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9.1 Introduction

The following sections provide general guidelines and requirements for laboratory safety. This chapter covers the following topics:


Note: for any Faculty or Staff that is retiring or resigning the Safety Officer must sign off on your "Final Paycheck" form if you were in the possession of research laboratory or chemicals.

9.2 General Safety Guidelines
Because laboratories involve numerous chemicals, biological agents, procedures and operations, they require extensive safety precautions. Laboratory safety involves chemical safety, fire safety, electrical safety, and other safety issues. Follow the guidelines in this chapter for general laboratory safety, but refer to other chapters in this manual for specific information.

Examples of common hazards include the following:

  • Chemical Hazards - Toxins, corrosives, flammables, and reactives.
  • Biological Hazards -Microbes, animals, plants and genetically modified agents.
  • Radiation Hazards - Ionizing and non-ionizing radiation.∙ Physical Hazards - Heating
      devices, noise, projectiles, fire, cold, etc.
  • Electrical Hazards - Fire, shock.
  • Mechanical Hazards - Moving machinery and parts.
  • Airborne Hazardous Materials -Vapors, dust, etc.
  • Ergonomic Factors - Standing, repetitive motion, etc.

Food and Drink are not permitted in laboratories.

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9.3 Controlling Laboratory Risks
Administrative and engineering controls can help minimize laboratory risks. However, safety conscious workers using good laboratory practices are the most important component of laboratory safety. The following factors are important for safe laboratory operations:

  • Adequate Facilities - Proper ventilation, non-slip surfaces, hand washing facilities.
  • Available and Appropriate Safety Equipment - Personal protective equipment, laboratory equipment, safety devices on laboratory equipment, and instruments.
  • Appropriate Emergency Equipment - Fire extinguishers, emergency showers, eye wash stations, spill equipment.
  • Appropriate Procedures - Good housekeeping, personal hygiene (e.g., washing hands.)
  • Knowledgeable Workers - Experienced, trained.

All laboratory doors must be labeled with emergency contact information. If an incident occurs during off-hours, respondents need to know the names and telephone numbers of the people responsible for laboratory operations. Note: 911 is NOT a legitimate emergency phone number. Keep this information current and accurate.

Properly trained and experienced workers have the greatest ability to control laboratory risks. By using good laboratory practices, workers can minimize hazards, exposure, contamination, and work place accidents.

9.4 Safe Laboratory Practices 

To ensure laboratory safety, follow safe laboratory practices, including the following:

  1. Know about the chemicals and hazards associated with your laboratory.
  2. Know what to do in emergency situations.
  3. Know how to read and interpret Material Safety Data Sheets (MSDSs).
  4. Wear personal protective equipment, as appropriate. Safety glasses/goggles should be worn at all times.  For contact lens wearers it is especially important to wear appropriate eye protection because the contacts may increase injury from chemical splashes or vapors.
  5. Follow safe practices for working with chemicals. (Refer to the Chemical Safety chapter for more information.)
  6. Ice from a laboratory ice machine is not to be used for human consumption.
  7. Dedicate refrigerators and microwave ovens and other heating devices exclusively for food or for laboratory operations. Ensure that they are clearly labeled to indicate their function.
  8. Do not eat, drink, apply cosmetics, or use tobacco products in the laboratory.
  9. Protect unattended operations from utility failures and other potential problems that could lead to overheating or other hazardous events.
  10. Avoid working alone in a laboratory.
  11. Avoid producing aerosols.
  12. Use extreme care when working with needles, blades, and glass.
  13. Use a mechanical pipetting device. (NEVER mouth pipette.)
  14. Clean contaminated equipment and spills immediately. Avoid contaminating equipment with mercury. Clean mercury spills immediately. 
  15. Do not allow children in the laboratory. (It is a violation of state law for a child to be unattended in a place that presents a risk of harm.)
  16. Keep laboratory doors closed.
  17. Avoid using dry ice in enclosed areas. (Dry ice can produce elevated carbon dioxide levels.)
  18. Remember that dry ice mixed with acetone, isopropanol, or ethanol may cause frostbite.
  19. Hallways, corridors, and exit ways must be kept clear. Do not locate (even temporarily) laboratory equipment or supplies in these areas. If equipment is to be located outside of the lab space - it must be labeled with emergency contact information.

IMPORTANT: Never underestimate the hazards associated with a laboratory. If you are unsure about what you are doing, get assistance. Do not use unfamiliar chemicals, equipment, or procedures alone.

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9.5 Equipment Safety

There are four fundamental elements of equipment safety: 

  1. Use the Correct Equipment
  2. Know How to Operate the Equipment
  3. Inspect the Equipment
  4. Use the Equipment Properly

Use equipment for its intended purpose only. Do not modify or adapt equipment without guidance from the equipment manufacturer or the Safety Office. Do not defeat, remove, or override equipment safety devices.

Working in a laboratory requires various types of equipment. To ensure equipment safety, you must be familiar with the following:

  • Equipment operation
  • Applicable safeguards
  • Maintenance requirements

Always inspect equipment before using it. Ensure that the equipment meets the following requirements:

  • Controls and safeguards are adequate and functional
  • Location is safe (and well ventilated, if necessary)
  • Equipment works properly

IMPORTANT: Disconnect any equipment that is unsafe or does not work properly and remove it from service. Notify other users of the problem.

Refer to other sections in this manual for specific information on operating laboratory equipment, such as fume hoods, heating devices, vacuums, etc.

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9.6 Aerosol Production

The term "aerosol" refers to the physical state of liquid or solid particles suspended in air. Aerosols containing infectious agents and hazardous materials can pose a serious risk because:

  1. Small aerosol particles can readily penetrate and remain deep in the respiratory tract, if inhaled.
  2. Aerosols may remain suspended in the air for long periods of time.
  3. Aerosol particles can easily contaminate equipment, ventilation systems and human skin.

The following equipment may produce aerosols:

  • Centrifuge
  • Blender
  • Shaker
  • Magnetic stirrer
  • Sonicator
  • Pipet
  • Vortex mixer
  • Syringe and needle
  • Grinder, mortar and pestle
  • Test tubes and culture tubes
  • Heated inoculating loop
  • Separatory funnel

Follow these guidelines to eliminate or reduce the hazards associated with aerosols:

  • Conduct procedures that may produce aerosols in a biological safety cabinet or a chemical fume hood
  • Keep tubes stoppered when vortexing or centrifuging
  • Allow aerosols to settle for one to five minutes before opening a centrifuge,
    blender, or tube
  • Place a cloth soaked with disinfectant over the work surface to kill any
    biohazard agents
  • When combining liquids, discharge the secondary material down the side of the container or as close to the surface of the primary liquid as possible
  • Avoid splattering by allowing inoculating loops or needles to cool before touching biological specimens
  • Use a mechanical pipetting device

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9.7 Laboratory Animals

9.7.1 Laboratory Animals and Hazardous Materials
Any research or instructional use of hazardous materials in live animals requires the submission of an Animal Use Protocol (LINK) to the appropriate Animal Care and Use Committee. The Protocol must be fully approved before any researcher may acquire, house or use animals.

IMPORTANT: With the increasing prevalence of animal testing, there comes a greater need to protect researchers. Consider both the direct hazards associated with research animals and the hazardous metabolic byproducts produced by research animals.

9.7.2 Animals and Toxic Chemicals
Animal research or testing with toxic chemicals (including known or suspected carcinogens) may produce aerosols, dusts, or metabolic byproducts that contain toxicants. The animal bedding, equipment and surrounding atmosphere may become contaminated.

When working with research animals and toxic chemicals, always wear proper gloves and button your laboratory coat. Wetting animal bedding before cleanup will help reduce aerosols. Follow all instructions outlined in the approved Animal Use Protocol for handling these agents.

If aerosol production cannot be controlled, use a respirator. A respirator with a HEPA filter will protect you from airborne particulates, but it will not protect you from chemical vapors. Prior to wearing a respirator, you must notify the Safety Office and be both medically evaluated and fit tested.

9.7.3 Animals and Infectious Agents

Personnel performing animal research with infectious agents or working with animals that carry potential zoonosises must utilize isolation procedures. The extent of isolation must be appropriate for the infection risk. The Biosafety Committee (LINK) must approve all work with these agents. Examples of zoonotic diseases that pose a hazard to humans include the following:

  • Brucellosis
  • Herpes B-Virus
  • Pasteurellosis
  • Q Fever
  • Rabies
  • Ringworm
  • Salmonellosis
  • Shigellosis
  • Tuberculosis
  • Tularemia
  • Viral Hepatitis

Conduct work with infectious agents according to good laboratory procedures and containment practices. For information on proper disposal methods, refer to the Biological Safety chapter in this manual.

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9.7.4 Animals and Radioactive Materials
The UT Radiation Safety Officer must approve the use of radioactive materials in animals. Permits to use radioisotopes must be acquired through the Office of Radiation Safety.

9.7.5 Animal Handling
Animal handling injuries are the most common hazard associated with animal research. Animals are capable of inflicting extensive injury to humans. Most research animals can bite or scratch. Livestock, and large and small animals can bite, batter, or crush. Because bites and scratches easily spread disease and infection, researchers must take special care when working with animals.

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9.7.6 Animal Allergies
Researchers who work with animals may develop allergic reactions, including rhinitis, conjunctivitis, asthma, and dermatitis. Symptoms of animal allergy may include nasal congestion, sneezing, watery eyes, hives and eczema. Rabbits and rodents are the most common research animals that cause severe allergic reactions. Animal dander, fur, bedding, urine, saliva, and tissues are the primary sources of allergic antigens. Mold spores and proteins in animal feed may also act as antigens.

To reduce exposure to animal allergens, minimize the generation of aerosols and dust and wear protective equipment. Take special care to wear gloves when feeding animals, handling animals, changing bedding or cleaning cages.

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9.7.7 Indirect Animal Hazards
Indirect hazards occur when research animals are intentionally exposed to biological agents, chemicals, and radioactive materials. Because animal bedding, equipment, waste products, and surrounding atmosphere may become contaminated, these items can be hazardous. To protect personnel, manage all animal products and areas according to specific procedures approved by the appropriate oversight committee.

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9.8 Centrifuges
Centrifuging presents the possibility of two serious hazards: mechanical failure and aerosols. The most common hazard associated with centrifuging is a broken tube. To ensure safety when operating a centrifuge, take precautions to ensure the following:

  • Proper loading (accurate balancing)
  • Safe operating speeds (do not exceed manufacturing recommendations)
  • Safe stopping
  • Complete removal of materials
  • Proper cleanup

Follow these guidelines when working with a centrifuge: 

  • When loading the rotor, examine the tubes for signs of stress and discard any
    tubes that are damaged.
  • Inspect the inside of each tube cavity or bucket. Remove any glass or other
    debris from the rubber cushion.
  • Ensure that the centrifuge has adequate shielding to guard against
    accidental 'flyaways'.
  • Use a centrifuge only if it has a disconnect switch that deactivates the rotor
    when the lid is open.
  • Always keep the lid closed during operations and shut down. Do not open the lid until the rotor is completely stopped.
  • Do not brake the head rotation by hand.
  • Do not use aluminum foil to cap a centrifuge tube. Foil may rupture or detach.
    When balancing the rotors, consider the tubes, buckets, adapters, inserts and
    any added solution.
  • Stop the rotor and discontinue operation if you notice anything abnormal such
    as a noise or vibration.
  • Rotor heads, buckets, adapters, tubes and plastic inserts must match.

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High-speed centrifuges pose additional hazards due to the higher stress and force applied to their rotors and tubes. In addition to the safety guidelines outlined above, follow these guidelines for high-speed centrifuges:

  • Filter the air exhausted from the vacuum lines.
  • Keep a record of rotor usage in order to avoid the hazard of metal fatigue.
  • Frequently inspect, clean and dry rotors to prevent corrosion or other damage.
  • Follow the manufacturers operating instructions exactly.

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9.9 Compressed Gases

Compressed gases in the laboratory present chemical and physical hazards. If compressed gases are accidentally released, they may cause the following:

  • Depleted oxygen atmosphere
  • Fire
  • Adverse health effects

IMPORTANT: Cylinders that are knocked over or dropped can be very dangerous and can cause serious injuries. If a valve is knocked off a compressed gas cylinder, the cylinder can become a lethal projectile. Damaged cylinders can travel through walls much like a torpedo travels through water. They can cause structural damage, severe injury and death. Because disposal of compressed gas cylinders is difficult and expensive, be sure to arrange a return agreement with suppliers prior to purchase.

Follow these guidelines to ensure safe storage of gas cylinders:

  • Secure all cylinders in racks, holders, or clamping devices individually (not ganged) in a well-ventilated area.
  • Do not rely on color to identify container contents. Check the label.
  • Close valves, and release pressure on the regulators when cylinders are not in use.
  • Minimize the number of hazardous gas cylinders in a laboratory. Do not exceed the following:
    a. three 10" x 50" flammable gas and/or oxygen cylinders, and
    b. two 9"x 30" liquefied flammable gas cylinders, and
    c. three 4" x 15" cylinders of severely toxic gases (e.g., arsine, chlorine, diborane, fluorine, hydrogen cyanide, methyl bromide, nitric oxide, phosgene)
  • Keep heat, sparks, flames and electrical circuits away from gas cylinders.
  • Store cylinders of flammable and oxidizing agents at least 20 feet apart, or separate these items with a fire wall.
  • Do not store gas cylinders in hallways or public areas.

When working with compressed gas cylinders, remember the following:

  • Never move a gas cylinder unless the cylinder cap is in place and the cylinder is chained or otherwise secured to a cart.
  • Do not move a cylinder by rolling it on its base.
  • Only use regulators approved for the type of gas in the cylinder.
  • Do not use adapters to interchange regulators.
  • When opening a cylinder valve, follow these guidelines:
    a. direct the cylinder opening away from people
    b. open the valve slowly.
  • If a cylinder leaks, carefully move the cylinder to an open space outdoors. Have the supplier pick up the cylinder.
  • Do not use oil or other lubricant on valves and fittings.
  • Do not use oxygen as a substitute for compressed air.
  • Do not lift cylinders by the cap.
  • Do not tamper with the safety devices on a cylinder. Have the manufacturer or supplier handle cylinder repairs.
  • Do not change a cylinder's label or color. Do not refill cylinders yourself.
  • Do not heat cylinders to raise internal pressure.
  • Do not use compressed gas to clean your skin or clothing.
  • Do not completely empty cylinders. Maintain at least 30 psi. 
  • Do not use copper (<65% copper) connectors or tubing with acetylene. Acetylene can form explosive compounds with silver, copper and mercury.
  • Always wear impact resistant glasses or goggles when working with compressed gases.

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9.10 Cryogenic Liquids
Cryogenic fluids, such as liquid air, liquid nitrogen or liquid oxygen are used to obtain extremely cold temperatures. Most cryogenic liquids are odorless, colorless and tasteless when vaporized. When cryogenic liquids are exposed to the atmosphere, however, they create a highly visible and dense fog. All cryogens other than oxygen can displace breathable air and can cause asphyxiation. Cryogens can also cause frostbite on exposed skin and eye tissue.

Cryogens pose numerous hazards. For example, cryogenic vapors from liquid oxygen or liquid hydrogen may cause a fire or explosion if ignited. Materials that are normally noncombustible (e.g., carbon steel) may ignite if coated with an oxygen-rich condensate. Liquefied inert gases, such as liquid nitrogen or liquid helium, are capable of condensing atmospheric oxygen and causing oxygen entrapment or enrichment in unsuspected areas. Extremely cold metal surfaces are also capable of entrapping atmospheric oxygen. Because the low temperatures of cryogenic liquids may affect material properties, take care to select equipment materials accordingly.

Follow these guidelines when working with cryogenic liquids:

  1. Before working with cryogenic liquids, acquire a thorough knowledge of cryogenic procedures, equipment operation, safety devices, material properties, protective equipment usage.
  2. Keep equipment and systems extremely clean.
  3. Avoid skin and eye contact with cryogenic liquids. Do not inhale cryogenic vapors. Never touch a dispensing nozzel barehanded after dispensing has begun.
  4. Pre-cool receiving vessels to avoid thermal shock and splashing.
  5. Use tongs to place and remove items in cryogenic liquid.
  6. When discharging cryogenic liquids, purge the line slowly. Only use transfer lines specifically designed for cryogenic liquids. Liquid nitrogen boils and spews out of containers (such as Thermo-Flasks or mortars) when room temperature objects are inserted. Avoid flying droplets!
  7. Rubber and plastic may become very brittle in extreme cold. Handle these items carefully when removing them from cryogenic liquid.
  8. Store cryogenic liquids in double-walled, insulated containers (e.g., Dewar flasks.)
  9. To protect yourself from broken glass if the container breaks or implodes, tape the exposed glass on cryogenic containers.
  10. Do not seal a container until it comes to ambient temperature. Sealed containers containing cryogenic samples may implode as the air space rapidly cools, or explode as the sample comes to room temperature.
  11. DO NOT pour excess cryogenic liquid down the drain! The plumbing will freeze and break.
  12. Do not store cylinders of cryogenic liquids in hallways or other public areas.

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IMPORTANT: Be aware of the tremendous expansion and threat of asphyxiation when a cryogenic liquid vaporizes at room temperature.

9.11 Electrophoresis
Electrophoresis equipment may be a major source of electrical hazard in the laboratory. The presence of high voltage and conductive fluid in this apparatus presents a potentially lethal combination. Many people are unaware of the hazards associated with this apparatus; even a standard electrophoresis operating at 100 volts can deliver a lethal shock at 25 milliamps. In addition, even a slight leak in the device tank can result in a serious shock. Protect yourself from the hazards of electrophoresis and electrical shock by taking these precautions:

  • Use physical barriers to prevent inadvertent contact with the apparatus.
  • Use electrical interlocks.
  • Frequently check the physical integrity of the electrophoresis equipment.
  • Use warning signs to alert others of the potential electrical hazard.
  • Use only insulated lead connectors.
  • Turn the power off before connecting the electrical leads.
  • Connect one lead at a time using one hand only.
  • Ensure that your hands are dry when connecting the leads.
  • Keep the apparatus away from water and water sources.
  • Turn the power off before opening the lid or reaching into the chamber.
  • Do not disable safety devices.
  • Follow the equipment operating instructions.

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9.12 Glassware

Accidents involving glassware are the leading cause of laboratory injuries. To reduce the chance of cuts or punctures, use common sense when working with glassware. In addition, follow special safety precautions for tasks that involve unusual risks. Follow these practices for using laboratory glassware safely:

  • Prevent damage to glassware during handling and storage.
  • Inspect glassware before and after each use. Discard or repair any cracked, broken or damaged glassware in a sturdy container.
  • Thoroughly clean and decontaminate glassware after each use.
  • When inserting glass tubing into rubber stoppers or corks, follow these guidelines:
    a. use adequate hand protection
    b. lubricate the tubing
    c. hold hands close together to minimize movement if the glass breaks
  • When possible, substitute plastic or metal connectors for glass connectors.
  • Large glass containers are highly susceptible to thermal shock. Heat and cool large glass containers slowly.
  • Use Pyrex or heat-treated glass for heating operations.
  • Leave at least 10 percent air space in containers with positive closures.
  • Never use laboratory glassware for vacuum operation.
  • Use round-bottomed glassware for vacuum operations. Flat-bottomed glassware is not as strong as round-bottomed glassware.

NOTE: Do not use chromic acid to clean glassware. Use a standard laboratory detergent. Chromic acid is extremely corrosive and expensive to dispose of. Chromic acid must not be disposed in the sanitary sewer system.

Follow these safety guidelines for handling glassware.

  • When handling cool flasks, grasp the neck with one hand and support the bottom with the other hand.
  • Lift cool beakers by grasping the sides just below the rim. For large beakers, use two hands: one on the side and one supporting the bottom.
  • Never carry bottles by their necks.
  • Use a cart to transport large bottles of dense liquid.

Follow these guidelines for handling and disposing of broken glass:

  • Do not pick up broken glass with bare or unprotected hands. Use a brush and dust pan to clean up broken glass. Remove broken glass in sinks by using tongs for large pieces and cotton held by tongs for small pieces and slivers.
  • Glass contaminated with biological, chemical, or radioactive materials must be decontaminated before disposal or be disposed of as hazardous waste.
  • Before disposing of broken glass in a trash can, place the glass in a rigid container such as cardboard and mark it "Broken Glass."

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9.13 Heating Systems

Devices that supply heat for reactions or separations include the following:

  • Open flame burners
  • Hot plates
  • Heating mantles
  • Oil and air baths
  • Hot air guns
  • Ovens
  • Furnaces
  • Ashing systems

Some laboratory heating procedures involve an open flame. Common hazards associated with laboratory heating devices include electrical hazards, fire hazards and hot surfaces.

IMPORTANT: Never leave an open flame unattended.

Follow these guidelines when using heating devices:

  • Ensure that heating units have an automatic shutoff to protect against overheating.
  • Ensure that heating devices and all connecting components are in good working condition.
  • Heating baths should be equipped with timers to ensure that they turn on and off at appropriate times.
  • Use a chemical fume hood when heating flammable or combustible solvents. Arrange the equipment so that escaping vapors do not contact heated or sparking surfaces.
  • Use non-asbestos thermal-heat resistant gloves to handle heated materials and equipment.
  • Perchloric acid (LINK) digestions must be conducted in a perchloric fume hood.
  • Minimize the use of open flames.

Heated chemicals can cause more damage and more quickly than would the same chemicals at a lower temperature.

RULE OF THUMB: Reaction rates double for each 10°C increase in temperature.

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9.14 Pressurized Systems
Do not conduct a reaction in, or apply heat to, a closed system apparatus unless the equipment is designed and tested to withstand pressure. Pressurized systems should have an appropriate relief valve. Pressurized systems must be fully shielded and should not be conducted in an occupied space until safe operation has been assured. Until safe operation is assured, remote operation is mandatory.

Safety Points to Remember:

  • Minimize risk and exposure
  • Identify and assess all hazards and consequences
  • Use remote manipulations whenever possible
  • Minimize pressure, volume and temperature
  • Use material with a predictably safe failure mode
  • Ensure that the components of the pressurized system will maintain structural integrity at the maximum allowable working pressure; avoid material that may become brittle.
  • Operate within the original design parameters
  • Provide backup protection (e.g., pressure relief valves, fail-safe devices)
  • Use quality hardware
  • Use protective shield or enclosures
  • Use tie-downs to secure tubing and other equipment
  • Do not leave a pressurized system unattended

IMPORTANT: Normally pressurized systems should not include glass components unless they are specially designed and intended for that purpose.

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9.15 Refrigerators/Freezers
Household refrigerators are not to be used to store flammable laboratory chemicals. This is extremely hazardous for several reasons. Many flammable solvents are still volatile at refrigerator temperatures. Refrigerator temperatures are typically higher than the flashpoint of most flammable liquids. In addition, the storage compartment of a household refrigerator contains numerous ignition sources including thermostats, light switches and heater strips. Furthermore, the compressor and electrical circuits, located at the bottom of the unit where chemical vapors are likely to accumulate, are not sealed.

Laboratory-safe and explosion-proof refrigerators typically provide adequate protection for chemical storage in the laboratory. Laboratory-safe refrigerators, for example, are specifically designed for use with flammable chemicals since the sparking components are located on the exterior of the refrigerator. Explosion-proof refrigerators are required in areas that may contain high levels of flammable vapors (e.g., chemical storage rooms with large quantities of flammable chemicals.)

Follow these rules for using refrigerators in the laboratory:

  1. Never store flammable chemicals in a household refrigerator.
  2. Do not store food or drink in a laboratory refrigerator/freezer.
  3. Ensure that all refrigerators are clearly labeled to indicate suitable usage.
  4. Laboratory-safe and explosion-proof refrigerators should be identified by a manufacturer label.
  5. Use "Not for Flammable Storage" labels, as appropriate.
  6. Refrigerators used to hold food should be labeled "For Food Only."

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9.16 Vacuum Systems

Vacuum systems pose severe implosion hazards. Follow these guidelines and requirements to ensure system safety:

  • Ensure that pumps have belt guards in place during operation.
  • Ensure that service cords and switches are free from defects
  • Always use a trap on vacuum lines to prevent liquids from being drawn into the pump, house vacuum line or water drain
  • Replace and properly dispose of vacuum pump oil that is contaminated with condensate. Used pump oil must be disposed as hazardous waste
  • Place a pan under pumps near containers of flammable chemicals
  • Do not place pumps in an enclosed, unventilated cabinet

IMPORTANT: All vacuum equipment is subject to possible implosion. Conduct all vacuum operations behind a table shield or in a fume hood.

CAUTION: Do not underestimate the pressure differential across the walls of glassware that can be created by a water aspirator.

The glassware used with vacuum operations must meet the following requirements:

  • Only heavy-walled round-bottomed glassware should be used for vacuum operations. The only exception to this rule is glassware specifically designed for vacuum operations, such as an Erlenmeyer filtration flask.
  • Wrap exposed glass with tape to prevent flying glass if an implosion occurs.
  • Carefully inspect vacuum glassware before and after each use. Discard any glass that is chipped, scratched, broken or otherwise stressed.

Glass desiccators often have a slight vacuum due to contents cooling. When using desiccators, follow these guidelines:

  • When possible, use molded plastic desiccators with high tensile strength.
  • For glass desiccators, use a perforated metal desiccator guard.

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9.17 Cold Traps

A cold trap is a condensing device used to prevent moisture contamination in a vacuum line. Guidelines for using a cold trap include:

  1. Locate the cold trap between the system and vacuum pump.
  2. Ensure that the cold trap is of sufficient size and cold enough to condense vapors present in the system.
  3. Check frequently for blockages in the cold trap.
  4. Use isopropanol/dry ice or ethanol/dry ice instead of acetone/dry ice to create a cold trap. Isopropanol and ethanol are cheaper, less toxic and less prone to foam.
  5. Do not use dry ice or liquified gas refrigerant bath in a closed system. These can create uncontrolled and dangerously high pressures.

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9.18 Fume Hoods
Fume hoods provide primary confinement in a chemical laboratory. They exhaust toxic, flammable, noxious, or hazardous fumes and vapors by capturing, diluting, and removing these materials. Fume hoods also provide physical protection against fire, spills, and explosion. Fume hoods provide the best protection when the fume hood sash is in the closed position. All chemical fume hoods must be exhausted to the outside of the building.

9.18.1 Special Fume Hoods
Special fume hoods are necessary when working with certain chemicals and operations. Examples of special fume hoods include the following:

Perchloric Acid Fume Hoods. (LINK to Perc Table) These fume hoods have a water spray system to wash down the entire length of the exhaust duct, the baffle, and the wall. The water spray is used periodically or after each use to remove any Perchloric Acid or organic material that may have accumulated.

Radioisotope Hoods. These hoods are labeled for use with radioactive materials. The interior of these hoods is resistant to decontamination chemicals. If special filtration is necessary with these fume hoods, contact the Office of Radiation Safety.(LINK)

Canopy Hoods. These hoods capture upward moving contaminants and are good for heat-producing operations. Workers may be exposed to contaminants if they work under the hood, however.

9.18.2 Fume Hood Safety Considerations

The potential for glass breakage, spills, fires, and explosions is great within a fume hood. Due to the chance for fires or explosions, fume hoods should be located towards the back of a laboratory, away from primary and secondary exits. Practice safe work habits when working with fume hoods, including the following:

Air Flow and Ventilation. Employee traffic in front of a fume hood or opening/closing laboratory doors can interfere with hood performance. Ensure that there is sufficient aisle space in front of fume hoods.

Fume Hood Type. All fume hoods are not appropriate for all types of work. Ensure that hazardous chemicals are used in the proper type or class of hood. For example, use Perchloric Acid only in fume hoods specifically designed for Perchloric Acid.(LINK to Perc Table)

NOTE: Biosafety cabinets are not to be used for hazardous / toxic chemicals.

9.18.3 Fume Hood Use and Care
A fume hood is designed to protect the operator from exposure to aerosolized materials. It is sometimes difficult to tell whether or not the fan motor is operational. Without the fan, the fume hood system will not provide adequate protection. Prior to using the hood verify the fan is operational. If your fume hood is not equipped with an airflow monitor, a piece of surveyors tape or a "Kim Wipe" mounted at the bottom of the sash will give an indication of air movement into the hood.

The face velocity is checked annually by the Safety Office. (Radiation Safety monitors radiation hoods.) The Safety Office (LINK) should be notified immediately if the fume hood is not operational.

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9.18.4 Guidelines for Effective Fume Hood Use

  • Know the physical, chemical, and toxicological properties of the materials with which you are working.
  • Keep the hood clear and uncluttered
    All work should be performed at least 6 inches inside the hood.
  • When large equipment is used, elevate the equipment at least 2 inches to allow for air flow under the object.
  • Always lower the sash to the lowest possible level, and use the sash as a shield.
    Never place your head inside the hood.
  • Avoid rapid movement in front of the hood. Avoid drafts created by turbulence from exterior air supplies or created by people moving in front of the hood.
  • Fume hoods are not to be used for disposal of hazardous materials. Always recap the waste bottle immediately.
  • Set the baffles according to the nature of the work being performed.
  • For work with volatile materials, position the baffles so that the air is exhausted out the top of the hood.
  • For normal work, locate the baffles in the center position - air will be exhausted form all three positions.
  • For work with chemicals that have a high vapor density, position the baffles so that the air is exhausted from the bottom of the hood.

9.18.5 Fume Hood Inspections

Fume hoods are tested at least annually. The Safety Office performs fume hood inspections and testing. The test includes an inspection of the hood system, airflow measurements and an assessment of the use of the fume hood. If you suspect a problem with your fume hood, please contact the Safety Office (LINK) (4-1153). Fume hoods should also be tested in the following circumstances:

  • When an employee requests an inspection.
  • When a procedural change requires a hood classification upgrade
  • After major repair
  • After a fume hood is moved

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9.19 Personal Hygiene

  1. Wash promptly whenever a chemical has contacted the skin. Know what you are working with and have the cleaning / neutralization material on hand and readily available.
  2. No sandals, open toed shoes or clogs shall be worn by laboratory personnel.
  3. Clothing worn in the laboratory should offer protection from splashes and spills, should be easily removable in case of accident, and should be at least fire resistant. Nonflammable, nonporous aprons offer the most satisfactory and the least expensive protection. Lab jackets or coats should have snap fasteners rather than buttons so that they can be readily removed. These coats are to be fastened closed while working and removed prior to exit from the laboratory.
  4. Laboratory clothing should be kept clean and replaced when necessary. Clothing should be replaced or laundered using appropriate decontamination procedures whenever contamination is suspected.
  5. Lab coats are not to be worn outside the laboratory, especially in rest room or break facilities. Any lab coats, respirators, or other protective gear must be left in the lab areas. Employees must, as a matter of routine, be responsible for washing, cleaning, and any other decontamination required when passing between the lab and other areas. Washing should be done with soap and water; do not wash with solvents.
  6. Inhalation is one of the four modes of entry for chemical exposure. "Sniff-testing" should not be done.
  7. Never pipette by mouth. Always use a bulb to pipette.
  8. Do not drink, eat, smoke, or apply cosmetics in the laboratory or chemical storage areas.
  9. Do not use ice from laboratory ice machines for beverages.
  10. No food, beverage, tobacco, or cosmetics products are allowed in the laboratory or chemical storage areas at any time. Cross contamination between these items and chemicals or samples is an obvious hazard and should be avoided.

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9.20 Working Alone
Never work alone in a laboratory while performing dangerous chemical procedures. Be sure there is someone in the immediate vicinity you can reach in case of an emergency.

In the event this procedure must be carried out after hours, an emergency contact should be informed of your location and a regular check-in procedure should be established. 

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9.21 Housekeeping
Areas should be kept clean and free of clutter. This includes bench tops, aisles and hallways.

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