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Picric acid becomes shock sensitive and explosive if it dries out. Laboratory fires can by caused by bunsen burners, runaway chemical reactions, electrical heating units, failure of unattended or defective equipment, or overloaded electrical circuits. Familiarize yourself with the operation of the fire extinguishers and the location of pull stations, emergency exits and evacuation routes where you work. In the event that the general alarm is sounded use the evacuation routes established for your area and follow the instructions of the Evacuation Monitors.
Once outside of the building, move away from the doors to enable others to exit. Fire cannot occur without an ignition source, fuel and an oxidizing atmosphere usually air , the three elements that comprise what is called the "fire triangle":. Fire will not be initiated if any one of these elements is absent, and will not be sustained if one of these elements is removed.
This concept is useful in understanding prevention and control of fires. For example, the coexistence of flammable vapours and ignition sources should be avoided, but when flammable vapours cannot be controlled elimination of ignition sources is essential. These are:. Familiarize yourself with the fire class ratings of the extinguishers in your work area so that you will know what types of fire you can attempt to extinguish with them.
Learn how to use the extinguisher in your lab, as there will be no time to read instructions during an emergency. Attempt to fight small fires only, and only if there is an escape route behind you. Remember to have the extinguisher recharged after every use: inform Building Services at local local at Macdonald Campus. If you do fight a fire, remember the acronym "PASS" when using the extinguisher:. Use the following precautions when working with or using flammable chemicals in a laboratory; keep in mind that these precautions also apply to flammable chemical waste.
In the event that the general alarm is sounded, follow the evacuation routes established for your area; do not use the elevators. Follow the instructions of the Evacuation Monitors. Once outside the building, move away from the doors to allow others to exit. In order to minimize the amount of hazardous waste presented for disposal, it is important to follow these guidelines:. Sharps are defined as any material that can penetrate plastic bags: examples include syringe needles, scalpel blades, glass and plastic pipettes, disposable pipette tips, etc.
General ventilation, also called dilution ventilation, involves dilution of inside air with fresh outside air, and is used to:. General ventilation systems comprise an air supply and an air exhaust. Laboratory air may be exhausted through either local exhaust devices or air returns connected to the HVAC system.
Local exhaust ventilation systems capture and discharge air contaminants biological, chemical, radioactive or heat from points of release. Common local exhaust ventilation devices found in laboratories include:. Chemical fume hoods are enclosed units with a sliding sash for opening or closing the hood. They are able to capture and exhaust even heavy vapours, and are preferred for all laboratory procedures that require manual handling of hazardous chemical material. Refer to Section 7. Canopy hoods are designed to capture heat from processes or equipment, such as atomic absorption spectrophotometers or autoclaves; a canopy or bonnet is suspended over a process and connected to an exhaust vent.
The following limitations make canopy hoods poor substitutes for chemical fume hoods, because they:. Slotted hoods, or benches, have one or more narrow horizontal openings, or slots, at the back of the work surface; the slots are connected to exhaust ducting.
Their design and function continue to improve. But others have learned why. Are noise levels measured with a sound level meter or an octave band analyzer and are records being kept? Health hazards may be more costly to correct. Each OSHA cooperative program has individual web pages describing program elements and highlighting successes of the participants. Farm safety Chemicals and spray drift Sprayed chemicals can drift over neighbouring properties or water sources, and can affect human health, animals or the environment Wind blowing through the windows and high-velocity vortices caused when doors open can strip contaminants out of the chemical hoods and interfere with laboratory static pressure controls.
These special purpose hoods are used for work with chemicals of low to moderate toxicity only, such as developing black and white photographs. They are not recommended for use with hazardous chemicals because most models recirculate air into the laboratory, and because the HEPA filter that is integral to the protective function can be damaged by some chemicals.
Direct connections provide direct exhausting of contaminants to the outdoors and are used for venting:.
By regulation, more air is exhausted from a laboratory than is supplied to it, resulting in a net negative pressure vacuum in the laboratory. Negative pressure draws air into the laboratory from surrounding areas, and serves to prevent airborne hazardous chemicals, radiation or infectious microorganisms from spreading outside the laboratory in the event of an accidental release inside the laboratory. Balancing of laboratory ventilation must take into consideration the amount of air exhausted by local ventilation devices such as fume hoods. Modern laboratories do not have operable windows, as opening of windows tends to pressurize a room, pushing air from the laboratory into adjacent non-laboratory areas.
Fume hoods properly used and maintained, will render substantial protection, provided the user is aware of its capabilities and limitations. The performance standard for fume hoods is the delivery of a minimum face velocity of linear feet per minute at half sash height. An anemometer for determining a fumehood's face velocity is available from Environmental Health and Safety. To ensure your fume hood provides the highest degree of protection observe the following guidelines:.
Compressed gases are hazardous due to the high pressure inside cylinders. Knocking over an unsecured, uncapped cylinder of compressed gas can break the cylinder valve; the resulting rapid escape of high pressure gas can turn a cylinder into an uncontrolled rocket or pinwheel, causing serious injury and damage.
Poorly controlled release of compressed gas in the laboratory can burst reaction vessels, cause leaks in equipment and hoses or result in runaway chemical reactions. Compressed gases may also have flammable, oxidizing, dangerously reactive, corrosive or toxic properties. Inert gases such as nitrogen, argon, helium and neon can displace air, reducing oxygen levels in poorly ventilated areas and causing asphyxiation. Cryogenics are very low temperature materials such as dry ice solid CO2 and liquefied air or gases like nitrogen, oxygen, helium, argon and neon.
The following hazards are associated with the use of cryogenics:. Pressure differences between equipment and the atmosphere result in many lab accidents. Glass vessels under vacuum or pressure can implode or explode, resulting in cuts from projectiles and splashes to the skin and eyes.
Glass can rupture even under small pressure differences. Rapid temperature changes, such as those that occur when removing containers from liquid cryogenics, can lead to pressure differences, as can carrying out chemical reactions inside sealed containers. Ergonomics is concerned with how the workplace "fits" the worker.
Performing certain work tasks without regard for ergonomic principles can result in:. Every effort should be made to prevent equipment from becoming contaminated. To reduce the likelihood of equipment malfunction that could result in leakage, spill or unnecessary generation of aerosolized pathogens:.
The following sections outline some of the precautions and procedures to be observed with some commonly used laboratory equipment. Improperly used or maintained centrifuges can present significant hazards to users. Failed mechanical parts can result in release of flying objects, hazardous chemicals and biohazardous aerosols. The high speed spins generated by centrifuges can create large amounts of aerosol if a spill, leak or tube breakage occurs. To avoid contaminating your centrifuge:.
Heating baths keep immersed materials immersed at a constant temperature. They may be filled with a variety of materials, depending on the bath temperature required; they may contain water, mineral oil, glycerin, paraffin or silicone oils, with bath temperatures ranging up to o C. The following precautions are appropriate for heating baths:.
When used with infectious agents, mixing equipment such as shakers, blenders, sonicators, grinders and homogenizers can release significant amounts of hazardous aerosols, and should be operated inside a biological safety cabinet whenever possible. Equipment such as blenders and stirrers can also produce large amounts of flammable vapours.
The hazards associated with this type of equipment can be minimized by:.
Laboratory ovens are useful for baking or curing material, off-gassing, dehydrating samples and drying glassware. The following instructions for safe use of analytical equipment are general guidelines; consult the user's manual for more detailed information on the specific hazards:. Sample preparation for atomic absorption procedures often require handling of flammable, toxic and corrosive products.