What does LEL Mean? What is an LEL Gas Detector?

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What does LEL Mean? What is an LEL Gas Detector?

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Gas detection and other processes associated with it are important in construction, oil and gas, and many other industries. These procedures are crucial in maintaining safety. If a leak occurs, it may put people’s health or even lives at risk. However, it is possible to prevent such a negative scenario. In this article, you will find out about LEL and LEL gas detectors.

What is LEL?

LEL (Lower Explosive Limit) is the lowest gas/vapor concentration (by percentage) in air that can produce a flash of fire if there is a source of ignition nearby, for example flame, arc, etc.

Note that LEL is not the same for all gases, however, for most flammable gases it is less than 5% (by volume). It means that relatively low gas/vapor concentration is needed for a high risk of explosion.

If to consider special gas-detection systems, the amount of gas percent is specified as the percentage of LEL. 0% LEL means that there is a combustible gas-free atmosphere. On the other hand, 100% LEL means that gas is at the lower flammable limit in an atmosphere.

It is important to know that there are 3 components for a fire to ignite and burn: heat, fuel, oxidizing agent. In order to prevent or extinguish the fire, you need to remove one of these components.

What is an LEL Gas Detector?

An LEL gas detector is a special device designed to detect dangerous levels of combustible gases or solvent vapors in air. The results of this detection are shown in percent LEL.

Nowadays, devices that can detect the lower explosive limit of gases are more accurate than their predecessors. Thanks to well-developed modern technologies, early warnings are now possible. As a result, hazards are identified faster.

How does an LEL Gas Detector Work?

Let’s consider the working principle of an LEL gas detector.

In each LEL gas monitor, there is a built-in sensor. The most common one is considered to be a catalytic bead combustible sensor. For gas detection, the process of catalytic oxidation is used.

Let’s take a closer look at the catalytic bead sensor.

LEL gas monitor

Essentially, there are 2 coils of fine platinum wire. Each of them is embedded in a bead, connected electrically in a Wheatstone bridge circuit, which is used to measure an unknown electrical resistance by balancing two legs of a bridge circuit, one leg of which includes the unknown component. One of the undeniable benefits of this circuit is providing accurate measurements.

In a catalytic bead sensor, one of the beads is active, and the other one is used as a reference. To the active bead, voltage is applied. The bead is heated to a point that sustains combustion. Detectable gas is introduced and the active bead heats up more, which causes a measurable change in electrical resistance. As a result, we have the % LEL reading on our gas monitor.

Before working with your LEL gas monitor, it is important to calibrate it to the target gas so the sensor is programmed to detect the gas expected to infiltrate the workplace. After that, don’t forget to set the alarm on your gas detector when the gas reaches a certain % LEL. Most devices have default alarm settings.

The Best LEL Gas Monitors

When it comes to safety, there should be no compromises. To measure the lower explosive limits of combustible gases, you will need a reliable gas detector. On Mega Depot, you can choose from a selection of best-in-class gas monitors. These devices are known for their excellent performance yet they are pretty affordable as well. In addition, the detectors are user-friendly, everything was made for simple operation and maximum efficiency. Let’s consider some of them in more detail.


Hopefully, now you can answer the following questions: What does LEL stand for?, What is LEL on a gas detector?, you also know what an LEL gas detector is and how it works. In addition, we recommended top-quality devices for accurate measurements. Choose from these and other solutions on our website!

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