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lABORATORY SAFETY PRECAUTIONS

Introduction

Teaching science to students through practical activities conducted in laboratories can be exciting, particularly when it done in a proper manner. However, less experienced students may, out of curiosity, indulge in risky behavior in the laboratory. For example, they may be tempted to touch hot objects and apparatus, mix reagents and even taste specimens. Such behaviour may cause serious injury or, even, prove fatal. Science teachers must, therefore, be familiar with basic laboratory safety precautions in order to prevent such accidents in the laboratory. Students also MUST be taught about safety in the laboratory.

General Guidelines for Students:
Conduct yourself in a responsible manner at all times in the laboratory.

Be familiar with your experimental assignment before you come into the laboratory. Follow all written and verbal instructions carefully. If you do not understand a direction or part of a procedure, ask the teacher before proceeding.
Never work alone. No student may work in the laboratory without a teacher present.
When first entering a science room, do not touch any equipment, chemicals, or other materials in the laboratory area until you are instructed to do so.
Do not eat food or drink beverages in the laboratory. Do not use laboratory glassware as containers for food or beverages. Never eat a specimen provided.
Perform only those experiments authorised by the teacher. Never do anything in the laboratory that is not in accordance with the laboratory procedures or asked for by your teacher. Carefully follow all instructions, both written and oral. Unauthorized experiments are prohibited.
Safety goggles and aprons should, if available, be worn when you work in the laboratory. Gloves should be worn whenever you use chemicals that cause skin irritations or need to handle hot equipment. Wear older clothes that cover the maximum amount of skin.
Observe good housekeeping (tidiness) practices. Work areas should be kept clean and tidy at all times. Bring only your laboratory instructions, worksheets, and/or reports to the work area. Other materials (books, purses, backpacks, etc.) should be stored in the classroom area.
Know the locations and operating procedures of all safety equipment including the first aid kit, eyewash, spill kit, fire extinguisher and/or fire blanket.
Be alert and proceed with caution at all times in the laboratory. Notify your teacher immediately of any unsafe conditions you observe.
Dispose of all chemical waste properly. Never mix chemicals in sink drains. Sinks are to be used only for water and those solutions designated by the teacher. Solid chemicals, metals, matches, filter paper, and all other insoluble materials are to be disposed of in the proper waste containers, not in the sink. Cracked or broken glass should be placed in the special container for "Broken Glass".
Labels and equipment instructions must be read carefully before use. Set up and use the prescribed apparatus as directed in the laboratory instructions provided by your teacher.
Keep hands away from your face, eyes, mouth, and body while using chemicals. Wash your hands with soap and water after performing all experiments. Clean, rinse, and dry all work surfaces and equipment at the end of the experiment.
Experiments must be personally monitored at all times. You will be assigned a laboratory station at which to work. Do not wander around the room, distract other students, or interfere with the laboratory experiments of others.
Students are never permitted in the science storage rooms or preparation areas unless given permission by the teacher.
Know what to do if there is a fire during a laboratory period; containers must be closed, gas valves turned off, fume hoods turned off, and any electrical equipment turned off.
If you spill acid or any other corrosive chemical on your skin or clothes immediately wash area with large amounts of water (remember that small amounts of water may be worse than no water at all). After this get the teacher's attention.
At the end of the laboratory session see that:
a) Main gas outlet valve is shut off

b) The water is turned off

c) Desk top, floor area, and sink are clean

d) All equipment is cool, clean, and arranged.

Clothing

Any time chemicals, heat, or glassware are used, students will wear laboratory goggles when available. Contact lenses should not be worn in the laboratory unless you have permission from your instructor.
Dress properly during a laboratory activity. Long hair, dangling jewellery, and loose or baggy clothing are a hazard in the laboratory. Long hair must be tied back, jewellery and loose or baggy clothing must be secured. Shoes must completely cover the foot. No sandals are allowed.

Accidents and Injuries

Report any accident (spill, breakage, etc.) or injury (cut, burn, etc.) to your teacher immediately, no matter how trivial it may appear.
If a chemical should splash in your eye(s), immediately flush with running water for at least 20 minutes. Notify the teacher immediately.

Handling Chemicals

All chemicals in the laboratory are to be considered dangerous. Do not touch, taste, or smell any chemical unless specifically instructed to do so. The proper technique for smelling chemical fumes (when instructed to do so by the teacher) is to gently fan the air above the chemical toward your face. Breathe normally.
Check the label on chemical bottles twice before removing any of the contents. Take only as much chemical as you need. Smaller amounts often work better than larger amounts. Label all containers and papers holding dry chemicals.
Never return unused chemicals to their original containers.
Never use mouth sucking to fill a pipette. Use a pipette bulb or pipette filler.
Acids must be handled with extreme care. ALWAYS ADD ACID SLOWLY TO WATER with a slow stirring motion, being careful of the heat produced, particularly with sulphuric acid.
Handle flammable hazardous liquids over a pan to contain spills. Never dispense flammable liquids anywhere near an open flame or source of heat.
Never take chemicals or other materials from the laboratory area.
Take great care when transferring acids and other chemicals from one part of the laboratory to another. Hold them securely and in the method demonstrated by the teacher as you walk.

Handling Glassware and Equipment

Inserting and removing glass tubing from rubber stoppers can be dangerous. Lubricate glassware (tubing, thistle tubes, thermometers, etc.) before attempting to insert it in a stopper. Always protect your hands with towels or cotton gloves when inserting glass tubing into, or removing it from, a rubber stopper. If a piece of glassware gets stuck in a stopper, take it to your teacher for removal.
When removing an electrical plug from its socket, grasp the plug, not the electrical cord. Hands must be completely dry before touching an electrical switch, plug, or outlet.
Examine glassware before each use. Never use chipped or cracked glassware. Never use dirty glassware. Do not immerse hot glassware in cold water; it may shatter.
Report damaged electrical equipment immediately. Look for things such as worn cords, exposed wires, and loose connections. Do not use damaged electrical equipment.
If you do not understand how to use a piece of equipment, ask the instructor for help.

Heating Substances

SHOULD THE BUNSEN BURNER GO OUT, IMMEDIATELY TURN OFF THE GAS AT THE GAS OUTLET VALVE. If you wish to turn off the burner, do so by turning off the gas at the gas outlet valve first, then close the needle valve and barrel. Never reach over an exposed flame. Light gas burners only as instructed by the teacher.
Never leave a lit burner unattended. Never leave anything that is being heated or is visibly reacting unattended. Always turn the burner or hot plate off when not in use.
You will be instructed in the proper method of heating and boiling liquids in test tubes. Do not point the open end of a test tube being heated at yourself or anyone else.
Heated metals, glass, and ceramics remain very hot for a long time. They should be set aside to cool on a stand and then picked up with caution. Use tongs or heat-protective gloves if necessary. Determine if an object is hot by bringing the back of your hand close to it prior to grasping it.
Everyone must be responsible for everyone else in lab. No rough play is ever allowed. Lack of pre-lab preparation is the biggest problem related to lab safety. If you or your group members are unprepared for lab you will waste time and have a good chance of making mistakes.

Eye Washing:

Eyelids have to be forcibly opened to ensure effective washing behind the eyelid.
Be sure to wash from the nose out to the ear. This will avoid washing chemicals back into the eye or into an unaffected eye.
Flood eyes and eyelids with water for a minimum of 15 minutes.
Contact lenses should not be worn during labs. If you are wearing them when involved with an accident, remove them as soon as possible to rinse eyes of any harmful chemicals.
After the teacher determines that the eyes are completely flushed, both of the victim's eyes should be covered with clean or sterile gauze.

Fire Blanket:

Fire blankets are not the best means to extinguish a fire. They may be used to extinguish clothing that is burning, but should never be used on any other type of fire.
Fire blankets are a good means to keep shock victims warm or to cover large chemical spills.

Fire Extinguisher:

Fire extinguishers are classified according to a particular fire type and are given the same letter and symbol classification as that of the fire.
Type A - combustible wood, cloth, paper, rubber, and plastics.
Type B - flammable liquids, oil, grease, and paint thinners.
Type C - energised electrical equipment
Type D - combustible metals (Mg, Ti, Na, Li, K)
Multipurpose Extinguishers are effective against types A, B, and C fires
To effectively operate an extinguisher, think P-A-S-S

            P - pull the pin
            A - aim the hose at the base of the fire
            S - squeeze the handle
            S - sweep the hose back and forth

Never use water on a Type B fire. These liquids float on water and, thus, water can spread the burning liquid. Water makes hot grease splash, and can result in burns. Cover the burning grease with sand, baking soda, or with the metal lid of the frying pan.
Never use water on a Type C fire. Water can cause a severe electric shock.

Being Prepared: Checklist

Know all exits.
Practice drills seriously.
Know locations of safety equipment and extinguishers.
Report any safety hazards to the teacher.
Be sure smoke detectors work.

Common Sense Guidelines:

Fire Hazards:

Worn electric cord, electric cords under rugs, near heat sources
Many appliances plugged into one outlet
Combustibles (paper, drapes) near heat source
Oil-soaked rags in open container
Flammable liquids in open container
Using flammable liquid in unventilated areas
Using gasoline to start fires
Adding starter fluid to hot coals

Danger or risk symbols
Below are some of the safety signs that you ought to learn for your own safety in the laboratory. They are normally printed on the label of reagent bottles or containers.

Harmful Substances which present moderate risk to health by inhalation, indigestion or skin absorption	Explosive Substances which may explode under the effect of flames or heat.	Dangerous to the environment Substances which would present an immediate or danger for one or more living things in the surrounding.
Corrosive Substances which destroy living tisues, wood and metal.	Toxic Substances which present a serious risk of cute or chronic poisoning, by inhalation, ingestion or skin absorption.	Oxidising Substances which give rise to highly exothermic reactions in contact with other substances especially flammable substances.
Flammable Flammable liquids catch fire easily.	Radioactive Substances which emit radioactive rays that penetrate the body.	Irritant Substances which are non-corrosive but are liable to cause inflammation through immediate, prolonged or repeated contact the skin or mucous membrane.