Petroleum jelly is a semi-solid blend primarily composed of mineral oils and waxes. It is widely used as a skin protectant and moisturizer. Many people wonder about its flammability, especially given its petroleum origins. Understanding how petroleum jelly interacts with heat and flame requires a closer look at the science of combustion.
Understanding How Substances Ignite
For any substance to ignite and burn, three elements must be present: fuel, oxygen, and an ignition source. This is often called the “fire triangle.” The fuel provides the material to burn, oxygen supports the chemical reaction of combustion, and an ignition source provides the initial energy. Without all three components, a fire cannot start or sustain itself.
Materials have distinct temperatures at which they produce enough flammable vapors to ignite. The “flash point” is the lowest temperature at which a liquid produces enough vapor to form an ignitable mixture with air. Above this, a momentary flash of fire can occur if an ignition source is introduced. The “fire point” is a slightly higher temperature where the substance produces enough vapor to sustain combustion for at least five seconds. Substances with lower flash points are generally considered more hazardous because they can ignite more easily at typical ambient temperatures.
Petroleum Jelly’s Ignition Profile
Petroleum jelly is a mixture of hydrocarbons, making it inherently combustible. However, it is not considered “flammable” in the same way highly volatile liquids like gasoline or alcohol are at room temperature. This distinction is important because petroleum jelly does not readily produce ignitable vapors under normal conditions. Its flash point typically ranges between 185°C to 210°C (365°F to 410°F).
For petroleum jelly to burn, it must first be heated significantly to melt and then vaporize. Only these vapors will ignite, not the liquid or semi-solid jelly itself. Once ignited, petroleum jelly burns slowly and steadily, similar to how candle wax burns. The heat from the flame continuously melts the jelly, allowing it to produce more vapors that sustain combustion. It does not explode or ignite spontaneously from a casual spark at room temperature.
Handling and Storing Petroleum Jelly Safely
Given its combustible nature, proper handling and storage of petroleum jelly prevent potential fire hazards. Keep petroleum jelly away from direct heat sources, open flames, and high temperatures. This includes avoiding storage near stoves, heaters, or in direct sunlight, which could cause it to melt and potentially reach its flash point if an ignition source is present.
A safety consideration involves its use in environments with increased oxygen concentrations, such as during oxygen therapy. While petroleum jelly is not highly flammable at room temperature, oxygen strongly supports combustion. Materials burn much more readily in oxygen-enriched environments. Therefore, using petroleum-based products around oxygen tanks or medical devices poses a fire risk. Healthcare professionals advise using water-based lubricants instead.