Camera booth Cam, Cam 4 if needed
P(oint) O(f)
balloon and 6 foot radius
Notes discretion until burner approach balloon, POI before ignition
Story Balloons, tethered and/or attached to a rod, are brought each in turn to location 3. Each is ignited in turn with a long burner rod before next balloon is brought to location 3. Depending on balloon contents, a loud explosion is observed, with small fireball, a fireball of approximately 6 feet diameter is observed, with little sound, -- or something in between. Most often, a series of 3-5 balloons are ignited.
Preview MOVIE is from cam 4, booth Cam probably better

The following notes are intended ONLY for internal use by UCB CCHEM Demo Lab staff.

Note: Demo Lab staff will always wear hearing protection when participating in, or working in the same room as, the preparation, transportation, performance, and recovery of any experiment that is intended to can explode or produce a fireball.

When igniting balloons with a long Bunsen burner, or other method, approach the balloon from the side, about mid-point in the balloon (the equator), and such that the tip of the burner tube is well below the point at which the balloon will burst. This is to prevent the rapidly exiting balloon contents from extinguishing the burner, and in the case of dense hydrocarbon gases, to direct the fireball in a safe direction (the fireball will propel outward from the point of balloon skin compromise).

These hearing protection recommendations are not conservative.
H2 (external air only) - hearing protection suggested
2H2 + O2 - hearing protection highly recommended
CH4 (external air only) - hearing protection not needed, heat/fireball
CH4 + 2O2 - hearing protection highly recommended
C3H8 (external air only) - hearing protection not needed, substantial heat/fireball
C3H8 + 5O2 - hearing protection highly recommended
C4H10 (external air only) - hearing protection not needed, substantial heat/fireball
C4H10 + 61/2O2 - hearing protection highly recommended
C2H6 + 7/2O2 - hearing protection highly recommended
C2H4 + 3O2 - hearing protection essential, experimenter should orient body non-frontally relative to balloon (do not face balloon, shock wave is substantial)
C2H2 + 5/2O2 - hearing protection essential, experimenter should orient body non-frontally relative to balloon (do not face balloon, shock wave is substantial) acetylene not available effective Summer session 2005+

Heat Energy vs Sound Energy -- Total energy per mole butane
(9")(0.1 mole)butane, (12")(0.2 mole)butane, (12")(0.1 mole)butane+(0.1 mole)Oxygen
(9") C4H10, (12") C4H10, (12") C4H10 + O2

We use twelve-inch balloons (except for acetylene, ethane and ethylene) in GPH (~550 seats, high ceiling). In 120 Latimer (~150 seats, normal height ceiling), we sometimes use twelve-inch balloons, but nine-inch probably would be adequate. For acetylene-oxygen, a nine-inch balloon filled to less than capacity (perhaps to about 6-8 inches diameter is plenty - perhaps excessive). We squirt a couple of milliliters of water into balloons before filling - thinking, perhaps wrongly, that this will reduce the chance of problems due to static electrical buildup.
[ Note: On Jan 26, 2005, we did have an uncommanded explosion of an acetylene-oxygen balloon, almost certainly due to static discharge -- and we did use water in the balloon. -- more information to be added shortly. ]

Acetylene without oxygen results in a sooty flame, and is not advised. Butadiene has been used resulting in an excellent fireball (a dark red color inside a smoky envelope which is consumed), and seems soot-free, but there may be toxicity issues, and butadiene seems to seep through balloons (as do butane and acetylene).
Heat producing exploding gases will, upon exploding, frequently ignite the balloon, which will melt and drip (onto your hand - we have found out the hard way).

Rev. 20050816