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What Is a Bunsen Burner? How It Works and How to Use One Safely
The Bunsen burner is the single most recognisable piece of equipment in a school science lab, and for good reason. It gives you a controllable, adjustable flame for heating, sterilising, and combustion experiments, using nothing more than gas and air.
It's also one of the few pieces of lab equipment where getting it wrong has real consequences, since you're working with an open flame. This guide covers how it actually works, the difference between its two flame types, how to light and use one safely, and where to buy one in South Africa.
What Is a Bunsen Burner?
A Bunsen burner is a small gas burner used in laboratories to provide a single, open flame for heating. It consists of a vertical metal tube (the barrel) sitting on a stable base, with a gas inlet at the bottom and an adjustable air hole partway up the tube. Turning a collar over the air hole controls how much air mixes with the gas before it burns, which is what lets you switch between a small, safe pilot flame and an intense heating flame.
The design was developed in 1854 to 1855 by the German chemist Robert Bunsen, working with Peter Desaga, the mechanic at the University of Heidelberg. Bunsen wanted a flame hot and clean enough for the spectral analysis work he was doing with physicist Gustav Kirchhoff, and the key idea was mixing the gas with air before ignition rather than at the point of the flame itself, an improvement on an earlier burner design by Michael Faraday. Bunsen and Desaga never patented it, which is a large part of why it spread to labs and schools worldwide.
Parts of a Bunsen Burner
- Base. A heavy, stable metal foot that keeps the burner upright and prevents tipping.
- Gas inlet. Where the rubber or silicone gas tubing connects, usually at the side or bottom of the base.
- Barrel. The vertical metal tube the flame burns at the top of.
- Air hole (collar). An opening near the base of the barrel, covered by a rotating metal collar. Turning the collar opens or closes the air hole, controlling the air-to-gas ratio.
- Gas tap or needle valve. Depending on the model, either a simple on-off valve or, on adjustable burners like the Teclu design, a fine needle valve that lets you control the gas flow rate itself, not just the air mixture.
How Does a Bunsen Burner Work?
Gas flows up through the barrel from the base. As it rises, it passes the air hole, where it mixes with a controllable amount of air before reaching the top and igniting. How much air gets into that mixture determines the type of flame you get, and that's really the entire working principle of the burner.
- With little or no air mixed in, the gas burns incompletely, producing a soft yellow, flickering flame.
- With plenty of air mixed in, the gas burns completely, producing a much hotter, near-invisible blue flame that roars audibly.
Safety Flame vs Roaring Flame
These two flame types have specific names and specific jobs. Knowing which one you're looking at matters for safety, not just for the experiment.
| Flame Type | Air Hole | Appearance | Approximate Temperature | When to Use It |
|---|---|---|---|---|
| Safety flame | Closed | Yellow, soft, flickering, visible in normal light | Roughly 300°C | When the burner is lit but not actively heating something |
| Roaring flame | Open | Blue, with a distinct inner cone, makes a rushing sound, hard to see in bright light | Up to roughly 1,500°C at the tip of the inner cone | Active heating only, never left unattended |
The yellow safety flame isn't just a weaker version of the blue flame for convenience. It's genuinely a safety feature: it's easy to see against a bright classroom background, which the nearly invisible blue flame is not. That's exactly why you switch to it whenever the burner is lit but you're not actively using the heat, such as while you set up glassware or read instructions.
How to Light a Bunsen Burner Safely: Step by Step
- Check the equipment first. Inspect the gas tubing for cracks or a loose connection at both ends before you do anything else.
- Tie back hair and secure loose clothing. Long hair, scarves, and loose sleeves are a genuine fire risk near an open flame.
- Put on safety goggles. Non-negotiable, every time, no exceptions.
- Place the burner on a heat-resistant mat. Never directly on a wooden bench.
- Close the air hole. Turn the collar so the air hole is fully closed. This gives you the safer yellow flame to start with.
- Light your igniter first, then open the gas. Hold a lit safety lighter or striker just above and to the side of the barrel opening, then turn on the gas supply. Never open the gas first and look for a lighter afterwards. A cloud of unlit gas building up is far more dangerous than the flame itself.
- Adjust the air hole once lit. If you need the hotter blue flame for active heating, gradually rotate the collar to open the air hole while watching the flame change.
- Return to the safety flame between uses. Close the air hole again as soon as you stop actively heating something, and never walk away from a lit burner in the roaring flame state.
- Turn off at the gas tap when finished. Shut off the gas supply completely once you're done, not just the burner's own valve if your setup has a separate tap.
Types of Bunsen Burners
Not every Bunsen burner is built the same way, and the right one depends on what you're using it for.
- Standard adjustable burner. The everyday classroom option, with a die-cast metal base and a cut-away valve for controlling gas flow. This is the burner most South African schools use day to day, typically run on LPG (bottled gas) rather than piped natural gas, since mains gas supply is uncommon here.
- Teclu burner. A variant that uses a needle valve for finer control of the gas flow itself, on top of the usual air hole adjustment. It's capable of a hotter, more precisely controlled flame, which makes it better suited to glassworking and soldering than everyday heating tasks.
Bunsen Burner Safety Rules
- Never leave a lit burner unattended, even on the safety flame.
- Keep the roaring flame for active heating only. Switch back to the safety flame the moment you're not using the heat directly.
- Keep flammable materials well away from the bench you're working on, including paper, hair, and loose clothing.
- Always light the igniter before opening the gas, never the other way around.
- Use a heat-resistant mat and a stand such as a tripod and gauze when heating anything above the flame, rather than holding it by hand.
- Know where the gas shut-off point is for your bench before you start, in case you need to cut the supply quickly.
- Report any smell of gas immediately and do not attempt to relight anything until the source has been checked.
Where Bunsen Burners Are Used in Real Life
- Education. Grade 8 to 12 science practicals covering combustion, heating, and flame tests, mapped to the CAPS curriculum.
- Microbiology. Flame sterilising inoculation loops and the necks of glass containers to maintain a sterile field.
- Glassblowing and glasswork. Hotter variants such as the Teclu burner are used to soften and shape glass tubing.
- Chemistry demonstrations. Flame tests for identifying metal ions by the colour they produce when heated.
- General lab heating. Any task needing a controllable, adjustable open flame rather than an electric hotplate.
Buy a Bunsen Burner in South Africa
SmartLabs supplies schools, universities, and industrial labs across South Africa with Bunsen burners and heating accessories. We dispatch nationwide from Johannesburg with fast, traceable delivery.
- Bunsen Burner, Adjustable, Cut Away Valve (LPG): the standard classroom option with a stable die-cast base.
- Bunsen Burner - Teclu: a hotter, needle-valve burner suited to glasswork and soldering.
- Clay Pipe Triangle: for supporting crucibles directly over the flame.
Need a quote for a school order or a custom volume? Contact our team and we'll come back to you the same business day.
Frequently Asked Questions About Bunsen Burners
Who invented the Bunsen burner?
Robert Bunsen, a German chemist at the University of Heidelberg, designed the concept in 1854 to 1855, and the university's mechanic, Peter Desaga, built it to Bunsen's specifications. It improved on an earlier burner design by Michael Faraday. Bunsen and Desaga never patented the design, which helped it spread quickly to labs worldwide.
What is the difference between the safety flame and the roaring flame?
The safety flame is yellow, produced with the air hole closed, and burns at a lower temperature of roughly 300°C. The roaring flame is blue, produced with the air hole open, burns much hotter at up to roughly 1,500°C at its hottest point, and makes an audible rushing sound. The safety flame is used when the burner is lit but not actively heating something, since it's easier to see.
Why is the blue flame hotter than the yellow flame?
The blue flame gets more air mixed in with the gas before combustion, which allows the gas to burn completely. Complete combustion releases more heat than the incomplete combustion that produces the yellow flame, which is also why the blue flame burns cleaner with far less soot.
What gas do Bunsen burners in South Africa typically use?
Most South African schools and labs run their Bunsen burners on LPG, supplied from a gas bottle, since piped natural gas is not common infrastructure here. Standard adjustable Bunsen burners are designed to work with either supply.
Why should you light the burner before turning on the gas?
Opening the gas supply before you have a lit flame ready lets unburned gas build up around the burner and in the surrounding air. Lighting your igniter first, then opening the gas, means the gas ignites immediately as it reaches the burner tip instead of accumulating first.
Where can I buy a Bunsen burner in South Africa?
SmartLabs supplies Bunsen burners to schools, universities, and industrial customers across South Africa. We ship nationwide from Johannesburg with traceable courier delivery.
Final Word
The Bunsen burner has stayed at the centre of the school science lab for over 150 years because it does exactly one job, controllably and reliably: it gives you fire you can turn up, turn down, and trust. Understanding the difference between the safety flame and the roaring flame, and following a proper lighting procedure every time, is what keeps that flame a useful tool instead of a hazard.
If you supply a school, run a lab, or just need a reliable source of heating equipment, browse our full range of Bunsen burners and heating equipment or get in touch. We're always happy to help you choose the right tool for the job.