Industrial Hazards and Its types (Basic Chemical Engineering)
Workers in a factory, a manufacturing plant or a chemical plant remain exposed to moving conveyers, machines, dangerous chemicals, heat, pressures, high electric fields, accelerating objects and other sources of hazards.
If workers are not protected from these hazards, there are chances of incidents to take place, which may result from a simple injury to death of a person.
Types of Hazards in Industry
Heat and Temperature
Sources of heat: boilers, kilns, incinerators, evaporators and cryogenic facilities.
High and lower temperatures, heat and cold can directly lead to sources of injuries to personnel and also may damage the equipment.
The immediate means by which the temperature and heat can injure the personnel is through burns, which can injure the skin and muscles as well as other tissues below the skin.
The same degrees of exposure may produce different effects, depending on the susceptibility of the person exposed.
High and low temperatures affect the personnel’s performance.
Long exposure to high temperatures does affect the human performance.
The effects of heat and temperature do not only affect the workers but also the equipment's and the process. For example, certain chemicals have a low boiling point and increased temperature can cause an explosion.
Pressure Hazards
Pressure hazard is quite frequently reported in process facilities and is caused due to over pressurization of the process equipment.
On release this pressure energy produce shock waves accompanied with fire (in case of flammable chemicals).
This over pressurization may be due to various reasons, the proposed facility, vent sizing setup, over pressurization mechanism under different condition and design of pressure relief system to prevent accident.
It is also commonly and mistakenly believed that injury and damage will result only from high pressures.
Electrical Hazards
Electrical power is beneficial and at the same time it is hazardous if not properly used. The hazards involved are mainly:
Shock to personnel
Short circuiting and overheating
Ignition of combustible materials
Electrical explosions
Inadvertent activation of equipment
Electromagnetic effects on equipment's and personnel.
Mechanical Hazards
Most of the injuries in industrial plants are originally from mechanical causes.
These industrial plants have belt-driven rotating equipment, open geared power-presses, power hammers, cutter conveyers, kilns and incinerators.
These different kinds of mechanical equipment are used in industrial plants and each has its own mechanical hazards including cutting, tearing and breaking.
Toxic Materials
Highly reactive chemicals are being used more frequently in industries, agriculture, research and defense.
Many of these chemicals are found to be carcinogenic, teratogenic and a cause of long lasting injuries.
There is a need to understand the ways by which these chemicals enter the human body and their physiological effects to the tissues. The preventive measures should be exercised to avoid this absorption.
A material is considered toxic when a small quantity will cause injuries to the body of an organism. Almost all materials are injurious to health but at different levels.
The oxygen we breathe can be dangerous if taken at 100% without dilution.
The nitrogen and carbon dioxide can b dangerous at high concentrations although they are present in the air and lungs.
The concentration or the toxicity level of the substance is not the only factor of a toxic chemical. The susceptibility of the human body to toxic chemicals and their concentrations also a major factor.
The other factors, which affect the severity of the injury, the concentration, duration of exposure, the route, etc.
The toxic materials may be solid, liquid or gas. The solid toxic materials are radioactive substances and metals such as Pd, Cd, As, Cr, Al and others in various forms.
The chemicals are mostly in liquid and gaseous forms. For example, diethyl bromide, chlorofluoro carbons (CFCs), trichlorethane (choloroform) or trichloromethane are liquids while phosgene, chlorine, carbon monoxide, hydrogen cyanide and isocyanate are gases.
What happens in an industrial plant when a leak of some toxic gases like isocyanate, ethane or others occurs?
The concentration of these gases in air increases while the concentration of oxygen decreases.
The worker feels suffocation or asphyxia.
The concentration of carbon dioxide increases which lowers further the concentration of oxygen.
What happens in an industrial plant when a leak of some toxic gases like isocyanate, ethane or others occurs?
The worker undergoes a condition of hypoxia (hypo: below; oxia: oxygen).
The effect of hypoxia includes loss in perception, decrease in the brain activity, unconsciousness, and deep breathing.
It may lead to irreversible damage to brain, paralysis and ultimately death.
It may also cause the inflammation of skin, eyes, and respiratory tracts.
Some chemicals like nitrates, nitrites or other oxidizing agents are also harmful to the human body.
Some chemicals are carcinogenic (cancer producing). They are eliminated or replaced by non carcinogenic chemicals.
Asbestos is a particulate matter that causes cancer of lungs, rectum and stomach. OSHA has imposed a ban on zero fiber of particulate matter in the working environment.
Ammonia, acrolein, hydrofluoric acid, and asbestos can cause injuries to the upper respiratory tract, while chlorine, fluorine, ozone, nitric acid and nitrogen tetroxide affect the lower portion.
All industrial plants are obligated to observe criteria given in OSHA standards, which include the exposure to different chemicals and their threshold limit for industrial workers.
Personnel Protective Equipment (PPE) must be used for protection from toxic gases and vapors.
Safety respiratory protective equipment is required for normal hazardous operations like working in a spray painting plant, production and utilization of toxic chemicals.
Fire and Explosion
Fire and explosion are the common incidents in many chemical industries.
A fuel, an oxidizer and a source of ignition are required to start a fire. However, fire and explosion take place only when there are appropriate conditions for it.
Many types of fuel and oxidizers are available in any industry. There are three types of fuel. They are mainly solids, liquids or gases.
The chemicals that are used as cleaning agents or solvents act as fuels. Lubricants, coatings, paints, industrial chemicals, refrigerants, hydraulic fluids, polymer plastics, and paper wood cartons are potential fuels.
The next element for fire is an oxidizer. The most common oxidizer is the oxygen in air, which helps in oxidizing the fuel. Pure oxygen is a strong oxidizer.
Sometimes a chemical can be self ignited in the presence of an oxidizer.
For example, white phosphorus catches fires as soon as it comes into contact with air.
Fluorine is another strong oxidizer. It can react with moisture in air and catch fire. It is normally used diluted with nitrogen.
These oxidizers should be handled with care and their contact with fuel should be avoided.
The source of ignition consists of materials that may initiate a fire on friction. The igniter may be sunlight, or an electrical spark.
The common sources of electrical ignition in an industrial plant are the sparks of the electric motors, generators or electrical short circuits, etc.
The fires can have tremendous effects on human live and the immediate surroundings and even on the environment.
Fire produces carbon monoxide, carbon dioxide, solid carbon particles, and smoke. Death may occur as the concentration of the oxygen in air decreases in case of fire.
In any industrial plant, there are devices installed to detect any kind of fire, smoke, or heat.
The suppression of the increasing fire can be carried out by various methods.
The very first method is the isolation of the fire which means to cut the supply of fuel to the fire.
Fire suppression can also be achieved by blanketing a fire or by covering it with inert solid, foam, thickened water or cover it with nonflammable gas such as CO2.
The other available method is the dilution of the fuel, if it is a liquid fuel, by adding noncombustible liquid into it and, if it is a gas, by adding nonflammable gas.
Fire is a chain process. It can be stopped by breaking this chain.
When fire is ignited due to fuel and there is no electrical hazard nearby, water is used as a fire suppressant.
Sometimes thickening agents are added to the water to increase the residence time of water and its effectiveness. The thickening agents such as clays, gums, and sodium and calcium borates are used in forest fires.
Gas extinguishers may be used for enclosed spaces. Carbon dioxide (CO2) is widely used as a fire extinguisher. When carbon dioxide is sprayed on fire it emerges as snow and lowers the temperature.
Halogenated hydrocarbons act solely by inhibiting chain reactions. The less reactive would be the best fire extinguisher. However, the problem with these halogenated compounds is their toxicity which limits their use.
Foams are also used as fire suppressants. They suppress fire by cooling, blanketing, and sealing the burning fuel from the surrounding atmosphere.
Solid extinguishers such as sand or clay are also used to cover the oil or greases under fire.
Sodium and potassium bicarbonate are also use as solid extinguishers for liquid fuel.
Fire extinguishers are available which work automatically. They sense temperature, gas or fumes and start sprinkling the extinguishing materials (CO2 or others).
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