CHEMICAL SAFETY

Dilip KumarO&M CHEMISTRY, NTPC Ltd, INDIA.

CLASSIFICATION OF HAZARDOUS CHEMICALS

CORROSIVE

A corrosive substance is one that will destroy or irreversibly damage another surface or substance with which it comes into contact.

Common types of corrosive substances

Strong acids: sulfuric acid, nitric acid and hydrochloric acid

Bases: sodium hydroxide & potassium hydroxide

DANGEROUS FOR ENVIRONMENT

Chemicals enter air as emissions and water as effluent. Industrial and motor vehicle emissions of nitrogen and sulphur oxides cause acid rain, which poisons fish and other aquatic organisms in rivers and lakes and affects the ability of soil to support plants. Carbon dioxide causes the greenhouse effect and climate change.

e.g., Hydrazene hydrate(N2H4), effluents from DM plant and main plant, emissions etc.

EXPLOSIVE

explosive, is a reactive substance that contains a great amount of potential energy that can produce an explosion if released suddenly, usually accompanied by the production of light, heat, sound, and pressure.A chemical explosive may consist of either a chemically pure compound, such as nitroglycerin, or a mixture of a fuel and an oxidizer, such as black powder or grain dust and air.(e.g., nitroglycerin, TNT, HMX, PETN, nitrocellulose)

TOXIC

Any chemical or mixture having capability to harm the environment, living being’s and to human health by any mode of exposure (if inhaled, swallowed, or absorbed through the skin) is termed as Toxic chemical.

e.g., Hydrazine

OXIDISING

oxidizing agent is a substance that is not necessarily combustible, but may, generally by yielding oxygen, cause or contribute to the combustion of other material.

e.g., Hydrogen peroxide, potassium dichromate.

HARMFUL

harmful substances as chemical substances, or biological agents, that are evidenced to cause harmful health effects. Harmful health effects include, but are not limited to, respiratory infections, skin rashes, burns and neurological damage.

HIGHLY FLAMMABLE

Substance which catches fire easily and burns rapidly. Liquids classified as flammable have flash points below 100 degrees Fahrenheit. At normal room temperature, flammable liquids are a much greater fire hazard than combustible liquids. Flammables include lacquer thinner, turpentine, acetone, ether, alcohol, gasoline, toluene and shellac. For example, ethyl ether (a common solvent) has a flash point (FP) of –49 deg. F and acetone has a FP of 0 deg. F.Combustibles: These liquids have vapors which burn when heated above 100 deg. F. Combustibles include fuel oil, kerosene, mineral oil and paints.

BULK HAZARDOUS CHEMICALS USED IN POWER PLANT

CHLORINE

SULFURIC ACID

HYDROCHLORIC ACID

CAUSTIC SODA

AMMONIA

HYDRAZENE

HYDROGEN

CHLORINE Chlorine is a toxic gas that irritates the

respiratory system. Because it is heavier than air, it tends to accumulate at the bottom of poorly ventilated spaces. Chlorine gas is a strong oxidizer, which may react with flammable materials.

Chlorine is detectable with measuring devices in concentrations of as low as 0.2 parts per million (ppm), and by smell at 3 ppm. Coughing and vomiting may occur at 30 ppm and lung damage at 60 ppm. About 1000 ppm can be fatal after a few deep breaths of the gas.[

CHLORINE Chlorine is used as a disinfectants in the

treatment of drinking water. This is a yellow-green gas that has a

distinctive strong odor, familiar to most from common Household bleach

CHLORINE

HEALTH EFFECT

Low concentrations: burning in the eyes, nose, and throat, redness in the face, sneezing, and coughing.

High concentrations: tightness in throat and chest - pulmonary edema. 1000 Parts Per Million (PPM) is rapidly fatal.

CHLORINE SAFETYChlorine need not be a serious hazard if the people working with it are properly trained in its handling.

The following are some guidelines for assuring the safe handling of chlorine.

1. Provide proper instruction and supervision to workers responsible for chlorine equipment.

CHLORINE SAFETY

2. Provide proper and approved self-contained breathing apparatus in areas where chlorine is stored or used.

3. Keep all breathing apparatus stored outside the chlorine area.

CHLORINE SAFETY4. Prepare escape plans from areas where there might be a chlorine emission. Remember to move uphill and upwind.

5. Never store combustible or flammable materials near chlorine containers.

6. Never apply heat directly to a chlorine container.

CHLORINE SAFETY

7. Never attempt to weld an “empty” chlorine pipe line without purging it with air first.

CHLORINE SAFETY8. Install safety showers and eye wash stations near chlorine equipment.

9. If there is a leak, at least two persons should make the repairs.

SAFETY SHOWER

10. Never spray water on leaking containers; it can make the leak worse.

11. When entering an equipment area, take shallow breaths until you are sure that there is not a chlorine gas leak.

CHLORINE SAFETY

12. Always keep ready Chlorine Leak Absorption System

CHLORINE SAFETY

SAFETY SIRENS

SIREN TYPE DURATION

Normal factory siren 1 minute continuous

In case of fire 5 sec on 2 sec off- 3times

In case of heavy chlorine leak 20 sec on 10 sec off-5times

All clear siren Continuous 3 minutes- once

FIRST AID INHALATION(1) Remove victim from contaminated area.(2) Keep victim warm in a reclined position with head and shoulders elevated.(3) Give artificial respiration, if necessary.(4) Give oxygen as soon as possible.(5) Call emergency personnel or a physician immediately.SKIN CONTACT(1) Shower victim, removing all contaminated clothing.(2) Wash affected area with soap and water.EYE CONTACT(1) Irrigate eyes with water for 15 minutes, holding eye lids wide apart.(2) Call emergency personnel or a physician immediately.(3) Irrigate for second 15-minute period if emergency personnel or physician is not immediately available.

SULFURIC ACIDUSE IN PLANT: Sulfuric acid in the treatment of condenser cooling water, lead storage batteries, and laboratory.

PROPERTIES: Sulfuric acid is a highly corrosive strong mineral acid. It is a colourless to slightly yellow viscous liquid and is soluble in water at all concentrations. The corrosiveness of it is mainly due to its strong acidic nature, strong dehydrating property and if concentrated strong oxidizing property.

SULFURIC ACIDHEALTH HAZARDS:it decomposes animals' muscles due to its acid hydrolysis with proteins (chemically known as amides) and fats (chemically known as ester), the corrosive properties of sulfuric acid are also accentuated by its highly exothermic reaction with water. Burns from sulfuric acid are potentially more serious than those of other comparable strong acids, as not only does it cause chemical burn but also secondary thermal burn which poses additional tissue damage due to the heat liberated by the reaction with water.

SULFURIC ACID FIRST AID/SAFETY

The standard first aid treatment for acid spills on the skin is, as for other corrosive agents, irrigation with large quantities of water. Washing is continued for at least ten to fifteen minutes to cool the tissue surrounding the acid burn and to prevent secondary damage. Contaminated clothing is removed immediately and the underlying skin washed thoroughly.

SULFURIC SAFETY

Use safety gloves, goggle and safety suit to prevent skin contact.

Keep ready safety shower to remove acid spillage.

HYDROCHLORIC ACID

USE IN PLANT: In the regeneration of cation exchange resin.

PROPERTIES: Hydrochloric acid is a solution of hydrogen chloride (HCl) in water, that is a highly corrosive, strong mineral acid with many industrial uses. It is found naturally in gastric acid.

HYDROCHLORIC ACID SAFETY

Concentrated hydrochloric acid (fuming hydrochloric acid) forms acidic mists. Both the mist and the solution have a corrosive effect on human tissue, with the potential to damage respiratory organs, eyes, skin, and intestines.

Personal protective equipment such as rubber or PVC gloves, protective eye goggles, and chemical-resistant clothing and shoes are used to minimize risks when handling hydrochloric acid.

CAUSTIC SODA (NaOH)

USE IN PLANT: it is used in the regeneration of anion exchange resins.

PROPERTIES: Pure sodium hydroxide is a white solid available in pellets, flakes, granules, and as a 50% saturated solution. It is hygroscopic and readily absorbs carbon dioxide from the air, and should be stored in an airtight container. It is very soluble in water and is highly exothermic when dissolved in water.

CAUSTIC SODA SAFETY

Solid sodium hydroxide or solutions of sodium hydroxide may cause chemical burns, permanent injury or scarring if it contacts unprotected human, or other animal, tissue. It may cause blindness if it contacts the eye. Protective equipment such as rubber gloves, safety clothing and eye protection should always be used when handling the material or its solutions.Dissolution of sodium hydroxide is highly exothermic, and the resulting heat may cause heat burns or ignite flammables.

CAUSTIC SODA SAFETY

AMMONIA

USE IN PLANT: In the treatment of feed water system to protect boiler and pre-boiler equipments from corrosion.

PROPERTIES: Ammonia is a colourless gas with a characteristic pungent smell.

AMMONIA SAFETY

The toxicity of ammonia solutions does not usually cause problems for humans and other mammals, as a specific mechanism exists to prevent its build-up in the bloodstream.

. Ammonia even at dilute concentrations is highly toxic to aquatic animals, and for this reason it is classified as dangerous for the environment.

Use protective eye goggles during handling of ammonia.

HYDRAZINE

USE IN PLANT: In the treatment of feed water system to protect boiler and pre-boiler equipments from oxygen attracts.

PROPERTIES: Hydrazine is a colourless flammable liquid with an ammonia-like odor. Hydrazine is highly toxic and dangerously unstable unless handled in solution.

HYDRAZINE SAFETY

Hydrazine is highly toxic and dangerously unstable, especially in the anhydrous form.

Symptoms of acute (short-term) exposure to high levels of hydrazine may include irritation of the eyes, nose, and throat, dizziness, headache, nausea, pulmonary edema, seizures, coma in humans. Acute exposure can also damage the liver, kidneys, and central nervous system. The liquid is corrosive and may produce dermatitis from skin contact in humans and animals. Effects to the lungs, liver, spleen, and thyroid have been reported in animals chronically exposed to hydrazine via inhalation.

HYDROGEN

USE IN PLANT: In the cooling of generator rotor due to its specific heat capacity being considerably higher than any other gas.

PROPERTIES: hydrogen is a colourless, odourless, non-metallic, tasteless, non-toxic, highly combustible diatomic gas with the molecular formula H2.

HYDROGEN SAFETY

Hydrogen poses a number of hazards to human safety, from potential detonations and fires when mixed with air to being an asphyxiant in its pure, oxygen-free form.

Hydrogen gas leaking into external air may spontaneously ignite. Moreover, hydrogen fire, while being extremely hot, is almost invisible, and thus can lead to accidental burns.

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