For each fuel, ignition occurs only within a certain range of concentration, known as the upper and lower flammability limits. For example, for methane and gasoline vapor, this range is 5-15% and 1.4-7.6% gas to air, respectively. An explosion can only occur when fuel concentration is within these limits.
When the mixture of natural gas and air reaches the correct composition (between 5% and 15% gas) any spark or flame is enough to create a violent gas explosion.
Is Natural Gas Explosive? A natural gas leak can create an explosion if there is an ignition source and the leak is severe enough. While this is fairly rare, gas leaks are incredibly dangerous and should be handled with urgency.
There Is the Potential for a Gas Explosion
Possibly the greatest danger of all that could result from a gas leak is an explosion. Even a small leak in a confined space that builds up over time can cause an explosion if there is a spark or some sort of ignition source.
Natural gas has a flammability range of approximately 5 to 15 percent. That means that any mixture containing less than 5 percent or greater than 15 percent natural gas to air would not support combustion. Natural gas, when mixed with air and exposed to an ignition source, is combustible.
Atmospheres with a concentration of flammable vapors at or above 10 percent of the lower explosive limit (LEL) are considered hazardous when located in confined spaces. However, atmospheres with flammable vapors below 10 percent of the LEL are not necessarily safe. Such atmospheres are too lean to burn.
At a concentration in air lower than the LFL, gas mixtures are "too lean" to burn. Methane gas has an LFL of 4.4%. If the atmosphere has less than 4.4% methane, an explosion cannot occur even if a source of ignition is present.
Is a small gas leak dangerous? Yes, it is. A small gas leak can still catch on fire and trigger an explosion from another fire source or electrical spark.
Gas leaks are subtle in smell but very obvious in bills. They can even go on for months undetected. But if there's a significant amount of gas escaping from your system, it can cause a spike in your gas bill. Pay attention to any sudden changes in your monthly invoice.
Typically, you'll need to allow your home to air out for fifteen minutes to a few hours, but the exact timeframe depends on the severity of the leak and wind conditions in your area.
"If you smell natural gas and you have an attached garage, don't start your car. It could trigger an explosion."
The most obvious sign of a gas leak is a stinky smell. Gases used in homes for appliances and heating are odorless, so manufacturers add ethyl mercaptan because its potent “rotten egg” smell is easily noticeable. People sometimes say gas smells like sulfur or cooked cabbage.
At 75% gas, a person is immediately incapacitated and death will occur in a matter of minutes.
Natural Gas Explosion Prevention
There are about 286 serious natural gas explosions per year. These are the type of gas explosions that cause property damage, severe injury, or loss of life.
Small gas leaks may not have a smell or other physical signs. However, if there is a gas leak in the home, a person may notice: the smell of sulfur or rotten eggs. a hissing or whistling sound near a gas line.
Sickness and Fatigue
Exposure to a slow gas leak in your house or apartment may cause deadly symptoms including sickness, weakness, nausea, suffocation, and headaches. If you feel sick or abnormal, immediately call an ambulance to confirm if you have been exposed to gas poisoning.
Gas leaks are very common in our home. They can be very dangerous due to the increased chances of them causing a fire, explosion or even carbon monoxide poisoning. They can go unnoticed for a long period of time because some of them, such as carbon monoxide is colorless and also odorless.
Remember it's important call the National Gas Emergency Service number if you smell gas or suspect a gas leak as quickly as possible to avoid putting yourself in further danger.
This is the dust combustibility range which is LEL 2.5ug/m³ and 15mg/m³. This is called the minimum explosive concentration (MEC).
Remember that gasoline is highly volatile! Just one gallon of gasoline is equivalent to 14 sticks of dynamite in explosive force. GASOLINE SAFETY: Vapors from gasoline are also dangerous!
Oxygen, heat, and fuel are frequently referred to as the "fire triangle." Add in the fourth element, the chemical reaction, and you actually have a fire "tetrahedron." The important thing to remember is: take any of these four things away, and you will not have a fire or the fire will be extinguished.
LEL sensors measure percent of LEL. For example, Gasoline has an LEL of 1.4%. Therefore, 100% of LEL is 14,000 ppm of gasoline, 10% of LEL is 1,400 ppm of gasoline and 1% of LEL is 140 ppm of gasoline.