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CERTIFICATION QUESTIONS/WITH ANSWERS
1. One of the major hazards which face a laboratory chemist is that of fires. It is necessary that each worker know the location of fire extinguishers and fire alarm pull stations. It is also very important to know the types of fire for which various commercial extinguishers are designed. There are four general classes of fires which are likely to pose a genuine threat to your laboratory safety. List each of the classes of fires and the type of extinguisher which would be required to put out the fire. ANSWER : Class A Fires : Ordinary combustible solids: paper, rubber, textiles. Frequently accompanied by destructive distillation producing flaming vapors or toxic gases. Also may leave hot ash or residue capable of re-ignition. Effectively extinguished by water which is recommended if the water would pose no further hazard. Also extinguished by CO 2 , N 2 , volatile halocarbons (CF 3 Br, etc.) and dry chemical extinguishers though these may lead to spreading ashes due to rapid release of compressed gas from the extinguisher cylinder. Dry ice will usually rapidly smother these fires if it is rapidly at hand. Class B Fires : Involves flammable liquids. Spreading of the fires is a major complication which is commonly encountered if the vessel of flaming liquid is overturned or broken. Easily extinguished by the exclusion of air by covering if in an upright vessel or by blanketing in foam, CO 2 , N 2 , volatile halocarbons or sometimes dry chemical (depending on the situation). Again, dry ice or liq. N 2 is very effective if it is at hand. Compressed gas extinguishers can lead to spreading and worsening of the fire if the force from the extinguisher overturns a
vessel containing a flammable liquid. Class C Fires : These are Type A or B fires in which electrical equipment is involved. Can be treated as class A or B if the power is turned off. It is a better practice never to use water as an extinguisher, even in the event power is disabled (some electrical equipment will store charge). If the power cannot be turned off the fire must be extinguished with inert gas or dry chemicals. Again, dry ice or liq. N 2 is very effective if available. Class D Fires : These fires involve reactive metals (e.g., Li, Na, K, Zn, Al, Mg, etc.) or active hydrides (NaH, KN, LiAlH 4 , etc.). These fires cannot be extinguished by CO 2 or H 2 O) or volatile hydrocarbons. Inert powder must be used (sand, talc, or alkali metal salts). Bicarbonate base extinguishers may not be effective. Metal-X extinguishers are recommended. 2. Chemical hazards are also a problem in the laboratory and it is important to know the hazards you might encounter in a lab. If you are working with a chemical and you do not know the hazards associated with it, you should ask your supervisor or consult the references listed at the beginning of the quiz. Name some common hazards associated with chemicals. ANSWER :
- Common chemical hazards include:
- Fire hazards
- Explosions hazards
- Extremely toxic chemicals
4. What does the fire alarm sound like and what is its function? ANSWER : These alarms are loud clanging bells throughout the building. They call the University Police Department and alert occupants to leave the building. 5. In the event of a fire, chemical spill or other emergency, appropriate safety equipment should be easily accessible and an emergency response plan initiated. What are appropriate circumstances for using fire fighting equipment and indicate an initial response plan that you should follow? ANSWER : Lab personnel should attempt to put out only small fires when they are confident the fires can be extinguished rapidly and when they themselves are not endangered. They should then notify the University Police Department and Chemistry Department Safety Committee to report the fire and use of equipment. In the case of large fires, you should immediately call the Police at 911 or use one of the hallway emergency response telephones, activate a fire alarm to evacuate the building and meet the firefighters at the building entrance (by the receiving dock) to direct them to the fire. A similar initial response plan should be instituted for large chemical spills. 6. In the event of an accident, health-related or other emergency, appropriate first aid and an emergency response plan should be initiated. What are appropriate circumstances for using first-aid equipment and an initial response plan that you should follow?
ANSWER :
First aid should be administered, if possible, to a person who is injured or ill to prevent death or further injury until professional medical help arrives, only if this poses no threat to yourself. This includes removal of the victim from the source of the injury and control of life- threatening conditions such as bleeding or shock and lack of breathing or heartbeat. In the case of an accident or emergency health problems you should immediately call University Police at 911 or use one of the hallway emergency response telephones, and meet the emergency personnel at the building entrance (or by the receiving dock) to direct them to the emergency. 7. The fume hoods in the labs are designed to operate in conjunction with the ventilation system for the building. The hood doors should always be kept at the appropriate level when you are not actively working in the hood area. (Under no circumstances should the hood doors be removed.) This will aid in the proper ventilation of the building and help prevent contaminated air from re-entering the lab. The hoods should always be on, but in the case of certain types of fires the hood may actually serve to fan the fire making it difficult to extinguish. One cutoff for each hood is located in the penthouse service area but there is no cutoff in your lab area. In the event of a fire emergency, how should you leave your hood area and how should the hood sash be positioned? ANSWER : If possible you should pull the hood sash to the closed position before leaving you lab area.
potentials as high as 208 volts. Frayed electrical wires could easily cause a very dangerous exposure to high voltage. 10. The storage of solvents in a chemical laboratory may pose a serious hazard to the safety of the laboratory personnel. Waste solvent collected in the lab should be properly labeled, tightly capped and should regularly be removed from the laboratory area for disposal. Solvents used and reused in large quantities must be adequately stored in nonbreakable containers (fireproof if the solvents are flammable) and under no circumstances should multiple (more than one) glass gallon containers be used for solvent storage in a single aisle. There is also a 10-gallon upper limit for flammable solvent storage in a lab. The department of Environmental Health and Safety has a regular solvent disposal system. Solvents for disposal are best stored if the containers used are fireproof cans or polyethylene jerricans, and are closed and properly tagged or labeled. Outline the reasons for use of these types of containers and the solvents which should be kept in each. ANSWER :
- The fireproof cans should be used with flammable non-corrosive solvents such as ether, hexane, toluene and alcohol. These solvents will not lead to corrosion of the metal can and thus leakage, but the can will provide protection in the event of a fire, as will an approved polyethylene FLAMMABLES can.
- The polyethylene jerricans are also used for corrosive nonflammable solvents. These could be strong acid solvents or solvents likely to contain acids which do not pose a serious fire hazard. Methylene chloride, chloroform and acetic acid are
examples. The polyethylene containers will provide protection from corrosion from the solvents with no danger of breakage. 11. Broken glassware poses a serious threat to your laboratory safety. Frequently, people are cut by broken drip tips on funnels or by glass tubing which has not been fire polished. What precautions should you take in this regard? ANSWER : Broken glassware must be repaired immediately so that there are no exposed sharp edges. When cleaning up broken glassware be sure to use protective leather gloves. In some cases broken glassware should never be handled directly (e.g., a broken flask which contained ethanolic KCN). Such equipment should be cautiously swept into a dustpan or similar equipment. A clean and neat bench reduces the likelihood of breakage. Unusable broken glassware or pipettes should be collected in a labeled glass waste disposal box. When full, notify your maintenance cleaning person for disposal. 12. Due to the building's ventilation system, the internal pressure of the building is less than the outside pressure. Since the drainage system is vented to the atmosphere on the roof, it is easy for odors and noxious gases to be swept back into your lab through open sinks and floor drains. How can this be avoided? ANSWER : Keep all sink traps filled with water and regularly check infrequently used floor drains and cup sinks. Do not pour noxious substances with high vapor pressure down the drains (solutions of H 2 S, mercaptans or
use with lasers and other radiation emitting equipment. A complete face shield should be used in particularly hazardous procedures (e.g., the generation of diazomethane). 15. To keep the air circulation in your hood working properly and to reduce the chance of initiating dangerous electrical fires in your hood, the hoods have been designed to allow routing of cords and cables in a special way. What features are available? ANSWER : Wires, cords or tubes should not be routed between the doors or out either side of the hood face. There is a flap at the front of each hood which is designed for the passage of wire or cords which will not alter the air flow. The shelf under your hood is the proper place for Variacs and other non-explosion proof electrical control equipment. 16. In the event of a laboratory accident, what sources of help will always be available? ANSWER : The University Police Department is available to assist in emergencies 24 hours/day by dialing 911 from any University phone. The University Police dispatcher will contact the most appropriate emergency response personnel and send them to your aid. When using this number, it is always important to let the emergency dispatcher hang up first. This will verify that the dispatcher has all the necessary information. 17. Unlabeled chemicals are a very dangerous hazard in the lab. Labels should always be securely placed on stored chemicals. Even if
you think you can remember, don’t trust your memory -- something could happen to you to prevent you from identifying these materials. Also, we have no mechanism for disposing of unknown chemicals (current regulation of the U.S. Environmental Protection Agency makes it illegal to dispose of any unknown chemicals), so someone will have to identify the chemical before it is disposed of. Identification may be difficult, dangerous, and expensive. If you find unlabeled chemicals in your laboratory, how should you treat them? ANSWER : They should be disposed of properly and promptly and not stored indefinitely as frequently happens in refrigerators. Identify the chemical to the best of your ability (consult your co-workers and research adviser as a first step). Particular hazards should be noted on the label (explosive, pyrophoric, highly toxic, etc.). The material should then be taken to the hazardous waste collection site. 18. The clothing you wear in the laboratory is a factor which will influence your safety. Outline the do’s and don’ts of the clothing worn in a chemical laboratory. ANSWER :
- Loose clothing should not be worn since it may be accidentally exposed to chemical contact or become caught in machinery. It also presents a greater fire hazard. Long hair can also be a problem by easily catching fire or becoming entangled in equipment. Skimpy clothing will offer little protection in the event of a chemical spill or splash. Shoes must be worn at all times. Perforated shoes or sandals should not be worn in lab. Further information is available in Prudent Practices, p. 158.
20. A properly designed and supported lab shield should be used when working with pressurized equipment or reactions which are known or suspected to be potential explosion hazards. These shields are a necessary supplement to the explosion protection offered by your hood design. Explain the explosion protection afforded by your hood. ANSWER : The doors to the hood are made of laminate safety glass to be blast resistant. There is also a blast vent on the top front of the hood which will be blown open during an explosion, thus providing an outlet for the blast force while directing it up and away. 21. In the event of chemical splashes or spills it is urgently necessary to thoroughly flush chemicals from contact with your skin. For spills on your hands or arms you will usually be able to wash the chemicals off over your sink. Remember you should use cool water to rinse with since warm water will open your pores making systemic absorption faster. The affected areas should be washed for at least 15 minutes. For large chemical spills or contamination in or around the eyes, each lab should have access to a safety shower and an eye wash. Where are these located and how are they marked and used? ANSWER : Contact of Chemicals with the Eyes: Take the victim immediately to the nearest eyewash station. Flush the eyes for at least 15 minutes. Eyelids must be held open with the eyeballs continuously rotating for optimum flushing. Immediately call Public Safety at Ext. 911 for additional assistance.
Contact of Chemicals with the Skin over a large part of the body: Help the injured person to the safety shower, and flush skin exposed to the chemical for at least 15 minutes. Remove all layers of contaminated clothing, shoes, and jewelry. If clothing or jewelry adheres to a chemically-burned area of skin; do not pull it away. Immediately call University Police at 911 for additional assistance. Contaminated clothing should be removed. It would be desirable for there to be a change of clothes in the labs for such emergencies. Sweats are recommended because of the size adjustment. 22. Compressed gas cylinders can pinwheel or rocket through masonry walls if the regulators or valves are broken off and can explode if substantially weakened structurally. What precautions can be taken to avoid rocketing, damaged cylinders? ANSWER : Cylinders should be firmly secured at all times with a belt or chain and capped when not in use. An appropriate hand cart with a cylinder strap should be used for moving cylinders. Cylinders should be kept away from sources of heat or ignition. Routinely check for leaks. 23. Chemicals should be separated from each other by hazard class, whenever possible to avoid unwanted reactions in the event of a fire or due to leaking or broken containers. Acids should always be separate from cyanides and from bases, while oxidizers should always be kept away from organics and reducers. Carcinogens should be stored in ventilated cabinets. List the five hazard classes recommended for segregating chemicals in storage.
which would likely endanger building occupants. What procedures can be followed to minimize the chance of breaking glass bottles? ANSWER :
- Always use a bottle carrier when transporting glass containers in halls, stairwells and elevators.
- Never store glass containers on the floor where they can be accidentally kicked or positioned on a stool or other insecure surface.
- Minimize the size of working containers. 27. Working alone in the lab can be very hazardous under most circumstances. Describe some of the laboratory situations under which you should never work alone. ANSWER :
- Never work alone in a laboratory unless assistance is close at hand and others are aware of your presence.
- Definitely never work alone when working with the following:
- High energy materials or high pressures
- Quick-acting, highly toxic materials (e.g. HCN)
- Transfer of flammable material except in small quantities
- Experimental research or laboratory procedures where previous experience has shown the desirability of having assistance available. 28. The Environmental Protection Agency requires that all waste solvent containers be kept capped and clearly labeled. The
Environmental, Health and Safety Office recommends emptying the containers regularly regardless of how full they are and using polyethylene jerricans for collecting both halogenated and non- halogenated waste solvents. Why shouldn’t metal safety cans or glass bottles be used for collecting waste solvents? ANSWER :
- Problems arise from using metal safety cans for any waste because the safety cans frequently get plugged from solid materials and eventually rust through because it is difficult to keep chlorinated and/or corrosive materials out of any waste solvents.
- Glass bottles shouldn’t be used to collect waste solvent because they are too easily broken. 29. All lab workers generating hazardous waste should should set up and follow a waste minimization program. Minimizing wastes also minimizes safety hazards. List several procedures for minimizing hazardous waste. ANSWER :
- Periodically inspect inventory of chemicals and discard those which are outdated or for which you have no further use.
- Avoid purchasing larger quantities than needed.
- Check the departmental chemical inventory lists for items before ordering from an outside vendor.
- Minimize the amount of required materials -- can the experiment be performed on a smaller scale?
- Substitute less hazardous materials for more hazardous materials used in experiments.
- Store the compound in an obvious location where it will not be forgotten.
- Check ether solvents and other peroxides formers for peroxides six months after opening the containers and every six months thereafter or dispose of them. Peroxide test strips can be purchased from safety suppliers laboratory. 32. Mercury vapor is highly toxic and mercury spills are very difficult to clean up because the mercury breaks into microscopic balls which roll into cracks and crevices where they cannot be easily seen or removed. What can be done to reduce the chance of mercury spills? ANSWER :
- Use a catch pan of appropriate size and depth under all mercury- containing equipment.
- Use non-mercury-containing thermometers where possible.
- Never use a mercury thermometer in a heated oven. 33. Teflon, a common component of lab supplies (e.g. containers, tubing, and stir bars) is considered inert in most circumstances, but what common substance can react explosively with Teflon at elevated temperatures? ANSWER : Potassium metal. 34. In the event of a small solvent or corrosive liquid spill which you can clean up yourself, explain the four steps for cleaning up spills. ANSWER :
1.Personal safety -- if someone comes into contact with a non- water reactive chemical, immediately rinse the affected area thoroughly with water for at least 15 minutes and contact Public Safety at Ext. 911. Wear appropriate personal protective equipment when cleaning up the spill. 2.Containment of the spill -- close lab doors and windows. Outline the area of the spill with spill adsorbent. Use Activated charcoal (organic solvents spill), sodium bicarbonate /speediDri (acid spill) or Citric acid/speediDri (base spill). Containers of these materials are available in each emergency closet located in your research areas. Adsorb the spill -- begin to adsorb the rest of the spill with the appropriate adsorbent. Use a dustpan or scoop to stir the mixture. 3.Cleanup -- for solvents, scoop the spill mixture into a plastic bag, label the container, and call Environmental Safety and Health at 777-2211 for pickup. 4.Neutralize the spill
- Procedure for neutralizing most inorganic acid spill materials: 1.Slowly add the beaker content to a large volume of cold water (approximately a 1: dilution). Never add water to acid, this causes excessive generation of heat in a very localized area and may result in an explosion (especially in the case of sulfuric acid). 2.Check pH. If neutral, skip step 3 and proceed to step 4.
