- Shelf-Collapse Causes Spill and Fire
- Carbon Disulfide
- Fire From Diethyl Ether Spill
- Lithium Aluminum Hydride
- Sodium Hydride
- Solvent Explosion and Fire
- Letter from a Post-Doc Burned in a solvent
Clean Bench Fire
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 occured 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
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
A fire occured 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 initialy 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:
- 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
- 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
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.
- Experiments with potential danger should never be left unattended, especially when an open flame is involved.
- 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.
- 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 Cabinet
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.
- 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.
Fire/Burn from Heating Flammable Solvent with a Heat Gun
Key Instruction Points:
- 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.
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.
Hotplate and Hotplate/Stirrers
Hood Fire Involving Unattended Operation with Hexane Near Hot Plate
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
Key Instruction Points:
- Replace worn component
- Secure hoses / tubing
- Include temperature control
- Keep sash to lowest height possible
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.
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.
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).
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.
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.
- 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.
- Replace all tubing -All tubing is to be replaced if old or worn, regardless of the experiment to be performed.
- Secure all hoses/tubing -All hoses are to be securely fixed to water faucets and equipment, preferably with hose clips.
- 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).
- 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.
- Keep sash down - The fume hood sash is to be kept down at all times during the experiment.
Hot Plate Fire
- Lockout / tagout – Positively disconnect or lock power to unused equipment which would be an uncontrolled hazard if energized.
- Human factors – Recognize Potential for employee/student confusion in selection of operating controls (what if analysis).
- Fire extinguisher training – Reduce potential property damage by training students and employees on use of fire extinguishers.
Effects of incident
Damage to hotplate and hood work surface. Fire was discovered immediately and extinguished by attending personnel. Had this incident occurred when lab was unattended, the impact would have been greater.
A fire retardant polypropylene chemical hood was used for chemical work. The hood contained both a recessed hot plate and two portable hot plates which were located on the hood surface. The hood had been relocated from another lab and the recessed hot plate was determined to be non-operational. The recessed area above the hotplate was then covered with a polyethylene top and sealed to provide additional work surface. However, the power to the hotplate had never been disconnected. A student, mistaking the recessed hotplate power switch on the hood console for the control to one of the surface mounted portable hotplates, turned it to the “on” position. Upon seeing evidence of fire beneath the work surface, the employee left the lab to obtain assistance from a coworker, who was trained in use of fire extinguishers, who then pried off the polyethylene cover and extinguished the fire.
- Confusion on hot plate controls.
- Availability of power to a piece of equipment which was not intended to receive power – Failure to disconnect power.
Corrective actions to prevent reoccurrence
- Power was positively disconnected to any recessed hotplates not intended for use – Reminder sent to lab community to check for similar hazards in their labs.
- Lab occupants contacted fire marshal for fire extinguisher training – Reminder to lab community on availability of fire extinguisher training.
- Reminder to lab community on safety training available which includes human factors and process safety awareness.
Fume Hood Fire Involving A Combination Hotplate And Stirrer
Key learnings: Having dual purpose equipment, such as a combination hotplate and stirrer, provides advantages. However, in some situations dual purpose equipment may contribute to an "error likely situation" when two identical dials turn on two different functions. In this case, a liquid in a plastic container was being stirred and the heater was turned on, inadvertently. This caused the plastic container to melt allowing the combustible liquid to contact a hot surface resulting in a fire. To prevent similar events when stirring liquids in plastic containers, use a stirrer that does not have a hotplate capability.
Effects of incident: The incident caused damage to the laboratory fume hood and its contents. See photo. There were no injuries.
Description: At approximately 8:00 a.m. on October 22, 2012, a researcher and a co-op student used a combination hotplate/ stirrer and sonicator to suspend ultrafine copper particles in approximately 900 mL of a synthetic heat transfer fluid. The sonication process required monitoring at fifteen-minute intervals. At the conclusion of the sonication, the researcher asked the co-op student to remove the sonicator from the plastic container and continue stirring the fluid. At approximately 11:00 a.m. the co-op student removed the sonicator, covered the plastic fluid container, removed it from the hotplate/ stirrer, cleaned the sonicator tip, and placed the sonicator in the rear of the hood. Next, the co-op student placed the plastic container back on the hotplate/ stirrer, checked to make sure the liquid was being stirred, and left the laboratory immediately thereafter.
The bottle melted and its contents, a combustible liquid, ignited on the hotplate/ stirrer. Then at approximately 12:00 noon, two employees passing the lab noticed the fire, and used a hand-held extinguisher to put-out the fire. The fire was limited to the hotplate platform and initially the smoke was contained within the lab hood. However the discharge of the extinguisher’s dry chemical forced some of the smoke out of the lab hood, and this smoke activated the room’s fire alarm system.
The photo taken a short time after the fire was extinguished indicated that the hotplate and the stirrer adjustment dials were in the "on" position. The heater control knob was found to be turned to near its maximum heat setting.
During the sonication activity the hotplate was in the "off" position. Although it is not known how the hotplate dial was placed in the "on" position, the incident investigation team identified two likely scenarios that could not be substantiated. Scenario #1 - the hotplate dial was bumped into the "on" position when either the sonicator was removed from the plastic container or during equipment movement within the lab hood; or, Scenario #2 - the co-op student inadvertently placed the hotplate dial in the "on" position when checking to make sure the liquid was being stirred. The co-op student did not recall checking to make sure that the hotplate dial was in the "off" position prior to leaving the room. Also, the researcher did not check to ensure the hotplate/stirrer was in the proper configuration, i.e., the hotplate was "off" and the stirrer was "on."
Causation: Having dual purpose equipment, such as a hotplate and a stirrer combination, provides advantages in some applications. However, in this case it may have contributed to an "error likely situation" because two identical dials (one for each function) turn on the heater and the stirrer. Specifically, a plastic container with combustible liquid inside was placed on the hotplate/ stirrer combination for stirring. Both the stirring and heating function were turned on, inadvertently. Heating caused the plastic container to melt. The melted plastic container released the combustible liquid to the hot surface resulting in a fire on the hotplate platform.
Causal mapping was performed and identified three factors:
- Causal factor #1: A plastic container was placed on a hotplate/stirrer to stir a combustible liquid.
- Causal factor #2: The hotplate was in the on position.
- Causal factor #3: A check of the hotplate/ stirrer configuration was not performed by either the co-op student or the researcher.
Corrective actions to prevent reoccurrence:
To address causal factors 1 & 2:
- Require stirrers without heating capability be used when stirring plastic containers.
- In areas where hotplate/ stirrers are present, post signage stating that plastic containers shall not be used on hotplate/stirrers.
If the continue the use of the dual purpose hotplate/ stirrer is necessary, then periodic checks of the hotplate stirrer settings is necessary by laboratory personnel. However, requiring the use of stirrers without the hotplate function is a more acceptable engineering control.
Additionally the design of the hotplate dial can be improved by having a locking feature, e.g., locking the dial in the "off" position and requiring a lifting of the dial and turning to place the hotplate dial in the "on" position.
Fire from Electrocautery Pen in a Sharps Container
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:
- The wire tip of all pens will be removed with a hemostat prior to disposal of the device, as per manufacturers instructions.
- An unlined, metal sharps containers will be used for the disposal of the electro cautery pens.
- All personnel who use these devices will be educated on how to dispose of it.
- Instructional signage will be prominently posted describing disposal procedures.
- Hemostats will be stored and kept in the room where the devices are used.