Fire and Electricity By Dr Ali Saleh Fire
Fire and Electricity By Dr. Ali Saleh
Fire • The fire triangle 1. Oxygen – air which contains 20% oxygen 2. Fuel – Flammable gases, liquids, solids 3. Ignition source – – – Hot surfaces Electrical equipment Static electricity Smoking materials Naked flame
Fire Development Stages • Incipient stage — No visible smoke, flame, or significant heat develops but a large amount of combustion particles is generated over time. (Ionization detectors) • Smoldering stage — the combustion particles increase until they become visible, a condition described as “smoke. ” No flame or significant heat has developed. (Photoelectric detectors)
Fire Development Stages • Flame stage — As the fire condition develops further, ignition occurs and flames start. The level of visible smoke decreases and the heat level increases. (Infrared Detectors) • Heat stage — At this point, large amounts of heat, flame, smoke, and toxic gases are produced. (Thermal detectors)
Fire risk assessment • Step 1: Identify the hazards within your premises • Step 2: Identify people at risk • Step 3: Evaluate, remove, reduce and protect from risk – – – – Replace highly flammable materials with less flammable ones Separate flammable materials from sources of ignition Nonor safe-smoking policy. Suitable fire exit doors Emergency lighting. Suitable fire-safety signs Training for your staff Maintain your fire safety systems.
Fire risk assessment • Step 4: Record, plan, instruct, inform and train • Step 5: Review
Fire Causes: • Rubbish • Smoking • Heaters • Electricity • Dangerous substances
Fire general precautions • Provide enough signed exits for everyone to get out easily. • Provide fire escape doors, which can be opened easily from the inside whenever anyone is on the premises. • Never wedge fire doors open – they are there to stop smoke and flames from spreading. • If you have a fire alarm, check regularly that it is working. • Provide enough properly serviced fire extinguishers of the right type.
Fire general precautions • Ensure that in accord with the Health and Safety (Safety Signs and Signals) Regulations, running person signs and direction arrows are correctly deployed. • Ensure everyone knows what to do in the event of a fire. • Ensure everyone knows how to raise the alarm and how to use the extinguishers.
Electricity Main hazards: • Live electrical parts • Fire from overheating or overloading • Explosion
Ensuring that the electrical system is safe • Damage to the cable covering (cuts, scratches, abrasions). • Damage to the plug. • Non standard joints such as taped joints in the cable. • Overheating, shown by burn marks or stains. • Evidence that the equipment has been used in unsuitable conditions such as a place that is wet or very dusty.
Ensuring that the electrical system is safe • The colored insulation of the internal wires showing. • The outer covering of the cable not being gripped at the point where it enters the equipment or the plug. • Loose parts. • Loose screws. • The outer casing of the equipment being damaged.
Dangers associated with electricity Shock: o Contacts both wires of an electrical circuit o Contacts one wire of an energized circuit and the ground o Contacts a “hot” metallic part that has become energized and the ground – Causes muscular spasm – Can interfere with the regular action of the heart and cause fibrillation of the heart muscles or complete cardiac arrest – Can cause respiratory failure
Dangers associated with electricity Burns and Other Injuries : – Three types of burns can result from shocks: • Electrical burns: current flowing through tissue or bone, which are damaged by the intense heat. • Thermal burns: skin comes into contact with the hot surfaces of overheated conductors or other energized parts. • Arc burns: caused by high temperatures near the body and are produced by an electrical arc or explosion.
Dangers associated with electricity Arc eyes: – From ultraviolet rays when looking at electric arc or welding flash – Symptoms like conjunctivitis – Temporary condition lasting three or four days – Does not affect contact lens Fire: – From electrical arc – Overloading of conductors – Discharge of static electricity
Welding Safety Welding Types: • Gas Welding: by directing a gas flame over the metals until a molten puddle is formed. • Arc Welding: by generating an electric arc between a covered metal electrode and the base metals • Oxygen and Arc Cutting: by using both gas flame and electric arc
Welding Safety • Proper personal protective equipments: Helmets, hand shields, goggles, and safety glasses. • Filter lenses and plates must meet the test for transmission of radiant energy. • Protect users from arc rays and from weld sparks. • Environment must be free of flammable substances. • Fire extinguishing equipment should be maintained.
Machine Safety and Guarding • Guard all point-of-operation exposures, such as blades, knives, and cutting heads. • Cover or guard power transmission exposures such as belts, pulleys, shaft, or gears. • Guard top, bottom, and backside exposures such as the underside of table saws. • When removing a guard, shut down the control switch, lock, and tag in the “OFF” position. • Affix guards to the machine. • If possible use a hinged type of guard to make maintenance or adjustments easier to perform.
Machine Safety and Guarding • Use personal protective equipment (e. g. eye or face protection). • Should not wear loose-fitting clothing, rings, bracelets, or other apparel that may become entangled in moving machinery. • Should not wear gloves when they could be caught in machinery. • Ear plugs or muffs should be worn around noisy machinery.
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