If you work around sources of gas that are flammable, you may have noticed the term LEL, a term that is short for Lower Explosive Limit. Monitoring for hazardous levels of LEL is important if you want to maximize safety and minimize the risk of fire or explosions in your facility. The terms “gas monitor” and “gas detector” are sometimes used interchangeably when monitoring for explosive gases. 

If there is a risk that hazardous levels of combustible gas may be present, safety and insurance conditions may require a fixed combustible gas detection system and/or portable gas detectors. Both types of products will help you monitor the combustible gas concentration in your facility and will provide early warning in the unfortunate event a leak were to occur. 

Defining LEL (Lower Explosive Limit)

What is LEL? LEL stands for “Lower Explosive Limit” and is the lowest percentage concentration of a particular gas that has the potential to be flammable. Most gases have a lower explosive limit (LEL) and an upper explosive limit (UEL). Below the lower limit, there is insufficient gas for the mixture to ignite. Above the upper limit, there is insufficient oxygen to support combustion.

For example, methane or natural gas has a 5% by volume LEL and 17% by volume UEL. The upper limit is not important when considering the risk of explosion, but if the percent volume of methane present was 5% gas (95% AIR) then the gas monitor would display 100% LEL. 

LEL Gas Detection Options

When trying to measure the LEL level inside a building or confined space, there are two different types of detectors: portable gas detectors and fixed gas detectors. 

Portable gas detectors are often issued to maintenance personnel and will emit a loud warning tone if combustible gas is present. This can give the wearer time to evacuate the area, but unless someone is present in an area, the presence of combustible gas will not be identified. 

Fixed LEL gas detectors are permanently installed in a facility and monitor the atmosphere for combustible gases 24 hours per day, seven days per week. This is very important, as dangerous leaks or spills may go unnoticed during nights or weekends.

Fixed LEL detectors are typically installed close to sources of leaks, adjacent to air handler return vents or in the ceiling of an enclosed building or room. In most cases, fixed LEL monitors are connected to a central controller that can sound warning tones or activate strobe lights in the monitored area as well as in a centrally-located control room. The GASMAX II or GASMAX CX are examples of a fixed gas monitor or detector. 

Another type of LEL monitor is called a Sample Draw Monitor or Sample Draw Detector. This device uses a pump to pull a sample from a remote location and push it across the sensor. A sample draw monitor allows the gas detector to be mounted in an area that provides easy access and maintenance while sampling air inside confined spaces like paint cabinets or combustible gas storage rooms. The GDS-58NXP is an example of a sample draw monitor. 

Pro Tip: Protect your facility from the risk of explosion by installing a fixed combustible gas detection system to reliably detect the flammable levels of your gas materials.

Install Gas Detection in Your Facility  

To abide by the local and federal regulations of storing combustible materials, it’s crucial to have a reliable gas detection system in your warehouse. With industry-grade accuracy and nationally recognized hazardous area certifications, our LEL gas monitors/detectors will keep your facility safe.

Does your industry store or work with combustible gases? Connect with our engineers to help you design and install a system to monitor for the presence combustible gases.