Presentation on theme: "B Phaneuf 2014. 2 The Fire Triangle In order to understand how fire extinguishers work, you first need to know a little bit about fire. Four things must."— Presentation transcript:
B Phaneuf 2014
2 The Fire Triangle In order to understand how fire extinguishers work, you first need to know a little bit about fire. Four things must be present at the same time in order to produce the fire: Enough Oxygen to sustain combustion, Enough Heat to raise the material to its ignition temperature, Some sort of Fuel or combustible materials. Then we have a Chemical, Exothermic Reaction that is fire.
Oxygen, Heat, and Fuel are frequently referred to as the “fire triangle.” Add in the fourth element, the Chemical Reaction, and you actually have a fire “tetrahedron.” The important thing to remember is: take any of these four things away, and you will not have a fire or the fire will be extinguished. Essentially, fire extinguishers put out fire by taking away one or more elements of the fire triangle/tetrahedron. Fire safety, at its most basic, is based upon the principle of keeping fuel sources and ignition sources separate. 3
Not all fires are the same, and they are classified according to the type of fuel that is burning. If you use the wrong type of fire extinguisher on the wrong class of fire you can, in fact, make matters worse. It is therefore very important to understand the different fire classifications. 4
wood cloth paper rubber many plastics solid combustible materials that are not metals gasoline oil grease tar oil-based paint lacquer flammable gases Acetone Any non-metal in a liquid state on fire. 5
6 energized electrical equipment As long as it’s plugged in, it would be considered a Class C fire. magnesium sodium potassium titanium zirconium other flammable metals Class D fires produce an intense flame that may be water reactive.
7 Class K Fires – Cooking Media Recognized by NFPA 10 Fires involving combustible vegetable or animal non- saturated cooking fats in commercial cooking equipment.
8 Water CO 2 Foam Dry Chemical FM-20 (takes the place of halon)
10 Class “A” fires only 2.5 gal. Water at psi (up to 1 minute discharge time) Has pressure gauge to allow visual capacity check ft. Maximum effective range Can be started and stopped as necessary Extinguishes by cooling burning material below the ignition point Pressurized Water
11 Class “B” or “C” fires lbs of CO 2 gas at psi (8-30 seconds discharge time) Has NO pressure gauge – capacity verified by weight 3-8 ft. maximum effective range Extinguishes by smothering burning materials Effectiveness decreases as temperature of burning material increases Carbon Dioxide (CO 2 ) All CO 2 extinguishers need to undergo hydrostatic testing and recharge every five (5) years.
12 Class “A”, “B”, or “C” fires lb dry chemical (ammonium phosphate) pressurized to psi by nitrogen gas (8-25 seconds discharge time Has pressure gauge to allow visual capacity check 5-20 ft. maximum effective range Extinguishes by smothering burning materials Multipurpose Dry Chemical These extinguishers are extremely effective at putting out a fire.
13 Class “D” combustible metal fires only 30 lb pressurized dry powder optimized for specific combustible metal (also available in bulk containers for hand scooping onto fire to extinguish) 6-8 ft. maximum effective range To activate, must first open nitrogen cylinder on back to pressurize body Extinguishes by smothering burning materials Combustible Metal
13 Fire extinguishers will have their rating (A,B,C, etcetera) displayed on the body of the cylinder. Some type A and B extinguishers also have numbers. The number in front of the “A” is the equivalent number of US gallons of water x 1.25 the contents represents. ( A 5A extinguisher would contain the equivalent suppressant of 6.25 US gallons of water) The number in front of the “C” represents how many square feet of coverage the unit contains.
14 Know department emergency procedures and evacuation routes. Know locations of extinguishers in your area and how to use them. Always sound the alarm regardless of fire size. Avoid smoky conditions. Ensure area is evacuated. Don’t attempt to fight unless: -alarm is sounded -fire is small and contained -you have safe egress route (can be reached without exposure to fire). -available extinguishers are rated for size and type of fire. If in doubt, get out!
15 However, before deciding to fight the fire, keep these rules in mind: Never fight a fire if: You don’t know what is burning. If you don’t know what is burning, you don’t know what type of extinguisher to use. Even if you have an ABC extinguisher, there may be something in the fire which is going to explode or produce highly toxic smoke. Chances are, you will know what’s burning, or at least have a pretty good idea, but if you don’t, let the Emergency Response Team handle it. Or...
16 The fire is spreading rapidly beyond the spot where it started. The time to use an extinguisher is in the incipient, or beginning stages of a fire. If the fire is already spreading quickly, it is best to simply evacuate the building, closing doors and windows behind you as you leave.
18 This will allow you to discharge the extinguisher. If you aim at the flames (which is frequently the temptation), the extinguishing agent will fly right through and do no good). You want to hit the fuel. This depresses a button that releases the pressurized extinguishing agent in the extinguisher. Until the fire is completely out. Start using the extinguisher from a safe distance away, then move forward. One the fire is out, keep an eye on the area in case it re-ignites. Just remember, always keep an exit at your back.
19 An AFFF (aqueous film forming agent) agent forms an aqueous film of the surface of hydrocarbon fuel. An alcohol-resistant concentrate (ARC) will form a polymeric membrane on a polar solvent fuel. Firefighting foam agents suppress fire by separating the fuel from the air (oxygen).
20 Depending upon the type of foam agent, this is done in several ways: Foam blankets and the fuel surface, smothering the fire and separating the flames from the fuel surface. The fuel is cooled by the water content of the foam. The foam blanket suppresses the release of flammable vapours that can mix with air.
Inspection An inspection is a "quick check" that an extinguisher is available and will operate. It is intended to give reasonable assurance that the fire extinguisher is fully charged and operable. This is done by verifying that it is in its designated place, that it has not been actuated or tampered with, and that there is no obvious or physical damage or condition to prevent its operation. Fire extinguishers should be inspected when they are initially placed in service and thereafter at 30- day intervals. They may require more frequent inspections if circumstances dictate. 21
Inspection Procedures: Located in designated place No obstruction to access or visibility Operating instructions on nameplate legible and facing outward Safety seals and tamper indicators not broken or missing. Fullness determined by weighing or "hefting". The pressure is at the recommended level. On extinguishers equipped with a gauge that means the needle should be in the green zone - not too high and not too low. Examination for obvious physical damage, corrosion, leakage, or clogged nozzle. There are no dents, leaks, rust, chemical deposits and other signs of abuse/wear. Wipe off any corrosive chemicals, oil, gunk etc. that may have landed on the extinguisher. Pressure gauge reading or indicator in the operable range or position. Note: Internal pressure is affected by temperature. 22
Dry Chemical Stored-Pressure Water Foam (FFFP)Halon 1211 Monthly inspection (by user) Yearly maintenance 6-year maintenance Hydrostatic test (every 5 years) Foam replace (every 3 years) 6-year maintenance Hydrostatic test (every 12 years) Hydrostatic test (every 5 years) Hydrostatic test (every 12 years) 24
When a fuel and an oxidizer react so rapidly on being mixed at room temperature that combustion starts immediately without an outside ignition source. The term, hypergolic reaction, originated with rocket propellants. Similar chemical reactions have caused accidental fires in the oil and gas industry. 27
Summarize the most significant critical risk factors affecting fire and explosion hazards. Each one listed on the following page has a critical affect on fire and explosion safety and requires careful consideration in operational and control decisions. Because operation-specific variables make it impossible to prescribe controls that will work effectively in every circumstance, companies must do the homework necessary to evaluate whether or not planned control measures will be effective. If critical risk factors exist, a site-specific fire and explosion prevention plan may be required to effectively manage potential fire and explosion hazards. 28
1. Presence of liquid hydrocarbons and other flammable liquids 2. Presence of hydrogen sulphide (H2S) The introduction of air- oxygen into ‘systems’ containing H2S should be avoided altogether. 3. Addition of hydrocarbon-based workover fluids 4. Fluid mixtures with different chemical properties 5. Elevated operating pressures and temperatures 6. Potential for rapid pressure or temperature changes 7. Flowing explosive mixtures into ‘closed’ systems 8. Pre-existing trapped air 29
The regulations require employers to first try to eliminate hazards. If elimination is not possible, hazards should be controlled using one of the following options: Engineering controls Administrative controls Personal protective equipment A combination of controls. The options should be considered in the order listed. 30
There are three widely recognized types of hazard controls, each with different functions. They are listed in the order of their effectiveness, with engineering controls being more dependable than those that rely solely on human behaviour. 31
The objective of engineering controls is to eliminate or reduce the hazard. This is the preferred type of control whenever feasible. These controls relate to the design of the processes, equipment, and tools being used. They are the standards, specifications, and design criteria that apply to an operation. The basic functions engineering controls perform include: 32
Elimination: Designing equipment to minimize the release of hazardous substances. Substitution: Utilizing non-hydrocarbon drilling or workover fluids, where possible. Isolation: Enclosing equipment or adding emergency shutdowns to eliminate or reduce the amount of hazardous substances that will be released in the event of a failure. Ventilation: Providing mechanisms for exhausting hazardous substances from the work area. 33
Administrative controls address hazards through the development and application of suitable work systems. Their effectiveness depends on the integrity of the processes used to develop them, and their proper implementation and enforcement. Examples include: Work practices and procedures On-the-job training Worker selection and supervision 34
Protective equipment is “the last line of defense”. PPE does not control or prevent incidents; it will only protect workers from injury should an incident occur. Examples include: respiratory protective equipment hand and body protection including Fire Resistant Clothing (FRC), hearing protection, etc. 34
The safety of jobsite operation relies on effective communication of the hazards involved, and effective implementation of the steps required to eliminate or reduce those hazards. Those conveying such information are reminded that: Communication needs to be two-way. Communication should be documented (i.e. safety meeting summary). Communication needs to include factual information about: the planned operations, the hazards, and the steps required to eliminate or reduce the hazards. Communication between site personnel as activities progress is essential to keep the work on track according to the fire and explosion prevention plan. 37
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