Laboratory Safety Manual
1. Introduction
Safety should always be the first priority when working in the laboratory. This primer outlines many of the important chemical, electrical, and radiation safety considerations germane to research in the School of
Materials Science and Engineering at Georgia Tech. Beyond protective clothing, sensors, and hardware, the most important safety protection is knowledge. A fundamental understanding of potential occurrences in a
chemical reaction may be deduced from thermodynamic calculation, and purview of MSDS1 (material safety data sheets), or phone consultation with the Georgia Tech Department of Environmental Science, Health and Safety (DESHS). Electrical safety stems from knowledgeable use of multimeters and reading of circuit diagrams. In all cases, precautions must be made so that the laboratory environment is not booby trapped for future users-sloppy wiring or mis-labeled chemicals are disasters awaiting unknowing downstream researchers.
2 Accidents and Emergencies
POLICE, FIRE, AMBULANCE: 4-2500
For medical emergency and/or police, dial 4-2500. For fire, pull nearest alarm and call the campus police at 4-2500. Dialing 911 will circumvent the university police, but ambulance response will be slower. In the
case of clear emergency, instruct the campus police to call the ambulance immediately, rather than waiting for an officer to arrive and assess the situation. Provide adequate information on the phone: name,
telephone number, building, floor, room number, condition of any injured individuals (e.g., unconscious, burned, trapped), type of fire, if any. Do not move seriously injured people unless they are in danger of
further injury.
If there is a fire, use proper extinguishers-cut off electrical circuits, gas lines. Close doors. If clothing is on fire, help the individual to the floor and roll him or her around to smother the flames, or if a
safety shower is immediately available, douse the person with water. Running to a not immediately accessible safety shower or other source of water will only serve to fan the flames and intensify the clothing fire.
Fire blankets are intended primarily as a first-aid measure for prevention of shock rather than against smoldering or burning clothes. By wrapping a person who is on fire, heat is retained and the clothing may
continue to smolder, resulting in serious burns. In addition, if the person who is wrapped in the safety blanket is standing, a chimney effect may occur-smoke from the smoldering clothing would continue to rise past
the person's face.
If chemicals have been spilled over large area of the body, quickly remove all contaminated clothing while using the safety shower. Immediately flood the exposed areas with cold water for a least 15 minutes; resume
if pain returns. Wash off chemicals by using a mild detergent or soap (preferred) and water; do not use neutralizing chemicals or salves.
If chemicals have been spilled on a confined area of the skin immediately flush with cold water and wash by using mild detergent or soap (preferred) a water. Remove any jewelry in the affected area. If a delayed
action the chemical is possible (e.g., methyl and ethyl bromides), obtain medical attention promptly.
If a chemical has been splashed into the eyes, immediately wash the eye and inner surface of the eyelid with copious amounts of water for 15 minutes. The eye must be held open. Check for and remove any contact lenses
at once (contact lenses should not be used in the laboratory). An eyewash fountain should be used if available.
In case of ingestion of a toxin, dilute the poison by having the victim drink large amounts of water (do not give liquids to an unconscious or convulsing victim). Attempt to learn what the ingested substances were.
Save the label or container for transportation with the victim to the medical facility.
Water fire extinguishers are effective against burning paper and trash. They should not be used on electrical, liquid or metal fires. Carbon dioxide extinguishers are effective against burning liquids such as
hydrocarbons, and electrical fires. They are recommended for fires involving delicate instruments and optical systems because they do not damage such equipment. They are less effective against paper, trash or metal
fires and should not be used against lithium aluminum hydride fires. Dry powder extinguishers are also effective against liquid and electrical fires. They are less effective against paper/trash and metal fires.
Met-L-X extinguishers and others that have special granular formulations are effective against burning metal. Included in this category are fires involving magnesium, lithium, sodium, and potassium; alloys of
reactive metals; and metal hydrides, metal alkyls, and other organo-metallics. These extinguishers are less effective for the other types of fires.
Any student with working status is protected under the Workers' Compensation plan.
Benefits are paid to cover injuries resulting from work, whether the injury occurred on or away from the employee's normal work site. Regardless of the nature or severity, all injuries incurred must be reported immediately to your supervisor and to MSE's Facilities Manager, Tim Banks in room 181, Love Building. Procedures and information on this policy is posted in all labs.
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3. Compressed Gas Cylinders
One great concern with compressed gas cylinders is that they fall over and the valve stem is sheared off. These cylinders are typically charged to 1500-2500 psi (that is the pressure on a square inch of your hand
would feel like 2500 lbs.) In such a case the cylinder functions like a rocket, blasting through wall after wall, or could behave as a grenade. For that reason, cylinders must be chained or strapped in place to
prevent them from falling over. Metal cylinder caps for valve protection should be kept on at all times when the cylinders are not in use. Do not use cylinders without a pressure regulator. Inspect regulator inlets
and cylinder valve outlets for foreign matter; it is essential that the threads aren't damaged so that a tight seal can be maintained. These regulators are intended for use with specific gases, and to ensure
compatibility, the threads on regulators vary. Make sure the connections are compatible; if the inlet of the regulator does not fit the cylinder valve outlet, do not force it! Contact the supplier or producer of the
gas or regulator if advice is needed on the selection of a regulator.
Transport cylinders only via hand truck; attempting to rock-walk the cylinder runs the danger of the cylinder slipping and falling. All gas cylinders should be labeled to identify their contents. Do not rely on color
codes. Close cylinder valves when not in use. Do not rely on a regulator to stop the gas flow overnight. Close valves on empty cylinders and mark the cylinder ``empty". Store and use in well-ventilated areas,
away from heat or ignition sources. Store oxygen away from flammable gases. A regulator, valve or other equipment that has been used with another gas should never be used with oxygen.
Note that H2 is extremely flammable, beware of any reaction in which this is given off as a product. O2readily supports combustion and is thus also considered flammable. Serious explosions have resulted from contact
between oil and high-pressure oxygen. Oil should not-be used on connections to an O2 cylinder. Cylinders of combustible gases, e.g. CH4, H2, O2 should be stored in continuously exhausted areas. Inert gases can act
as suffocants, so make sure that adequate ventilation exists when large quantities of N2, Ar, He and other inert gases are used.
4. Electrical Safety
High voltage is dangerous, not high current, unless of course the current is running though the human body. For example, if one grabs the two live ends of a SiC heating element which is drawing 20 A at an applied
40V, what determines the current though the grabber's body is the 40 volts and the resistance of the current path through the body. The 20A in the parallel circuit is immaterial. High voltages are especially
accessible in our furnace room. Technically, touching a live connection (that is a connection which has a potential relative to ground), will not cause electrocution unless a portion of the body also touches ground.
This is easy to do since all metal casings for electrical devices must be, by law, connected to ground. For this reason, when working/debugging malfunctioning equipment, it is good idea to avoid working with two
hands; if one hand touches a live location while the other hand touches grounded metal, the current path goes through the human heart. Shoes are essential in this environment since naturally moist feet in contact
with the floor make an excellent ground connection. The fluid in the body acts as an excellent electrical conductor, and the dominant resistance to current flow is the skin. Therefore, avoid working with wet hands,
and take precautions against electrical components piercing the skin. Voltages on the order of flashlight batteries may be fatal if the skin is pierced.
When trouble-shooting equipment, make sure that all power has been removed from the equipment. It is good practice to always know where the upstream breaker box for an given power source is. Also, be aware that
removal of power from equipment does not mean that high voltages will not persist, particularly if the equipment contains sizable capacitances which are charged by high voltage. An ``off'' switch does not guarantee
that all power to an instrument box is off. To work on instrument electronics, it is better to unplug it and/or flip the upstream breaker. Before touching a malfunctioning instrument, it is a good idea to test
separately for ac and then dc voltages using a multimeter: touch one end to the location of interest, and the other to ground. All metal enclosures are, by law, grounded, so touching one probe to a screw (avoid
painted surfaces) on the box will be a ground connection.
One of the most important safety precautions when building or repairing equipment is to make sure that it is adequately grounded. Electrical work has strict color conventions, the most important of which is that the
green wire is ground. This wire should connect at one end to the ground connection from the power supply (e.g. the ground plug on a 110V wall receptacle) and at the other end, intimately to the metal housing. The
purpose of this is so that if a live wire makes contact to the chassis, extreme current will pass though the metal which will immediately blow a fuse. Fuses and breakers thus serve a very important function and
should never be bypassed. Note that if a high frequency (e.g., rf) ground is required, the shape of the conductor may differ from that used for a D.C. ground. When designing high power apparati for a moist
environment, ground fault circuit interruption should be added to the design.
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5. Radiation Safety for X-ray Diffraction and Spectroscopy
Analytical x-ray machines produce intense beams of ionizing radiation that are used for diffraction and fluorescence studies. The most intense part of a beam is that corresponding to the K emission of the target
material and is called characteristic radiation. In addition to the characteristic radiation, a continuous radiation spectrum of low intensity is produced ranging from a very low energy to the maximum kV-peak
setting. This is referred to as ``bremsstrahlung" or white radiation.
X-rays in the range of 15 to 40 keV produced by diffraction machines are readily absorbed in the first 5-10 millimeters of the skin, and do not contribute to a deep dose to the internal organs of the body. However,
the eyes, because of the aqueous nature of the tissue, do receive deep dose. Overexposure of lens tissue can lead to the development of lens opacities and cataracts; therefore, safety glasses should be worn when
operating x-ray producing equipment (for this application, glass lenses are preferred).
Absorbed doses on the order of 100 rads may produce a reddening of the skin (erythema) which is transitory in nature. Higher doses - 10,000 rads and greater - may produce significant cellular damage resulting in
pigment changes and chronic radiation dermatitis. It should be remembered that exposure to erythema doses may not result in immediate skin reddening. The latent (waiting) period may be from several hours to several
days. (Note: X-rays used for medical diagnosis are about one order of magnitude shorter in wavelength for tissue penetration and are carefully filtered to avoid x-ray damage to the skin caused by the longer
wavelengths).
Avoiding the primary beam does not necessarily mean that one is not being exposed to ionizing radiation. Faulty high-voltage vacuum-tube rectifiers may emit x-rays of twice the kilovoltage applied to the x-ray tube.
Other sources of potentially hazardous radiation are: 1. Secondary emission (scattering) from the sample, shielding material, and fluorescent screens. 2. Scattering from a faulty beam trap. 3. Leakage of primary
x-rays through gaps and cracks in shielding. 4. Penetration of the primary beam through faulty shutters, or through insufficient thickness of shielding material.
The equipment operator is responsible for his own safety and the safety of others when using an analytical x-ray machine. The written procedures developed for individual instruments should be sequentially followed.
Never put any part of the body in the primary beam. Exposure of any part of the body to the collimated beam for even a few seconds may result in damage to the exposed tissue. A person not knowledgeable about x-ray
equipment should not attempt to make repairs or remedy malfunctions. Always consult the designated representative first. Remember, safety devices and warning systems are not fool-proof or fail-safe. A safety device
should be used as a back-up to minimize the risk of radiation exposure. Never as a substitute for proper procedures and good judgment. The operator may use a radiation survey meter to detect the presence of unwanted
radiation and to trace the origin of leaks. The recommended instrument is a Geiger-Mueller meter with a thin window "pancake" detector. It should be remembered that most meters do not respond accurately
all the energies used for analytical x-rays. Correction factors of 3x to 10x may be required. Each user of APD x-ray equipment is recommended to wear a film badge. It must be recognized that the badge indicates only
the level of whole body radiation dose intercepted by the badge, or the level of scattered radiation in the room. The office of radiation safety offers a quarterly course on radiation safety.
In the event of an accident or unusual incident involving an analytical x-ray machine, proceed as follows: 1.Turn off the machine. 2. Call the Office of Radiation Safety at 894-3600. 3. Call the principal
investigator responsible for the machine. 4. Record all important parameters (e.g. kV-peak, mA, nature and duration of the possible exposure, and distance from the x-ray source).
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6. Lasers
Lasers present an eye hazard if a person stares into the beam and resists the natural reaction to blink or turn away. Lasers with powers in excess of 500 mW may produce eye or skin damage from diffuse scattered
light. Laser warning signs need to be posted for lasers with power in excess of 5 mW. A warning light should be activated when the laser is on.
Eye protection is required not only from direct impact of the direct beam, but also reflection (diffuse or concentrated) from surfaces. Goggles or safety glasses specifically designed for laser work are needed. They
need to be fitted so that stray light cannot come in from oblique angles. The type of glasses needed depends on the laser type, wavelength, and optical density. Undesirable reflecting surfaces can be rough-finished
and painted with flat charcoal black paint.
Direct laser impingement on the skin may cause considerable damage, especially where it is pigmented. A temporary injury to the skin may be painful and treated symptomatically. Injury to larger areas of the skin are
far more serious as they may lead to serious loss of body fluids, toxemia, and systematic infections. Injuries to the skin can result either from thermal injury (temperature elevation in skin tissue) or from a
photochemical effect (e.g. ``sunburn''). The warmth sensation resulting from absorption of radiation energy normally provides adequate warning for an avoidance reaction to prevent thermal injury of the skin from
almost all sources except some high-powered, far infrared lasers.
Potentially toxic vapors which may result from laser-heating of materials need to be accounted for. Ozone is produced at times from flash lamps and high repetition rate lasers as the beam propagates through air.
Ozone is extremely toxic. Proper ventilation is needed when vapors from liquid nitrogen coolants might otherwise starve the room of oxygen.
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