What Is The Temperature Of Fire? How Hot Does It Get? - SConFIRE

Fire from a lit match will often be around 1,100°F but there will still be slightly different temperatures around different parts of the flame.

It’s also worth noting that different materials can produce different types of flame and, therefore, different temperatures.

In this guide, we’ll be explaining everything you need to know about fire, how different materials can affect it and how hot it can possibly get.

What Is Fire?

Before we find out how hot different fires can get, let’s first take a look at what fire is and how it works. Don’t worry, we won’t be getting too scientific!

Fire is a simple chemical reaction that takes place between three different things: fuel, oxygen and heat. These three elements are known as the fire triangle and flames can not be created if even one of them isn't present.

Let’s look at the example of a simple match and find out how it uses the fire triangle to produce a flame:

• Fuel - This is the matchstick itself. The wood itself on the stem and the chemically formed head of the match are what provide fuel for the fire to burn.
• Oxygen - Quite simply, the air around the match is what provides it with enough oxygen to burn. Whilst you probably won’t find yourself in this situation, it would be impossible to light a match in space, as there would be no oxygen.
• Heat - Heat is generated when you strike the match against the side of the box. This motion creates friction, which provides enough heat for the head of the match to burst into flame.

Of course, the fuel and heat source can be different under different circumstances. However, these three principles will always remain the same when it comes to creating fire.

Once a flame has been produced (this is known as the ignition process), it will often continue to burn on its own, using the fuel source as it does so. The fire will then produce its own heat and can be used to transfer heat to other things, such as a stove or a cigarette.

Different Types Of Flame

As we said before, the source material used to create fire will have an impact on the size and color of the flame. In this section, we’ll take a closer look at these properties and how they affect the temperature of a fire.

Size

Quite simply, the size of a flame will not affect how hot a fire will burn. As long as the source materials are the same, a fire will reach the same temperature when it is a few inches tall as it will when it fills an entire room.

One thing that size does affect is how well a fire can transfer heat to other fuel sources. For example, a house fire often begins as a single, small flame from a stovetop in a kitchen.

However, the flame grows bigger when it comes into contact with other materials in the kitchen, such as food and furniture. This increases its size and allows it to spread further and grow bigger.

Color

On the other hand, the color of a flame does actually indicate how hot it might be. The best way to think about it is; the hotter a flame is, the lighter its color will be.

For example, a dark red or orange flame will often be around 1,000°F-1,500°F. Alternatively, the brightest white flame will usually be as hot as 2,300°F-2,700°F.

It should be noted, though, that the hottest flames of all are usually a blue color. This might seem a bit counterintuitive because blue is a color we often associate with cold.

However, if you’ve ever used a bunsen burner in a science class at school, you will probably have been taught to heat things on a blue flame because it’s the hottest.

A common, and pretty fun, experiment often done in high school science lessons is burning certain chemicals to produce a different colored flame. Below, is a list of the commonly used chemicals for this type of experiment:

• Potassium chloride - Purple
• Copper oxide - Blue
• Copper sulfate - Green
• Copper chloride - Light green
• Lithium chloride - Red
• Magnesium sulfate - White

In these cases, the chemical is used up as a source material for the fire pretty quickly. This means that the flame will only remain that color for a few seconds if only a gram or two of the chemical is used.

What’s The Hottest Part Of Fire?

You may already know that different parts of flame are hotter than others. Of course, with something like a barbecue or a log fire, temperatures will vary depending on how much fuel and space for oxygen there is at different parts of the fire.

However, when we talk about a single, solitary flame, from something like a match, the hottest part is always the base.

This is the part of the flame that is closest to the source material and, because it’s the hottest part, it will burn with a brighter (potentially blue) color than the rest of the flame.

As you move out away from the source material, the flame will be less hot and will therefore have a slightly darker color around the edges.

Temperatures of different types of flame

Now, let’s take a look at some of the different source materials that can be used to create fire and find out how hot each of them can get:

Candles

These are quite easy to determine the temperature of, because they only produce a single, isolated flame around a fixed point. Candles use a wick to hold the flame centrally, in one place.

However, the wax surrounding it actually acts as the fuel source for the flame. With certain candles, as the wax melts, it will produce a pleasant aroma throughout a room.

The hottest part of a candle can get up to around 2,500°F at the base of the flame, while the outer edges will be around 1,800°F.

Log Fires

A log fire in a home can create the perfect cozy atmosphere on a cold winter evening. People will often use some kind of fossil fuel based fire lighter to get the flames going but it’s the kindling and larger logs of wood that provide the fuel for the fire to keep burning.

Surprisingly, a log fire will actually burn colder than a candle, at around 1,100°F. However, log fires will often be inconsistent in temperature across the entirety of the flames.

Bonfires

Similar to a log fire that you might assemble in a fireplace in your home, with bonfires we’ll look at different source materials. They will mostly use wood, which brings fire to the same temperature as an indoor log fire.

However, some bonfires will also use charcoal and other fuels to make the flames hotter.

A bonfire will burn at around 2,000°F. That’s definitely hot enough to roast a marshmallow!

Bunsen Burners

We’ve already looked at bunsen burners a little in this article. Most bunsen burners will use a natural gas like methane to provide fuel for the flame. The gas is supplied at the bottom of the burner’s ‘chimney’ and ignited nearer the top, producing a thin, controlled cone of flame.

The hottest part of a bunsen burner’s flame is just above the tip of the primary flame. It will reach around 2,700°F at its peak.

Propane Torches

As you might have guessed, the fuel source for these implements is propane. Propane torches are used in construction and will often be employed to solder pipes together.

The reason they are so useful is because they are able to create a controlled, but very powerful flame that can transfer heat effectively to a desired material, such as copper.

The temperature of a flame produced by a propane torch is around 3,400°F, making it one of the hottest flames we’ve looked at!

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