what is lel and hel

What is LEL and UEL in gas?

LEL and UEL Explained (Explosive Gas) The lower explosive limit (LEL) is the minimum concentration of a specific combustible gas required to fire combustion when in contact with oxygen (air). If the concentration of the gas is below the LEL value, the mix between the gas itself and the air is too weak to spark.

What is Lel in gas detection system?

In g as detection systems the amount of gas present is specified as a percentage (%) of LEL. Zero percent Lower Explosive Limit (0% LEL) denotes a combustible gas-free atmosphere. One hundred percent lower explosive limit (100% LEL) denotes an atmosphere in which gas is at its lower flammable limit.

What is meant by 100% LEL?

One hundred percent lower explosive limit (100% LEL) denotes an atmosphere in which gas is at its lower flammable limit. The relationship between percent LEL and percent by volume differs from gas to gas. The example below demonstrates the flammability of Methane (Natural Gas) in Air.

What is Lel in calibration?

If you spend much time working with Calibration Gas it's very likely that you will see the term LEL used extensively. LEL, short for Lower Explosive Limit, is defined as the lowest concentration (by percentage) of a gas or vapor in air that is capable of producing a flash of fire in presence of an ignition source (arc, flame, heat).

What is meant by LEL and UEL?

Lower explosive limit (LEL): the lowest concentration of gas or vapour which will burn or explode if ignited. Upper explosive limit (UEL): the highest concentration of gas or vapour which will burn or explode if ignited. From the LEL to the UEL, the mixture is explosive.

Whats does LEL mean?

The Lower Explosive Limit (LEL) is the lowest concentration of a gas or vapour that will burn in air. The Lower Explosive Limit (LEL) varies from gas to gas, but for most flammable gases it is less than 5% by volume.

What does LEL mean in confined space?

the lower explosive limitSection 1915.12(b)(3) Flammable atmospheres. 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.

What is LEL and UEL of methane?

Methane - LEL.. 5% by volume in Air / UEL.. 17% by volume in Air.

What does LEL mean on a gas monitor?

lower explosive limitThe lower explosive limit (LEL) of any given gas is the lowest point of concentration (percentage by volume) at which it becomes flammable in the atmosphere. A 0% LEL would indicate a combustible gas-free atmosphere.

What is LEL and UEL of hydrogen?

The lower and the upper explosion values (LEL and UEL) define the required level of concentration by type of gas. Explosions will occur for gas concentrations within the LEL and the UEL value, not above or below, and the maximum explosive power will be for concentration at the midpoint of the flammable range.

What is difference between LEL and LFL?

Lower flammability limit (LFL): The lowest concentration (percentage) of a gas or a vapor in air capable of producing a flash of fire in the presence of an ignition source (arc, flame, heat). The term is considered by many safety professionals to be the same as the lower explosive level (LEL).

What does LEL mean OSHA?

Lower explosive limitLower explosive limit (LEL) means the minimum concentration of vapor in air below which propagation of a flame does not occur in the presence of an ignition source.

What is the difference between LEL and PPM?

ppm: gas volume percentage per million, it is a dimensionless unit. i.e.: 5ppm carbon monoxide means that the air contains 5 per million of carbon monoxide. 2. LEL: the minimum volume percentage concentration of combustible gas in air that can detonate, that is, the lower limit of gas explosion concentration.

What is LEL and UEL of so2?

Molar Mass: 64.07 g/mol. Flash Point: - Lower Explosive Limit(LEL): - Upper Explosive Limit(UEL: - TWA: 2ppm.

What is a safe LEL level for hot work?

What concentration is safe? Safety concentrations are not specified under OSHA's Process Safety Management standard. But OSHA's Confined Space Standard specifies a maximum percent LEL of 10 percent for work inside a confined space.

Why is LEL important?

Why is the LEL Important? Because most gases are engaged when they are predominately lean, they would have to increase in richness to become explosive. This means the LEL would be the primary indicator of when a gas is moving into the danger zone to become explosive.

How does a LEL detector work?

Combustible-gas detectors are generally catalytic-bead sensors. They measure in the 0-100 per cent LEL range. The LEL (lower explosive limit) is basically the concentration of gases that could go “boom” when they hit 100 per cent, if there were an ignition source.

What is UFL and LFL?

The lower flammability limit (LFL) identifies the smallest mixture able to sustain a flame. The upper flammable limit (UFL) identifies the richest flammable mixture. A quantifiable difference exists between the flammability limit and explosive limit.

What's KEK mean?

The main meaning of “kek” is “lol,” or, “laugh out loud.” This word is an interesting one. It's used to show a comical reaction to something. That is to say that someone's actions, words, or current situation caused the reader to “laugh out loud.”

What is the means of LOL?

laugh out loudlaugh out loud; laughing out loud.

1-Detection of Gases, Gas Concentration Measurements

Before going into the details of LEL and UEL concepts, it is useful to have information about the importance of gas detection systems and gas-related hazards. For more information, you can read article Detection of Gases.

2- What are LEL and UEL?

LEL and UEL are the abbreviations of the English words “Lower Explosive Limit” and “Upper Explosive Limit”, respectively. (Also used as LFL and UFL.)

5- What is PPM?

It is an abbreviation for “parts per million”. Similar to the percentage (%) that is frequently used, the ppm measure is not a dimensional measurement unit like kg or L, but a dimensionless measure that indicates the ratio of substances in mixtures to the whole mixture.

How to find LEL of gas?

To compute the LEL of any gas in air, divide the unknown concentration by the LEL listed in the NFPA Handbook. 100% LEL's for 9 of Gasco's more common gasses are shown in the table above. For example, if you take 2.5% Methane in air and divide it by 100% LEL of methane (5%), the result is 50% LEL. (2.5% ÷ 5% = 50%) The same theory can be applied to any of the gasses listed here. Conversely you can multiply the % LEL of the unknown concentration by the 100% LEL to obtain the % by volume. (50% LEL methane x 5% = 2.5% volume).

What does LEL stand for in a gas?

LEL, short for Lower Explosive Limit, is defined as the lowest concentration (by percentage) of a gas or vapor in air that is capable of producing a flash of fire in presence of an ignition source (arc, flame, heat).

What is the concentration of methane in air?

In concentrations of 0-5% Methane in air, the mixture is too lean to ignite or burn. Methane concentrations between 5% and 17% will support ignition and are considered highly flammable. At levels above 17%, the atmosphere is too rich for the methane to ignite.

What are the elements that make up a fire?

It's also important to remember that in order to ignite and burn, a fire requires three elements: heat, fuel, and an oxidizing agent (usually oxygen). The fire can be prevented or extinguished by removing any one of these elements.

Is methane flammable without oxygen?

Since air is made up primarily of 20.9% Oxygen with the balance being nitrogen, if you take Oxygen out of the equation, the methane is no longer flammable at any concentration. This is important when ordering mixtures with no oxygen content; without oxygen, LEL is not a factor. URL Name.

How to find LEL of gas?

To compute the LEL of any gas in air, divide the unknown concentration by the LEL listed in the NFPA Handbook. 100% LEL’s for 9 of Gasco’s more common gasses are shown in the table to the left. For example, if you take 2.5% Methane in air and divide it by 100% LEL of methane (5%), the result is 50% LEL. (2.5% ÷ 5% = 50%) The same theory can be applied to any of the gasses listed here. Conversely, you can multiply the % LEL of the unknown concentration by the 100% LEL to obtain the % by volume. (50% LEL methane x 5% = 2.5% volume).

What does LEL stand for in calibration gas?

If you spend much time working with calibration gas, it’s very likely that you will see the term “LEL” used extensively. LEL, short for “Lower Explosive Limit“, is defined as the lowest concentration (by percentage) of a gas or vapor in air that is capable of producing a flash of fire in presence of an ignition source (arc, flame, heat, etc.). Concentrations lower than the Lower Explosive Limit are ‘too lean’ to burn; those above the Upper Explosive Limit (UEL) are too rich to burn.

What are the elements that make up a fire?

It’s also important to remember that in order to ignite and burn, a fire requires three elements: heat, fuel, and an oxidizing agent (usually oxygen). The fire can be prevented or extinguished by removing any one of these elements.

Is methane flammable without oxygen?

Since air is made up primarily of 20.9% Oxygen with the balance being nitrogen, if you take Oxygen out of the equation, the methane is no longer flammable at any concentration. This is important when ordering mixtures with no oxygen content; without oxygen, LEL is not a factor.

Is 5% methane flammable?

In concentrations of 0-5% Methane in air, the mixture is too lean to ignite or burn. Methane concentrations between 5% and 17% in will support ignition and are considered highly flammable. At levels above 17%, the atmosphere is too rich for the methane to ignite.

What is the LFL reading on a combustible air monitor?

Percentage reading on combustible air monitors should not be confused with the LFL concentrations. Explosimeters designed and calibrated to a specific gas may show the relative concentration of the atmosphere to the LFL—the LFL being 100%. A 5% displayed LFL reading for methane, for example, would be equivalent to 5% multiplied by 4.4%, or approximately 0.22% methane by volume at 20 degrees C. Control of the explosion hazard is usually achieved by sufficient natural or mechanical ventilation, to limit the concentration of flammable gases or vapors to a maximum level of 25% of their lower explosive or flammable limit .

What is the flammability limit?

Flammability limit. Mixtures of dispersed combustible materials (such as gaseous or vaporised fuels, and some dusts) and oxygen in the air will burn only if the fuel concentration lies within well-defined lower and upper bounds determined experimentally, referred to as flammability limits or explosive limits.

What is the flammability rating of Class II liquids?

Class II liquids with a flash point equal to or greater than 100 °F (38 °C), but less than 140 °F (60 °C) and class IIIA liquids with a flash point equal to or greater than 140 °F (60 °C), but less than 200 °F (93 °C) have a NFPA 704 flammability rating of 2.

What is the UFL?

Upper flammability limit (UFL): Highest concentration (percentage) of a gas or a vapor in air capable of producing a flash of fire in the presence of an ignition source (arc, flame, heat). Concentrations higher than UFL or UEL are "too rich" to burn. Operating above the UFL is usually avoided for safety because air leaking in can bring the mixture into combustibility range.

What is the difference between deflagration and detonation?

A deflagration is a propagation of a combustion zone at a velocity less than the speed of sound in the unreacted medium. A detonation is a propagation of a combustion zone at a velocity greater than the speed of sound in the unreacted medium.

What are the factors that affect flammability?

Temperature, pressure, and the concentration of the oxidizer also influences flammability limits. Higher temperature or pressure, as well as higher concentration of the oxidizer (primarily oxygen in air), results in lower LFL and higher UFL, hence the gas mixture will be easier to explode. The effect of pressure is very small at pressures below 10 ...

What is the flash point of Class IIIB?

Class IIIB liquids with a flash point equal to or greater than 200 °F (93 °C) have a NFPA 704 flammability rating of 1

What is the LEL of methane?

Using methane in air as an example, the LEL of methane is 5% by volume. So an LEL Detector or an LEL analyzer, working as part of a complete LEL Gas Detection System, that’s calibrated to detect methane in air in a range of 0-100% LEL Methane will detect the presence of methane in air between 0-100% LEL, or 0-5% by volume. An LEL Meter in a fixed gas detection system calibrated for 0-100% LEL methane when reading 50% LEL methane will read the equivalent of 2.5% Methane by volume in air.

What is a LEL detector?

An LEL Detector or LEL Meter detects dangerous levels of a combustible gas or solvent vapor in air, expressed in percent Lower Explosive Limit, or LEL. An LEL Detector is an integral part of a complete gas detection system and can be referred to as a Gas Detector or just a fixed gas detection system.

What sensors are used in LEL detection?

It is also important to understand the differences and apply the correct LEL Meter sensor technology to the application for LEL safety. Catalytic Bead sensors and Infrared sensors are used in LEL Detection, and each has advantages and disadvantages that need to be fully understood before selecting the proper technology to be used in a fixed gas detection system that uses an LEL analyzer.

Is LFL the same as LEL?

LFL is the same as LEL. Combustible Gases and Solvents also have an Upper Flammable Limit (UFL), which is the same as with UEL, or Upper Explosive Limit. An LEL Detector simply detects, indicates and alarms for levels between 0-100% LEL of materials it is calibrated to monitor and detect.

Is a combustible fuel/air mixture hazardous?

Generally, the dangerous areas where these combustible materials remain or get used are regulated by local, state and federal entities, and designated as hazardous locations.

1-Detection of Gases, Gas Concentration Measurements

2- What Are Lel and UEL?

3- What Is %Lel?

• LEL and UEL dimensions indicate the ratio of flammable gas to the mixture of flammable gas and air by volume. To elaborate on the frequently used methane gas example, the air mixture containing 5% methane is flammable-explosive. Even when the methane content of the mixture is increased up to 15%, it remains flammable. A mixture outside this range i...

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4- What Is %Vol?

5- What Is Ppm and Ppb?

6- What Is Mg/M3?

7- How to Make %LEL – %Vol – Ppm Conversions?