Other Hazards

Compressed Gas Cylinders

There is no central storage of compressed gas cylinders in French Science Center. Vendors deliver and remove cylinders regularly from individual labs. Cylinders of compressed gases, including "unreactive" gases such as nitrogen and argon, should be treated as potential rockets. When a cylinder is delivered to your lab, keep the valve protection cap on until the cylinder has been secured against a wall or bench or placed in a cylinder stand and is ready to be used. Cylinders should not be stored near sources of heat e.g. ovens, sunlight. In the laboratory, gas cylinders of all sizes must be supported by straps, chains or a suitable stand attached more than halfway up the tank to prevent them from falling over. Never drop cylinders or permit them to strike each other violently. If the valve breaks off a cylinder, the rapid release of the compressed gas may cause the cylinder to start moving rapidly and dangerously. It is the responsibility of the user to install and remove the regulating valves. Be sure to use the appropriate regulator for each gas cylinder; note that different regulators have different couplings. For information about the proper use of the valves and regulators, contact OESO. Regulating valves are not to be used as shut off devices. Never tamper with safety devices in valves of cylinders. Never oil cylinder regulators or valves since this could result in a fire or an explosion. If the valve is stuck and will not close, empty the tank and request that the vendor remove it from your lab. When not in use, cylinder valves should be closed tightly and stem protector caps secured. All tanks should have a small white label on the top front of the gas cylinder indicating the present status of the tank. Indicate the status as: FULL, IN USE or EMPTY. When the cylinder is empty (<15 lbs residual pressure), request that the vendor remove/replace the cylinder. If you need to move a large cylinder more than a few feet, secure the protector cap, place the cylinder on a gas cylinder cart, and strap the cylinder securely in place. A cart may be obtained from outside the stockroom (1126) and should be returned there after use. A more detailed discussion of using compressed gases is available at http://www.airgas.com/content/details.aspx?id=7000000000010.

Liquid Nitrogen, Dry Ice

Liquid nitrogen is available from the storage closet next to room 1238 and dry ice is available from the large blue chest located inside the building near the door to the loading dock. The first time you must obtain either of these substances, ask an experienced member of your research group to show you the proper procedures for handling them. Although liquid nitrogen is the colder, dry ice has the larger heat capacity; so both can cause severe "burns". Wear appropriate thermal protecting gloves whenever handling dry ice or liquid nitrogen; and take great care when pouring liquid nitrogen or when immersing objects at room temperature in liquid nitrogen — eye protection, of course, must be worn. Bare glass Dewar flasks used for cold traps should be wrapped with medical adhesive tape or glass fiber tape, to prevent flying glass in case the Dewar implodes. Dry Ice Baths do not use acetone or ether as the liquid, since they are too volatile and flammable. Suggested alternatives are trichloroethylene or isopropanol (flammable).


  • Extremely cold liquid and exhaust gases - USE GREAT CAUTION. Effluent lines may be at dangerously low temperatures. Do not use cloth gloves, as the liquid can saturate the material, resulting in more extensive cold damage.
  • Make sure that storage Dewars have safety necks. Periodic inspections (at least once a day) should be made to insure that no air or ice plugs exist in the neck opening.
  • When a 175 liter liquid nitrogen tank is depleted, close the pressure buildup valve (the valve with the metal tag marked "PB"). If the gauge shows a pressure of more than 50 lbs/sq. in, open the vent valve until the gauge reads less than 50 LB/sq. in. Follow the directions posted in the storage closet to inform the appopriate administrative staff of the empty tank to facilitate a refill request.
  • Condensed liquid air (such as may accumulate in a vacuum line cold trap cooled by liquid nitrogen) will be enriched with liquid oxygen and an explosive condition may result; surfaces which may condense liquid oxygen (air) must be clean from grease and oil.
  • On equipment using liquid helium, make sure that relief valves (pop-offs) are installed and that they are large enough to vent a sudden vaporization of all the liquid should the insulating vacuum fail. Note that sudden vaporization of liquid cryogens can result in an explosion due to sudden pressure changes.
  • Use liquid cryogens (helium and nitrogen) in a well-ventilated area — these gases do not support life. If these liquids are to be used long term on a regular basis, an oxygen monitor should be installed in the lab.

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Electrical Equipment

  1. The Chemistry Building uses several different electrical supplies: 110V, 220V, etc. The wall outlet of each requires a differently-shaped plug, so there should be no danger of accidentally plugging into the wrong supply.
  2. All electrical equipment should be grounded properly through a 3-pronged plug (consult the electrical shop if a floating ground is required). In general, other metal equipment, such as vacuum racks, should also be grounded. Protection from static electricity: ensure that metal tanks and containers are grounded (e.g. to the metal water pipes) while pouring solvents, to prevent fire or explosion from static sparks.
  3. Electrical equipment which is run overnight should be fused adequately and protected against damage in the event of a power failure.
  4. High voltage equipment (over 400V) should be clearly labeled; all high voltage leads should be caged or completely insulated.
  5. Check wiring to equipment periodically — chemicals corrode insulation. Avoid long cables along the floor of the lab. Electrical connections must be made by using terminal strips, not by twisting two pieces of flex together. Particular attention should be given to Variac, heating bath and magnetic stirrer power cords. Fraying of the wire on these appliances is particularly hazardous, due to their use near flammables and water. Equipment with bad cords should be repaired by a professional.
  6. Do not alter manufactured equipment. Disconnect electrical equipment before attempting any repairs.

If in doubt, consult the building manager (room 1133, 919-971-2517).

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Procedures in Case of Electrical Power Failure

Total power outages are not expected to occur in French Science Center since there is a backup generator in operation. It would still be prudent to consider potential hazards or difficulties that would result from power failure and we recommend that you ask yourself what will happen in your laboratory:

  1. When the power goes off.
  2. When the power goes back on after a period of several hours.
  3. When the power goes on after several days (if there is an extended power outage).

We note the following as sources of hazard in the event of a power failure:

  • All hoods will stop, until the backup generator starts. You should be prepared to deal immediately with toxic or inflammable gases.
  • All pumps will stop. Vacuum lines are apt to flood with pump oil. Liquefied gases in vacuum lines may be a hazard as the supply of Dry Ice runs out.
  • Refrigerators and freezers and cold rooms will warm up after a few hours. Explosive vapors may accumulate, and detonate when the power goes on. Although the thermostats in older refrigerators in research labs have been modified to reduce the potential for explosion, the compressors are not sealed and are a potential ignition source. It is therefore important to keep the contents of the refrigerator cold by keeping a block of Dry Ice in the freezer compartment for the duration of the outage.
  • Power surges or sparks from switches may be a hazard for delicate equipment when the power goes on.
  • The elevator will continue to operate on backup generator power.
  • Assuming that the generator operates correctly, all lights except one safety light in each lab and safety lights in each corridor and stairwell will go out. If the generator fails, all lights will go out. You should bring a flashlight to work and keep it available in your working area.
  • If a power failure appears to be extended you should go home and stay there after leaving your laboratory in safe condition. It will not be practical to do research anyway!

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Overnight and Unattended Operation of Equipment

Do not run equipment or experiments overnight, unless it is absolutely necessary. If it is necessary, discuss with your colleagues the best and safest way to set up the equipment. Some suggestions follow.

  • Where continuous water cooling is required, Tygon or metal tubing should be used and connected to faucets and apparatus by clamps or wired on. Screw-on high pressure clamps and hairpin type clamps which make it easier to clamp and unclamp hoses on condensers for overnight reactions are available in the stockroom. Water cooled equipment or hazardous reactions should be powered through an I2R water-controlled switch which will turn off the equipment if water flow drops below a safe level.
  • Electrical equipment, e.g. vacuum pumps, must be fused adequately and protected against a power failure.
  • Distillations and chemical reactions should involve small quantities of reagents only and be set up in a fume hood.

Whenever equipment is run unattended overnight, an Unattended Experiment Form must be completed with the name and phone number of the research worker concerned and action to be taken in emergency. Use full chemical names and not chemical symbols. This form should be posted prominently on the door of the lab where the experiment is taking place.

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(see also power failure) A directive from the City of Durham Fire Marshal requires that all refrigerators, freezers or coolers utilized in laboratories where chemicals are used be prominently labeled to indicate whether they are or are not suitable for storing flammable liquids. Class I flammable liquids are defined as "any liquid having a flash point below 100 degrees F and having a vapor pressure not exceeding 40 PSI absolute at 100 degrees F". Class one liquids are subdivided as follows:

  • Class I‹A Those liquids having a flash point below 73 degrees F and a boiling point at or below 100 degrees F.
  • Class I‹B Those liquids having a flash point below 73 degrees F and a boiling point above 100 degrees F.
  • Class I‹C Those liquids having a flash point at or above 73 degrees F and below 100 degrees F.

Refrigerators utilized for storage of chemicals in laboratories generally fall within the following three types:

  1. Refrigerators designed to store flammable liquids with all electrical equipment that meets Class I, Division I requirements.
  2. Refrigerators that have been modified by a licensed electrician that meet the class I, Division I requirements.
  3. Residential-type refrigerators that cannot be utilized to store flammable liquids, but are used for storage of other chemicals.
  • Type 1 & 2 refrigerators will require a blue and white label affixed to the refrigerator which states: "NOTICE ‹ This refrigerator is approved for the storage of flammable materials. No food or drinks may be stored in this refrigerator."
  • Type 3 refrigerators will require a red and white label affixed to the refrigerator which states: "WARNING ‹ This refrigerator is not approved for the storage of flammable materials. No food or drinks may be stored in this refrigerator."

Appropriate labels for your refrigerators may be obtained from the Fire Safety Division of the OESO, 684-5609.

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Vacuum Pumps

All vacuum pumps should be equipped with V-belt guards to protect the operator from possibly being caught in the belt. If any pumps are found to have this guard missing, they should be taken out of operation and sent to a repair shop for installation of proper guarding.

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Radiation Safety

The safety aspects of ionizing radiation, including radioactivity and x-ray sources, fall within the general supervisory and advisory responsibilities of the University's Radiation Safety Officer who reports directly to the Chancellor. The Radiation Safety division of the OESO has the responsibility of monitoring all radiation activities on the campus. The director of any research group who contemplates using radioactivity must apply to the Radiation Safety Office to become an Authorized User under the University's license from the Nuclear Regulatory Commission. While the Radiation Safety Office surveys laboratories and monitors personnel exposures, the responsibility for safe practices in any lab rests solely with the research director. It is his responsibility to see that each member of the group has been trained in the safe use of radioisotopes. This need for explicit training is unique to radioisotope work. Injunctions to "be careful" are not enough. The Radiation Safety Office will present a training course several times a year. Two other essential prerequisites for any laboratory using radioactivity are a sensitive survey meter and a carefully delineated procedure for decontaminating glassware and equipment.

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The Duke University Laser Safety Program is based on the American National Standards Institute (ANSI) document Z136.1-1993, American National Standard for The Safe Use of Lasers. The Program and its requirements will be described in the Duke Laser Safety Policy Manual and Procedures Manual. All laboratories in which lasers are used must contact the Radiation Safety Office (RSO) to register their laser system and schedule an initial laser site visit. The phone number for the RSO is 684-2194. A laser registration form is also available online.

Alignment Guidelines for Class 3B & 4 Lasers

  1. Allow only trained personnel to be present during alignment.
  2. Minimize the number of personnel present during alignment.
  3. Assure that all personnel present wear appropriate laser eye protection, i.e., correct wavelength and optical density.
  4. Avoid using beam paths that are at eye level while sitting or standing.
  5. Where feasible, use low power (class 2 or 3a) visible lasers to simulate the path of high power and/or invisible lasers.
  6. Where feasible, terminate laser beams and specular reflections on diffuse reflecting beam blocks.
  7. Use phosphor cards, UV/IR viewers, video cameras, or other beam display devices to locate invisible beams.
  8. Locate any specular reflections of the beam and block them as near their source as possible.
  9. Whenever possible, reduce all high power laser beams to the minimum possible power.
  10. Use beam shutters to block high power beams any time they are not actually needed.
  11. Avoid directing laser beams toward doorways, windows, or other viewing portals.

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Smoking in French Family Center

Smoking is prohibited in French Family Science Center.

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Alcohol and Medications

People who are under the influence of alcohol or medications that impair an individual should never conduct experiments.

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Duke University prohibits its members of its community, both individuals and groups, from manufacturing, selling, delivering, possessing, using, or being under the influence of a controlled substance without legal authorization.  A controlled substance includes any drug, substance or immediate precursor covered under the North Carolina Controlled Substances Act, including but not limited to opiates, barbiturates, amphetamines, marijuana, and hallucinogens.

The possession of drug paraphernalia is also prohibited under North Carolina state law and university policy.  Drug paraphernalia includes all equipment, products and material of any kind that are used to facilitate, or inteneded or designed to facilitate, violations of the North Carolina Controlled Substances Act.

In addiiton to disciplinary action, the conduct officer, or designee, may require a student to take a leave of absence, and return to campus may be conditional upon proof of completion of a substance abuse treatment program.  Last updated:  08/04/2011. Policy owner:  Dean of Students.

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