to extinguish the flames. A nearby safety shower was blocked by equipment. The student was able to leave the building with help from colleagues where he waited for emergency response. After initial treatment by fire department technicians, an ambulance arrived and transported him to a regional burn treatment center.
There was no written standard operating procedure and apparently this was an elementary procedure that the student had performed thousands of times. The lab manager had performed and reviewed the procedure with the student but the procedure was not documented in the students notebook or in the Laboratory Safety Plan. The student had recently attended a general department training program.
During the two years prior to the fire, the lab had undergone three safety inspections. The inspection reports documented many deficiencies in procedure and had noted the extremely crowded laboratory conditions. The PI had not responded to the reports.
Several steps could have been taken to prevent or mitigate incidents.
· Check glassware
before using it for cracks or scratches. Replace
damaged glassware.
· Use plastic coated
glassware for transporting or holding solvents. When
glassware is replaced, order some of the break resistant glassware.
· Allow more space
for workers. There were at times as many as
14 people in the lab
· Work at least 6
inches inside the chemical hood. This is
critical for containment of vapors. In addition, the work top on the chemical hood is
dished and will contain a spill.
· Work with the
chemical hood sash pulled down to shoulder height. The
sash can protect the workers face and breathing zone from a deflagration and can greatly
reduce exposure to gases and vapors in the hood. With
the sash at this height, a hood may contain a fire.
· Do not block safety
equipment such as the safety shower.
· Do not house drying
ovens under chemical hoods.
· Require lab
personnel to wear long pants and shoes in the laboratory.
Prohibit shorts and sandals. In
addition, goggles and lab coats should be required for procedures involving large
quantities of hazardous liquids.
- Document
training. Training must be documented for new
workers and annually thereafter. Require
training for all personnel working in the laboratory.
Assure that laboratory workers document safe procedures in their notebooks,
send students to the fall departmental training sessions and hold periodic meetings with
staff. At lab meetings, include a safety
related agenda and file the agenda.
________________________________________________________
Carbon Disulfide Fire (top)
Key Instruction Points
1. Store liquids in stable containers or use racks.
2. Recognize location of nearest ignition sources when
using flammable liquids
Incident Description: We have four gas chromatographs (GCs) on two sides of one
ten-foot-long aisle of our laboratory. One of our analysts was working at one of the GCs
and was choked by a cloud of some sort of gas of an unknown origin and nature. After
looking around for a second or two and not finding the source, she called out for everyone
to get out of the lab and set off the fire alarm in the hallway, waiting for the Fire
Department HazMat team and finally our own staff to identify what the problem was.
What we finally discovered was the following: another analyst in our lab, a contractor,
had set an open vial (with an inward-tapered opening at the top) of carbon disulfide, used
for flushing GC autosamplers, on top of another GC across the aisle. Somehow, the vial
tipped over and rolled into the opening at the top of the GC where the heated injector is
located. Presumably the CS2 heated up the vial when it came into contact with the
injector, and sprayed out CS2 vapor. The vapor burst into flame (because of the
very low auto-ignition temperature) when it came in contact with the injector, producing a
nearly-suffocating cloud of SO2 and unburnt CS2 which passed over
the other analyst, moving in the direction of the nearby fume hood. The entire incident
was over in perhaps 10 seconds (but we didn't know that at the time)!
The analyst who breathed the combustion products was checked and found to have suffered
no ill effects. The GC where the fire took place has a few scorch marks around the
injector, but otherwise suffered no damage. The lost time of the several hundred people
that work in our 7 story building and were kept outside for about 2.5 hours was
significant.
The primary cause of the incident was putting a narrow-based vial with a highly
flammable solvent on top of an instrument.
We put a stop to the practice of putting things on the top of Gcs immediately. After
the incident we had the carpentry shop fabricate a half dozen small tube racks that will
hold GC vials of the appropriate size. There is one such rack next to every GC in the lab
now. We have established a rule that nothing will be put on top of any GC - or any other
instrument - but only in a rack, on the bench top.
We were fortunate that we had no injuries or property damage, but the cost in lost time
to ourselves and others in our building was significant.
______________________________________________________________
Azobisisobutyronitrile Fire (top)
Summary:
Explosion and fire occurred in a lab in X Hall. A graduate student
was thrown four feet and cracked a rib. Her hair was singed from the fire ball. She
was heating dioxane, a flammable solvent, and azobisisobutyronitrile on a hot plate in a
glove box when a leak was suspected to have developed in the box. The hot plate’s
thermostat probably served as the ignition source. She did not have the MSDS for
azobisisobutyronitrile and she was unaware that upon heating this chemical produces an
acutely toxic chemical, tetramethylsuccinonitrile (TMSN). TMSN is immediately dangerous to
life and health (IDLH) at 5 ppm. For comparison, cyanide gas has a IDLH at 25 ppm.
Personnel from the Health and Safety Office entered the room to
retrieve coats and open the windows not knowing the presence of this chemical. Their
selection of personal protective clothing was insufficient to protect them from the TMSN.
Both became ill from exposures.
Description of Incident
The experiment involved heating 300 mL of dioxane, 30 grams of
N-isopropylacrylamide, and 6.24 grams of azobisiosobutyronitrile ("VAZO" 64) in
an inert atmosphere, on a hot plate. Early in the experiment the student suspected
there might be an air leak because the gloves which normally were inflated were sagging.
The graduate student spilled approximately 10 mL. Working within the gloves, she wiped up
the spill with some paper toweling. Suddenly, with no warning, the reaction exploded and
threw her 3 to 4 feet into the bench behind her.
Another student phoned Security and the Environmental Health &
Safety office. He evacuated the hallway and all the adjacent labs,
grabbing the book of MSDSs before leaving. She informed the Health and Safety Office of
only three of the four chemicals that were involved in the incident. The company had never
sent her a MSDS for "VAZO". She was visibly shaken and her eyelashes
and hair was singed. The Health and Safety Office recommended that she shower, change
clothes, and get a medical examination.. The weather was freezing and students were
requesting their coats, lap-top computes and other belongings from the affected area. An
employee from The Health and Safety Office entered the lab with a half face respirator
with organic vapor cartridges to shut down the experiment, retrieve personal items, and
open windows. The Health and Safety Office found that many of the windows which had been
designed to open were sealed shut. After about 20 minutes, a pane of glass was
broken for ventilation.
An emergency response team from ________ was called after several
hours to appraise the situation because of the persistent smell. The emergency
response team wore Self Contained Breathing Apparatus (SCBA).
Neither student experienced any chemical exposure symptoms, although
both were examined by physicians. The student involved in the explosion did crack a rib as
a result of her impact with the counter.
The next day the student was interviewed again. She informed the
Health and Safety Office of the chemical she neglected to mention the day before.
The missing chemical was the azobisiosobutyronitrile or "VAZO" 64. She
thought it was causing the residual smell in the room. Researching the chemical, The
Health and Safety Office discovered that upon heating the "VAZO" readily
converts to Tetramethylsuccinonitrile, an odorless chemical that is highly
toxic and can be fatal in very small doses. Concentrations of
Tetramethylsuccinonitrile are Immediately Dangerous to Life and Health (IDLH) at 5 ppm.
[For reference NIOSH lists Sodium Cyanide, gas, at 25 ppm., both by inhalation.] Both
health and safety office personnel who had entered the room experienced temporary symptoms
from exposure to the Tetramethylsuccinonitrile that had penetrated their cartridges.
Conclusions:
The heating of flammable solvents should be done so as to
avoid any contact with ignition sources. An explosion proof hot plate is recommended for
future experiments. The glove box is unsuitable for the use of flammable liquids due to
the factory installed electrical outlets. Due to the air leak, all the elements were
present for the fire ball that resulted. Students should have researched each
of the reactants and had a thorough understanding of their properties and decomposition
products.
The Health and Safety Office should not have entered an area that
has an unknown atmosphere.
Students possession should never have been taken from the room
without being decontaminated. These items were collected for cleaning.
Recommendations:
In the future, an explosion proof hot-plate and a non-electric
balance should be used.
The glove box manufacturer should be contacted and asked if the box
is acceptable for use with flammable solvents.
A written standard operating procedure (SOP), that includes safety
procedures, should be developed. The SOP should demonstrate a thorough
understanding of all chemicals involved. SOPs should be reviewed by students and
supervisors.
Provide closer supervision of graduate students.
After incidents similar to this one the contents of the room
should stay undisturbed until a thorough evaluation is completed.
No chemical should be used until the MSDS is obtained and reviewed.
Lithium Aluminum Hydride Fire
(top)
A laboratory worker was attempting to distill tetrahydrofuran (THF)
using lithium aluminum hydride (LAH). THF is a highly flammable liquid that can cause
severe eye irritation and central nervous system depression. LAH is a water-reactive,
flammable
solid.
The laboratory worker was slowly pouring approximately 1 gram of LAH from a plastic bag
into a flask containing 500 ml of THF inside a fume hood. A small amount of LAH leaked
from a small hole in the bag, onto the surface of the hood and burst into flames,
startling the worker and causing him to drop the remainder of the bag (8-10 grams of LAH)
onto the fire. Concerned about the flask and bottle of THF inside the hood, the worker
immediately removed his lab coat and placed it onto the fire in an attempt to smother it.
Since the appropriate extinguishing agent was not available, .the worker pulled the
flaming lab coat and LAH out of the hood onto the floor. Once the LAH fire had burned
itself out, the worker used a dry chemical extinguisher to put out the coat fire.
Since the incident, Met-L-X extinguishers were mounted inside the door of the laboratory.
The laboratory worker keeps a supply of sand (in a plastic milk jug with the top cut off)
on the floor at the side of the hood where this work is done.
-Know the hazards of the materials, including appropriate
extinguishing agents, before using chemicals.
-Carbon dioxide reacts with LAH explosively; thus, a carbon dioxide
extinguisher could have made the situation worse. A Met-L-X fire extinguisher (for
flammable solids) or dry sand should have been immediately available.
-Do not pour solids such as LAH directly from the container into
another chemical or reaction vessel. Measure out what is needed, then pour it.
Sodium Hydride Fire (top)
Sodium hydride (NaH) can react with water or spontaneously with
moist air to generate highly flammable hydrogen gas and corrosive sodium hydroxide. A few
months ago, a graduate student was attempting to convert some unneeded NaH into a less
reactive compound, a process known as quenching, prior to disposing it. The reaction was
conducted in an ice bath and when the extreme heat liberated by the process ruptured the
reaction beaker, a brief, though very intense fire occurred. Fortunately, no one was
injured.
This accident provides a backdrop for considering the following
points about procedures for hazardous waste disposal, fire safety, and working with
chemicals posing particular hazards.
1. Many chemicals used in the laboratory, including NaH, are legally
considered regulated hazardous waste once they are designated for disposal. Many Research
Institutions are not licensed to treat (e.g., quench) such waste on site. Contact your
safety office to arrange for the safe and legal disposal of hazardous chemicals through
your institution’s hazardous waste vendor.
2. Fires involving reactive chemicals may not be extinguishable by
the carbon dioxide (BC) or dry chemical (ABC) extinguishers typically provided to
laboratories. If water reactive chemicals are used or stored in the laboratory, consider
keeping a small amount of sand or limestone on hand. Consult the manufacturer’s
Material Safety Data Sheets for the recommended type of extinguisher for these materials.
3. The fume hoods in many of the newer laboratory buildings are
sprinklered. Sprinkler activation during a fire will exacerbate the situation when a water
reactive chemical is involved. It is best to let this type of fire burn itself out rather
than attempting to fight it yourself. Lower the sash if possible, leave the area, and
activate the building fire alarm. Call your institution’s emergency phone number from
a safe location and provide details about the fire.
Solvent Explosion and Fire (top)
At the University of X, a 55 gallon drum containing 30 gallons of
mixed organic solvents exploded, launching upward into the ceiling, within the hazardous
waste storage facility and began a significant fire. Luckily, no one was hurt. The mixed
organic solvents in the drum had been consolidated from solvent waste containers from
laboratories across the campus. A similar consolidation process is used at many research
institutions.. Solvents are consolidated because there is significant cost savings in
disposing of one large drum as opposed to many smaller containers. This incident
demonstrates how important it is for each lab to fully report the contents on each
container on the hazardous waste label.
Letter from a Post Doc Burned in a
Solvent Fire (top)
The author of the following letter is a former University of X
graduate student now working as a post-doc at another institution. It was forwarded to the
Health and Safety Office by one of his former colleagues. Identifying
information including the names of the people involved and the name of the institution
where the incident occurred have been changed.
Hey Stan,
I've been trying to email you for some time but the computer
wouldn't let me through for some reason - hope we have better luck now. I wanted to tell
you some news in the meantime - I was in a serious lab accident here in John’s lab
and was quite badly hurt. Before I relate the rest of the tale (it is quite frightening)
let me assure you that I am basically OK, I'm not disabled or horribly disfigured or
anything.
What happened is a there was an explosion and fire in the lab in
which I was actually set on fire and badly burned. Friday afternoon September 11th. This
?#%&* lab technician was working at her bench with a burner going full blast; John and
I were standing about 6 feet away. She proceeded to pour from a full one gallon glass
bottle of methanol with the mouth of the bottle only a few inches from the flame. John and
I stared in horror at the stupidity of the action; I took a few steps toward her as I told
her to stop what she was doing and get the bottle away from the flame ASAP, about to give
her the safety lecture of her life.
The whole thing exploded in my face; all I saw was a ball of blue
flame as the entire bay was drenched with burning methanol. It was like I was hit by a
flamethrower - I looked down and flames were coming from my chest and arms. The whole
episode only lasted for 5 or 10 seconds before I got under the emergency shower (thanks to
cool thinking by Sam Smith who basically saved my life). I was burned over about 20% of my
body surface - a mixture of 1st, 2nd, and 3rd degree burns on my chest, left side, left
arm and hand, right forearm, the front of my neck, and the bottom half of my face. The
sprinkler system extinguished the rest of the fire. No one else was hurt - the person who
was responsible left the next day for another position so I couldn't even have the
pleasure of firing her.
I spent 10 days in the Hospital Intensive Care Unit, and had skin
graft surgery to repair the worst of the burns. There are whole days of my time in the ICU
that I have no recollection of, but what I remember was a nightmare.
But in the end I walked out of the hospital on my own two feet. The
good news is the burns to my face and neck were very superficial so they healed up nicely
and I'll have no scarring there - with a long sleeved shirt on you'd never know anything
had happened to me (in fact I look even better after the accident - the facial burn was
like having a chemical face peel, and I lost around 15 pounds in the hospital plus I have
a new spiky punk haircut from when the ICU nurse cut away all of my burned hair, so people
at first think I went to a spa or something). My chest and left arm are a different story
- I'll definitely have some scarring there but its too early to tell what it will look
like. Considering how easily I could be dead/blind/horribly disfigured I consider myself
very, very lucky indeed. Five weeks after the accident I was back in the lab at work.
So now I preach lab safety to everyone I talk to. Tell your people
to be careful with flammable solvents and remember what I learned the hard way - it
doesn't matter how careful you are, someone else's stupidity can get you killed.
Dan
Flame/Ethanol Sterilization
Fires (top)
Clean Bench Fire (top)
An individual was decontaminating the surfaces of a clean bench with
70% alcohol while a bunsen burner was lit. A fire erupted which ended up catching
the filters on fire. Severe damage to the hood and the laboratory occurred in 10
minutes. Since a fresh supply of air was delivered to the burning filters....you can
imagine the intensity of the resultant fire.
2 Flaming Loop Fires, both inside a Biosafety Cabinet (top)
Two reported laboratory fires, fueled by natural gas associated with
the use of Bunsen burners should compel researchers to rethink how, and if, they should
use them. Both fires occurred at the University of X. Fortunately, no one was
seriously injured.
In one case, gas leaked from a loose tubing connection and
accumulated to where it was ignited by the burner's flame, causing a small explosion.
Isopropanol in a nearby flask inside the cabinet also caught fire.
In the other incident, a researcher inadvertently turned on the gas
thinking he was turning on the vacuum line. Realizing his mistake, he turned off the
gas. When he subsequently attempted to light the burner, the residual gas in the
cabinet ignited, burning his arms (first degree) and singeing his hair. He had not
waited long enough for the gas to dissipate.
Bunsen burners are typically used inside Biological Safety Cabinets
for sterilizing inoculating loops and test tube lips. However, this task can be
accomplished using a small electric "furnace" - a device expressly designed to
eliminate the need for using flammable gas in a safety cabinet (available from Fisher) or
consider using pre-sterilized, disposable loops.) Accidentally released gas may also
be ignited by sparks or heat from the motors and switches on cabinet fans and lights.
Consider these four points when using a flame:
* Use a burner equipped with a pilot light, in place of older
models with a blow torch-like flame;
* Do not use latex tubing (the stretchy yellow material).
It tears easily and is prone to pinholes; use butyl rubber instead;
* Check tubing regularly for cracks and tears;
* Replace tubing at the first sign of wear or deterioration.
______________________________________________________________
Flame-Sterilizing Fire Incident (top)
A fire occurred when a lab worker was flame-sterilizing
slip-glasses. The slip-glasses were in a small container of ethanol inside a
biosafety cabinet. The slip glasses were being removed, one-at-a-time, with
tweezers as the employee held each one in the flame of a small gas burner unit and then
placed in a holder.
The employee could not see flames but noticed heat emanating
from the supply container holding the unsterilized slip-glasses. She attempted to
extinguish the fire by placing an aluminum-foil cover over the container (the
container’s cover was not available). The aluminum foil cover blew off, so the
employee attempted to cover the container with a petri dish. However, a pipetter in
the cabinet had caught fire (probably due to ethanol spilling into
heat-induced cracks in the container).
She went for a fire extinguisher, only to find upon return that the
door to the room had shut and was locked. She did not have the key. At this
point the employee called 911 and activated the building fire alarm system. Damage was
limited to the interior of the biosafety cabinet and the pipetter. The employee’s
actions in response to this incident were admirable. She initially attempted to extinguish
the fire; when unable to do so, she called for additional help. The only improvement would
have been if someone else had been able to call 911 and activate the fire alarm while the
first employee was still trying to extinguish the fire. This fire was probably
started by an [invisible] burning drop of ethanol falling into the supply container.
The lessons to be learned for anyone doing similar work are:
1. Position the container of ethanol, supply of slip-glasses
and the destination container so that there is no potential for carrying the sterilized
slip-glasses over it
2. Be sure to have a key on your person at all times for any
room in which you’re working whose latch is set to lock every time the door is
closed.
_______________________________________________________________
Unattended Use of Bunsen Burner in
a Biological Safety Cabinet (BSC) (top)
Recently, a researcher left a lit Bunsen burner inside a BSC, closed
the sash and walked away. The type of biological safety cabinet she was using recirculates
about 70% of the air with 30% of the air goes out the exhaust. When the sash is closed
there is no bypass to allow fresh air into the cabinet. Thus, no exhaust was leaving the
cabinet. Heat within the BSC built up quickly. The situation was discovered only after the
flame had burned for a few minutes. The BSC was hot to the touch on the outside.
1. Experiments with potential danger should never be left
unattended, especially when an open flame is involved.
2. A standard Bunsen burner is only appropriate for open-bench
usage. Inside a BSC, an electric furnace such as a Bacti-cinerator,
or a device such as the Touch-O-Matic
Bunsen Burner should be used. This type of burner is built in a way that a platform is
connected to the burner itself. A flame is only produced when the user's hand rests on the
platform. When the user's hand moves away, only a pilot light burns. Touch-O-Matic Bunsen
Burner also serves the purpose when a continuous flame is needed, the platform only needs
to be pressed and slightly twisted. Consequently, the risk of leaving a full flame on by
accident is reduced.
3. Open flames should not be necessary in the near microbe-free
environment of a biological safety cabinet. On an open bench, flaming the neck of a
culture vessel will create an upward air current which prevents microorganisms from
falling into the tube or flask. In a BSC, however, an open flame creates turbulence which
disrupts the pattern of HEPA-filtered air supplied to the work surface. Disposable sterile
loops (example)
should be considered so no flame sterilization is necessary.
Flammable Storage Cabinets
(top)
Flammable Storage Cabinet Prevents Ignition
of Flammable Solvents
A laboratory fire started in a refrigerator, used
for storing experimental samples - small quantities of solvents, and other chemicals. It
is thought that an electrical fault may have been the cause. Apparently, the fire burned
for some time, igniting the plastic refrigerator lining before burning through the door
seal and spreading into the room.
The refrigerator was adjacent to the Flammable Storage Cabinet
pictured above, which contained a large quantity of flammable solvents. The photo
shows the cabinet after the fire. The scorch on the right side of the cabinet was caused
by the burning frig (at the seat of the fire). The mark at the top of the door was caused
by burning material (e.g.. plastic light fitting) which dripped on to the cabinet and
continued to burn.
The second photo (below) shows the upper door frame and cabinet
interior. Although burning material has dripped into the lap seal above the door, there is
no sign of any flame within the cabinet, and the interior paint finish is in original
glossy condition.
Soot has outlined the storage bottles on the shelf. Although the
soot was drawn into the cabinet by the ventilation fan, anti-flash vents have prevented
flames from entering the cabinet.
Conclusion
- The flammable storage cabinet isolated a large quantity of flammable
solvents from the fire, even in close proximity to the seat of ignition.
- The anti-flash vents allowed the cabinet to breathe but still
prevented internal fire.
________________________________________________________
Heat Gun (top)
Fire/Burn from Heating Flammable Solvent with a Heat Gun (top)
A laboratory worker was using a heat gun to heat approximately 0.5
liters of heptane in a Pyrex beaker by hand over an open bench. A splash of heptane came
in contact with the elements of the heat gun, igniting the heptane and causing him to toss
the beaker away from him. The sleeve of the worker's shirt caught fire. The flaming beaker
landed on another work surface, spreading the fire to his computer. The worker immediately
used a safety shower to put out the fire on his clothing, then used a dry chemical fire
extinguisher to put out the other fire.
The worker received burns to his hand. The computer containing his
thesis was destroyed by the powder from the extinguisher.
-Flammable liquids should be handled in a fume hood to prevent
accumulation of vapors.
-Heat guns and other equipment capable of igniting flammable vapors should not be used to
heat flammable vapors.
-Heating operations should not be carried out by hand. Instead, a lab stand and clamps
should be used for this type of work.
-Carbon dioxide extinguishers should be used around sensitive equipment. Dry powder
extinguishers can damage such equipment.
-If clothing is on fire, smother the flame by rolling on the ground or use a safety shower
to extinguish the fire, as was done in this incident.
Hotplate and Combination Hotplate/Stirrer Fires
(top)
Hood Fire Involving Unattended
Operation with Hexane Near Hot Plate (top)
A fire erupted inside a hood containing two reactions running unattended. A laboratory
worker had placed nitrobenzene inside an oil bath atop a hot plate. The hot plate had been
operating for three days, heating the oil bath to 200° C. A plastic squeeze bottle of
hexane was placed next to the hot plate. Eventually, the squeeze bottle warmed enough to
pressurize the container, forcing liquid hexane out of the bottle and onto the hot plate,
where it ignited. Another laboratory noticed the smoke and attempted to put out the fire
using a dry chemical extinguisher. A maintenance worker also noticed the fire and assisted
the laboratory worker. Their attempts were not successful.
The fire department was dispatched. Since the Emergency Information Poster on the door to
the laboratory was inaccurate and there was a significant language barrier between the
laboratory worker and the fire department personnel, a hazmat response team was
dispatched. Three buildings were evacuated for more than three hours. The laboratory
worker and the maintenance worker were showered and scrubbed by the hazmat team and their
clothing was confiscated (it was later washed and returned to them). While this was
probably an overreaction by the emergency response personnel, it illustrates the
implications of not having an accurate, up-to-date emergency information poster.
Containers of volatile liquids placed near heat sources can become pressurized.
Materials not involved in an experiment should be removed, as possible, to avoid having
them become involved in a fire or other incident. Keeping the Emergency Information
Poster up-to-date helps to ensure a proportionate response by emergency response
personnel. Evaluate the potential problems related to experiments left unattended
for days at a time.
A Report on a Fire Incident During Sublimation of a Colorant Intermediate using a Cold Finger and Oil Bath (top)
Key Instruction Points:
1. Replace worn component
2. Secure hoses / tubing
3. Include temperature control
4. Keep sash to lowest height possible
Introduction
In November 1999, a graduate student conducted an experiment to purify by sublimation a
colorant intermediate. An oil bath used for heating purposes caught fire. no
physical injury resulted and minor damage to the ceiling tiles above the fume hood where
the experiment was conducted was caused by smoke. The incident was immediately reported to
EH&S. The following day, the Environmental Health and Safety department, the Chief
Deputy Fire Marshall, and the faculty advisor to the student running the experiment
reviewed the scene of the incident. Since then, corrective action was identified and has
been implemented. This report outlines the procedure used for the sublimation experiment,
provides a hypothesis of how the fire originated, and details the corrective action.
Experimental
1. Equipment.
The equipment employed for the sublimation experiment consists of a hot plate onto
which is placed an oil bath. In this particular experiment only a small amount of oil was
placed in the bath. A sublimation apparatus was mounted so that only the bottom of the
apparatus was submerged in the oil bath. The sublimation apparatus consists of two glass
chambers of differing size. The smaller chamber is designed to be inserted into the larger
chamber and sealed with a ground glass joint and grease. The pressure in the outer chamber
is reduced during the experiment, and this chamber becomes hot when in contact with the
oil. The inner chamber is the ‘cold finger’, or condenser, which is cooled by
running a water stream through it. The oil employed for heating was purchased from Aldrich
Chemical, and is designed specifically as a heating medium. Flash point of the oil is
310-325....C, fire point is 360....C, and melting point is 60....C. The flammability
properties of the oil used were appropriate for operation of a cold finger sublimation
experiment at less than 150 degrees C.
2. Procedures
A small amount (approximately 200 mg) of the compound to be sublimed was placed in the
outer glass chamber of the sublimation apparatus. The glass joint between the head of the
cold finger and the main chamber was lubricated. The cold finger unit was positioned so
that the bottom of the outer chamber was slightly submerged under the surface of the
pre-heated oil. Input/output hoses were connected to the cold finger head and water was
passed through the hoses in a slow stream. A vacuum hose was connected to the outer
chamber and the pressure reduced using in-house vacuum. The normal procedure results in
vaporization of the test compound in the outer chamber and slowly condensation of the
vapor onto the outer wall of the cold finger. The slow condensation promotes purification
and slow crystal growth of the compound. This was the objective of the experiment.
However, in this case, some time after heating of the cold finger began, a water hose
became disconnected from the cold finger and water ran into the oil bath. A fire commenced
immediately afterwards, and oil burned in the fume hood for several seconds. Use of the
fire extinguisher was not attempted (students present were not trained in the use of the
fire extinguisher).
3. Discussion
The purpose of the experiment was to purify a compound by sublimation. Particularly
high purity was required in the present compound, as it was to be employed in x-ray
crystallographic analysis. While purification by sublimation is not a procedure commonly
employed in our laboratory, the graduate student had conducted similar experiments in
another University previously. The equipment is simple to operate and the procedure is
straightforward, if performed correctly.
Examination of the equipment after the incident revealed the following:
• old and weak hoses were employed,
• no devices were employed to secure the hoses to the condenser,
• the oil bath used was large relative to the sublimation apparatus,
• the volume of oil used was very low relative to the size of the container,
• no temperature controller was employed with the oil bath,
• there was no loss of compound from the sublimation chamber.
Conditions that led to the fire
The observations listed above contributed to the development of conditions that
produced the fire. It is likely that the oil was heated to a higher temperature than was
required, due to the small volume of oil placed into the large container (glass dish).
Furthermore, it is likely that the hot plate setting was set higher than required.
This conclusion was reached following a recent attempt to reconstruct the conditions of
the experiment, and it was found that a high temperature (e.g., sufficiently high to
produce smoking) could only be achieved if the hot plate setting was relatively high.
Hence, the low volume of oil used produced a large surface area relative to the volume,
and the hot plate was probably set sufficiently high to increase the temperature
significantly above that required to perform the experiment. If a larger amount of oil was
used in the oil bath, it is likely that greater temperature control, with far slower rate
of temperature increase, for example, would have been achieved. It is likely that the two
conditions of high temperature setting and low oil volume were required in combination to
bring about the possibility of a fire. A temperature of less than 150 degrees C
should have been sufficient to perform the experiment, which is far below the flash point
and fire point of the oil.
A further condition that appeared to actually start the fire was
that worn and unsecured water hoses were employed during the reaction. Some minutes
following commencement of the experiment, one of the hose connections came loose from
it’s fitting to the cold finger, and water ran into the hot oil bath. The violent
spitting of oil and water that resulted caused some of the oil to splash on the (very hot)
hot plate. It is likely that the temperature of the hot plate was sufficient to bring the
splashed oil to its flash point, and therefore start the fire that spread to the rest of
the oil bath. Therefore, it is likely that the fire was due to the combined hazards of an
insufficient amount of oil used, temperature of the hot plate was too high and was not
controlled, and loose hoses on the condenser connections were used. Following the
examination of the equipment immediately after the fire incident and a later
reconstruction of the experiment, the following corrective action items were identified.
Corrective Action
The following list of corrective action items has been identified. Some of the items
are specific to experiments of the type described in this communication, while others
resulted from general observations of how safety can be improved in our laboratories. The
actions are intended to reinforce University Safety policy, and to provide additional
guidelines to researchers working with oil-based heating devices.
1-Fire extinguisher training All graduate students in our department
are now required to undertake fire extinguisher training. Due to scheduling conflicts, to
date approximately half of the students have completed the training. The remainder will be
trained during the present semester.
2-Replace all tubing -All tubing is to be replaced if old or worn,
regardless of the experiment to be performed.
3-Secure all hoses/tubing -All hoses are to be securely fixed to water
faucets and equipment, preferably with hose clips.
4-No oil bath to be used without temperature control -All oil baths
will be operated with appropriate temperature controllers. The oil baths may be controlled
manually if the operator is monitoring the bath temperature and the experiment
continuously (i.e., the operator will stand by the experiment at all times).
5-Know all flash points of oil used -The flash point, and all other
essential flammability characteristics, of all oils to be employed for heating will be
known by the operator. If there is doubt regarding the type of oil in a bath the oil will
be discarded and fresh oil of appropriate and known flammability characteristics used. In
cases where high temperatures are required, in which there is a risk of reaching the flash
point, then Wood’s metal will be used in place of oil.
6-Keep sash down - The fume hood sash is to be kept down at all times
during the experiment.
Stirrers and Stirrer/Hotplates (top)
Valuable Research Material Ruined In Coldroom Fire Due To Unattended Western Blot
Valuable crystals of proteins being studied by X-ray crystallography, the culmination of 3 years of work, were ruined as a result of a midnight fire in the cold room where they were stored. An Engineering employee discovered the fire when responding to an unrelated fire alarm activation that night.
A Western Blot procedure, using polyacrylamide gel and transfer buffer containing 30% methanol, was being run unattended since 6 pm that evening. A Corning Hot Plate/ Stirrer combination unit was being used. The Western Blot procedure utilizes electrophoresis to separate proteins based on molecular weight. The buffer transfer taking place at the time of the fire was most likely being performed in the cold to minimize (1) the diffusion of proteins in the gel, as well as (2) the evaporation of the methanol in the fixative buffer.
Causes of the Fire
Electrical outlets in the coldroom were inspected and found to be properly wired. The post-doc who was conducting the procedure had intended to only use the stirrer without activating the hotplate function. However, examination of the burnt unit confirms that the hotplate had been inadvertently turned on, which was most likely the cause of the fire. (See photo below).
Fires from the Western Blot procedure using combination units are fairly common. For example, similar incidents involving unattended Western Blots in cold rooms occurred recently at _______ and ________. Even without the hotplate being turned on, stirrers can cause fires. They have a brush-type motor which can act as an ignition source if there is a build-up of flammable vapors. A fire involving a stirrer that was being used with a flammable liquid occurred inside a chemical hood several years ago at _______. Presumably, this incident occurred because the hood was overcrowded, impeding the flammable vapors from being exhausted through the slot in the back.
Emergency Response
The Engineering employee who discovered the fire immediately put it out using a carbon dioxide extinguisher. He then notified Security, who in turn notified the Fire Department. Security was able to reach one of the emergency contacts listed on the door of the room who provided information to HazMat about the type of procedure being conducted. HazMat checked for radioactivity using a Geiger counter and then gave the "all clear" for cleanup of the area to begin.
Cleaning and ventilating of the room occurred for several days before the room was reopened for use. No personal injury occurred as a result of this incident although an odor remained in the room for a long time.
Steps to Prevent Future Occurrences:
1. Combination stirrer/hot plates are no longer allowed in cold or warm rooms and are no longer allowed for stirring solutions containing flammable liquids. If the hotplate is inadvertently used, its maximum temperature of 550o C (for most unit) could easily exceed the melting point of the polycarbonate transfer tank (267o C)
2. Consider using an air-operated turbine magnetic stirrer, available for under $40. This type of unit operates by compressed air and does not act as an ignition source.
3. Do not reuse transfer buffer solutions because reused transfer buffers are overheated more easily than fresh buffers.
4. Since the probability of overheating is proportional to the duration of transfer the procedure should not be performed for longer than the needed period of time.
5. The transfer should be performed during hours when lab occupants can be present to check for unsafe conditions.
6. A sign must be posted on the door with details about the unattended operation and emergency contact information when a Western Blot is left unattended.
7. To stress caution in responding to a fire, personnel are reminded that a fire alarm must be activated before any steps are taken to extinguish a fire.
_______________________________________________________________
Surgical Equipment
(top)
Fire from Electrocautery Pen in
a Sharps Container (top)
Recently, a fire started in a sharps container where someone had disposed of an
electrocautery surgery pen. It is believed that the little switch which activates
the pen (see photo below) was inadvertently pressed when waste was put into the container
the next day. There was damage to the wall and a lot of smoke. An ABC extinguisher was
used to extinguish the fire and the extinguishing agent blanketed the room.
The electrocautery pens are very dangerous. It is very easy to switch the pen on. It
has apparently been standard practice to dispose of used cautery pens in a sharps
container. The batteries are not removable. The cautery pen can be activated even with the
cap on. If the cover is not put on it properly it can activate the unit.
The following actions will be taken to prevent a similar incident in the future:
1. The wire tip of all pens will be removed with a hemostat prior to disposal of the
device, as per manufacturers instructions.
2. An unlined, metal sharps containers will be used for the disposal of the electro
cautery pens.
3. All personnel who use these devices will be educated on how to dispose of it.
4. Instructional signage will be prominently posted describing disposal procedures.
5. Hemostats will be stored and kept in the room where the devices are used.
Lit Cautery Pen
Disclaimer
Revision Date: June 15, 2007
url: http://www2.umdnj.edu/eohssweb/aiha/accidents/fire.htm
American Industrial Hygiene Association
2700 Prosperity Ave., Suite 250
Fairfax, VA 22031
(703) 849-8888 (703) 207-3561 fax
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