Laboratory safety : Safety, Health and Wellbeing : The University of Western Australia
Harry Potter. Popular Features. New Releases. Description The purpose of this book is to provide the user with a concise summary of the physical properties, detection methods, handling precautions and of the biochemical and physiological effects of gases and fumes found in the working environment so that they may be handled safely.
The substances dealt with in this book vary considerably in their properties, whether it be chemical, physical or physiological, and as a consequence in the risks they pose to health and safety and the conditions demanded of staff and workplaces which handle them. It is therefore important not only to be able to identify both the gases and fumes themselves, but the dangers which they pose and the consequent measures necessary to deal with those dangers, whether it be as a precautionary measure or in response to an incident.
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.
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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.
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.
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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.
Familiarize yourself with the physical, chemical and toxicological properties of these materials and follow the recommended safety precautions. Atomic absorption equipment must be adequately vented, as toxic gases, fumes and vapours are emitted during operation. Other recommendations to follow when carrying out atomic absorption analysis are:.
Mass spectrometry requires the handling of compressed gases and flammable and toxic chemicals. Consult MSDSs for products before using them. Specific precautions for working with the mass spectrometer include:. Gas chromatography requires handling compressed gases nitrogen, hydrogen, argon, helium , and flammable and toxic chemicals. Consult product MSDSs before using such hazardous products. Specific precautions for working with gas chromatographs include:. The superconducting magnet of NMR equipment produces strong magnetic and electromagnetic fields that can interfere with the function of cardiac pacemakers.
Users of pacemakers and other implanted ferromagnetic medical devices are advised to consult with their physician, the pacemaker's manual and pacemaker manufacturer before entering facilities which house NMR equipment.
Engineering Controls for Laboratory Safety
Precautions for work with NMR include the following:. HPLC procedures may require handling of compressed gas helium and flammable and toxic chemicals. Familiarize yourself with the hazardous properties of these products, as well as recommended precautionary measures, by referring to MSDSs. Consult product MSDSs before using them. Note that hazardous materials include those defined by WHMIS legislation as "controlled products", as well as open radioactive sources as defined by Canadian Nuclear Safety legislation. Appropriate protective clothing e.
Instructions for selection and use of protective laboratory clothing are as follows:. In the laboratory, gloves are used for protection from radiation, chemical products, biohazardous material and physical hazards such as abrasion, tearing, puncture and exposure to temperature extremes. Natural latex is derived from the sap of the rubber tree and contains rubber polymers, carbohydrates, lipids, phospholipids and proteins.
During the manufacturing process additional chemical agents are added to impart elasticity, flexibility and durability to the latex. Because of these properties, and because of their high tactile strength and low cost, latex gloves are used for many laboratory procedures. Unfortunately, for some people, wearing latex gloves can cause skin reactions; these can be either irritant or allergic in nature, and can be caused by:.
Related Hazardous Gases and Fumes - A Safety Handbook
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