How do fire extinguishers work?
One of them is a solid, liquid, or gas substance for fighting the fire. The other one is called a propellant and is a pressurized chemical that makes the fire-fighting substance come out when you press the extinguisher handle. Next time you see a fire extinguisher, take a good look. Have you noticed that fire extinguishers are always really strong steel canisters? That because the propellant is stored inside at a high pressure. Strong canisters are needed to stop the extinguishers exploding!
How do you put out a fire?
A fire can burn when all these things are present; it will stop when at least one of them is removed. As any fire-fighter will tell you, putting out a fire involves breaking the fire triangle —which means removing either the fuel, the heat, or the oxygen. Suppose a fire breaks out in a pan on top of your cooker, the first thing you normally do is switch off the heat. If that doesn't work, you might soak a towel with water and place it very carefully over the pan (or, better still, use a fire blanket ). The towel is designed to block off the supply of oxygen to the fire (the water stops the towel from catching fire and making things worse). Every fire-fighting technique you can think of involves removing heat, oxygen, or fuel—sometimes more than one of those things at the same time. Fire extinguishers work by removing heat, air, or both.
What is the white cloud from the horn?
The white cloud coming from the horn is formed when liquid carbon dioxide stored under pressure in the extinguisher turns back to a freezing cold gas. Photo by Sgt. Jeremiah Johnson courtesy of US Army.
Why do you use a towel when you are on fire?
The towel is designed to block off the supply of oxygen to the fire (the water stops the towel from catching fire and making things worse). Every fire-fighting technique you can think of involves removing heat, oxygen, or fuel—sometimes more than one of those things at the same time.
How many types of fire extinguishers are there?
There are four main types of extinguishers and they work in slightly different ways:
Why is it important to use the right fire extinguisher?
It's important always to use the right extinguisher for the fire. Using the wrong extinguisher can put your life in danger and make the fire worse. For example, you must never use water extinguishers on electrical fires because you could electrocute yourself and the people nearby. If you're in the slightest doubt about tackling a fire, leave it alone and get yourself to safety. Once you've done that, call the fire department.
Why is the design of a fire extinguisher's nozzle important?
One thing to note is that the design of a fire extinguisher's nozzle is as important as (often more important than) the rest of the mechanism, because how the extinguishing chemicals arrive at the fire is critical. That's why a lot of patents focus on the specifics of the nozzle.
How Do Fire Extinguishers Work?
Fires are chemical combustion reactions ignited in an atmosphere with oxygen and a fuel source. Fires produce extreme heat and can spread easily when near combustible materials such as wood, paper, rubbish, or grease, among others.
How Does a C02 Fire Extinguisher Work?
A C02 fire extinguisher works similar to other types, except for a few differences. Out of the handle is attached a large, cone-shaped horn, usually black in color. This allows the carbon dioxide gas to expel, then expand, and turn into a mixture of gas and a frozen snow-like substance.
How Does a Water Fire Extinguisher Work?
Water fire extinguishers are very common and works similar to a dry powder type. It contains a small gas compartment inside the metal cylinder which forces out the water through the nozzle when it is released. The stored gas is usually carbon dioxide or nitrogen.
How Does a Foam Fire Extinguisher Work?
Foam fire extinguishers, also called aqueous film-forming foam or AFFFs, have the added benefit of producing more sprayable contents compared to a similar sized water fire extinguisher. The foam mixture produces more spray quantity than water alone because it expands when mixed, which makes these very effective fire extinguishers.
How Does a Fire Extinguisher Gauge Work?
Fire extinguisher gauges are included on fire extinguishers to show how much pressure is stored within the container. If the pressure drops too low, the extinguisher will not have enough to force the contents out.
To Close
Fire extinguishers are very effective at what they do and are designed as such. However, they must be kept functioning properly over time so they can be relied upon when you really need them. So, make sure your fire extinguishers are inspected in regular intervals.
Why is a fire extinguisher used in restaurants?
This sort of fire extinguisher is common in restaurants because it won't contaminate the cooking equipment or food. Advertisement.
How to remove oxygen from a fire?
To remove oxygen, you can smother the fire so it is not exposed to air. One way to smother a small fire is to cover it with a heavy blanket. Another way is to dump nonflammable material, such as sand or baking soda on top of it. Removing the fuel is the most difficult approach for most fires.
What happens when a decomposed gas is hot enough?
When the gas is hot enough, the compound molecules break apart, and the atoms recombine with the oxygen to form water, carbon dioxide and other products. The gases, which rise through the air, make up the flame.
How does wood burn?
Here's the sequence of events in a typical wood fire: 1 Something heats the wood to very high temperatures. This could be any number of things -- focused light, friction, something else that is already burning. 2 When the wood reaches about 500 degrees Fahrenheit (260 degrees Celsius), the heat decomposes some of the cellulose material that makes up the wood. 3 Decomposed material is released as volatile gases, typically a compound of hydrogen, carbon and oxygen. 4 When the gas is hot enough, the compound molecules break apart, and the atoms recombine with the oxygen to form water, carbon dioxide and other products. 5 The gases, which rise through the air, make up the flame. Carbon atoms rising in the flame emit light as they heat up. (Check out How Light Bulbs Work to find out why heated objects emit light.) 6 The heat of the flame keeps the fuel at the ignition temperature, so it continues to burn as long as there is fuel and oxygen.
What is the reaction between oxygen and fuel?
For the combustion reaction to take place, the fuel has to be heated to its ignition temperature. Fire is the result of a chemical combustion reaction, typically a reaction between oxygen in the atmosphere and some sort of fuel (wood or gasoline, for example).
How to put out a fire?
To put a fire out, you need to effectively remove one of these elements. The best way to remove heat is to dump water on the fire. This cools the fuel to below the ignition point, interrupting the combustion cycle. To remove oxygen, you can smother the fire so it is not exposed to air.
Why doesn't wood catch fire?
Of course, wood and gasoline don't spontaneously catch on fire just because they're surrounded by oxygen. For the combustion reaction to take place, the fuel has to be heated to its ignition temperature.. Here's the sequence of events in a typical wood fire: Something heats the wood to very high temperatures.
How Does a Dry Powder Chemical Extinguisher Work?
Each type of extinguisher works by attempting to remove one of the elements that are needed for a fire to flourish. Most ABE extinguishers are filled with monoammonium phosphate which has the ability to flow easily and melt so it continues to cover the flames as it moves over the fire. BE powder does not melt so it is ineffective against class A fires.
What is a dry chemical fire extinguisher?
A Dry Chemical Fire Extinguisher is the most common type used in Australia. It is also known as a DCP, BE, or ABE fire extinguisher. To determine if a fire extinguisher is a dry chemical type, one simply needs to look for the white band that runs around the tank.
What is a good heat shield?
Good Heat Shield - The discharge of dry powder creates an effective shield against radiated heat. In cases where large quantities of powder are discharged, this has the potential to shield surrounding structures and personnel from the damaging effects of the fire. Wide Range Of Use – Dry powder extinguishers can be used on class A,B and C Fires. ...
What is quick knockdown powder?
Quick Knockdown - Dry powder , when correctly applied and at the required application rate, has the ability to ensure an initial quick knockdown of the fire.
What are the problems with dry powder?
Visibility Problems - The application of dry powder and generation of a dense powder cloud will dramatically reduce the visibility of the operator so they may not be able to use vision to judge the effectiveness of the powder on the fire or may jeopardise escape in a fire.
What temperature to use for fire extinguisher?
Wide Range Of Use – Dry powder extinguishers can be used on class A,B and C Fires. Wide Temperature Range – Typically can be used between -20oc to +60oc. Mass for mass the most effective fire-fighting medium.
Where is the white band on a fire extinguisher?
DCP fire extinguishers are easily distinguishable by the white band that is around the fire extinguisher cylinder near the top and if installed in a building they should also be identified by what is known as a description sign, which describes what fires the fire extinguisher can and cannot be used for.
