The Lower Explosive Limit (LEL) and Flammable Vapors
Certain conditions must exist for a fire or explosion to occur involving flammable gases
The gas and oxygen must exist in specific proportions to create an optimal ratio. With an ignition source, such as a spark or flame, the gas will ignite or combust. However, the fuel and oxygen ratio will vary depending upon the gas or vapor in the area. The minimum concentration of a specific gas or vapor that will support combustion is defined as the Lower Explosive Limit (LEL) for that gas. Below this level, the mixture is considered too lean to burn. This means that there is too much air and not enough gas present. The maximum concentration of a gas or vapor that will burn is defined as the Upper Explosive Limit (UEL). Anything above this level is considered too rich to burn. There is too much gas present and not enough air. But between the range of the LEL and the UEL, combustible and flammable gases will burn or explode.
Lower Explosive Limit and Upper Explosive Limit Values
The flammable range is considered the values between the LEL and UEL. At these ratios, the combustible and flammable gases and vapors will burn or explode if an ignition source is present.
Flammable gases such as Butane, Ethane, Hexane, Hydrogen, Methane and Propane may be present in a workplace. For additional gases, you may want to consult a more comprehensive list.
NevadaNano’s LEL Sensors and the Lower Explosive Limit
NevadaNano’s Molecular property Spectrometer (MPS) is the next generation of gas detection. These LEL sensors enhance worker safety by providing accurate leak detection in many industries. These industries include drilling, transportation, and the production of oil, gas, and chemical products. Users can trust that these sensors will deliver an accurate LEL reading.
These smart LEL sensors have built-in environmental compensation. They can detect and report on over a dozen gases and gas mixtures. The reading can accurately provide this information and concentration to the user in an easy-to-understand format. The LEL values for a mixture of gases achieve the same accuracy as single gas detection. Additional intelligent algorithms enable the determination of the class of gas present.
As the world’s first intelligent flammable gas LEL sensors, they provide accurate readings. This is true even when exposed to rapid temperature and humidity changes. Other sensors may temporarily shut down when faced with common environmental changes. These new capabilities eliminate false positives, nuisance alarms, and false negatives, providing improved ease of use and user safety. Equipped with built-in environmental monitoring, the advanced algorithms of the MPS enable accurate results. These results are achieved even in temperatures ranging from -40˚C to 75˚C.
The MPS LEL sensor uses a micro-electromechanical system (MEMS) transducer. This transducer consists of an inert, micrometer-scale membrane with an embedded heater and thermometer. The MEMS transducer measures changes in the thermal properties of the surrounding air and gases in its proximity. The output reading contains multiple measurements, similar to a thermal spectrum. And environmental data that can be used to identify the type and concentration of any flammable gases present.
The MPS Flammable Gas Sensor is intrinsically safe, robust, and highly poison-resistant. It is calibrated for all gases by performing a single calibration with methane. The MPS sensor is the best option for accurate readings of Lower Explosive Limits of gas and vapor concentrations.
