SAFETY. General Laboratory Guidelines. 2 Gloves should be worn when necessary especially when handling corrosive and toxic materials.

Transcription

1 SAFETY Safe practices in school laboratories reduce the risk of accidents and offers students safer places to experience the excitement of practical chemistry. This section contains some practical suggestions for teachers to put into practice in their laboratories, if they have not done so already. More detailed instructions on the best practice in school science and dealing with chemicals in schools can be obtained from Safety in School Science and Safety in the School Laboratory published by the Department of Education and Science and circulated to all schools. General Laboratory Guidelines 1 Laboratory coats and eye protection should be worn at all times during practical work. 2 Gloves should be worn when necessary especially when handling corrosive and toxic materials. 3 Eating, drinking or smoking must never be allowed in the laboratory. 4 Long hair must always be tied back securely. 5 Any cut, burn or other accident must be reported at once to the teacher. Details of any accident, however trivial, must be entered as soon as possible on the Laboratory Accident Record Book and then on the school accident report form and submitted to the school management. 6 Classes in other practical subjects should not be conducted in biology, chemistry or physics laboratories.

2 7 Non practical subjects should not be taught in the biology, chemistry or physics laboratories. 8 Laboratory doors should be locked when not in use. 2 9 Every laboratory should have good ventilation. The build up of corrosive or flammable fumes should be kept to a minimum. Liquids with high vapour pressure should be kept out of the sun. 10 Hazardous chemicals should not be kept in the laboratory but if they have to be, they should be locked in cupboards. The quantities of made up solutions kept available in the laboratory should be kept to a minimum. 11 Everybody using the laboratory should know the location of the master control shut off valves for electricity, gas and water. 12 A means of communication to the main office is recommended. 13 Teachers and students should wash their hands after using chemicals and before leaving the laboratory. 14 It is advisable to use daily, weekly and once a term checklists. 15 The following extra safety apparatus should be available in the laboratory. Safety screen Face shield (for teachers only) Eye wash/shower an eye wash stand or eye wash bottle or a fixed rubber tube on a convenient tap. Fire extinguishers (CO 2 /dry powder) Fire blankets Fire buckets Chemical spill Clean up kit First aid kit. 2

3 3 Chemical Storage Storage of laboratory chemicals presents an ongoing safety hazard for school science departments. There are many chemicals that are incompatible with each other. Improper storage of chemicals is the cause of many laboratory accidents. Chemical Storage Groups The organisation of storage of chemicals should be simple and straightforward and in such a way as to minimize possible hazards. The shelves should be clearly labelled or colour coded. All people using the chemical store should have some indication of where each substance is stored. A suggested system for categorising chemicals is to use six different storage groups each with its own colour code. The shelves and cupboards in the chemical store should also be colour coded. This will prevent incompatible chemicals from being near neighbours. STORAGE GROUPS RED GREY BLUE YELLOW GREEN WHITE Flammable storage General chemicals no particular storage hazard Toxic or health hazard Oxidising chemicals Corrosives alkaline Corrosives acids 3

4 4 Further Segregation Segregation of Flammables. Flammable liquids should be stored separately from flammable solids. Two fire resistant cupboards would be ideal, one larger one for bottles of flammable liquids and a smaller version for the flammable solids. Harmful chemicals can be further isolated by using (i) plastic tray/boxes or (ii) outer container. (i) Plastic Trays/Boxes A number of compatible chemicals are placed in a plastic tray or plastic box and a label put on the outside of the tray/box to indicate what chemicals are stored within. (ii) Outer Container Put the container in a heavy duty plastic bag (freezer bag), tie the bag, place it in an outer container (an unused paint can or a snap open secure container) with some absorbing agent and securely fix on the lid. Further considerations which should be taken into account when storing chemicals safely include: Only authorised persons should have access to chemical stores, which should be locked when not in use. Chemicals that are no longer required should be carefully disposed of. The chemical store should be well ventilated: this includes forced ventilation from floor to ceiling. Chemicals should not be stored in shelves above eye level. If chemicals have to be stored above this level it should be restricted to smaller bottles and steps should be available. Avoid floor chemical storage, if possible. 4

5 5 Shelves should have anti-roll off lips and should not be overcrowded. A chemical should not be hidden behind a larger container. Containers should not be stacked upon each other. Ideally shelf assemblies should be of wood construction and should be firmly secured to walls. Island assemblies should be avoided. Chemicals should be returned to storage area immediately after use. Chemicals should not be stored in fumecupboards while the cupboard is designated for other purposes. Chemicals should not be stored in a household refrigerator. All electric devices should be non sparking. Fire, smoke and heat detectors should be fitted. Appropriate fire extinguishers should also be fitted. There should be an emergency evacuation plan and a means of spillage control. Spill Control A means of controlling spillages and releases within the storage area is required. A chemical spill Clean up kit should contain:- 1. A bucket of dry sand. 2. A bucket of an absorbing agent. 3. A bucket of anhydrous sodium carbonate (for acid spills). 4. Plastic dust pan and brush. 5. Heavy duty plastic bags. 6. Two warning notices Provide precautions against skin and eye contact. Material Safety Data Sheets (MSDS), and the Department of Education and Science publication Safety in the School Laboratory will detail any specific precautions. 5

6 6 Chemical Storage contd. Any storage system should fulfil the following requirements:- 1. Chemicals should not be stored in alphabetical order as this can result in incompatible neighbours e.g. ammonia vapour and bromine :- unstable nitrogen tribromide is formed and an explosion may result sodium nitrate and sodium thiosulfate :- A mixture of dry materials may result in an explosion. 2. Chemicals should not be stored according to poorly chosen categories: all acids together or all organics together. Some acids are also reducing agents and some are oxidising agents (ethanoic acid and nitric acid). Some oxidising agents are incompatible with each other e.g. hydrogen peroxide and potassium manganate(vii). 3. Store flammable liquids away from sources of heat and ignition. Ensure containers are securely closed and specifically designed for the purpose. They should be stored in a fire resistant cupboard. If this is not possible they should be stored in a cool well ventilated area so that they cannot come in contact with oxidising agents, particularly nitric acid, hydrogen peroxide and potassium manganate(vii). 4. Flammable solids e.g. Group I (Li,Na,K) and Group II (Be,Mg) metals and some hydrides (NaBH 4, LiAlH 4 ) should be stored separately in a different fireproof cabinet, if possible, with phosphorous being kept apart from flammable metals. 5. Corrosive substances burn skin and eyes and may also react with incompatible packaging or metals like storage racking. Store away from flammable liquids and gases, oxidising agents and organic peroxides. 6

7 7 6. Methanal is a class 3 carcinogen. Fumes of hydrochloric acid and methanal when mixed form the potent carcinogen chloromethoxychloromethane. These two chemicals should be stored in separate rooms. 7. Oxidising substances can assist other materials to burn rapidly. Most oxidisers are extremely reactive and should be kept away from flammable materials. Store with other strong oxidising agents provided they are compatible. Organic peroxides should be stored separately from flammable, corrosive and toxic materials. 8. The main risk with toxic substances during storage is failure of containment. Consult label and MSDS for degree of toxicity. Store away from flammables and oxidising agents. 9. All explosive material should be stored well away from other chemicals. The Department of Education and Science and the members of the Chemistry Support Service will not be held responsible for any loss damage or injury arising in the context of the implementation of the recommendations contained in this document. References Safety in School Science Department of Education and Science Safety in the School Laboratory Department of Education and Science Safeguards in the School Laboratory ASE Topics in Safety ASE Flinn Chemical Catalogue Flinn Scientific Hazardous Chemicals (A manual for Science Education) SSERC HAZCARDS CLEAPSS 7

8 8 Emergency Services Fire Doctor Hospital Gardai Water Electricity Gas National Poisons Information Centre Beaumont Hospital Dublin 9 Telephone (01) / (01) Ring 999 or 112 for all Emergency services 8

9 Colour codes for L.C. Chemicals 9 Chemical Name Storage Group Aluminium foil Aluminium Metal Sheets (20 pack) Aluminium Oxide Aluminium Powder Aluminium Sulfate Ammonia 0.88 Ammonium Chloride Ammonium Iron(II) Sulfate Ammonium Metavanadate Ammonium Molybdate Ammonium Nitrate Ammonium Phosphate Ammonium Sulfate Anti-bumping granules Barium Chloride Benzaldehyde Benzoic Acid Bismuth (III) Chloride Bleach (liquid) Bleaching Powder Bromine Buffer Solutions, ph 4,7,10 Butan-1-ol Butanal Butanoic Acid Butanone Calcium Carbide Calcium Carbonate Calcium Carbonate - Marble Chips Calcium Chloride Calcium Granules Calcium Hydroxide Calcium Oxide Candles Carbon Electrodes (packet) Citric Acid Cloves Cobalt Chloride Copper (I) Oxide Copper (II) Carbonate Copper (II) Chloride Copper (II) Oxide Green White White 9

10 10 Chemical Name Storage Group Copper (II) Sulfate Copper (II) Sulfate Anhydrous Copper Electrodes Copper Turnings Copper wire (bare 22 swg) Cyclohexane Decon 90 Detergent Dyes, Water Soluble, & EDTA Disodium Salt Ethanal Ethanedioic Acid (Oxalic Acid) White Ethanoic Acid Ethanol 95% (Industrial Methylated Spirits) Ethyl Benzoate Ethyl Ethanoate Fehling's Solution No. 1 Fehling's Solution No. 2 Green Glass Wool Glucose - Anhydrous Glycerol Heptane Hexane Hydrochloric Acid White Hydrochloric acid-ampoules (box) White Hydrogen Peroxide vol Indicator paper box (selection) Iodine Iron (II) Sulfate Iron (III) Chloride Iron tablets (packet) Lard Lauroyl Peroxide Lead Bromide Lead Electrodes Lead Ethanoate Lime Water (Calcium Hydroxide) Green Lithium Lithium Chloride Litmus Powder Lycopodium Powder Magnesium Carbonate Magnesium Powder Magnesium Ribbon Magnesium Sulfate Manganese Dioxide Manganese Sulfate Dihydrate 10

11 11 Chemical Name Storage Group Methanal (Formaldehyde Solution) Methanoic Acid (Formic Acid 90%) White Methanol Methyl orange powder Methylated Spirits Methylbenzene (toluene) Nichrome Wire Nitric Acid Octane Paraffin - liquid Paraffin - Light Pentane Petroleum Ether (40/60) Petroleum Jelly Phenothalien solid Platinum Wire Poly(chloroethene) -PVC Poly(ethene) (low density) Poly(ethene)(high density) Polypropene Polystyrene (Poly(phenylethene) Polytetrafluoroethene (PTFE) Potassium Bromide Potassium Chloride Potassium Chromate Potassium Dichromate, crystalline Potassium Hydroxide Green Potassium Iodate Potassium Iodide Potassium Metal Potassium Nitrate Potassium Permanganate Potassium Permanganate -Ampoules (box) Potassium Sodium Tartrate Potassium Thiocyanate Propan ol Propan ol Propanal (propionaldehyde) Propanone Silver Nitrate Sodium Carbonate - Anhydrous Sodium Carbonate - Hydrated Sodium Chloride Sodium Dichromate - Crystalline Sodium Ethanoate Sodium Hydrogencarbonate Sodium Hydroxide Green 11

12 Chemical Name Sodium Hydroxide - Ampoules Sodium Hypochlorite Solution Sodium Metal in paraffin Sodium Sulfate Sodium Sulfite Sodium Thiosulfate Solochrome Black Sphere poly:pk/100 25mm Starch - soluble StrontiumChloride Styrene (Phenylethene) Sugar Sulfur - Fine Powder Sulfuric Acid Tin Plate or Foil (25 mm2) Trimethylpentane, 2, 2, 4, (iso-octane) Universal Indicator Solution Urea Vinegar Wooden Splints (100 Pack) Zinc Carbonate Zinc Electrodes Zinc Granulated Zinc Powder 12 Storage Group Green White 12