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As noted in the May 1999 Hazmat Studies column, chemicals can degrade, dehydrate or form dangerous compounds as they age. Many compounds that are normally safe may become shock- or heat-sensitive explosives when old. This can create risk for emergency response personnel.
Photo by Robert Burke
Ether containers should be dated and disposed of six months after opening.
Listed below are some common laboratory chemicals that become increasingly dangerous as they age:
Ethyl ether, and other ethers, are organic compounds that form explosive peroxides when in contact with air. They are found in college, high school, research and industrial laboratories. When a container of ether is opened, oxygen from the air bonds with the single oxygen present in each ether molecule and forms an organic peroxide.
These peroxides are very unstable, and become sensitive to shock, heat and friction. Moving or shaking a container can cause an explosion. Ethers are also very flammable, with wide flammable ranges. Fire is likely to follow an explosion of an ether container.
Ethers were once used extensively as anesthetics in hospitals and, while not highly toxic, could injure or impair emergency responders. Ethers in laboratories, should be dated when opened and discarded after six months in storage; otherwise, they run the risk of peroxide formation.
Potassium metal, a metallic element from family one on the Periodic Table of Elements, is soft and silvery in color, and frequently found in high school and college laboratories. In transport, it is found in metal containers stored under kerosene or naphtha to keep it from contact with air. While not air reactive, potassium and other metals of family one can react to the moisture in the air.
When encountered in labs, potassium and other family one metals are often stored in improper containers, such as mayonnaise or canning jars. This is dangerous - during an emergency, the glass containers can break and expose the metal to the air and spill the flammable liquid also in the container. Like other members of family one, potassium metal is a dangerous fire risk and reacts violently with water to liberate hydrogen gas (which is highly flammable). The heat from the reaction of the water and the potassium can be enough to ignite the hydrogen. When exposed to moist air, it can also ignite spontaneously.
Photo by Robert Burke
Picric acid was found in a high school chemistry lab in a dried-out and very dangerous condition.
Potassium metal is closely related to sodium and lithium metals, which are in the same family on the Periodic Table Of Elements. However, the similarity ends with their water- and air-reactive characteristics. Potassium metal becomes very dangerous in storage as it ages. Like ether, it forms explosive peroxides in long-term storage.
Potassium can form peroxides and superoxides at room temperature, and may explode violently when handled. Simply cutting a piece of potassium metal with a knife to conduct an experiment, could cause an explosion.
Potassium metal's dangers far outweigh its usefulness in lab experiments in schools and should be replaced with sodium or lithium metals, which also react with water, but do not form explosive peroxides.
Picric acid is a type of chemical that is shipped and stored with a minimum of 10% to 20% water in its container. While it is a high explosive when dry, it is classified as a 4.1 Flammable Solid, Wetted Explosive because of the moisture content in the container. It cannot be shipped when dry. As long as the moisture remains in the container, the compound is stable.
Picric acid is a yellow crystal that becomes highly explosive when it dries out and is shocked or heated. The structural and molecular formulas of picric acid, (the common name for tri-nitro phenol), and its close relative, tri-nitro toluene (TNT), are very similar. When dry, picric acid also closely resembles the explosive power of TNT pound for pound.
Picric acid is another chemical found in high school, college and research laboratories. As it ages, the moisture which keeps it stable evaporates, and it becomes an unstable high explosive. The structural and molecular formulas for TNT and picric acid are shown below. Note the similarities:
Benzoyl peroxide is a white, granular and crystalline solid that is highly flammable, explosive and toxic by inhalation. It also may explode spontaneously when it becomes dry.
Phosphorus is a wax-like crystal, transparent solid material. White or yellow (it is the same material, but can be called by either color) phosphorus is the most common form, and it is reactive and dangerous. Red and black phosphorus can also be found in laboratories, but do not possess the same dangers as white or yellow.
White phosphorus is an air-reactive material that must be stored under water or other liquid to keep it from igniting spontaneously. Like potassium and other metals, it is shipped in metal containers. However, many times it can be found in laboratories, especially high schools, in glass containers that can prove a significant hazard during an emergency. In addition to being air reactive, it is also quite toxic at 0.1 mg/m3 in air and is commonly used as a rat poison. It doesn't appreciably deteriorate with age, but is very dangerous if not properly stored and handled and can cause serious fire and burns.
Firefighting operations usually involve the application of water through a hoseline. Small fires in laboratories can be extinguished safely by using portable dry-chemical fire extinguishers. When metals such as potassium are involved, Class D dry-powder fire extinguishers should be used. Any other type will not be effective.
Inserting a hoseline into a lab chemical storage area can cause glass containers to break and mix chemicals together. Even a chemist couldn't tell you what the potential outcome would be if chemicals were mixed that are not normally placed together. Firefighters and other rescue personnel may encounter highly toxic and carcinogenic chemicals and mixtures along with explosive, flammable and water- and air-reactive materials. Great care should be taken when fires occur in laboratories. Runoff from firefighting can be very toxic and cause environmental damage, or at the very least danger to personnel and contamination of personal protective equipment. Some fires may be better left to the sprinkler system to extinguish or allowed to burn themselves out.
To ensure safety of personnel, some important steps should be taken in handling chemical fires and emergencies:
- Firefighters and other rescue personnel should never approach a chemical emergency scene or fire without self-contained breathing apparatus (SCBA) and proper protective clothing. Care should be taken to avoid contact any chemicals or runoff with turnouts.
- During overhaul, extreme care should be taken to ensure firefighters are not exposed to chemicals. Also, runoff water, which may have become contaminated during firefighting operations, should be controlled.
Prevention is always crucial. Some effective preventive measures include:
- Pre-plan schools, colleges and other locations where laboratories are located. Note locations of hazardous chemicals and use the NFPA 704 or other type of marking system to identify the locations of chemical use and storage.
- Conduct regular fire inspections of these facilities.
- Obtain inventories of chemicals stored in the lab areas and make them available to responders during emergencies.
- Remove explosive, reactive, severely flammable, toxic or no-longer-used chemicals from high school and college laboratories through the use of qualified chemical and explosives experts.
- Encourage teachers, researchers and lab technicians to order small amounts of chemicals in stead of large supplies that present a danger to response personnel or may become dangerous through long-term storage.
- For substances that become dangerous with age, instruct lab workers and instructors to date them when purchased and again when opened.
- Encourage lab managers to set up proper storage systems so the chance of incompatible chemicals combine is reduced. Flammables should be stored in approved cabinets or one-hour fire-rated storage rooms, with proper ventilation and sprinkler protection. Acids should be stored in approved acid cabinets away from flammable liquids and solids. Nitric acid should always be stored away from other acids. Bases should be stored separately from acids.
- Provide familiarization tours for fire and other emergency response companies so that personnel will have a better understanding of the hazards in laboratories.
Regulating Storage In Schools
Several states, including Iowa, Minnesota and Virginia, have developed plans to regulate chemical storage in public schools. The basic concept behind these programs is to make a one-time sweep through each state to remove and properly dispose of unwanted, dangerous and aging chemicals. This requires the cooperation of many state and local agencies. For instance, a state department of education may be involved in the notification process by mailing letters to school districts introducing the program and asking science teachers whether they have any chemicals that need to be removed. Inventories could then be compiled and forwarded to the state fire marshal's office to coordinate the removal of the chemicals.
Inventory lists may be divided into two categories, materials that can be destroyed and those that must go to a hazardous waste landfill. State fire marshal personnel may work with state police explosives technicians or local bomb squads to remove and dispose of explosive, flammable and reactive chemicals. Remaining toxic and carcinogenic chemicals could be collected at central locations throughout a state or city and packaged for shipment to a hazardous waste landfill.
In addition to removing dangerous chemicals from lab settings, it is important to educate teachers, lab workers and research personnel on proper storage, use and purchasing practices. High school and college instructors should also be given assistance to develop experiments using safer chemicals that produce similar results, but reduce the danger to students, teachers and emergency responders.
Through the cooperative efforts of school administrations, industry leaders, research organizations, and emergency response agencies, schools and lab settings can be made safer for occupants and response personnel. With proper training and preparation, emergencies involving hazardous chemicals in schools and laboratories can be managed safely and successfully.
Robert Burke, a Firehouse® contributing editor, is the fire marshal for the University of Maryland and has served on state and county hazmat response teams. Burke is a veteran of over 16 years in career and volunteer fire departments, serving as assistant chief and deputy state fire marshal. He holds an associate's degree in fire protection technology and a bachelor's degree in fire science, and is pursuing a master's degree in public administration. Burke is an adjunct instructor at the National Fire Academy and Maryland Fire and Rescue Institute, and is the author of the textbooks Hazardous Materials Chemistry For Emergency Responders, published in 1997, and Counter-Terrorism for Emergency Responders, to be published this year. He can be reached on the Internet at email@example.com.