Laboratory Burner Safety

Laboratory burners (e.g., Bunsen burners and alcohol burners (spirit burners)) are used in a variety of ways such as agar media preparation (air bubble removal) and flame sterilization. Open flames in a laboratory present a potential fire and/or injury threat. Wherever possible, use safer heat sources.

Flame sterilization can frequently be replaced by autoclaving, purchasing pre-sterilized items (e.g., disposable inoculation loops), or by using electric heat sources specifically sold for this purpose.

If a flame is deemed indispensable for a sterilization role, use a self-contained gas burner with push-button ignition, specifically manufactured for the role. Such burners extinguish immediately when the button is released and do not present nearly as high of a fire hazard as Bunsen burners and spirit lamps. If substituting safer heat sources for an open flame is not possible, then lab open flame operation shall follow NFPA 45 (2015), section 11.2.7.

For information on oxy-fuel gas setups. email labsafety@usc.edu.

 

Preparation

  1. NEVER use open flames as a heat source for chemical experiments, distillation, or boiling. Use electric hotplates and heating mantles instead.
  2. Use of open flames is strictly forbidden in tissue culture hoods and biosafety cabinets at USC – see CHP Section 4 for more details.
  3. Know how to use a fire extinguisher.
  4. Note the location of the laboratory fire extinguisher.
  5. Wear appropriate PPE:
    • Appropriate eye protection – splash goggles or safety glasses.
    • Flame-resistant or Nomex lab coat must be used.
    • Use insulating heat-resistant gloves when handling hot items.
  6. Manage personal items and clothing:
    • Tie back long hair.
    • Do not wear loose long sleeves.
    • Restrain (or remove) dangling jewelry.

Burner Setup

  1. Do not position the burner under shelving, cabinets, or overhanging equipment.
  2. Remove all combustible materials and flammable solvents near the burner.
  3. Ensure burner is outfitted with rated equipment.
  • Bunsen Burners
    • Use rated tubing/hose that fits the gas valve outlet and burner inlet. Rated tubing includes fabric-reinforced PVC, fabric-reinforced neoprene (polychloroprene), fabric-reinforced nitrile rubber (NBR), thick-wall non-reinforced neoprene, or tubing specifically designed for Bunsen use provided it is not natural rubber. Natural rubber tubing shall not be used for Bunsen burners because it is susceptible to cracking.
      • Examples of tubing specifically designed for Bunsens: Eisco Bunsen Burner hose (Fisher Scientific #S24487); Kantleke gas burner tubing (Fisher Scientific #14-185-5A or #14-185-5B); Science Equipment cloth-covered tubing (Fisher Scientific #S49140).
      • Tygon and silicone tubing are not suitable for use with Bunsen burners
    • Secure tubing ends with a hose clamp.
      • Clamp securely but do not over-tighten to avoid splitting the hose.
    • Ensure the hose is long enough that it sits comfortably on the bench top without strain on the connections.
      • Position the tube where it is not likely to be snagged, as that may cause the burner to fall over.
    • Connect the Bunsen burner to a plumbed natural gas turret and not to a flammable gas cylinder or canister.
    • Inspect:
      • Tubing for cracks, holes, or any other defects. Replace if necessary.
      • Bunsen burner for damage including the connections, wall outlet valve, needle valve (if fitted to burner), and barrel.
    • Clamp the burner in place to protect it from falling over.
  • Alcohol Burners
    • Only use ethanol, ethylene glycol, or diethylene glycol.
      • Ethylene glycol and diethylene glycol have much higher flashpoints and should be used whenever possible.
      • Do not overfill – 80% maximum.
      • Do not let the burner run dry, it can damage the wick.

Lighting Laboratory Burners

  • NOTE: Only strikers or long-reach lighters may be used at USC; never matches.
  • Ensure that hair, clothing, and hands are always a safe distance away from the flame.
  • Never reach over an exposed flame.

Lighting a Bunsen Burner

  1. Close the air vents on the Bunsen burner. When lit it will provide a yellow flame.
  2. Use a striker or long-reach lighter to ignite the burner.
  3. Adjust the air supply by turning the metal collar to get a blue flame.

Lighting an Alcohol Lab Burner

  • Remove the cap and light it with a long-reach lighter.

Lab Burner Usage

Best Practices – Bunsen Burner

  • Adjust to a yellow flame to make the flame visible if not in immediate use.
  • Never leave a lit Bunsen burner unattended. Always turn the Bunsen burner off when it is not in use.
  • Never leave anything that is being heated unattended.
  • Use tongs when holding objects in a flame and place hot objects on trivets or hot pads. Remember that objects heated by a laboratory burner retain their heat for a long time and while hot, remain a burn hazard. Use tongs or heat-resistant gloves to pick up heated clamps, tripods, rings, screens, glassware, or ceramics.
  • Never heat a closed container over a laboratory burner.
  • Never look into a test tube or container being heated. Never point the open end of a test tube being heated towards anyone.
  • Always use a laboratory burner in a fume hood if toxic chemical fumes will be produced during the heating process.
  • If the flame of a Bunsen burner goes out or begins to sputter, turn the wall outlet valve off immediately.
  • If you need to accommodate 2 Bunsen burners you can use a tube splitter (either brass or steel). Turn the gas line off at the main valve after every use.

Sterilization Techniques involving the Flaming-Off of Ethanol

On rare occasions, ethanol is used in conjunction with open flames for certain sterilization techniques. When such techniques are unavoidable, the following rules shall be adhered to:

  • There can be no more than 50 mL flammable liquid in an open container, which must be glass or metal, and must have a tight sliding (i.e., non-screw) lid which can be used to extinguish the liquid if it ignites.
  • The container of flammable liquid shall be:
    • Capped when not in use.
    • As remote as possible from the flame, and never closer than one foot.
  • Extraneous hazardous materials shall be removed from the area.
  • Combustibles shall not be within two feet of the flame.
  • Absorbent combustible material (e.g., paper) is not permitted under the flame source.

Post Usage

  1. Extinguish Burner:
    • Bunsen burners: Shut off gas valve when its use is complete.
    • Alcohol burners: put the cap on with tongs to extinguish – see figure above. This is safer than blowing the flame out.
  2. Allow the burner to cool before handling. Ensure that the main gas valve is off before leaving the laboratory.
    • Laboratory burners may remain hot for some time after the burner has been used. Carefully check to make sure the burner has cooled before moving it or putting it away.