Safety In Laboratory

6.3

SAFETY IN LABORATORY Generally every one’s feeling is that laboratory is one such area where there is no possibility of an accident. But it is not really so. Though the inventory and usage of chemicals in the laboratory is meager as compared to process plants, the possibility of risks of handling and using of chemicals is more or less equal as far as accidents are concerned. Only the degree of loss varies. Hence, it is always important to consider the laboratory hazards also with equal note that of plants.

6.3.1

General Safety Precautions

1. 2. 3. 4.

5. 6. 7. 8. 9. 10. 11. 12.

In areas where chemicals are being used, stored or handled, strictly avoid smoking, consuming any eatables and drinks. Only approved laboratory procedures and the safe methods laid down in this manual must be followed for carrying out all laboratory tests and experiments. Treat all chemical with respect. Some chemicals can injure or even kill if they are not handled properly. Read the labels on all the containers before use. Keep the chemicals in original containers until used. Never put chemical into unmarked or mislabeled containers. Even drinking water should not be stored kept in containers used in laboratory. Do not distract other’s attention and concentrate on your job at all times to prevent accidents. Always keep your work area clean and tidy. Objects lying on the ground can be hazardous and even small spills can be slippery hence. Clean them immediately. Test, requiring use of open flame shall be restricted & allowed only in designated location. Use had gloves, apron and eye protections while handling acids & corrosive chemicals etc., to avoid injuries. When drawing samples of toxic and corrosive chemicals use proper protective equipments. Chemical fires can start easily and spread quickly hence, remove sources of fire sparks from areas where chemicals are stored or used. Certain airborne dusts of chemicals can explode sometimes, so avoid all ignition sources in the area while working with such chemicals. Handle flammable chemicals with great respects. These chemicals catch fire easily at normal temperatures and the vaporus can explode violently by a spark, flame or heat source.

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14.

15. 16. 17. 18. 19. 20.

21. 22.

23. 24. 25. 26. 27. 28.

The vaporus of nearly all-flammable chemicals are heavier than air. This means that the vaporus can crawl along the ground to distant flames and sparks then flash back to the source. Ground and electrically interconnect all drums, containers before transferring flammable chemicals from one container to another. This prevents the hazards arising out of the source. Keep all containers of flammable liquids closed when not in use. Empty containers are dangerous as they may contain chemical vaporus or liquid residual, which can also be explosive. Keep away from all ignition sources. All laboratory personnel must be familiar with location and the use of fire extinguishers, eye baths, fire blankets, gas masks and electrical switches. Fire safety equipment should not be blocked by placement of materials. When there is a spill or leak of chemicals, extinguish all sources of flame or sparks. Shut off the leak if safe to do so. If hazardous chemical are spilled or released, evacuate the area immediately and re-enter only when you have worn the proper protective equipment. Do not operate any electrical switch as this may generate spark. Ensure proper ventilation while working in the laboratory. Do not depend on your sense of smell to warm you about vapours. Some chemicals can be hazardous in concentration too low to detect by smell. Other can deaden your sense of smell. Use all protective equipment precisely while handling hazardous chemicals. Before using any respirator check for proper operation. Wash your hands thoroughly with soap and water after handling any chemical or containers of chemicals. Always wash before eating, smoking or using toilet facilities. Laboratory electrical equipments should be properly earthen and one should ensure that before using the equipments. No electrical equipment should be tampered by unauthorised persons. Electrically operated equipments must be switched off immediately after use. Water supply to laboratory condensers should be turned off at the end of the day shift.

These are general guidelines. Follow instructions detailed under individual heads.

6.3.2

Common Cause of Laboratory Accidents

1. 2. 3.

Improper handling & storage of chemicals. Improper techniques of usage & storage of laboratory equipments. Bad housekeeping.

6.3.2.1

Handing & Storage of Chemicals

6.3.2.1.1

Handling of Chemicals 1.

Acids Operate under the chemical fume removal hood whenever heating acid or performing reactions, which may liberate acid fumes. When making reagents always add acid to water, keep acid off skin and protect eyes from splattering. Use protective safety appliances during handling acids.

2.

Alkalies Alkalies can burn skin, eyes and respiratory tract severely. Wear heavy rubber gloves and face shield to protect against concentrated liquids. Use effective fume removal device or gas mask to protect respiratory tract against alkali, dusts or vapours. Protect skin and eyes when working with alkalies as solids or concentrated solution.

3.

Flammable Liquids a. b. c. d. e.

4.

When using flammable, keep only required quantity in the work area for immediate needs. Store extra flammable chemicals in a separate place. While transferring form a large container to small container, ensure proper boding and earthing to avoid static electricity hazard. Keep all ignition sources away while working with flammable chemicals. Avoid spillage of flammable chemicals and in case there is spillage, clean the area of once and put the waste in a bin in safe area.

Toxic Chemicals a. Check up the label properly before you move or open or use the contents in it. b. Use appropriate protective equipment before handling toxic chemicals.

c. d.

6.3.2.1.2

Use only suction bulb (aspirator bulb) for drawing toxic chemicals along with pipe. Do not suck ‘Chemicals’ with mouth. Hot materials shall not be poured into a sink or drain as the presence of water in the drain might cause violent spattering. All waste toxic materials should be properly disposed off before draining them.

Storage of Chemicals in Laboratory 1. 2. 3. 4. 5.

Chemicals which might react together to give off dangerous fumes or cause fires or explosion on accidental breakage should be stored away from one another. Volatile liquids should not be stored near heat sources or placed in direct sun light. Stock reagents are best stored on open shelves within easy reach. The largest containers may be stored on the bottom of the shelves. The corrosive materials should be deep enough to hold contents of bottles if leakage occurs.

6.3.2.2

Handling & Storage of Laboratory Equipments

6.3.2.2.1

Handling of Laboratory Equipments Glass Apparatus 1.

2. 3.

4.

Discard irreparable, cracked or broken glass apparatus into properly labeled dustbin. Glass apparatus should be supported and braced in a manner, which will not result in excessive strain. Do not use glass bottles for liquids having vapour pressure above 15 psi at 1000 F (1 kg. At 380 C). Discard defective bottles immediately. Wear dry rubber gloves, goggles, gum boots and a rubber apron while handling bottles of acids or other corrosive chemicals are spilled on the skin or clothing, flood the affected area with copious amount of water. Do not force glass tubes or thermometers in or out of stoppers when dismantaling equipment. If the stopper gets stuck cut them away from the tubes. One should protect his hands by a dust cloth or towel while inserting glass tubes in corks.

5.

While using glass apparatus for heating or vacuum/pressure service, check for quality of glass and its withstanding capacity.

Ovens & Other Heating Media Check frequently the operation and accuracy of oven. Heating mantles, Hot Plates, Muffle furnace, & Liquid baths etc. temperature regulators and thermometers. Fume Cupboards Remove all non-essential apparatus and chemicals before working in the cupboard. Keep the windows lowered except removing or introducing apparatus or chemicals. Transferring of all fuming liquids, acids, toxic chemicals should be done under the fume cupboard to avoid gaseous pollution in the lab. Centrifuges The manufacturers must not operate centrifuges at speeds exceeding those maximums recommended. If excessive vibrations occur during operations, stop the centrifuge acid do not resume its operation until the cause of the vibration has been eliminated. Desiccators Keep the ground glass surfaces of desiccators greased. Seal and unseal desiccators by a siding action of the lids. Never seal a desiccators until its contents have cooled to a reasonable temperature. 6.3.2.2.2

Safe Storage of Laboratory Equipments 1. 2. 3. 4. 5. 6.

Vacuum desiccators and other glassware in which vacuum is created should be protected with a screen basket packed with asbestos wool. Store glass tubing and rods in a horizontal position with no place protruding over the coping. Store delicate glassware in separate cartons clearly marked for ready identification. Store glassware not higher than a person can reach easily without standing on a stepladder. Store heavy pieces on lower shelves. Store tall pieces at the back, smaller ones towards the front of the shelf. Special metal or plastic containers should be used to transport bottles of acids, alkalies etc.

6.3.2.3

Housekeeping 1. 2. 3. 4. 5. 6.

6.3.3

Great care should be taken to keep the working The spillages of chemicals should be immediately cleaned and floors should be washed with water and mopped up with a dry cloth. One should clean the sinks only after ensuring that broken glass pieces ate not lying in the sink. It is always necessary to keep proper labels on the reagent bottles and on sampling bottles to avoid complications. The glassware, laboratory reagents, chemical should always be kept in their appropriate places after use. Colour coding on various pipelines should be strictly followed.

Safe Methods of Working] 1.

2.

3.

4.

5. 6.

When distilling solvents, hydrocarbons or other liquids, do not fill a distillation flask to more than ¾ the of its rated capacity. Use bumping stones in distillation flask where bumping may occur. Never bring leaking sample containers into laboratory. Charged pressure sample containers should be stored outdoors and taken into the laboratory only when it is necessary to transfer the samples to apparatus. Use only approved ladders in good condition for climbing. Grip the ladder with both hands while ascending or descending. When using a portable ladder, station a person at its foot to hold it. Never place a ladder in front of an unlocked door. Consider all electric wires with defective insulation as live and dangerous. Do not overload electrical equipments. or use for any purpose other than that for which it was designed. When a liquid has been spilled over an electrical equipments, first of all turn off the current and then clean the equipment thoroughly and dry. Do not tamper with electrical equipment. consult the concerned electrical persons. When you find any electrical problem. It is always important to remember the location or first aid fire fighting equipment, eye wash showers, emergency safety equipments etc. in the laboratory. Gas burners should not be left unattended. The gas line tubing to be checked for leakages time to time.

7. 8. 9.

10. 11.

12. 13. 14. 15. 16.

Hot plates should not be kept in ‘ON’ conditions when it is not in use. All flammable and combustible materials should be kept away form hot plates. It is always important to keep the working area neat and clean to avoid any kind of untoward incidents because of bad housekeeping. Avoid keeping different chemicals in the same container. The practice of keeping laboratory chemicals in a refrigerator along with drinking water should be avoided. Do not keep food items drinks in refrigerator meant for storing of chemicals. While drawing chemicals in bottles from stores, they should be securely transferred on a trolley made for such bottles. While drawing chemicals form the plants all safety precautions should be followed. a. While drawing samples like Lactam, there is every possibility of choking in the sampling point. Due care should be exercised while removing the choking. b. At the time of drawing liquid gaseous samples, it is always important to drain the initial hold up by opening the valve very slowly to avoid sudden splashing. c. Before drawing samples, one should ensure that the sample is sufficiently cooled in the cool pot, to avoid cracking of sampling bottles. d. After drawing samples, a label should be put immediately on the sampling bottles. e. The person collecting the sample should wear the personnel protective equipment like hand gloves, face shield etc. f. Only authorized persons should collect the samples. Do not try to mix all the remnant chemicals after analysis for disposal. They should be treated individually as per the laid down procedure. Chemicals, which are required to be stored in dark area, should not get exposed to sunlight. Safety glass/Face shield needs be used while working with corrosive chemicals such as acids and alkalies so that a splash to the eyes can be avoided. While cutting glass rods using glasscutters, wear a face shield. Towels may be placed over the rod to protect the finger and the hands before breaking the piece. Glassware to be heated by an open flame should be rested on an iron wire mesh with an asbestos center to prevent the

17.

18. 19. 20. 21. 22.

23. 24. 25.

flame form coming in contact with the glass above the level of the liquid. This will avoid cracking of the vessel. Pressure flasks, which are to be heated under temperature control by a water bath or electric oven should be shielded so that in the event if the flask is ruptured, its contents and fragments of broken glass will be safety deflected. Pressure should be released from or applied to glass vessels slowly. It is generally unsafe to put pressure on laboratory glassware to expel its contents. Fill reagent and other bottles not more than 3/4th of their capacity at room temperature leaving one fourth of the capacity as outage to allow for expansion. Severe vibration of a vacuum container may result in collapse, equivalent to the shattering effect of an explosion. Vacuum desiccators may be transported in a wooden box. Carry beakers and all usual shapes of flasks and bottles with the fingers around the body of the vessel. Do not grasp or hold the volumetric and other long neck flasks at both top and bottom when their contents are being agitated. In washing glassware, no more than gentle pressure should be applied in wiping the insides. Cracked glassware or glassware with sharp or broken edges should be either fire polished or destroyed. The procedure for inserting glass tubing in stopper or rubber tubing is as follows. a. Never attempt to insert glass tubing having a jagged end b. Cut the glass tubing so that it has a smooth face, and then fire polish it. If it can not be fire polished, level the edge with the fire c. Bore the hole in the stopper large enough to obtain a snug fit without forcing. Select the rubber tubing which is slightly smaller in diameter than be glass tube d. Use water, soap solution, glycerin or Vaseline as lubricant to force the tube into the hole by a rotating motion e. The stopper should be grasped firmly in one hand and the glass tubing with the other. Always aim tubing away the palm of the hand holding the stopper or rubber. Use napkin cloth to protect palm/fingers.

6.3.4

Handling of Gas Cylinders in Laboratory 1.

2. 3.

4. 5. 6. 7. 8.

6.3.5

Keep all the Gas Cylinders outside the laboratory building in a ventilated roofed cylinder house. Required gases should be drawn in the laboratory through a well-designed gas distribution system. Keep all compressed cylinders in upright position duly secured with a chain to avoid free fall. While operating with compressed cylinders proper care should be taken by taking appropriate spanner for opening and closing the valves. Using wrong tools for this purpose is forbidden. Do not apply grease, wax or any oil etc. to compressed gas cylinder valves for lubrication. Use soap water for checking the leakage in the valve of the cylinder/gas distribution system. Note down pressure of cylinders at regular intervals to notice the leaks, if any. Do not drop the cylinders while handling. Use only cylinder trolleys for transferring. Do not try to tamper or damage the regulator valves of the cylinder. Bring it to the notice of the concerned person in case you find any problem with the regulator. Do not keep oxygen cylinders along with flammable gases like hydrogen, acetylene etc.

Waste Disposal

It is always important to dispose off chemicals after the experiments are over as it is dangerous to keep them exposed for long time. Acids All waste acidic chemicals should be neutralized with soda ash or lime or caustic soda solution before throwing them into drain. Alkalies All alkaline chemicals should be neutralized using acids before disposing them off into drain. Toxic Chemicals No toxic chemical should be drained before detoxifying its effect. They should be disposed off using specified procedure given in the laboratory operating manuals.

Flammable and Combustible Chemicals Any spill or waste combustible and flammable chemicals should be collected in a container and send them for BOD reduction to Effluent Treatment Plant time to time. 6.3.6

Some Incompatible Chemicals _________________________________________________________

Sr.

No.

Chemical

1. Acetone 2. Acetylene 3. Alkaline Materials (NaOH, KOH) 4. Ammonia (Anhydrous) 5. Chlorine

6. Fammable Liquids peroxide, 7. Hydrocarbons such as Benzene, butane, Propane Gasoline, Turpentine etc. 8. Hydrazine 9. Oxygen (Liquid or Enriched air) 10. Sulphur 11. Sulphuric Acid 12. Water 13. Alkaline metals Such as Powdered Aluminum or Magnesium Sodium, Potassium etc 14. Acetic Acid 15. Aniline 16. Carbon activated 17. Copper 18. Chlorates 19. Chromic

Incompatible Chemicals

Bromine. Chlorine. Nitric Acid & Sulphuric Acid Bromine, Chlorine, Copper, Fluorine, Mercury and Silver Carbon dioxide, Chlorinated hydrocarbons, Water and the Halogens Bromine Calcium, Hypochlorite, Chlorine, Hydrofluoric Acid, Iodine, Mercury and Silver Acetone, Acetylene, Ammonia Benzene Butadiene, Butane and Other Petroleum gases, Hydrogen, Finely divided Metals, Sodium Carbide & Turpentine. Ammonium nitrate, Chromic Acid, hydrogen Nitric Acid, Sodium peroxide & the Halogens Bromine, Chlorine, Chromic Acid, Fluorine, Hydrogen Peroxide & Sodium peroxide, Hydrogen persuade, Nitric Acid and other Oxidant Flammable gases, liquids or solids such as Acetone, Acetylene, Grease, Hydrogen, Oil and Phosphorous Any oxidizing materials Chlorates, Perchlorates & Permanganates Acetyl chloride, Carbides, Chromic Acid, Phosphorous oxychloride, Phosphorous Pentachloride, Sulphuric Acid and Sulphur trioxide Carbon tetra chlorides or Chlorinated Hydrocarbons, Carbon dioxide and the Halogens

Chromic & Nitric Acids, Hydroxyl compounds, Ethylene glycol, Perchloric acid, Peroxides, Permanganates Nitric Acid, Hydrogen peroxide Calcium, Hypochloride, all oxidizing agents Acetylene, Hydrogen peroxide Ammonia salts, Acids, Metal powders, Sulphur, Finely divided organic or combustible materials Acetic Acid, Naphthalene, Camphor, Glycerin, Turpentine, Alcohol and Flammable materials

20. Fluorine 21. Hydrocyanic Acid 22. Hydrofluoric Acid 23. Hydrogen sulphide 24. lodine 25. Mercury 26. Nitric Acid

Isolate from everything Nitric Acid, Alkalies Ammonia, aqueous & anhydrous Fuming Nitric Acid, oxidizing gases Acetylene, Ammonia, Hydrogen Acetylene. Fulminic acid, Ammonia Acetic Acid, Aniline, Chromic Acid. Hydrocyanic Acid, Hydrogen sulphide Flammable liquids and Gases 27. Oxalic Acid Silver, Mercury 28. Potassium chlorate Sulphuric and other Acids 29. Potassium perchlorate Sulphuric and other Acids 30. Potassium permanganate Glycerin, Ethylene, Glycol, Benzaldehyde Sulphuric Acid 31. Sodium Peroxide Ethyl & Methyl alcohols, Glacial Acetic Acid, Acetic anhydride, Benzaldehyde, Carbon disulphide, glycerin, Ethyl & Methyl acetates, Furfural 32. Phosphoric Acid Chlorides, Nitromethane, Sodium Tetrahydroborate 33. Perchloric acid Acetonitrile, Alochohols, combustibles dehydrating agents 34. Potassium Nitrate Powdered metals, Organic materials reducing agents, Sodium, Benzene trichloro ethylene, Zinc etc. 35. Sodium Nitrite Organic matter, Cyanides Butadiene Reducants. Urea, Wood. Sodium amide sodium disulphite etc. 36. Chloroform Dinitrogen tetraoxide, Fluorine. Metals trisopropylphosphine 37. Pyridine Oxidising materials 38. Trichloro ethylene Al, Ba, N2O4, Li, Mg, Liquid O2, O3 KOH, KNO3, Na, NaOH, Ti 39. Phenol Oxidising materials, Formaldehyde, Butadiene 40. Carbon Tetra Chloride Aluminium Trichloride, Dibenzoyl peroxide, Potassium tert-butoxide 41. Formaldehyde NO, performic Acid Nitromethane Magnesium Carbonate, H2O2 42. Methanol Beryllium, Dihydride, Oxidants, Potasium terbutoxide, Dichloromethane 43. Solvent Ethers Powerful oxidesers 44. Kerosene Oxidising materials 45. Hydrogen peroxide Charcoal, Coal, Metals, Metal oxides Metal salt, Dimethyl phenylphorphine Hydrogen salenide Lithium tetrahy-droluminate, Phosphorus, Phosphorus (V) oxide, Tin (11) Chloride, unsaturated organic Compounds 46. Oxalic acid Ag, Naclo3, Naocl 47. Boric acid K (CH3CO)2O