GOVERNMENT OF INDIA

DEPARTMENT OF ATOMIC ENERGY

HEAVY WATER BOARD ( CO )

MUMBAI

PUBLISHED BY

SAFETY, SAFETY ENGINEERING & PUBLIC AWARENESS GROUP HEAVY WATER BOARD (MUMBAI)

2008

COMPILED BY

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CONTENT

S.N. TITLE PAGE NO.

1 Introduction 3

2 History 3

3 Uses of chlorine 4

4 Occurrence 4

5 Physical & Chemical Properties 6

6 Toxic Properties 7

7 Health Hazards 9

8 Fire & Explosion Hazards 10

9 Construction Details & Safety features of

chlorine tonner

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10 Material of Construction 15

11 Safety in a. Storage of a tonner / cylinder

b. Handling of a tonner / cylinder

c. Loading & unloading of tonner

16

12 Monitoring & measurement of chlorine 21

13 Controls for chlorine leaks

a. Engineering Controls

b. Administrative Controls

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14 Emergency measures & first-aid 24

15 Case Studies 28

16 List of Suppliers 31

17 Annexure 32-37

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INTRODUCTION

In 2002-2003 the total chlorine production in our Country was 1.478 million tons

(worldwide production approx. 44 million tons). Out of this approximate 0.875

million tons was liquefied and transported to various destinations in the country.

With the transportation of liquid chlorine over long distances the hazards are no

longer confined to the place of its manufacture, storage and use but are spread all

over the country.

One of the greatest hazards associated with the use of chlorine is its familiarity due

to its common use. It is often forgotten that it is potentially dangerous. The

shipment of liquid chlorine in bulk from manufacturer to consumer involves

various handling operations, in which the principal risks are common. These are

attributable due to its toxicological character, physical properties, and chemical

reactivity.

The filling, possession, transport and importation of chlorine is governed by Static

& Mobile Pressure Vessel (Unfired) Rules. In case the quantity of storage exceeds

10 MT then the statutory requirements specified under MSIHC Rules are required

to be adhered.

HISTORY:

Chlorine was discovered by Karl Wilhelm Scheele, a Swedish chemist, in 1774.

Scheele thought that chlorine was an oxide of murium, or hydrochloric acid. He

did not, however, establish chlorine as an element. In 1810, chlorine was named

and classified as an element by Humphrey Davy. It was named after the Greek

word chloros, which means pale green.

Chlorine has also been used during World War-I. It was first introduced as a

weapon on April 22, 1915 at Ypres by the Germans. The results of this weapon

were disastrous because gas masks (canister) were not invented at that time. But,

some compounds of chlorine are more dangerous and have replaced chlorine gas

on the battle field. They are phosgene, chloropicrin, Lewsite, and mustard gas.

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USES OF CHLORINE

Although chlorine is highly toxic and hazardous in nature, at the same time it is

very useful for mankind and has become indispensable. It is used for disinfecting

drinking water, bleaching of textiles and paper, manufacture of insecticides,

pesticides and weedicides, pharmaceuticals, synthetic rubber, P.V.C./Plastics,

refrigerants, industrial solvents, rocket fuels and treatment of cooling water.

Owing to its strong oxidizing properties, chlorine is very effective in destruction of

bacteria, viruses, primitive life forms and algae. These properties are used very

widely today in the treatment of water for power stations and for drinking water

supplies. A small residue of chlorine is also left in the water to retain the necessary

antiseptic or fungicidal properties.

OCCURRENCE

The Natural Abundance of Chlorine: Chlorine's abundance is in igneous rock

which makes up 95% of the Earth's atmosphere. The most frequently seen form of

chlorine is in sodium chloride, NaCl, found in seawater.

Chlorine is never found in a free state; it combines with almost all elements.

Basic Properties of Chlorine

Atomic Mass 35.453

Atomic Number 17

Melting Point -101 oC

Boiling Point -34.6 oC

Density in natural state 1.56 g/cm3

Isotopes of Chlorine

Nominal Mass Accurate Mass % Natural Abundance

35 Cl 34.968 75.77

37 Cl 36.965 24.23

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These two isotopes have been used to define the atomic weight of chlorine to be

35.3. These isotopes have the same chemical properties, but, their masses are

different.

There is also a radioactive isotope of chlorine, including 36Cl.

The Structure of Chlorine

This is the structure of a chlorine molecule. The shared atoms are equidistant form the

atoms. Therefore, each atom has the same relationship for the shared atoms.

Chlorine is a member of the halogen family and group 17. It has seven valence

electrons. It consists of 17 protons, 18 neutrons, and 17 electrons. Its electronic

configuration is the following:

1s2 2s2 2p6 3s2 3p5

Because the element has only seven electrons in its outer shell, the atom is

unstable and will seek to find an element to combine with. All elements want to

have 8 valence electrons to secure stability.

How is chlorine made?

Chlorine is produced by electrolysis of brine solution (common salt dissolved in

water).

Essential by-products are caustic soda (sodium hydroxide (NaOH)) and hydrogen

(H2).

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PHYSICAL AND CHEMICAL PROPERTIES

Physical state Gas as well as liquid however, chlorine is a gas at ambient temperature

Colour Chlorine gas is Greenish yellow in colour Liquid chlorine is a clear, amber colored liquid

Smell Characteristic & suffocating Molecular Weight 70.9 Boiling Point ( Liquefying ) - 34. 6ºC (1 atm) Melting Point -101oC Specific Gravity (Water = 1) 1.41 (liquid) Density 3.209 g/l (1 atm, 0°C) Vapour Pressure, at 20oC 3.617 atm (0°C). Critical Temperature 144 ºC Critical Pressure 77.1 bar absolute Latent heat of vaporisation 63.2 kcal/kg Heat of reaction with NaOH 348 kcal/kg Solubility Chlorine is soluble in alkalis and only slightly soluble in water,

approximately 1 percent at 9.4ºC. The solubility decreases with rise in temperature up to the boiling point of water at which it is completely insoluble. Below 9.4°C chlorine hydrate known as ‘Chlorine-ice’ (Cl2.8H2O), may crystallize

Volumetric Expansion One volume of liquid chlorine when vaporized will yield about 457.6 volumes of gas at 0 deg. & one atm. Pressure. It expands about 0.15 % in volume for every ˚F increase in temperature

Relative density Chlorine is about 2 ½ times heavier than air. It seeks lowest level in the building / area where it leaks.

Fire / explosion hazards Neither liquid nor gaseous chlorine is explosive or flammable, but both react readily with many organic substances, usually with the evolution of heat and, in some cases, resulting in explosion. Chlorine is also capable of supporting combustion of certain materials.

Incompatibility � May cause fire & explosion with gasoline & petroleum products, turpentine, alcohol, acetylene, hydrogen, ammonia, sulfur and finally divided metals. � Chlorine will attack some form of plastic, rubber & coatings �Liquid chlorine attacks and dissolves P.V.C at ambient temperature.

Corrosivity Dry chlorine is not corrosive; however, it is strongly corrosive when moisture is present. Reacts slightly with water forming weak solution of HCl and HOCl H2O + Cl2 → HCl + HOCl That why moist chlorine is corrosive to most metals 1. At ambient temp. dry Cl2 reacts with Al, As, Au, Sn, Ti and Hg 2. It reacts with steels, Fe, Cu, Pb, Pt, Ag & Ni on heating above 120oC 3. At certain temp, Cl2 reacts spontaneously with H2 to form HCl. This occurs slowly in dark but explosively in sunlight or at more than 2500C.

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Reactivity

a. With metals

� Dry chlorine reacts with aluminium, arsenic, gold, mercury, selenium,

tellurium, tin and titanium

� At certain temperatures potassium and sodium burn in dry chlorine

� Carbon steel ignites at temperatures above 250°C

b. With other elements — Chlorine reacts with most elements under specified

conditions. Mixtures of chlorine and hydrogen composed of more than 5 percent

of either component may react with explosion. It reacts with ammonia, alkalis and

alkaline earth metal hydroxides.

c. With inorganic compounds — Chlorine has great affinity for hydrogen and as

such, removes hydrogen from some inorganic compounds to form hydrochloric

acid. It reacts with ammonia and ammonium compounds to form various mixtures

of chloramines and under proper conditions nitrogen trichloride which is

explosive. Chlorine reacts readily with lime and caustic soda to form hypochlorite

which is well-known bleaching agents.

The following chemical reactions take place between chlorine and lime or caustic

soda:

2Ca(OH)2 + 2Cl2 + 2H2O = Ca(OCl)2.4H2O + CaCl2

2CaO + 2Cl2 + 4H2O = Ca(OCl)2.4H2O + CaCl2

2NaOH + Cl2 = NaOCl +NaCl + H2O

These reactions are important because lime and caustic soda solutions are used for

handling chlorine leaks. Chlorine reacts with moisture to liberate nascent oxygen

and form hydrochloric acid.

d. With organic compounds — Chlorine reacts with organic compounds to form

chlorinated derivatives and hydrogen chloride. Some of these reactions,

particularly those with hydrocarbons, alcohols and ethers may become explosive.

Gaseous chlorine, wet or dry, may be used with hard rubber equipment at normal

temperatures and pressures. However, neither soft nor hard rubber can be used

with liquid chlorine.

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TOXIC PROPERTIES (PPM OF Cl2 GAS IN AIR):

Concentration Effect 0.02 – 0.2 ppm Order of threshold 0.5 ppm TLV - TWA(ACGIH), Nasal Irritation & Coughing 1.0 ppm STEL 3.5 ppm Least amount for detectable odour 4.0 ppm Threshold of irritation 5.0 ppm Noxiousness, impossible to breathe 15 ppm Least amount causing irritation of throat 30 ppm Least amount causing cough 40-60 ppm Amount dangerous in ½ - 1 hour 50 ppm Concentration dangerous, for even short exposure 137 ppm/ 1 h IHL-RAT LC 50 (Lethal Concentration – Inhalation) 1000 ppm Fatal even if the exposure is brief

TLV (Threshold Limit Value): Concentrations of air contaminants in the working

environment to which all workers are exposed repeatedly day after day without

adverse effect. Normally, it is the TWA concentration in ppm or gm/m3 for a normal

8 hour work day or 40 hour workweek.

STEL (Short Term Exposure Limit): It is defined as a 15 minutes time weighted

average exposure, which should not be exceeded at any time during a workday even

if the 8 hours time weighted average is within the TLV. STEL should not be > 15

minutes and not more than four times per day with an interval of 60 minutes.

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PHYSIOLOGICAL EFFECTS OF CHLORINE

Chlorine gas is classified as a respiratory irritant. When a sufficient concentration

of chlorine gas is present in the atmosphere, it will irritate the mucous membranes,

the respiratory system and the spine. Relatively small amounts of chlorine can be

detected because of characteristic odour of the gas. Significant amounts cause

irritation of eyes, coughing and laboured breathing. If the duration of exposure or

the concentration of chlorine gas is excessive, it will result in general excitement

of the person affected and followed by restlessness, throat irritation, sneezing and

copious salivation. In extreme cases, the difficulty in breathing may increase to the

point where deaths can occur due to suffocation, or lung tissues may be attacked

resulting in pulmonary edema. Persons afflicted with asthma, bronchitis and other

chronic lung conditions or irritations of the upper respiratory tract should not be

employed in areas where chlorine is handled. Chlorine produces no cumulative

effects and complete recovery occurs from mild exposures.

HEALTH HAZARDS

General — Chlorine gas is primarily a respiratory irritant. The characteristic

penetrating odour of chlorine gas usually gives warning of its presence. At higher

concentration it is visible as greenish yellow gas.

Acute Local — Chlorine gas exposure to the skin is not much irritating or

corrosive for short time. Splashes of liquid chlorine on the eyes, skin and clothing

may cause immediate irritation, chemical burns and severe damage to body

tissues.

Acute, Systemic — Chlorine gas is extremely irritating to the mucous membranes,

the eyes and the respiratory tract. If the duration of exposure or the concentration

of chlorine is excessive, it will cause restlessness, throat irritation, sneezing and

copious salivation. In extreme cases, lung tissues may be attacked resulting in

pulmonary edema. The physiological effects of various concentrations of chlorine

gas are shown in table above.

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Chronic (Local and Systemic) — Chlorine gas produces no known cumulative

effects. A concentration of 1 ppm of chlorine gas may produce slight symptoms

after several hours’ exposure, but careful examination of workers exposed daily to

detectable concentrations reportedly has shown no chronic systemic effects. Local

chronic effects have not been clinically demonstrated. Sensitization has not been a

problem with chlorine. It has been observed that prolonged exposure to

atmospheric chlorine concentration of 5 ppm results in disease of bronchi and a

predisposition of tuberculosis while lung studies have shown that concentration of

0.8 to 1 ppm cause permanent, although moderate reduction in pulmonary

function. Acne is not unusual in persons exposed for long periods of time to low

concentrations of chlorine, and is commonly known as chlorance — Tooth enamel

damage may also occur.

FIRE & EXPLOSION HAZARDS

� Flammable gases & vapor will form explosive mixture with Cl2

� Reacts explosively to form explosive compounds with many common

chemicals specially acetylene, turpentine, ether, NH3, fuel gas, hydrocarbon, H2

& finally divided metals, saw dust & P

� Vapor is heavier than air. Local heating of steel equipment a Cl2-Fe fire may

develop.

� Container may burst if exposed to more 95 0C, due to rise in pressure above

design value.

� Chlorine reacts spontaneously with hydrogen slowly in the dark but explosively

in sunlight or at high temperatures, to form hydrogen chloride. This is very

important during manufacturing of chlorine by electrolysis. The lower

explosive limit of hydrogen-chlorine mixtures varies from 3.1 to 8.1 percent,

depending on pressure and other variables.

� Hot chlorine gas from electrolytic cells, may sometimes crystallize as chlorine

octahydrate (Cl2.8H2O) due to sudden cooling and clog the pipe lines resulting

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in hold up of the gas in the pipe lines and allied equipment. This will cause

back pressure inside the cells and escape of chlorine into air or into the

hydrogen chamber resulting in explosion

� Since liquid chlorine increases considerably in volume when evaporated,

hydrostatic rupture in containers, pipe lines and other equipments may occur

due to build up of excessive pressure. Particularly, the danger due to pressure

build up in a heated cylinder can lead to an explosion.

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CONSTRUCTION DETAILS OF CHLORINE TONNER

1 Design pressure 19.9 kg/cm2 (This is the vapour pressure of liquid

chlorine in equilibrium with its vapour at 65oC)

The pressure on a container is not a measure of the

amount of liquid chlorine in the container but is

only a function of its temperature. A container

having 900 kgs or 1 kg of liquid chlorine will have

the same pressure at a given Chlorine temperature

2 Design temperature 650C (India is a tropical country)

3 Capacity 900 kg. The volume of liquid chlorine in a container

becomes greater as its temperature increases. All

containers when filled, have about 12% free space at

68˚F, it is reduced to less than 8% at 100 ˚F.

Because of this characteristic chlorine containers

should be handled with care and never be heated.

4 Code of design BS:1500-1958 art II (Class I Vessel)

5 Corrosion Allowance 3.0 mm.

6 Joint Efficiency 95%

7 Radiography Full

8 Stress Relief Yes

9 Filling Ratio 1.19

10 Gross weight 1,500 kgs ( Filled with liquid chlorine)

11 Colour of Paint Golden yellow

12 Supports Allowance for thermal expansion / contraction over

design temp. range

13 Branches Dimensions to be limited to minimum required,

particularly liq. Lines.

14 Approval Petroleum & Safety Organisation, Dept. of

Explosives, Govt. of India, Nagpur

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SAFETY FEATURES OF A TONNER

The various safety measures related to Chlorine Tonners Design and Use are:

a) Concave Ends: The design of the concave heads is especially significant from

the safety angle. Due to accidental overfilling and subsequent warm-up of

liquid chlorine to ambient temperature, an excessive internal –pressure may

develop and then one or both the concave ends will partially reverse. This

increases the container volume (some more space is created for the liquid

chlorine to expand) and at the same time gives visual notice so that this

abnormal situation is corrected (the container should be emptied immediately

in such case) and a possible hazardous or fatal situation is averted. In case of

convex ends, the failure will result in bursting of toner directly (without any

such warning) thereby endangering the personnel around.

b) Valve protection hood: This protects the valves from any accidental damage

during loading/unloading and transportation of toners.

The ton container is equipped with two identical valves near the centre of one

end. Each valve connects with an ejection pipe fitted inside the container. Ton

container in a horizontal position and with valves in a vertical line delivers gas

from the upper and liquid from the lower valve.

A cylinder has one valve at the top for drawing chlorine as liquid or gas.

Cylinders deliver chlorine gas when in an upright position, and liquid in an

inverted position. A steel removable cap is provided for the protection of the

valve.

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c) 24 hours storage after filling for observation: During this period liquid

chlorine attains ambient temperature and the pressure in the container is

10Kg/cm2 (during summer months) or 6 kg/cm2 (during winter months). This

should be checked before the containers leave the factory.

d) Limitation of filling: 900 Kgs. liquid chlorine filling in the tonner: The

quantity of liquid chlorine to be filled in a tonner is dependent on its water

capacity.

Quantity of liquid chlorine (Kgs.) = Water capacity (1) X Filling density

(kg/l) = Water capacity x 1.19

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Filling density means the ratio of weight of liquefiable gas allowed in pressure

vessel to the weight of water that the vessel will hold at 150 C.

Generally the water capacity of tonners in our country is 760 liters.

MATERIAL OF CONSTRUCTION

1. Mild steel is suitable for dry chlorine handling.

2. Fiber reinforced plastic is commonly used for wet chlorine. However,

ebonite lined mild steel& rubber lined vessels and pipes are also suitable for

wet chlorine. Titanium is also suitable for wet chlorine.

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SAFETY IN STORAGE

STORAGE OF TON CONTAINERS

� Toner shall be kept in cool, dry & relatively isolated area protected from

weather and extreme temperature changes

� Tonner shall be kept under cover, should not be exposed to the Sun

� Ventilation should be sufficient to prevent accumulation of Cl2 vapors

� No welding/gas cutting work should be done near the place of storage

� Due to high expansion ratio, danger of pressure build-up is there. Hence, they

should be kept away from direct source of heat

� Floor should be maintained dry where container / cylinders are stored. Failing

which the container will be externally corroded and its life will be reduced

� Toner shall be kept on their sides on rollers, a few inches above floor. They

should not be stacked or racked more than one high

� Keep enough room between the containers so that they are accessible in case of

an emergency

� Store Cl2 in areas where there is no contact with such a material with which it

reacts.

� Storage area shall be constructed of non-combustible materials

� Keep inventory as low as possible

� Filled & empty containers should be stored separately. Even if the container is

empty, valve outlet caps and valve protection hoods should be in place.

Provision must be made to permit inspection and facilitate prompt removal if

any leak occurs.

� Chlorine should be used on FIFO (first in -first out) basis because valve

packing can harden during prolonged storage and may cause leakage when

containers are finally used

� The storage area should be separate from the area where other compressed gas

cylinders / containers are stored.

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Storage of cylinders

• Cylinders should be stored in an upright position.

• They should be secured to prevent from falling over.

• Full and empty cylinders should not be stored together.

• The storage area should be dry, well-ventilated, clean of trash, and protected

from external heat sources (steam pipes, etc). Sub-surface areas should be

avoided for storing chlorine cylinders.

• The valves on cylinders and ton containers should be protected by a stout metal

cap securely attached to the cylinder body. This cap should always be kept in

place on all containers in storage and at all times except during use of chlorine

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Handling of cylinders & tonners

1 Cylinders should never be lifted by holding through metal cap. The manila rope,

wire ropes or slings, chains or magnetic devices should not be used for lifting

cylinders. Unloading platforms should preferably be at truck or car-bed level.

The ton container should be handled with a suitable cradle with chain slings in

combination with a hoist or crane having at least 2 metric tonnes capacity.

2 Cylinders and ton containers being trucked should be carefully checked,

clamped, or otherwise suitably supported to prevent shifting and rolling. They

should not be permitted to drop, and no object should be allowed to strike them

with force. They should not project beyond the sides or ends of the vehicles in

which they are transported.

3 Use of Chlorine

a. From Cylinders — Cylinders normally should be emptied in the gas phase,

standing secured in an upright position. Connection of containers

discharging liquid to a manifold is not recommended.

b. Ton-containers set in a horizontal position, with the valves in a vertical

plane, deliver gas from the upper valve and liquid from the lower valve.

When emptied in the liquid phase, a vaporizer should normally be used.

4 The flow of chlorine-gas from any chlorine container depends on the internal

pressure which in turn depends on the temperature of the liquid chlorine.

Discharge rates may, however, be increased by forced circulation of room-

temperature air around the container.

a. If the gas discharge rate from a single container will not meet demand

requirements, two or more container may be connected to a manifold and

discharged simultaneously, or a vaporizer may be used. When discharging

through a manifold, care shall be taken that all containers are at the same

temperature, particularly when connecting a new container to the manifold.

If there is a difference in the temperature of the liquid chlorine, it will be

transferred by distillation from the warm to the cool container, and the

cooler container may become completely filled with liquid. If this should

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occur and the container valve remains closed, hydrostatic pressure may

cause bursting. For this reason, extra precautions shall be observed when

closing valves of containers connected to a manifold. Connection of

cylinders or ton containers discharging liquid chlorine to a manifold is not

recommended.

5 A flexible connection between the container and the piping should be used;

annealed copper tubing (9.5 mm outside diameter × 0.889 mm wall), suitable

for 35.2 kg/cm2 service is recommended. A clamp and adapter connector is

preferred; if a union connector is used, the threads on the connector shall match

the valve outlet thread. (Valve outlet threads are straight threads, not standard

taper pipe threads.) A new gasket (lead) should be used when making a

connection.

6 Valves should be opened counter-clockwise with square box wrench not over

152 mm long. If the valve is difficult to open, the packing nut may be struck

with the heel of the hand, no other implements should be used.

7 Tonner/cylinder valves should not be used as controlling valve for flow of

liquid/gas. Separate valve should be provided at the source of consumption for

regulating the flow.

8 When chlorine is being absorbed in liquid, a barometric leg should be provided

to prevent suck-back of the liquid into the container when it becomes empty.

BAROMETRIC LEG

A suck back of process liquid can occur whenever Chlorine gas is injected into

the process liquid if there is a loss of pressure on the supply side. This

condition occurs if the supply container is emptied or if the chlorine supply is

interrupted. This suck back of liquid results in internal corrosion in the

Chlorine containers thereby decreasing their life. This can be prevented by

installing a suitably designed BAROMETRIC LEG in the system. In systems

working at atmospheric pressure, the height of the Barometric Leg should be

h = 34/d ft

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where ‘d’ is the density of the liquid (water or liquid used) in gm/cc (in case

there is a change in the density of the process liquid during Chlorination

reaction then the lowest value of density should be taken into consideration).

9. Always empty ton containers on scale, in order to know at all times the amount

of Chlorine in the container. The pressure in container is not a measure of the

amount of Chlorine in the container. The pressure varies with the temperature

of Chlorine gas. At any given Chlorine temperature, the pressure on the

container holding one Kg and 900 Kgs Chlorine will be the same.

As soon as the container is empty, the valve should be closed and the lines

disconnected. The outlet cap should be applied promptly and valve protection

hood attached. The open end of the disconnected line should be plugged to

keep atmospheric moisture out of the system.

10 OTHER FACTORS

a. TEMPERATURE

Liquid chlorine expands about 0.15 % in volume for every ˚F increase in

temperature this factor is very significant in handling chlorine in pipelines,

since liquid chlorine trapped in length of pipe subjected to a rise in

temperature can easily build up enough hydrostatic pressure to rupture the

pipe.

b. OVERFILLING

Over filled containers can also fail for the same reason.

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LOADING / UNLOADING OF CONTAINERS

A permanent system should be installed for loading/unloading of containers;

a) Manually operated Chain pulley block. They should be provided with suitable

slings, lifting beams and hooks etc.

b) In the absence of above, a platform with a ramp will also serve this purpose.

MONITORING & MEASUREMENT

As soon as there is any indication of the presence of chlorine in the air,

immediate action should be taken to locate the leak:

a. This is best done with the help of aqua Ammonia. Tie a cloth to the end of a

stick; soak the cloth with aqua ammonia and hold it close to the suspected

area. A dense white smoke of Ammonium Chloride develops which will

reveal the point from which the Chlorine is escaping.

b. Use of detector tube

Principal: Detector tubes have base impregnated with ortho-toludiene whereby

this turn in yellow color on exposure of chlorine present in ambient air.

Cl2 + O-toludiene (Colourless) → Reaction product (yellow colour)

Appearance of dark colour indicates high concentration of chlorine. Bromine,

chlorates and nitrites give error.

c. Use of portable chlorine monitors.

Principal: The portable monitors have amperometric sensors and contains gel

filled electrochemical sensor mounted in area where chlorine monitoring is

required. Sensor is covered with membrane that is permeable to halogen family

chemicals notably chlorine. Any chlorine present in ambient air will flow

through permeable membrane & initiate ampherio-metric activity within

sensor. A platinum electrode & silver anode are joined vai salt bridge circuit.

With low voltage applied constantly across the electrode, contact with chlorine

gas generates a flow of current that is instantly measured & displayed on

electronic control unit. Operating ranges are 0 – 2 ppm & 0 – 20 ppm.

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CONTROLS FOR CHLORINE LEAK

ENGINEERING CONTROLS a. Local exhaust ventilation system should be provided.

b. Proper access for maintenance and inspection

c. The storage shall be preferably located in open air.

d. Online monitoring devise (chlorine monitors) shall be installed in storage area

to get early warning alarm.

e. The low lying areas, trenches and drains near storage / handling areas shall be

avoided.

f. Periodic & regular inspection to detect corrosion

g. The tonner / cylinder storage area shall be located such that there is no air

intake for the ventilation system of buildings like control rooms etc & fumes

can spread to other areas.

h. Care to be taken against possible damage from flooding

i. Minimum distance 25 m from public roads and main railway lines

j. Provision of emergency lighting

k. Adequate storage space for emergency equipment (gas canisters, breathing air

sets, & other PPE’s) should be provided in a safe location to be readily

available.

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ADMINISTRATIVE CONTROLS

a. Operator selection: Trained operator should be deployed.

b. Operating instructions: Detailed operating instructions and procedure for

unloading the tonner and use of Cl2 shall be displayed in operating area.

c. Training: Periodic training should be conducted for both new and old

employees to keep them conscious and informed of the hazards. Periodic

emergency exercises and instruction regarding location, purpose and use of

personal protective equipment, safety showers, eye fountains, chlorine

emergency kit, first aid box, etc. be a part of periodic training. They should

be told to report to proper authorities immediately in case of any leakage for

abnormal condition.

d. Monitoring & Surveillance: Containers, piping and equipment should be

checked for leaks daily. If a leak is detected it should be reported and

immediate steps taken to correct the conditions.

e. Availability of emergency equipments: Eye wash fountain cum safety

shower, BA set & Cl2 emergency kit shall be available promptly

f. Pre-placement medical examination: It is recommended for all new entrants

and follow-up medical examinations at suitable intervals for all workers

handling chlorine

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EMERGENCY MEASURES

General — wherever chlorine is handled a potential risk is involved and a serious

emergency might suddenly and unexpectedly occur. Emergency situations should

be anticipated, emergency action plans should be established and persons trained

to counteract emergencies, if any.

Handling Leaks — Chlorine leaks always get worse unless they are corrected

promptly. Chlorine leaks should be investigated by authorized, trained personnel

equipped with suitable gas masks. If the leak is extensive an effort should be made

to warn all persons in the path of the gas. Chlorine is heavier than air; therefore

persons should be instructed to keep above and upwind or perpendicular to wind

direction prevailing.

a. Water shall never be used on a chlorine leak as it always makes the leak worse

due to the corrosive effect. In addition, heat supplied by even the coldest water

to a leaking container causes liquid chlorine to evaporate faster. A leaking

container shall not be immersed or thrown into a body of water as the leak will

be aggravated due to the corrosive effect and the container may float when

partially full, allowing gas evolution and dispersion at the surface.

b. Equipment and Piping Leaks — If a leak occurs in equipment in which chlorine

is being used, the supply of chlorine shall be shut off and chlorine which is

under pressure at the leak shall be disposed off safely.

c. Leaks around valve stems usually may be stopped by tightening the packing nut

or gland. If this does not stop the leak, the container valve shall be closed and

the chlorine, which is under pressure in the outlet piping, shall be disposed off.

If a container valve does not shut off tight, the outlet cap or plug should be

applied. In case of a valve leak on a ton-container, the container shall be rolled

so that the valves are in a vertical plane with the leaking valve on top; so that

gaseous chlorine leaks & not the liquid.

d. If practical, the pressure in the container should be reduced by removing the

chlorine as gas (not as liquid) to process or a disposal system. In some cases it

25

may be desirable to move the container to an isolated spot where it will do the

least harm.

e. In case of chlorine leaks all exhaust mechanisms should be turned on

immediately. BA sets & other PPEs should be located outside the probable area

of contamination so that it will be possible to reach them in emergency.

f. As a regular part of chlorine storage and use, provisions shall be made for

emergency disposal of chlorine from leaking cylinders or ton-containers. One

vessel should always be kept empty as to allow transfer the content in case of

emergency.

i) Chlorine may be absorbed in solutions of caustic soda or soda ash, or in

agitated hydrated-lime slurries. Caustic soda is recommended as it absorbs

chlorine more readily.

ii) A suitable tank to hold the solution should be provided in a convenient

location. Chlorine gas should be passed into the solution through an iron

pipe or rubber hose properly weighted to hold it under the surface; the

container should not be immersed.

g. Display of MSDS will help as ready reckoner during emergency.

h. Chlorine Emergency Kits — It is advisable for the consumers to purchase

chlorine leak arrest kit and to train employees in their use. These kits may be

used to stop most of the leaks in a chlorine cylinder, ton container etc. (Ref.

annexure)

i). In Case of Fire — In the event of fire, chlorine containers should be moved

from the fire zone immediately. If chlorine containers cannot be moved, water

should be applied to cool them provided no chlorine is escaping.

26

FIRST-AID

General — All minor accidents and also report any sickness should be reported.

Any one overcome by or seriously exposed to chlorine gas should be removed at

once to uncontaminated area.

Inhalation — If breathing has not ceased, the patient should be placed on his

back, with head and back elevated, and kept warm, using blankets, if necessary.

Rest is essential.

i. If breathing apparently has ceased, artificial respiration shall be started

immediately. A physician shall be called immediately. If oxygen-inhalation

apparatus is available, oxygen should be administered immediately.

ii. Adequate oxygenation should be maintained, and any drugs for shock treatment

should be given only by a physician. Milk may be given in mild cases as a

relief from throat irritation. Nothing should ever be given by mouth to an

unconscious patient.

iii. Skin and Clothing — If liquid chlorine or chlorinated water has contaminated

skin or clothing, the emergency shower shall be used immediately. Skin areas

should be washed with large quantities of soap and water. No attempt shall be

made to neutralize chlorine with chemicals. No ointment shall be applied for 24

hours. Contaminated clothing should be removed immediately.

iv. Eyes— If eyes have been affected with liquid chlorine or high concentrations

of chlorine gas, they shall be flushed immediately with running water for at

least 15 minutes. (No attempt shall be made to neutralize with chemicals). No

oils or oily ointment should be used unless prescribed by an eye specialist.

v. Ingestion — The swallowing of liquid chlorine is extremely unlikely. However,

if a person has swallowed chlorine and is conscious, he should immediately be

made to drink copious amounts of lime water, milk of magnesia, or fresh water

if the others are not readily available. Sodium bicarbonate shall not be given.

The victim may be expected to vomit spontaneously, but no attempt should be

made to induce vomiting. A physician shall be called immediately.

27

First-Aid Equipment — All employees should be given comprehensive

instructions on the use of first-aid equipment mentioned below;

a. Eye wash fountain cum safety shower should be available at convenient

locations and they should be properly maintained.

b. Oxygen administration apparatus should be available in the central control

room, first-aid center. Trained persons shall be available all the time.

c First-aid boxes — Distinctly marked ‘First-Aid’ boxes shall be provided in

readily accessible positions like control rooms. These should not contain

anything except the prescribed medical appliances and requisites. A list of

contents should be fixed inside the box. A sufficient number of persons should

be imparted effective training in First-Aid.

General Principle

· All individuals who have developed symptoms as a result of an acute

overexposure to chlorine gas by inhalation should be placed under the

supervision of qualified health care personnel.

· There is no known specific antidote for acute chlorine exposure. Prompt medical

assessment and supportive measures are necessary to obtain good therapeutic

results.

28

Case study No.1

Chlorine Tonner Explosion

In a large factory producing Chlorine, Hydrogen, Caustic lye, Caustic Flakes,

Chloroform, Methylene etc. an accident of Chlorine Tonner Explosion took place

on 5th Sept 2002 at about 11 A.M.

Incident: In the filling section of the plant, liquid chlorine is filled at 11 kg./cm2

pressure. Filling was started in tonner no. GC 1606 88. This tonner had come from

Anugrah In Organic, which manufactures monochloro acetic acid. After sometime,

operation checked the temperature of the tonner from the outside, with his hands.

Operator felt it hot. He immediately stopped the filling operator and tonner was

removed from the filling line and with help of crane, he took it to the neutralization

bay for neutralization purpose. While taking to the neutralization bay, the tonner

exploded on the hanging position.

Cause of the incident: Due to the chemical reaction between chemicals inside the

tonner pressure inside the tonner tremendously increased and exploded the tonner

in the hanging position and there was liquid spray splash but no chlorine leakage.

The spray contained mono chloro acitic acid.

Area & persons affected: Due to the explosion, atmosphere in the plant became

fumming and because of the splash of the chemicals which were inside the tonner,

24 workers who were working of the filling section, nearby and passing by this

area were affected and out there workers, 4 workers expired.

Action to be taken for non repetition of such incident:

• Empty chlorine tonner received back, be sent to tonner preparation section for

evacuation of gases of tonner, valves / spindle checking.

• Before filling and during filling, weight of tonner, physical condition and

temperature be kept under watch.

• Use of BA set or face mask while filling.

• Chlorine monitors should be installed at different locations.

29

Case Study No.2

In a public water works, chlorine gas leaked from Chlorine tonner on 7-10-2003 at

17.45 hrs.

Incident: Chlorine gas leaked at about 17.45 hrs. Contractor Supervisor was on the

job noticed the leakage. He immediately informed the Supervisor of filtration Plant.

He rushed to the site at 18.00 hrs. And checked the tonner, connection etc. and

noticed the leakages of Chlorine gas from valve spindle. He immediately called the

fire brigade. Fire-brigade personnel came to site and tried to close the leakages of

Chlorine gas. However it could not be controlled. At last, they pushed the toner in

the alkali pit. At night (01-30 hrs.) after ensuring that chlorine gas has been emptied

out from the tonner; the tonner was taken out from the pit and placed at a safe

place.

Cause of the incident: Leakage of chlorine gas from valve spindle of the tonner.

Area and persons affected: People residing in nearby area were affected due to

leakage of chlorine gas and 74 people were hospitalized.

Action taken for non-repetition of such incidents:

1. Emergency kit for chlorine shall be provided and kept.

2. FRP hood shall be provided around chlorine tonner to restrict leaked gas from

spreading around.

3. Two nos. of self-breathing apparatus shall be provided and workers shall be

given periodical training to handle it safely in case of emergency.

Case Study No.3

At Madras on 9th February 1971

Incident: Chlorine from a cylinder was used for chlorination of swimming pool

water regularly in a college campus.

Cause & consequences: Cylinder was found to have two holes on the body

Area and persons affected: 200 students got affected

30

Case Study No.4

At Bombay on 13th December 1973

Incident: Two chlorine cylinders kept inside the heap of scrap material in an

abandoned chemical factory released the gas when involved in a fire.

Cause & consequences: Improper storage & bursting of cylinders due to fire.

Area and persons affected: 7 fireman and 89 residents of surrounding locality got

affected.

Case Study No.5

At Madras on 22nd March 1974

Incident: Valve of one of the chlorine cylinder got damaged while unloading from

the truck.

Cause & consequences: Cylinder’s valve cap was not provided.

Area and persons affected: 1 killed and 41 injured.

Case Study No.6

At Aleppy, Kerla, on 23rd April 1981

Incident: A Czechoslovakian cylinder meant for CO2 after getting proper

clearance but one of its valves was not changed to suit chlorine. When gas started

leaking through it, the cylinder was shifted to drain duct so that the gas will get

dissolved in water. Gas gushed out from one hole in the cycle neck and spread to

nearby ladies hostel.

Cause & consequences: Cylinder was kept in water; the body got corroded very

fast thus causing heavy leakage. .

Area and persons affected: 3 killed and 154 injured.

31

Case Study No.7

At Kolkatta 16th February 1990.

Incident: Chlorine from a 100 kg cylinder kept in a small factory in a congested

locality started leaking during mid-night and spread over the nearby area.

Cause & consequences: Cylinder was badly corroded..

Area and persons affected: 04 killed and 87 injured.

LOCAL EXHAUST VENTILATION

LIST OF SUPPLIERS

S.

No.

Name of supplier,

M/s

Address of supplier Phone Number

1 Chlorination

Systems

Engineers & Manufacturers, Unit

No. 4104, 4th Floor,

Bhandup Industrial Estate,

Pannalal Compound,

Bhandup (West),

Mumbai – 400078

022 - 25967882

2 S M Polymers Office – 4B/8, Om Sudama Arts,

Kalwa, Thane - 400605

022 - 25368908

3 Banaco

Technologies Pvt.

Ltd.

A/702, Sagittarius, Divya Park,

Off Marve Road, Malad (West),

Mumbai - 400095

022 - 39516813

4 Pennwalt Limited D-221, M.I.D.C., T.T.C, Thane

Belapur Road, Nerul,

Navi Mumbai – 400706.

022 - 27632503

32

Annexure-I

VAPOUR PRESSURE CURVE OF CHLORINE

33

Annexure-II

34

Annexure-III

USE OF CHLORINE EMERGENCY KIT

35

Annexure-V

USE OF CHLORINE EMERGENCY KIT

36

Annexure-VI

BAROMETRIC LEG

37

Annexure-VII

LOCAL EXHAUST VENTILATION