Essential Safety and Setup
The Bunsen burner is a laboratory apparatus that safely mixes a flammable gas, typically natural gas or propane, with ambient air before ignition to create a controlled, single open flame. This device is employed across science for tasks such as heating substances, sterilization of equipment, and controlled combustion experiments. Mastering the correct lighting procedure is essential for safety, ensuring the apparatus functions effectively without creating fire hazards or releasing unburned gas.
Preparation begins with a check of the workspace and equipment. The area surrounding the burner must be clear of all flammable materials, including papers and excess chemicals. The burner should be placed on a stable, heat-resistant surface, ensuring no overhead shelves or equipment are within twelve inches of the barrel.
Personal safety requires approved safety goggles. Loose clothing, dangling jewelry, or long hair must be secured to prevent accidental contact with the flame. The rubber hose connecting the burner to the gas outlet must be inspected for cracks or wear before being securely attached. Confirm the location of the laboratory’s main gas shutoff valve before proceeding.
Step-by-Step Lighting Procedure
Successful ignition requires a precise sequence, starting with the air adjustment collar at the base of the burner. Turn this collar to fully close the air intake holes, ensuring the initial flame is visible and manageable. If present, the burner’s needle valve should also be closed to maintain control over the gas flow.
Hold the ignition source, such as a flint striker or lighter, ready. Turn on the main gas valve on the workbench. If the burner has a needle valve, open it slightly to allow gas to flow up the barrel. Immediately bring the ignition source to the top edge of the barrel to ignite the exiting gas.
The flame should appear instantly as a tall, luminous yellow color, known as the safety flame. If the gas does not ignite within three seconds, immediately shut off the main gas valve to prevent a buildup of unburned gas. The yellow flame confirms a gas-rich mixture with insufficient oxygen, setting the stage for adjustment.
Adjusting the Flame for Different Uses
The initial yellow flame is cool and luminous because insufficient oxygen causes incomplete combustion. This process generates tiny, incandescent carbon particles that glow yellow and deposit soot on objects they touch. While unsuitable for heating tasks, this flame serves as a highly visible indicator that the burner is operating.
To transition to a hotter, non-luminous flame, gradually rotate the air adjustment collar to open the air intake holes. As more air is drawn into the barrel, the gas-to-air mixture optimizes for complete combustion. The flame will shorten, lose its yellow luminosity, and turn blue as the carbon particles are oxidized.
The ideal blue flame, often called the “roaring flame,” is achieved when a distinct, pale blue inner cone appears within a larger outer cone. The hottest part of the flame is located just above the tip of this inner blue cone. This adjustment provides maximum heat output without the production of soot.
Safe Shutdown and Storage
Extinguishing the flame prioritizes safety by cutting off the fuel supply at the source. Turn off the main gas valve at the workbench first, allowing the flame to consume the gas remaining in the hose and die out. This prevents unburned gas from escaping into the laboratory environment.
Once the flame is extinguished, close the burner’s needle valve and the air adjustment collar, returning them to their starting positions. This prepares the apparatus for the next use and ensures no residual gas flow. The metal barrel retains significant heat and must cool completely before the apparatus is touched or moved for storage.