Mobile Toilet Explosion Experiment

The mobile toilet explosion experiment shows that under specific conditions, methane can trigger an explosion in a mobile toilet, but the amount of methane produced by human waste is insufficient to cause an explosion.

Experiment Purpose and Background

The experimental team conducted a mobile toilet explosion experiment to test whether methane could blow up a portable toilet. This experiment is from the documentary MythBusters, and it emphasizes that it should be carried out in a professional venue and should not be imitated.

Methane Production from Human Waste

When testing whether human waste could produce enough methane to cause an explosion, only a very small amount of methane was produced in the first flask, and the methane reading in the second test was still very low. This indicates that the amount of methane produced during the natural decomposition of human waste is extremely small, and it is impossible to produce enough methane to cause an explosion.

Experiment Process with Commercially Available Canned Methane

The subsequent test used commercially available canned methane. Methane was injected into the toilet and vented to a safe area a hundred feet away. The gas concentration needed to be maintained between 10% and 15%, as too much or too little would not cause an explosion. A dummy was used to block the holes to prevent methane leakage. During the first attempt to ignite it, due to the highly effective ventilation, the methane concentration dropped to 1.5% and failed to ignite. Afterwards, all ventilation openings were sealed, filling the toilet with methane. When ignited, the dummy caught fire but did not explode; it was because the toilet paper burned and then fell to burn the dummy's crotch.

Final Successful Explosion

The MythBusters team's Plan B was to first light a flare and then slowly feed gas until an explosion occurred. The lit flare was placed into the portable toilet, the toilet door was blown open, and finally, a successful spark was achieved. However, unexpectedly, the meter only measured a methane concentration of 0.9% when it was ignited. The problem lay in the position of the meter. It was likely that 0.9% was measured at the bottom, but the overall concentration had reached 15%. When the initial 15% was measured, the concentration was already too high, and the lighter could not ignite it at all because there was no oxygen. This further illustrates that a methane explosion requires an appropriate concentration range and sufficient oxygen and other conditions.