580 likes | 623 Views
Fire Safety. Fire. Heat Light Burning ??????. Fire. Heat Light Burning Toxic gases Carbon monoxide. Fire Triangle. FUEL. OXYGEN. +. +. +. HEAT. Oxygen. Surrounding air Oxygen tanks/piped oxygen lines Oxidizing agents (self-producing). AIR. OXIDIZING AGENTS
E N D
Fire • Heat • Light • Burning • ??????
Fire • Heat • Light • Burning • Toxic gases • Carbon monoxide
Fire Triangle FUEL OXYGEN + + + HEAT
Oxygen • Surrounding air • Oxygen tanks/piped oxygen lines • Oxidizing agents (self-producing)
AIR OXIDIZING AGENTS (SELF-PRODUCING) COMPRESSED GASSES PIPED O2 Oxygen
Fuels • Gases • Liquids • Solids What really burns?
Flammable & Combustible Liquids • Flammable liquids have a flash point below 100oF • Combustible liquids have a flash point at or above 100oF Note: General Industrial Standard
Fire Tetrahedron • Oxygen • Fuel • Heat • Chain reaction
Open flame Hot surfaces Sparks Arcs (electrical energy) Arcs (static electricity) Friction Sun’s heat Compressing gases Heat Sources
Fire Tetrahedron • Oxygen • Fuel • Heat • Chain reaction
Fire Tetrahedron FUEL OXYGEN + + CHAIN REACTION + HEAT
Chain reaction • All areas of the fire tetrahedron must be present for a fire to start. • Some examples of no chain reaction: • A plug shorting out, producing a spark but not a fire. • Using alcohol to cook with (in most cases). • Dropping a lit cigarette on the counter top and picking it up.
Spontaneous combustion • Internal combustion arising with no external energy when all four parts of the tetrahedron are present. • All four parts of the fire tetrahedron might not physically appear to be present. • Heat is still being produced by a chemical reaction.
Heat transfer • Exothermic reaction • Conduction • Radiant heat • Direct • Convection
Heat transfer Exothermic reaction
2nd FIRE 1st FIRE Heat transfer Conduction
Heat transfer Radiant
EXIT Heat transfer DIRECT
Heat transfer Convection
1300 o F HIGH HEAT Ceiling Breathing Zone MEDIUM HEAT 600 o F 90 o F Floor LOW HEAT Thermal layering
Fire phases • Incipient: • The beginning phase of a fire. • In this phase, there is no need for special clothing, breathing apparatus, or evasive action.
Fire phases • Steady state (free burning): • The phase of the fire in which both oxygen and fuel are available, and the fire is spreading. • Hot gases and heated air are moving to the upper portions of the building, and the fire is approximately 1300oF.
Fire phases • Rollover • The process in which the super-heated vapors and gases reach their ignition point and start burning.
Fire phases • Flashover: • The phase of fire when everything in an area or room has reached a temperature that gives off vapors. • All these vapors ignite at once.
Fire phases • Backdraft • When oxygen is reintroduced (either naturally or through improper ventilation) to the hot smoldering phase; all items ignite at once, causing an explosion.
Fire phases • Hot smoldering: • In this phase, the oxygen level has fallen to about 15%. • This causes the visible flames to go out and the materials to smolder. • This is usually a precondition to backdraft.
Extinguishing fires • Removing fuel • Another method for extinguishing a fire is to remove the source fuel.
Extinguishing fires • Cooling • Using water to absorb the heat of the fire, bringing the fire below its ignition point.
Extinguishing fires • Removing oxygen • Can be accomplished through the use of another gas, such as CO2 or nitrogen.
A SINGLE SPRINKLER HEAD BEING ACTIVATED FOR A SMALL FIRE
MORE THAN ONE SPRINKLER HEAD BEING ACTIVATED FOR A LARGE FIRE
Fire classes Combustible Material
Fire classes Liquids
Live Electrical Circuits NOTE: After the electricity is disconnected, the class changes to Class A. Fire classes
Fire classes Metals Metals
Fire classes • There is an additional fire class but this class is not stated in OSHA regulations • Class K • Burning food
Fire extinguisher ratings • Class A • Class B • Class C • Class D
Fire fighting • Should I do this or even try? ? ? ? ?
OXYGEN FUEL + + CHAIN REACTION + HEAT How to put a fire out? • Removing at least part of the fire tetrahedron.
How do I use a fire extinguisher? P Pull the safety pin. A Aim the hose or horn at the base of the fire. S Squeeze the carrying handle and the discharge handle together. S Sweep the nozzle from side to side.
PULL AIM P A S S SWEEP SQUEEZE
Priorities in emergency response • Self-protection • Co-worker health and safety • Aiding injured co-workers/protecting patients • Prevention of property damage