|Thermal Oxidizer | High Level VOC's | VOC Control | High LEL's
At concentration in air below the LEL there is not enough fuel to continue an explosion.
Concentrations lower than LEL are "too lean" to burn. eg: Methane gas has a LEL of 4.4% (at 138
degrees C) by volume, meaning 4.4% of the total volume of the air consists of methane. At 20
degrees C the LEL is 5,1 % by volume. If the atmosphere has less that 5.1% methane, an explosion
cannot occur even if a source of ignition is present.
When methane(CH4)concentration reaches 5% an explosion can occur if there is an ignition
source. Each combustible gas has its own LEL concentration. These percentages should not be
confused with LEL instrumentation readings. Instruments designed and calibrated to read LEL also
read as percent values. A 5% displayed LEL reading for methane for example would be equivalent
to 5% divided by 5.1% methane by volume at 20 degrees C.
Thermal oxidation systems can release a significant quantity of energy during the oxidation process.
If the system is not designed properly, this energy release could result in harm to operating
personnel or damage to the thermal oxidizer.
In regenerative thermal oxidizers (RTO) safety issues relate primarily to the potential of fire or
explosion from auxiliary fuels or from waste streams with high VOC loadings. Common causes of
accidents include condensation and collection of VOCs in the ductwork, process upsets resulting in
unexpected high concentrations VOCs, inadequate or missing safety-related detectors or safety
interlocks, improper placement of detectors, and equipment or instrumentation failures.
American Environmental Fabrication & Supply LLC Fax: +1 (918) 772-3536
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AEFS Regenerative Thermal Oxidizer Systems
(RTO) controls, regulates and continually
monitors gas and vapor concentrations to be
maintained outside the lower explosive limits.
This is a major consideration when purchasing
your system as it relates to occupational safety
Lower Explosive Limit (LEL): The explosive limit
of a gas or a vapor is the limiting concentration
(in air) that is needed for the gas to ignite and
explode. The lowest concentration (percentage)
of a gas or a vapor in air capable of producing a
flash of fire in presence of an ignition
source(arch, flame, heat).
Air Pollution Control Equipment
American Environmental Fabrication & Supply, LLC
Call +1 (918) 708 - 1253