Chemical Safety


(A) Legislation

(B) Classification & Hazards of Chemicals

(C) Safe Handling and Storage of Chemicals

(D) General Safety Equipment in Laboratory

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S.K. Lam, HKPU



There are several pieces of legislation concerning the use of chemicals in laboratories and workshops, for examples, the F&IUO, the DGO, the CCO, etc.

It must be emphasized that some of the legislations do not apply to tertiary institutions, however, it is good practice that the same safety requirements stipulated in the law should also be adopted in educational institutions.



The Factories & Industrial Undertakings (Dangerous Substances) Regulations identifies certain chemicals which are dangerous and divided them into seven classes with different symbols. These seven classes are:

1.1.1 Corrosive

A substance or mixture that may on contact with living tissues cause severe damage to them at the site of contact. The action will not be spread to other sites. Examples of chemicals are: sulphuric acid, sodium hydroxide, hydrofluoric acid, etc.


1.1.2 Explosive

A substance or mixture that may explode under the effect of flame or that is more sensitive to shock or friction than dinitrobenzene.

Explosive effect is caused by chemicals which can bum at a very fast rate when exposed to an ignition source, and in so doing, creates violent movement of gases in the vicinity.


1.1.3 Flammable

A substance or mixture that:

(a) may become hot and finally catch fire when in contact with air at ambient temperature without any application of energy;

(b) is a solid and may readily catch fire after brief contact with a source of ignition and that continues to burn or be consumed after removal of the ignition;

(c) is gaseous and flammable in air at normal pressure;

(d) in contact with water or damp air, evolves highly flammable gases in dangerous quantities; or

(e) is a liquid having a flash point below 66oC.

The flammability of a chemical liquid depends on the flash point which is defined as the lowest temperature at which the chemical liquid will give off vapour which will ignite or explode if mixed with air and exposed to a naked light.

The lower the flash point, the more readily will the chemical liquid be burst into flame or exploded in the presence of an ignition source- The Fire Services Department classifies flammable liquids according to their flash points. For instance, substances with flash point lower than 23oC (benzene, benzine, lacquer thinners, MEK, etc.) between 23oC and 66oC (kerosene, methyl cellosolve), and above 66oC. (diesel oil, furnace oils, and fuel oils).

1.1.4 Harmful

Any listed substance that is classified in column 2 of the First Schedule in the legislation as harmful. Harmful usually means that the chemical substance bears adverse effects to living tissues.


1.1.5 Irritant

A substance or mixture that, through immediate, prolonged or repeated contact with the skin or mucous membrane, can cause inflammation.

Irritant materials are corrosive or vesicant in their action. In most cases, they inflame mucous membranes. For this reaction, the concentration of the irritants are more important than the duration of exposure. Some examples of irritants are: ammonia, sulphur dioxide, chlorine, etc. 

1.1.6 Oxidizing

A substance or mixture that gives rise to highly exothermic reaction when in contact with other substances, particularly flammable substances.

These are chemical substances having oxygen in their molecules which are easily available in reactions. Their presence can assist the reactions of other chemicals, sometimes in a violent manner. Examples of classes of chemical substances that have these properties are: perchlorate and peroxide compounds. 

1.1.7 Toxic

Any listed substance that is classified in column 2 of the First Schedule as toxic. The toxicity of a chemical substance is the ability of that substance to cause injury once it reaches a particular site (organ, tissue or cell).

A toxic chemical may have different toxic effects with different organs inside human body. Example is ethyl acetate which causes dermatitis with the skin, irritation in the lung and eyes, and narcotic effects in the nervous system.

In addition, a 'Dangerous Mixture' is defined as any mixture or preparation containing:

(a) more than 1 % by weight of any toxic substance or substances,

(b) more than 10% by weight of any harmful substances or substances; or

(c) such proportion of any other listed substance or substances as makes that mixture a corrosive, explosive, flammable, irritant or oxidizing mixture.



Containers which hold substance(s) that appears in the law must be labeled, but there are different exemption rules which are described below.

1.2.1 Listed Substance

Labels are required for containers of 'listed substances' unless one or more of the following exemption rules is met:

(a) the containers cannot be fitted with the appropriate label;

(b) a notice is put up in place of a label; or

(c) less than 125 ml of the listed substance is present.

1.2.2 Dangerous Substances

Labels (or notice) are also required for containers of dangerous mixture unless one of the following situations applies:

(a) the containers are already labeled by the suppliers to the same effects as required in the Regulation;

(b) the contents are produced in or not intended to be used in the premises; or

(c) the substance is less than 125 ml in volume and does not contain more than 1 % by weight of any toxic substance or substances.

1.2.3 Particulars Required on Labels

The label (or notice) for both listed substance and dangerous substance must include the following information:

(a) the chemical name or common name of the substance;

(b) the classification of the substance as stated in column 2 of the First Schedule;

(c) the symbol or symbols specified for that substance;

(d) the type of risks associated with the substance; and

(e) the type of safety precautions required.

1.2.4 Design of Labels

(1) The container must be labeled in both English and Chinese and in the form listed in the Ordinance.

(2) The particulars required above for that substance must be clearly and indelibly marked and stand out sharply from the background. They can be part of the outer packaging of the containers or a separate label.

The label must be securely fixed to the container with its entire back in contact with the container.

It may also be in a form acceptable by the authority.

(3) The dimensions of the label must be appropriate to the size of the container.

For container of 3 litres or less (label size not less than 50 x 75 mm)

For container > 3 litres, but =< 50 litres   (label size not less than 75 x 100mm)

For container > 50 litres, but => 500 litres (label size not less than 100 x 150 mm)

For containers exceeding 500 litres (label size not less than 150 x 200 mm)

(4) The size of any symbol required on the label must not be less than one- tenth of the areas of the label and must not be less than 100 sq. mm.

(5) If the information on the label does not reflect the true nature of the content or is confusing or misleading, then the label is not a valid one.

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(1) The management is responsible to ensure that all relevant information on the safe use of listed substances are available and supplied to the users.

(2) The management is also responsible to ensure that the users have the following training on the listed substances used:

(a) correct and safe methods of using listed substances;

(b) correct and safe methods of using personal protective equipment plus the limitation of such equipment; and

(c) the health hazards associated with the use of such materials.

(3) The management must make arrangement to supervise and to prevent the listed materials from causing bodily injury to users.



(1) The management is responsible to provide appropriate personal protective equipment to users of listed substances to protect them against bodily injury caused by such substances;

(2) The management must ensure that the personal protective equipment so provided must be properly used;

(3) The management must ensure that the personal protective equipment are maintained in good working order and are thoroughly cleansed or disinfected as appropriate after each use;

(4) The management must provide suitable storage facilities for such personal protective equipment.



The employees must:

(1) follow the safety instructions given in using such listed substances;

(2) observe and follow the safety precautions stated on the label or notice for such substances;

(3) not misuse or interfere with any label, notice or protective equipment provided;

(4) make full and proper use of the personal protective equipment supplied;

(5) leave the personal protective equipment in the storage place when not using them; and

(6) not eat, drink and smoke in the workplaces.



This Ordinance replaces the Acetylating Substances (Control) Ordinance as from 1 January 1996. The main enforcing authority is the Customs & Excise Department.

Twenty four chemicals are put under the control of this Ordinance and are classified into three schedules each of which has different levels of control.

2.1 Schedule 1

Acetic anhydride, acetyl chloride and acetyl bromide are in Schedule 1.

A licence is required to import, export, supply, procure, deal in, manufacture, possess, transport, and move Schedule 1 chemicals.

2.2 Schedule 2

Ephedrine, Ergotamine, Ergometrine, Pseudoephedrine, Lysergic acid, 1-phenyl-2-propanone, N-acetylanthranilic acid, Piperidine, Safrole, Isosafrole, Piperonal, Anthranilic acid, Phenylacetic acid, and 3,4-methylenedioxy-phenyl-2-propanone are in Schedule 2.

2.3 Schedule 3

Methyl ethyl ketone, toluene, potassium permanganate, sulphuric acid, acetone ethyl ether and hydrochloric acid are in Schedule 3.

A licence is required to export from Hong Kong, to any country specified in the same Schedule, e.g. most of the South American countries, and some of the Asian countries known for narcotic trading.

A licence is required to import, export, manufacture, transport and move chemicals in Schedule 2.


(B) Classification & Hazards of Chemicals

1. Pathological Classification of Chemicals

(1) Irritants - upper respiratory tract, upper and lower tract, and deep lung.

(2) Asphyxiants - simple and chemical (anemic and histotoxic) agents.

(3) Anesthetics and narcotic agents.

(4) Systemic agents.

(5) Sensitizers.

2. Routes of Entry

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(1) Inhalation (2) Ingestion
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(3) Skin Contact (4) Injection


(C) Safe Handling and Storage of Chemicals


a) Chemicals must not be stored at frequent-traveled locations.

b) No excessive chemicals should be kept in the laboratories. Only those quantities necessary for the activities should be kept. For the chemicals which are classified as Dangerous Goods under the law, no quantity of such chemicals in excess of the exempted amount can be kept.

c) Chemicals with similar properties/hazards can be stored together in the same location. Otherwise, they should be stored separately.

d) With the exception of small quantities of low-toxicity and frequently used working solutions, chemicals should be stored in lockable cabinets, especially those which are known to be highly toxic such as cyanides and arsenic compounds. The storage cabinets should be made from appropriate materials and have devices to contain possible leakage from the containers.

e) All chemical containers must be labeled. For hand-written labels, some identification should be included to identify the responsible persons who completed the labels. All labels should be inspected regularly and defaced labels should be replaced.

f) Chemical bottles should preferably be in plastic coating to minimize broken glass hazards and leakage problems. All chemical storage bottles should be inspected regularly for signs of leakage. Chemical bottles should have labels facing out for easy identification.

g) When storing on racks, large liquid chemical bottles should be placed on lower shelves. One rule of thumb is that containers should not be stored above average shoulder height to minimise breakage or spills. In particular, corrosive chemicals or large containers such as Winchesters should be stored as low as possible. Raised-edged shelving is preferable to the normal type as containers may be easily dislodged and slip off the latter. The storage racks should be located away from direct sunlight or be subjected to any direct heat source.

h) Excessive or unwanted chemicals should be returned to Dangerous Goods stores where appropriate, or disposed as waste chemicals.

i ) Dangerous Goods cabinets should be used to store flammable chemicals where appropriate.

j ) Only designated staff should have access to chemical storage. Students must not be allowed to remove the chemicals without supervision.

k) Spillage kits, clean-up equipment and appropriate personal protective equipment should be ready.

1) When handling hazardous chemicals, the MSDS for those chemicals must be studied and recommended safety procedures adopted.

m) Refrigerated storage may be necessary for some chemicals. Domestic refrigerators should not be used to store flammable chemicals.

n) Non-compatible materials must not be stored together. Examples are listed in the following table.

Chemical Not Compatible With
Acetic Acid Chromium (VI) oxide, nitric acid, alcohols, ethyleneglycol, perchloric acid, peroxides, permanganates
Acetylene Chlorine, bromine, fluorine, copper, silver, mercury
Activated charcoal Calcium hypochlorite, oxidizing agents
Alkali metals Water, carbon tetrachloride, all halogenated alkanes, carbon dioxide, halogens
Aluminum alkyls Water
Ammonia (laboratory gas) Mercury (e.g. In pressure gauges), chlorine, calcium hypochlorite, iodine, bromine, hydrogen fluoride
Ammonium nitrate Acids, powdered metals, flammable liquids, chlorates, nitrates, sulphur, fine particulate organic or combustible material
Aniline Nitric acid, hydrogen peroxide
Bromine Same as chlorine
Chlorates Ammonium salt, acid, powered metals, sulphur fine particlate organic or combustible substances
Chlorine Ammonia,. Acetylene, butadiene, butane, methane, propane, hydrogen, petroleum benzine, benzene, powered metals
Chromium (VI) oxide Acetic acid, naphthalene, camphor, glycerol, petroleum spirit, alcohols, flammable liquids
Copper Acetylene, hydrogen peroxide
Cumene hydroperoxide Acids, both organic and inorganic hydroperoxide
Cyanides Cyanides
Flammable liquids Ammonium nitrate, Cr(VI) oxide, sodium peroxide
Fluorine Store separately
Hydrocarbons Fluorine, chlorine, bromine, Cr(VI) oxide, sodium peroxide
Hydrogen fluoride Ammonia, laboratory gas
Hydrogen peroxide Cu, Cr, Fe, metals and metal salts, alcohols, acetone, organic substances, aniline, nitromethane, combustible substances
Hydrogen sulphide Fuming nitric acid, oxidizing gases
Iodine Acetylene, ammonia (lab. Gas or solution)
Mecury Acetylene, ammonia
Nitric acid, conc. Acetic acid, aniline, Cr(VI) oxide, prussic acid, hydrogen sulphide, flammable liquid and gases
Oxalic acid Silver, Mercury
Perchloric acid Acetic anhydride, bismuth and its alloys, alcohols, paper and wood
Phosphorus Sulphur, oxygen containing compounds such as chlorate
Potassium See alkali metals
Potassium chlorate See chlorates
Potassium permanganate Glycerol, ethylene glycol, benzaldehyde, sulphuric acid
Silver Acetylene, oxalic acid, tartaric acid, ammonium cpds
Sodium See alkali metals
Sodium peroxide Methanol, ethanol, glacial acetic acid, acetic anhydride. benzaldehyde, carbon disulphide, glycerol, ethylene glycol, ethyl and methyl acetate, furfurol
Sulphuric acid Potassium chlorate, potassium perchlorate, potassium permanganate


In terms of chemical groups, the rules outlined in the following table should be observed.

Number Chemical Group Incompatible with GU. No.
1 Inorganic acids 2-8,10,11,13,14,16-19,21-23
2 Organic acids 1,3,4,7,14,16-19,21-23
3 Caustics 1,2,5,7,8,13-18,20,22,23
4 Amines & alkanolamines 1,2,5,7,8,13-18,23
5 Hologenated compounds 1,3,4,44,14,17
6 Alcohols, glycols, glycol ether 1,7,14,16,20,23
7 Aldehydes 1-4,6,8,15-17,19,20,23
8 Ketones 1,3,4,7,19,20
9 Saturated hydrocarbonate 20
10 Aromatic hydrocarbonate 1,20
11 Olefins 1,5,20
12 Petroleum oils 20
13 Ester 1,3,4,19,20
14 Monomers, polymerizable 1-6,15,16,19-21,23
15 Phenols 3,4,7,14,16,19,20
16 Alkylene oxides 1-4,6,7,14,15,17-19,23
17 Cyanhydrins 1-5,7,16,19,23
18 Notriles 1-4,16,23
19 Ammonia 1-2,7,8,13-17,20,23
20 Halogens 3,6-15,19,21,22
21 Ethers 1,14,20
22 Elemental phosphorus 1-3,20
23 Acid Anhydrides 1,3,4,6,7,14,16-19


1) Good laboratory conduct.

   Fooling around in the laboratory can be dangerous.

2) No unauthorized experiments

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3) Laboratory neatness.

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4) Labelling chemicals

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5) Safety handling flammable liquid.

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6) Correct technique for transferring liquid

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7) Correct technique for carrying chemicals and equipment.

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8) Correct concern for working with test tubes.

Gently heat near liquid or solid surface. Be prepared to remove flame to avoid eruption. Never point a test tube towards yourself or another person. For safety and neatness, place test tubes in a rack.

9) Safety handling gas cylinders

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10) Safety use fume hood.

Use hood when working with toxic or flammable materials.

11) Good ventilation in the laboratory

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12) Safety handling sodium and potassium.

Store under light oil.

Fire or explosion may result from reaction with water.

Contact with skin may cause severe burns.

The metal is easily cut with a spatula on a paper towel.

Destroy residues with alcohol. Cool if necessary.

13) Correct concern for acid/alkali spills.

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14) Correct technique for handling mercury.

Spills break into microscopic droplets which can vaporize and endanger the atmosphere.

Do not use mercury over carpeted areas.

Spilled mercury should be picked up as completely as possible.

15) Correct concern for waste disposal

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16) Rapid treatment for chemicals in eye.

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17) Safety shower provided.

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1) 'NO SMOKING' signs are to be prominently displayed in the laboratory. Eating, smoking and drinking are prohibited in laboratories. 'Horseplay' is strictly prohibited in laboratories.

2) Adequate ventilation should be provided in the laboratory.

3) Do not store flammable liquids in the close proximity of an ignition source.

4) Flammable liquids should always be decanted in a well-ventilated area and away from the ignition source, e.g. in a fume cupboard.

5) Ensure that chemical containers are compatible with their contents, are in good condition and are positively identified.

6) The lids of flammable liquid containers are to be kept secure when not in use.

7) Never store containers on high shelving, as this may result in accidental breakage and spillage.

8) Use only the necessary amount of chemicals as required in the experiment.

9) When heating flammable liquids, extreme care must be taken not to overheat glass beakers, causing them to break. Where possible, the use of steam or water baths is recommended. If using, an electrical hot plate type of heater, ensure that it is spark proof and thermostatically controlled.

10) Flammable liquids must not be kept in domestic refrigerators as a spark may cause explosion. Where a domestic refrigerator is installed, a warning sign 'Flammable liquids must not be stored in this refrigerator' is to be displayed on the door.

11) Do not store flammable liquids with other incompatible liquids.

12) Know where your portable fire extinguisher is located and how to use it.

13) Conduct chemical experiments in fume cupboards as far as practical.

14) Observe the operating procedures and safety guide for fume cupboards.

15) Only when absolutely sure about the safety of the materials. otherwise, do not conduct experiments on open bench.

16) Get familiar with the University's health and safety regulations and procedures.

17) When in doubt, always ask someone who know. Do not operate until all safety concerns are satisfied.

18) Do not temper with safety installation in the laboratory. Report safety violations or failure of safety equipment.

19) Cooperate with the supervisor in using, the personal protective equipment whenever asked to.

20) Stop the experiment when your safety is in doubt.

21) Do not leave experiment unattended.



a) Should be installed at easily accessible locations possibly near egress and must not have obstruction in the access route.

b) Distance between work location and the eye wash should take less than 15 seconds to travel.

c) Small squeeze bottles containing limited quantity of water may be used as a temporary measure but cannot substitute eye wash station where flushing of eye should continue for at least 15 minutes after an accident.

d) Eyewash station should provide an ample amount of water, at least 1.5 litres per minute, at a relatively low pressure, 25 psi or less, in such a manner as to flood both eyes with aerated potable water.

e) Turning on the eyewash should require minimal manual dexterity. A simple paddle that the injured person can push aside to activate the eyewash is satisfactory.

f) The eyewash station must be checked periodically under full flow condition.


a) Showers should be installed at locations which are within 30 metres of the work locations in a laboratory. It is acceptable to install showers outside the laboratory if suitable space cannot be identified within the laboratory. However, the door should be designed in such a way that it must not slow down the personnel in case of accident/incident where the use of shower is required.

b) The location where showers are installed should not cause damage of equipment during its operation. It should also not close to any electrical device where electrocution may be possible.

c) Deluge showers should share the same unit as the eye wash should one required.

d) Water supply to shower should not be less than 114 litres per minute.

e) The mechanism for activating a shower on can be a paddle, or a chain, or any other design which requires minimal physical control or the manual dexterity.

f) Showers must be checked periodically.


3. FIRE ALARM & SUPPRESSION SYSTEMSwpe2E.jpg (3189 bytes)

a) All laboratories should be equipped with a fire suppression system.

b) A water sprinkler system is effective over 90% of the time in controlling or extinguishing fire in a laboratory.

c) Where water reactive chemicals or sensitive equipment may be used in the laboratory, alternative fire suppression systems that do not use water may be used. E.g. Halon 1301, carbon dioxide, foam, dry chemical, etc. This may be in the form of a carbon dioxide extinguisher.

d) Approval for installing the main fire suppression system must be sought from the authority and must be installed by contractors registered with the Fire Services Department.

e) Fire suppression system must be tested by the contractors on a periodical basis.

f) The fire detection and alarm system must be tested from time to time by approved contractors.


a) Suitable fume cupboards should be used for experiments which may generate chemical emissions in laboratory.wpe30.jpg (2812 bytes)

b) The fume cupboards and the associated fan unit must be made from materials which can resist chemical attack. The type of fans used should preferably be of explosion-proof design, otherwise, a warning notice must be posted to remind users on the limitation of the equipment.

c) The fume cupboards must be manufactured to an acceptable international standards. E.g. BS7258: Part 1 to 4:1994,  AS2243.8-1992, CSA Z316.5-94, or USA 29CFR 1910-1450.

d) Fume cupboards must not be used as storage cabinets for chemicals or equipment which are not required for the experiment.

e) When experiments are conducted in a fume cupboard, the sash should be kept at low position for protection.

f ) The face velocities of fume cupboards must be tested every six months.

g) Perchloric acid and radioisotopes must not be used in chemical fume cupboards, they must be used in fume cupboards specially designed for such materials.

h) The extraction ducting of the fume cupboards must be constructed from materials that can resist the corrosive action of the chemicals.

i ) For re-circulatory type fume cupboards, there are specific restrictions on the their applications which must be observed by the users.

j ) Biological safety cabinet have their own selection, installation and testing procedures which must not be confused with chemical fume cupboards.


5. FIRST AID & EMERGENCY RESPONSE KITSwpe31.jpg (3689 bytes)

a) The contents of first aid kits must be inspected periodically to ensure their currency. Expired items must be replaced.

b) First aid kits must be installed at easily accessible locations.

c) Emergency response kits should have contents commensurate with the type of activities in the laboratories.

d) The contents of the emergency response kits should be inspected periodically.

e) Training must be provided to the laboratory personnel on using such emergency equipment.

f) The emergency response kits may be installed in the laboratory, however, it is also acceptable for such kits to be installed outside the laboratory or shared by several laboratories within the same area.


a) Every chemistry laboratory must have a spillage kit. In addition, there should be other tools available such as plastic and metal buckets, mops, brooms, dust pans, large, heavy-duty polyethylene bags, duct tapes, and cloves for use when removing, the absorbent soaked with chemical spills.

b) The spillage kit must be inspected from time to time to ensure that items are not missing

The spillage kit must be installed at easily accessible locations in the laboratory.


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