Bunsen Burner – Definition, Principle, Parts, Functions

What is a Bunsen Burner?

  • A Bunsen burner is a laboratory device that plays a crucial role in scientific experiments and research. It was invented by German scientist Robert Bunsen in collaboration with his lab assistant Peter Desaga in 1857. The burner was named after Bunsen, recognizing his contribution to its design and development.
  • The primary function of a Bunsen burner is to produce a controlled flame for various scientific purposes. It utilizes a mixture of gas and oxygen, allowing for precise regulation of the flame’s size and heat. This controlled environment ensures safety and efficiency during experiments.
  • The construction of a Bunsen burner consists of a flat base with a vertically extending straight tube, commonly referred to as a barrel or chimney. At the bottom of the chimney, a supply of natural gas (typically methane) or liquefied petroleum gas, such as propane or butane, is connected through a rubber tube to a gas valve.
  • The flame produced by a Bunsen burner can be classified into two types: luminous and non-luminous. The luminous flame is achieved when the air-hole is partially closed, resulting in a bright flame with an orange hue. It operates at a moderate temperature and may appear unstable and flickering.
  • In contrast, the non-luminous flame is obtained by fully opening the air-hole, resulting in a blue-colored flame. However, this flame is not easily visible to the naked eye. The non-luminous flame is hotter and more stable compared to the bright flame, making it suitable for certain experimental procedures.
  • The Bunsen burner’s versatility lies in its ability to serve multiple purposes in the laboratory. It can be used for heating substances, sterilization of equipment, and combustion reactions. The controlled flame produced by the burner allows scientists and researchers to carry out their work with precision and accuracy.
  • In summary, a Bunsen burner is a laboratory gas burner invented by Robert Bunsen and Peter Desaga in 1857. It generates a safe, smokeless, hot, and non-luminous flame, making it an essential tool for scientific experiments and research. The burner’s design enables precise control of the flame’s size and heat, while its construction includes a base, chimney, and gas valve. Whether it’s heating, sterilization, or combustion, the Bunsen burner provides a reliable and efficient source of flame for various laboratory applications.

Definition of Bunsen Burner

A Bunsen burner is a laboratory gas burner that produces a controlled flame for scientific experiments and research purposes.

bunsen burner diagram
What is Bunsen Burner?

Principle of Bunsen burner

The Bunsen burner, a staple in scientific laboratories, operates on foundational principles of combustion and gas mixing. Constructed predominantly from metal, the burner stands firmly on a lab bench, anchored by its solid base. A rubber conduit facilitates the transfer of gas from the laboratory’s gas nozzle to the primary gas inlet situated at the base of the burner.


Central to the burner’s functionality is the pre-combustion mixing of the fuel with oxygen. This ensures an efficient and controlled burn. The mechanism responsible for this mixing is the Venturi-effect inlet valve, strategically positioned at the lower section of the burner column. Activation of the lab gas nozzle induces a suction effect, drawing in ambient air. The nozzle’s diameter is meticulously calibrated to correspond with the specific gas in use, ensuring optimal performance.

Above the primary gas entrance, the vertical tube is punctuated with minuscule apertures. These allow ambient air to laterally merge with the gas stream, further enhancing the air-gas mixture. Combustion is initiated at the burner’s apex, typically using a match or lighter.


The flame’s characteristics, both in intensity and hue, can be modulated by the adjustable valve or collar located at the base. This valve governs the volume of oxygen introduced into the mixture. A restricted air supply yields a subdued flame, whereas an augmented air supply intensifies the flame. The flame’s color serves as an indicator of its combustion efficiency:

  1. A completely sealed air hole produces a yellow flame, signifying a safety fire.
  2. A marginally opened air hole results in a reddish flame, indicative of low combustion power.
  3. When the air hole is half-open, a purple flame emerges, representing moderate combustion power.
  4. Maximum combustion, which is potentially hazardous, is denoted by a blue flame when the air hole is fully opened.

In summary, the Bunsen burner operates on the principle of controlled air-gas mixing prior to combustion. Its design and functionality are a testament to the meticulous integration of scientific principles to achieve precise and adjustable combustion in laboratory settings.

Principle of Bunsen burner
bunsen burner diagram – bunsen burner labeled

Types of Bunsen burners

Bunsen burners come in different types, each designed for specific purposes and gas sources. Here are some common types of Bunsen burners:

  1. Standard Bunsen Burner: The standard Bunsen burner is the most widely used type. It is versatile and suitable for various laboratory applications. The burner consists of a vertical metal tube with a flared base and a needle valve for adjusting the air intake. It can be used with natural gas or other compatible gas sources.
  2. Micro Bunsen Burner: The micro Bunsen burner is a smaller version of the standard burner. It is commonly used in smaller laboratory settings or for more delicate work where a smaller flame is required.
  3. Tirrill Burner: The Tirrill burner is a subtype of the Bunsen burner that features a disc valve at the base of the barrel. This valve allows for precise regulation of the gas flow into the burner, enabling finer adjustments to the flame intensity. The Tirrill burner is often used in applications that require more controlled and precise heat.
  4. Meker Burner: The Meker burner is designed to produce an extremely hot and stable flame. It features a wider barrel with a grid placed across the top. The grid divides the flame into smaller flames, resulting in a shorter, more powerful flame with a higher temperature (+1180 degrees Celsius). The Meker burner is commonly used in industrial settings where intense heat is required, such as in metalworking or high-temperature reactions.
  5. Fisher Burner: The Fisher burner is specifically designed for use with natural gas. It is commonly used in analytical chemistry applications. The Fisher burner may have specific modifications or features to optimize its performance with natural gas as the fuel source.

When using a Bunsen burner, it is important to select the appropriate type based on your specific requirements and the gas source available. Proper adjustment of the air intake using the needle valve allows for control of the flame type and intensity, ensuring safe and accurate heating in laboratory experiments.


Fuel Sources for Bunsen Burner 

The choice of fuel source for a Bunsen burner depends on various factors, including the specific application, availability of fuel sources, and safety considerations. Here are some commonly used fuel sources for Bunsen burners:

  1. Natural gas: Natural gas is a popular choice for Bunsen burners in locations with access to a natural gas supply. It is cost-effective and convenient, as it can be directly connected to the burner through a gas line. It is important to ensure that the gas line is equipped with a shutoff valve for safe and easy control of the gas supply.
  2. Propane gas: Propane gas is frequently used as a fuel source for portable Bunsen burners. These burners are often employed in field work or outdoor experiments where access to a natural gas supply may be limited. Propane gas is stored in portable tanks and can provide a reliable source of fuel for Bunsen burners in such settings.
  3. Butane gas: Butane gas is another option for portable Bunsen burners, particularly in field work or outdoor environments where natural gas is not readily available. Butane gas is commonly stored in small canisters or cartridges, making it convenient and portable for use with Bunsen burners.

When selecting a fuel source for a Bunsen burner, it is crucial to choose the appropriate burner designed for that specific fuel type. Using a burner intended for one type of fuel with a different fuel can be extremely dangerous and may lead to accidents or malfunctioning of the equipment. Therefore, it is essential to ensure compatibility between the fuel source and the burner to maintain safety and efficiency.


Overall, the choice of fuel source for a Bunsen burner depends on factors such as availability, portability requirements, and safety considerations. Whether it is natural gas, propane gas, or butane gas, selecting the right fuel source ensures proper functioning and reliable operation of the Bunsen burner for various scientific experiments and research purposes.

Bunsen burner Parts With their functions

Parts of Bunsen burner - bunsen burner labeled
Parts of Bunsen burner – bunsen burner labeled

The Bunsen burner, an indispensable tool in scientific laboratories, is an intricate assembly of various components, each serving a distinct purpose. Herein, we delineate the primary parts of a Bunsen burner and elucidate their respective functions:

  1. Base or Stand: This foundational component provides the requisite stability to the burner. Crafted in diverse shapes, the base ensures the burner’s secure placement on the laboratory bench. Integral to the base is a side tube, termed the gas tube, which facilitates the gas supply.
  2. Barrel or Chimney: Rising vertically from the base is the barrel, a cylindrical metal conduit approximately 5 inches in length. Near its base, the barrel features an air vent, constituted by two diametrically opposed holes. This design permits ambient air to merge with the gas. The upper terminus of the barrel is the site of combustion, where the gas-air mixture ignites to produce a flame.
  3. Collar: Bridging the base and the barrel, the collar is a diminutive cylindrical metal segment. It is punctuated by two antipodal holes. The collar’s pivotal role is in modulating the volume of air channeled into the barrel. By manipulating the collar, one can fine-tune the air-to-gas ratio, thereby influencing the flame’s attributes.
  4. Air Holes: Situated within the collar, these apertures permit atmospheric air to infiltrate the burner. The ingress of air, when combined with gas or a liquid fuel, is instrumental in achieving the desired combustion characteristics.
  5. Gas Valve: This component is paramount in governing the gas influx into the burner. By actuating the gas valve, users can calibrate the gas volume, thus adjusting the flame’s intensity to the requisite heat output.
  6. Gas Inlet: Serving as the conduit for gas supply, the gas inlet is the juncture at which a rubber tube connects, channeling gas from the lab bench’s source. This nexus ensures an uninterrupted gas provision, vital for sustained combustion.
  7. Flame Stabilizer (optional): Positioned atop the barrel, the flame stabilizer is a safeguard against erratic flame behavior. By mitigating the effects of ambient air currents, the stabilizer ensures a uniform and unwavering flame, enhancing the reliability of experimental outcomes.

In summation, the Bunsen burner is a harmonious integration of meticulously designed components, each contributing to its optimal performance. Understanding the function of each part is pivotal for safe and effective utilization in scientific endeavors.

bunsen burner diagram
Parts of Bunsen burner

Operating Procedure of Bunsen Burner

To operate a Bunsen burner safely and effectively, follow these steps:

  1. Prepare for Safety: Prioritize safety by wearing a lab apron and safety glasses. If you have long hair, tie it back to prevent any accidents or interference.
  2. Connect the Rubber Tube: Connect the rubber tube securely to a gas tap or gas source. Ensure a tight connection to prevent any gas leakage.
  3. Provide Heat Resistance: If you are using the Bunsen burner on a surface that is not heat resistant, place a suitable heat-resistant pad or mat underneath the burner to protect the surface.
  4. Adjust the Air Hole: Place a cover or close the air hole on the collar of the Bunsen burner. This will restrict the air supply and create a low-temperature flame, also known as the “safety mode.”
  5. Ignite the Burner: Hold a lit match or lighter approximately 3 cm above the top of the barrel. Carefully bring the flame near the barrel and ignite the gas. Be cautious and avoid any contact between the match or lighter and the gas outlet.
  6. Turn on the Gas: With the flame ignited, slowly turn on the gas faucet or valve to allow the gas to flow into the burner. Ensure a smooth and controlled gas flow.
  7. Extinguish the Match: Once the gas is flowing and the flame is stable, carefully extinguish the match or lighter. It is important to remove any potential ignition source once the burner is operational.
  8. Operate in “Safety Mode”: By keeping the air hole covered or closed, maintain the flame in the “safety mode” until you are ready to heat something. The safety mode produces a low-temperature flame with limited oxygen supply.

Remember to always exercise caution while operating a Bunsen burner. Keep a safe distance from the flame and be mindful of any flammable materials or chemicals in the vicinity. Follow proper laboratory protocols and guidelines to ensure a safe working environment.

During Use

  1. Never leave a burner that is on without watching it. Even if a draught, like one from a hood, puts out the flame, the gas will still be on. This could cause a bomb to go off.
  2. Never heat something in a test tube, beaker, or other container with the opening facing you or someone else close to the burner. A hot plate can be used instead of a Bunsen burner in some experiments.
  3. When heating liquids that can catch fire, you must use a hot plate or a heating mantle.

After Use

  1. If a Bunsen burner was used to heat something, it is likely to be very hot. Do not touch equipment with your bare hands unless the air around it feels cool.
  2. Use crucible tongs or thermal gloves if you need to handle something hot. If you put something hot on paper, it could catch fire. Let the machine cool down where it is, with the burner removed or turned off.
  3. Turn off the gas when you’re done.
  4. Wait until the burner is cool to touch it. Make sure the main gas valve is turned off before you leave the lab.

Uses of Bunsen Burner

The Bunsen burner finds a wide range of uses in various laboratory settings. Some of the common applications of the Bunsen burner include:

  1. Sterilization: The Bunsen burner is frequently used for sterilizing instruments such as loops, needles, and forceps. By exposing these tools to the high temperatures of the flame, any potentially harmful microorganisms are effectively killed, ensuring aseptic conditions for experiments and procedures.
  2. Heating and Heat Treatments: The Bunsen burner provides a controlled and adjustable source of heat, making it ideal for heating purposes in chemical laboratories. It can be used to warm up substances, facilitate reactions, or perform heat treatments on materials.
  3. Dehydration and Drying: The Bunsen burner is utilized in the dehydration process of complexes and the drying of salts. By applying heat, water molecules are removed, leaving behind the desired dry substance.
  4. Moisture Analysis: The Bunsen burner can be employed to measure the moisture content of a substance. By subjecting the material to heat, any moisture present evaporates, allowing for the determination of its moisture content.
  5. Flammability Testing: The Bunsen burner is used to assess the flammability of compounds. By bringing a sample into contact with the flame, researchers can observe if the substance ignites or catches fire, providing valuable information about its properties.
  6. Flash Point Determination: In the field of chemistry, the Bunsen burner aids in determining the flash point of solvents. The flash point is the lowest temperature at which a solvent gives off enough vapor to form an ignitable mixture with air.
  7. Melting and Boiling Point Analysis: The Bunsen burner is instrumental in classical calorimetry, enabling the determination of the melting point of substances. Additionally, the Thiele tube method utilizes the Bunsen burner to find the boiling point of liquids.
  8. Cleaning and Sterilization: Apart from sterilizing instruments, the Bunsen burner can also be used for cleaning purposes. It helps in sterilizing the mouth of test tubes by flaming them, ensuring a sterile environment for experiments.

These are just a few examples of the diverse applications of the Bunsen burner in laboratory work. Its versatility, controllability, and reliability make it an essential tool for various scientific experiments, research, and analysis.

Advantages of Bunsen Burner

The Bunsen burner offers several advantages that make it a popular tool in laboratory settings. Some of the key advantages of using a Bunsen burner are:

  1. Ease of Use: The Bunsen burner is known for its simplicity and ease of handling. It does not require complex setup or specialized training to operate, making it accessible to a wide range of users, including students and researchers.
  2. Versatility: The burner can be used in various locations as long as there is access to a suitable gas supply, such as coal gas or natural gas. This versatility allows for its use in different laboratory setups and fieldwork environments.
  3. Size Variability: Bunsen burners are available in different sizes, allowing users to select the appropriate size for their specific needs. Whether it’s a small-scale experiment or a larger heating requirement, there is a burner size that can accommodate the task at hand.
  4. Multi-Purpose Functionality: Apart from heating applications, the Bunsen burner can be utilized for other tasks such as basic glass-blowing tasks and air drying. This versatility expands its utility beyond heating, providing additional value to users.
  5. Cost-Effectiveness: The burner can run on low-cost fuels like coal gas and natural gas, which are readily available in many laboratory settings. This affordability makes it a cost-effective choice for heating applications compared to more complex heating systems.
  6. Adjustable Flame Temperature: One of the notable advantages of the Bunsen burner is its ability to produce flames with a range of temperatures. The adjustable air inlet allows for precise control over the flame intensity, enabling users to achieve the desired temperature for their specific needs.
  7. Sterilization Capability: The heat produced by a Bunsen burner flame creates a convection current that heats the area above the flame. This upward movement of air helps in sterilizing the workspace by removing airborne particles and maintaining a sterile environment for experiments and procedures.

These advantages make the Bunsen burner a versatile and efficient tool in laboratory settings. Its simplicity, accessibility, and range of applications contribute to its widespread use in scientific research, education, and various other fields.

Limitations of Bunsen Burner

While the Bunsen burner offers numerous advantages, there are also some limitations associated with its use. These limitations include:

  1. Fire Risk: The Bunsen burner operates by producing an open flame, which poses a constant fire risk if not handled with caution. The presence of an open flame requires strict adherence to safety protocols and precautions to prevent accidents, such as fire hazards or burns.
  2. Limited Temperature Control: Controlling the temperature precisely with a Bunsen burner can be challenging. Although the adjustable air inlet allows for some control over the flame intensity, maintaining a specific temperature can be difficult. The flame temperature may fluctuate, making it challenging to achieve and maintain a desired temperature for sensitive experiments or procedures.
  3. Limited Heating Uniformity: The heat distribution from a Bunsen burner flame may not be uniform across the heating area. The hottest point is usually at the tip of the inner blue cone of the flame, while the outer region of the flame may be significantly cooler. This non-uniform heating can affect the accuracy and consistency of heating applications, especially when precise and even temperature distribution is required.
  4. Limited Heating Capacity: Bunsen burners have a finite heating capacity, which may be insufficient for certain applications that require high temperatures or rapid heating. For tasks that demand extremely high temperatures or quick heating, alternative heating sources such as electric furnaces or specialized heating equipment may be more suitable.
  5. Dependency on Gas Supply: Bunsen burners rely on a continuous supply of gas, such as coal gas or natural gas. The availability and reliability of gas supply can pose a limitation, particularly in remote locations or situations where gas access is limited. In such cases, alternative heating methods may need to be considered.
  6. Limited Applications: While the Bunsen burner is versatile in many laboratory applications, it may not be suitable for all heating requirements. Certain specialized procedures or experiments may require precise and controlled heating methods that cannot be achieved with a Bunsen burner alone. In such cases, alternative heating devices or techniques may be necessary.

It is important to be aware of these limitations and exercise caution when using a Bunsen burner. Adhering to safety guidelines, understanding its temperature control limitations, and considering alternative heating methods when needed can help mitigate these limitations and ensure safe and effective laboratory practices.

Safety Rules for Bunsen Burner

When working with a Bunsen burner, it is crucial to prioritize safety to prevent accidents and ensure a secure laboratory environment. Here are some essential safety rules to follow when using a Bunsen burner:

  1. Personal Protective Equipment (PPE): Always wear appropriate safety gear, including safety glasses or goggles and a laboratory coat or apron. These items provide protection from potential splashes, sparks, or other hazards.
  2. Secure Long Hair: If you have long hair, tie it back or secure it properly to prevent any contact with the flame or other equipment.
  3. Proper Lighting Procedure: When lighting the Bunsen burner, ensure that the collar covering the air hole is in place. This helps establish the initial safety flame.
  4. Lighting the Burner: Before turning on the gas, use a match or a lighter to ignite the gas above the barrel of the Bunsen burner. Always light the match first before turning on the gas faucet.
  5. Gas Flow: Never turn on the gas faucet without a Bunsen burner attached and a lit match or flame above the barrel. This sequence ensures proper gas flow and ignition.
  6. Match Extinguishing: Extinguish the match as soon as the gas ignites. Safely dispose of the match in a designated container.
  7. Safety Flame: Keep the Bunsen burner on the yellow safety flame when not actively heating or using it. The safety flame indicates that the burner is operational but at a lower temperature.
  8. Heating Flame: When you need to heat something, switch the Bunsen burner to the blue heating flame by adjusting the air inlet and achieving the desired flame intensity.
  9. Hand Safety: Keep your hands and other body parts at a safe distance from the flame to avoid burns or accidental contact with hot surfaces.
  10. Shutting Off the Burner: To extinguish the Bunsen flame, always turn off the gas valve completely. This is the only safe method to stop the burner’s operation.
  11. Never Blow on the Flame: Never attempt to extinguish a Bunsen flame by blowing on it. Instead, use the gas valve to shut off the gas supply.
  12. Gas Leak or Flame Outage: If the flame accidentally goes out or if you detect a gas leak, immediately turn off the gas valve to ensure safety. Inform your instructor or supervisor about the situation.
  13. Emergency Situations: In case of a fire or any other emergency, prioritize personal safety. Immediately turn off the gas tap and follow the established emergency protocols for your laboratory or workplace.

Adhering to these safety rules will help prevent accidents, minimize risks, and ensure the safe and effective use of Bunsen burners in laboratory settings. Always consult your instructor or supervisor if you have any specific safety concerns or questions.

What is Flame?

  • A fuel and an oxidizer undergo a chemical reaction to produce flame (or oxidant).
  • In certain circumstances, the fuel and oxidant may be included within the same chemical molecule, as is the case with certain propellants and explosives.
  • Combustion refers to the chemical reaction between the fuel and oxidant, which is accompanied by the release of heat and, typically, the emission of visible light.
  • In the case of a premixed hydrocarbon flame burning in air, the light emitted is often blue if the mixture is fuel-rich, and it indicates the location of the flame and, in particular, the position of the flame front due to its greater intensity.
  • However, if the mixture entering the flame is rich in fuel, a yellow soot-producing flame known as a bright flame is formed.
  • Depending on the fuel-air ratio, flames are capable of reaching temperatures as low as 1300K. The majority of flames occur from highly exothermic reactions that produce flame temperatures of about 2200K.
  • Certain flames, termed “cool” flames, can be maintained below this temperature, although only partial combustion occurs.
  • Typical flames originate from the burning with air of a gaseous fuel, such as natural gas, commercial and industrial liquid fuels, sometimes referred to as fuel oils, which are burned as a spray, or by crushed coal particles suspended in air, as in a power plant boiler.
  • Depending on the manner in which the fuel and oxidant are mixed in a burner and their respective flow rates, many types of flames can result.
  • When fuel gas and air are mixed before to entering the burner, premixed gas flames can result; when they mix after leaving the burner, diffusion flames are produced. In the event that the gas flow rate is relatively low, the incoming gaseous flow of fuel and air is laminar, as is the flame.
  • When gas fluxes are strong, they may be turbulent. As seen in Table 1, flames can be laminar premixed, laminar diffusion, turbulent premixed, or turbulent diffusion.
  • As the flow velocity increases, there is a shift from laminar to turbulent flame. In addition, they can be classified as either stationary flames or propagating (moving) flames, with the former being the most common type of flame used in home or industrial burners and the latter being associated with explosions.
  • The most studied flame is the laminar premixed flame with a gaseous fuel and oxidant, often air, because it is the simplest flame and shares properties with many other systems.
  • Typical is the Bunsen burner flame, which is commonly utilised in gas fireplaces, gas ranges, and central heating equipment.
  • The flame of a Bunsen burner is depicted in Figure, however for research purposes, a special burner producing uniform flow is employed to produce a flat flame, as depicted in Figure.
  • However, the Bunsen burner demonstrates both the premixed flame and the diffusion flame theory.
  • The inner core of a premixed flame is the reaction zone, but the flame is fuel-rich, so the products of incomplete combustion burn as a diffusion flame with the surrounding air in the outer core.
  • The ratio of fuel to air determines the precise nature of the flame. If there is an abundance of fuel, it is considered rich, and the flame will be yellow and bright.
  • If there is an abundance of air (or oxygen), it is termed lean. It would be dubbed stoichiometric if it contained the ideal proportions of fuel and air.
  • Overall, the combustion products would be represented by the stoichiometric equation, which for methane (the most abundant component of natural gas) is:

CH4 + 2O2 → 2CO2 + 2H2O -ΔHc

  • where –ΔHc is the heat generated by burning, also known as the heat of combustion or calorific value (cv).
  • Stoichiometric refers to a scenario in which no fuel or oxidant is left over after complete combustion.
  • The zone of incomplete combustion in the flame depicted in Figure indicates only partial burning of the fuel, which produces carbon monoxide and hydrogen, which then combust with the secondary air to produce carbon dioxide and water.
  • This two-stage combustion can be represented, for example, by the processes for methane, by

CH4 → {CO,H2} → CO2, H2O

  • In general, all hydrocarbon flames, whether rich or lean, pass through this stage, where CO and H2 are formed in the first main reaction zone, and the second stage combustion of the CO and H2 initially formed is characterised by the emission of blue light; this blue emission being a defining characteristic of the combustion of all carbon (and hydrocarbon) containing fuels.
  • This phenomenon is referred to as afterburning and is more prominent in flames with a modest excess of fuel.
  • The burning velocity, flame temperature, and flammability limit of a premixed flame of a specific fuel-air mixture are determined by the pressure, temperature, and, of course, mixture ratio.
  • Premixed fuel air mixtures have a distinctive burning velocity, which allows flames to be stabilised on a burner, as depicted in Figures, if the flow rate of the gas mixture is equal to the laminar burning velocity.
 Bunsen burner
Bunsen burner
 Bunsen burner
Bunsen burner
  • The burning velocity is simply defined for a flat, laminar flame as shown in Figure, i.e., the approach velocity gives the burning velocity (relative to the unburned gas, Su), which is often expressed in metres per second.
  • The laminar flame for a conical flame is depicted in Figure. In the case of laminar diffusion flames, the fuel and oxidant only meet at the burner mouth (i.e., they are not pre-mixed) and combine by diffusion processes as the flame burns, as seen in Figure 1. In this instance, the fuel gas and oxidant gas streams are slotted, resulting in a flat flame. However, similar axisymmetric flames can be produced by using concentric tubes, with the fuel typically entering through the inner tube.
  • The proportion of the fuel-oxidant mixes that will support a stable flame is the flammability limit. There are two types of restrictions on the spread of a laminar flame.
  • The flammability limit is connected with the chemically reactive capacity of the combination to sustain a flame.
  • The second factor is gas flow impacts. The stoichiometric ratio for methane, where the lower and upper flammability limits are 5 and 14 mol%, is 9.47 mol%.
  • The limitations for n-heptane are 1 and 6 mol%, respectively, with a stoichiometric ratio of 1.87 mol%.
  • Combustion of liquid fuels or powdered coal (or pulverised fuel, both abbreviated as pf) is used extensively in industrial burners, particularly for big boilers used to generate steam for power generation.
  • Industrial flames are typically turbulent in nature and, for convenience and safety reasons, involve diffusion flames in which the fuel and air are injected separately for safety reasons and the lengthening of the diffusion flame after the burner exit occurs with an increase in gas flow velocity, as illustrated in Figure.
 Bunsen burner
  • There is a transition from laminar to turbulent diffusion combustion with increasing flow velocity, although some diffusion mixing does occur (turbulent diffusion).
  • The flames of liquid fuels can range from blue, premixed-like flames to highly brilliant coal-like flames, according to Williams (1990).
  • Liquid fuels must be entirely evaporated in order to produce a vapour that burns in the same manner as a gaseous flame. This type of spray combustion is known as “homogenous”
  • For more volatile fuels, the partially volatilized fuel burns as a spherical flame surrounding each droplet, as depicted in Figure 5. This type of spray combustion is referred to as “heterogeneous.”
  • The first style of combustion is illustrated by the burning of aviation kerosene in an aircraft gas turbine, where the fuel is largely vaporised following injection as a spray into the combustion chamber; however, some bigger droplets tend to burn heterogeneously and produce smoke.
  • Spray combustion is the second phase, in which burning occurs heterogeneously. This occurs in industrial furnaces and boilers as well as diesel engines.
 Bunsen burner

Types of flame on a Bunsen burner

Types of flame on a Bunsen burner
Types of flame on a Bunsen burner

The type of flame produced by a Bunsen burner can be controlled by adjusting the air intake using the needle valve. This allows for the selection of an appropriate flame for specific laboratory applications, ensuring accurate and safe results. Let’s explore the different types of flames produced by a Bunsen burner:

  1. Safety Flame: The safety flame is the smallest and least hot flame. It is designed to be easily visible in a well-lit room, serving as a reminder that the burner is on. The safety flame reaches temperatures of approximately 300 degrees Celsius and is not used for heating materials during experiments. It is produced when the air intake, or vent, is completely closed, resulting in incomplete combustion. The flame appears as a bright yellow color, resembling a candle flame.
  2. Yellow Flame: The yellow flame is produced when there is not enough air mixing with the gas, leading to incomplete combustion. This type of flame is not commonly used in laboratory work because it can contaminate samples with soot. It is important to ensure proper air adjustment to avoid the formation of a yellow flame.
  3. Medium Blue Flame: The medium blue flame is created when the air intake, or vent, is partially open. It reaches temperatures of around 500 degrees Celsius. In a brightly lit room, it can be challenging to see this flame clearly due to its blue color. The medium blue flame is often used for general heating purposes in laboratory experiments.
  4. Roaring Blue Flame: The roaring blue flame is the hottest flame produced by a Bunsen burner. It can reach temperatures of up to 1400 degrees Celsius, with the hottest part of the flame located at the tip of the white cone in the middle. This flame is created when the air intake is fully open, allowing for more complete combustion. The increased airflow results in a noisy, bluish-colored three-cone flame. The roaring blue flame provides the highest possible burner temperature and is often used for applications requiring intense heat, such as rapid boiling or sterilization.
Types of flame on a Bunsen burner
The flames in a Bunsen burner depend on how much air moves through the throat holes (on the burner side, not the needle valve for gas flow): 1. air hole closed (safety flame used to light or default), 2. air hole slightly open, 3. air hole half-open, 4. air hole fully open (roaring blue flame). | Source: Arthur Jan Fijałkowski, CC BY-SA 3.0, via Wikimedia Commons

What is an Alcohol burner?

  • A type of scientific equipment used to produce an open flame is an alcohol burner or spirit lamp. It may be constructed of brass, glass, stainless steel, or aluminium.
  • Alcohol burners are chosen over Bunsen burners for some applications due to safety concerns and in laboratories where natural gas is unavailable.
  • Their flame is restricted to around 5 centimetres (two inches) in height and has a lower temperature than the Bunsen burner’s gas flame.
  • While their flames are not as intense as those produced by other types of burners, they are hot enough to execute certain chemistry experiments, typical microbiology laboratory operations, and flame sterilise other laboratory equipment.
  • Standard fuels include denatured alcohol, methanol, and isopropyl alcohol.
  • Caps are used as snuffers to extinguish the flame.
What is an Alcohol burner?
Alcohol burner

Important Note

  • The colour of the flame can be used to determine its rate of combustion. Adjusting the collar or air hole produces different flame colours, as observed. For instance, if the air hole is
    • completely sealed, the flame will be yellow (safety fire).
    • Slightly opened produces a crimson flame (slightly combustion power).
    • A half-opened candle produces a purple flame (half combustion power).
    • Completely open produces a blue flame (powerful combustion, dangerous).
  • The air and gas combination (optimally around 1 part gas to 3 parts air) is forced to the top of the tube by gas pressure, where it is ignited using a match.
  • The primary function of the open flame in the aseptic technique is to produce a cone of hot air above and surrounding the laboratory bench, which reduces the viability of organisms on suspended dust particles and so provides a sterile working environment.
  • It is perfect for sterilising inoculating loops, warming glass bottlenecks, igniting alcohol on culture spreaders, etc. due to its flame’s ability to rapidly heat items.
  • The flames of a Bunsen burner depend on airflow in the throat openings (on the burner side, note the needle valve for gas flow).

The Origin of the Bunsen Burner

  • The famous laboratory gas burner is often associated with the German chemist Robert Wilhelm Bunsen (1811–1899). It was first described in detail in 1857 in the second of a series of papers on photochemistry written by Bunsen and the British chemist Henry Enfield Roscoe (1833–1915). However, the burner in question had been used in Bunsen’s Heidelberg laboratory since 1855.
  • At least as far back as the 1820s, when gas lighting started to be used in Europe’s larger cities and towns for the first time.
  • Michael Faraday, who lived from 1791 to 1867, wrote about one of these devices in the 1827 edition of his book Chemical Manipulation. Dolch and Kohn have also written about a number of lab gas burners that were used before Bunsen.
  • In his autobiography, Roscoe said that Bunsen’s burner was based on a modified “gauze burner,” which was a common gas burner in the Royal College of Chemistry and which Roscoe had brought to Germany from England.
  • As the name suggests, the gas and air were mixed in a cylinder-shaped metal chamber with a wire screen or gauze on top before it was lit. This was done to avoid a flashback (in keeping with the principles of the Davy safety lamp).
  • Unfortunately, the smudges on the metal screen made the flame spread out, stay relatively cool, and flicker and change colour a lot.
  • When you look at the paper by Bunsen and Roscoe, you can see that the main reason they used the new burner was to get a flame that was almost colourless, didn’t make soot, and was the same size all the time so that it could be used to set photometric standards.
  • This was done by letting the air and gas mixture come out of a long, thin tube or barrel under positive pressure before lighting it.
  • If the width and length of the tube are right, the flame won’t spread down the tube, and you won’t have to use a wire safety screen.
  • As a bonus, the burner also made a hotter, more concentrated flame that could be used in a normal lab.
  • By the end of the 1860s, laboratory gas burners had mostly replaced the older charcoal furnaces that had been used in chemistry for most of its recorded history.

Video Guide on Bunsen Burner

Bunsen Burner Basics – by Dr Sapna Gupta

How to use a Bunsen burner safely

How to Light a Bunsen Burner


What is the primary function of the base or stand in a Bunsen burner?
a) To regulate the gas flow
b) To mix air and gas
c) To provide stability to the burner
d) To ignite the gas-air mixture

Which component of the Bunsen burner is responsible for controlling the air-to-gas ratio?
a) Barrel
b) Gas Valve
c) Collar
d) Flame Stabilizer

What color flame indicates maximum combustion in a Bunsen burner?
a) Yellow
b) Red
c) Purple
d) Blue

The gas inlet of a Bunsen burner is typically connected to which of the following?
a) A water source
b) A rubber tube
c) An electrical outlet
d) A metal rod

Which part of the Bunsen burner is approximately 5 inches long and allows the gas to mix with air?
a) Collar
b) Base
c) Barrel or Chimney
d) Gas Valve

The flame stabilizer in a Bunsen burner helps in:
a) Mixing air and gas
b) Regulating gas flow
c) Maintaining a steady flame
d) Connecting to the gas source

Which flame color indicates a safety fire in a Bunsen burner?
a) Blue
b) Purple
c) Red
d) Yellow

The air holes in the collar of a Bunsen burner are essential for:
a) Igniting the flame
b) Cooling the burner
c) Forming a mixture of air and gas
d) Controlling the flame color

Which component of the Bunsen burner is responsible for adjusting the flame’s intensity?
a) Barrel
b) Gas Valve
c) Collar
d) Base

In a Bunsen burner, the gas burns and produces a flame at the:
a) Base
b) Collar
c) Upper end of the barrel
d) Gas inlet


How bunsen burner works?

Most Bunsen burners have a barbed fitting at the bottom of the chimney. This lets a rubber tube feed gas from a gas nozzle on the lab bench to the burner. The Bunsen burner works because it can mix gas or another fuel with oxygen before lighting the mixture (creating a premix of air and gas before combustion). This is done with an inlet valve at the bottom of the burner column, which uses the Venturi effect to pull in air while the gas goes through a nozzle whose diameter depends on the type of gas being used. At the top of the column, the mixture is then set on fire. The amount of oxygen that goes into the mix is controlled by the collar-shaped valve at the bottom. When the valve is closed, very little oxygen gets in, and a smoky yellow flame with a “low temperature” is made. When the valve is fully open, a roaring, hot flame with almost no colour comes out.

Bunsen burner depends on which principle?

The Bunsen burner principle relies on its ability to mix gas (or other fuel) with oxygen before the mixture is ignited (creating a premix of air and gas before combustion).

When borax is heated in a bunsenburner flame with coo on a loop of platinum?

There is the formation of a blue color bead. Borax on heating gets fused and loses water on crystallization. There is swelling of the chemical which results in the melting into a colorless liquid, which further forms a transparent glass bead consisting of Boric Anhydride and Sodium Metaborate.
On further heating of the obtained chemical with Cobalt Oxide on a loop of platinum wire, we get a blue-colored bead.

Which gas is used in bunsen burner?

Bunsen burners provide a flame with temperatures up to 1’200°C. Natural gas (primarily methane), liquefied petroleum gas such as propane, butane or a mixture of both are used as fuels. The gas flows through a small opening at the base of the barrel and is directed upwards.

Why is bunsen burner flame blue?

If the air hole is Completely open produces a blue flame (powerful combustion, dangerous). Combustion is incomplete and less energy is transferred. A blue flame from a Bunsen burner transfers more energy than a yellow Bunsen flame as complete combustion gives a blue flame.

What is bunsen burner in laboratory?

Robert Bunsen invented the Bunsen burner, which is a type of ambient air gas burner used in laboratories. It has a single open gas flame and is used to heat, sterilise, and burn things.


  • Jensen, W. B. (2005). The Origin of the Bunsen Burner. Journal of Chemical Education, 82(4), 518. doi:10.1021/ed082p518 
  • Ghosh, R. The Bunsen Burner. Reson 27, 745–751 (2022).
  • Russell, C. A. (1999). Bunsen without his burner. Physics Education, 34(5), 321–326. doi:10.1088/0031-9120/34/5/309 
  • Lockermann, G. (1956). The centenary of the Bunsen burner. Journal of Chemical Education, 33(1), 20. doi:10.1021/ed033p20
  • Zhen, H. S., Leung, C. W., Cheung, C. S., & Huang, Z. H. (2014). Characterization of biogas-hydrogen premixed flames using Bunsen burner. International Journal of Hydrogen Energy, 39(25), 13292–13299. doi:10.1016/j.ijhydene.2014.06.126 
  • Bykowski, T. & Verma, Ashutosh & Brissette, Catherine & Stevenson, B.. (2012). Aseptic techniques.. 
  • Mondal, Dr Sumanta. (2020). FIREBOY-Bunsen Burner. 10.13140/RG.2.2.18145.66401. 

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