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Topic: Lower explosive limit


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In the News (Mon 24 Nov 14)

  
  Explosive limit - Wikipedia, the free encyclopedia
The explosive limit of a gas or a vapour, is the limiting concentration (in air) that is needed for the gas to ignite and explode.
Concentrations of explosive gases are often given in terms of percent of lower explosive limit (%LEL).
Controlling gas and vapor concentrations outside the explosive limits is a major consideration in occupational safety.
en.wikipedia.org /wiki/Explosive_limit   (271 words)

  
 CANUTEC - Articles English - Confined Space   (Site not responding. Last check: 2007-10-17)
Explosive limits (also known as “flammable limits”), expressed in percentage (%), may be defined as the minimum and maximum concentrations of a flammable gas or vapour between which ignition can occur.
It is important to note that the explosive limits are normally for gas or vapour / air mixtures.
Explosion-proof fans may be used to lower the vapour concentrations to below the material’s LEL but employees must ensure the contaminated air discharged from the confined space is not hazardous to workers outside.
www.tc.gc.ca /canutec/en/articles/documents/confined.htm   (1678 words)

  
 eLCOSH : An Assessment of Metal Maintenance Workers' Solvent Exposures
Given the limited resources for the study, the authors decided to focus on work in closed elevator cars and not to characterize the hazards during refinishing of other metal surfaces (surfaces that are not in elevators).
A Biosystems PHD Flammable Vapor Meter was used to measure the maximum percentage of the lower explosive limit reached during the performance of stripping and spraying tasks.
In all cases in which 10% of the lower explosive limit was exceeded, the 10% level was reached within two to five minutes of door closure.
www.cdc.gov /elcosh/docs/d0100/d000013/d000013.html   (5679 words)

  
 [No title]   (Site not responding. Last check: 2007-10-17)
Underground construction gassy operations may be declassified to potentially gassy when air monitoring results remain under 10 percent of the lower explosive limit for methane or other flammable gases for three consecutive days.
This subsection applies in addition to the requirements for blasting and explosives operations, including handling of misfires, which are found in chapter 296-52 WAC.
Limit switches are to be used only to limit travel of loads when operational controls malfunction and shall not be used as a substitute for other operational controls.
www.leg.wa.gov /WAC/index.cfm?section=296-155-730&fuseaction=section   (7893 words)

  
 Moderate Risk Waste   (Site not responding. Last check: 2007-10-17)
When the concentration exceeds 10 percent of the lower explosive limit, the workers would be alerted by an alarm and can then take actions to prevent the concentrations from increasing to critical (combustible or explosive) levels.
Because the generation of the potentially explosive flammable vapors is associated with active waste handling, it is most appropriate to have the explosive gas monitoring system permanently installed in that area.
Multiple explosive (combustible) gas sensors can be used to provide coverage at different heights to provide safety redundancy in case a sensor malfunctions Multiple sensors would also be called for in order to monitor different working locations where explosive vapors may be expected to be generated.
www.ecy.wa.gov /programs/swfa/mrw/answer2.html   (837 words)

  
 STYRENE - (Organic Method #09)
The reliable quantitation limit and detection limits reported in this method are based upon the optimization of the instrument for the smallest possible amount of styrene.
This detection limit was established by injecting 1.0 µL of an analytical standard of 1.8 µg/mL concentration into a gas chromatograph.
This limit was found by plotting the amount of styrene spiked on the 100-mg portion of the charcoal tube against the amount recovered (Figure 4.2.).
www.osha.gov /dts/sltc/methods/organic/org009/org009.html   (2811 words)

  
 Chapter 296-304 Part 1 - Ship repairing, shipbuidling, and shipbreaking
Lower 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.
WAC 296-304-020(2) Definition of “Lower explosive limit.” The terms lower flammable limit (LFL) and lower explosive limit (LEL) are used interchangeably in fire science literature.
WAC 296-304-020(2) Definition of “Upper explosive limit.” The terms upper flammable limit (UFL) and upper explosive limit (UEL) are used interchangeably in fire science literature.
www.lni.wa.gov /WISHA/Rules/shiprepairbuildingbreaking   (8118 words)

  
 Worker Right-To-Know
Lower temperatures cause a decrease, and there is a direct relationship between the temperature of any given substance and its vapor pressure.
So limiting the surface of a spilled liquid is a common strategy in responding to a spill of a liquid that is evaporating.
This lowers the vapor pressure of the liquid in the tank, and may significantly slow the release of the gases from the tank.
www.chemicalspill.org /WorkerRTK/chemicals1.html   (2483 words)

  
 World Intellectual Property Organization   (Site not responding. Last check: 2007-10-17)
The present inventors thus are disclosing herein a solution to the aforementioned problems, which is based on a technique for sensing the presence of air-borne organic fuel vapors on the basis of their ability to change the bulk thermal conductivity properties of air and by processing this measurable change to provide an approximately universal (i.
The inventors have found that sensor TC-output approximately relates to the fraction of the lower- explosive limit (LEL) of an air-fuel mixture, due to the finding that the LEL concentration of vapors is generally near 50-60% of their stoichiometric concentration.
4% LEL mixture) and the butane concentration is 1 vol% (i.
www.wipo.int /ipdl/IPDL-CIMAGES/view/pct/getbykey5?KEY=03/106985.031224&ELEMENT_SET=DECL   (7180 words)

  
 11/04/1976 - Clarification Paint Spray Booth and Spray Areas.
In summary, adequate sampling in accordance with recognized methods are essential in sustaining the violation by establishing that a hazard did in fact exist due to documented evidence that the toxic limits of the material were exceeded or that the concentrations were above 25 percent of the lower explosive limits were exceeded.
1910.94(c)(6)(ii) establishes a requirement that the vapor concentration in the booth be kept below 25 percent of the lower explosive limit.
Therefore, if the concentrations are kept below 25 percent of the lower explosive limit in all areas of the booth, even though the air velocities in the cross sectional area of the booth are below that defined by table G10, 1910.94(c)(6)(ii), it is doubtful that a citation could be legally sustained.
www.osha.gov /pls/oshaweb/owadisp.show_document?p_table=INTERPRETATIONS&p_id=18571   (914 words)

  
 Firehouse.Com HazMat Zone - 1995 Hazmat Studies - Class 2 - Compressed Gases
The only way to determine if a material is present in a mixture with air that is in its flammable range is to use a meter to monitor for the lower explosive limit of the material.
The rule of thumb according to the EPA is when you reach 25% of the lower explosive limit; it becomes too dangerous for personnel to proceed any further.
It has a LEL of 16% and a range of 16% to 25%, which is 10 percentage points.
www.firehouse.com /training/hazmat/studies/1995/03_gas.html   (2491 words)

  
 Gas Glossary Of Terms - Gas Terminology   (Site not responding. Last check: 2007-10-17)
Methane gas has a LEL of 5.53% by volume.
Combustible alarm systems are set to alarm at a low percentage of the LEL of the target gas.
A fifteen-minute TWA exposure which should not be exceeded at any time during a work day even if the eight-hour TWA is within limits.
www.process-controls.com /Alpha/AirTest_gasglossary.htm   (468 words)

  
 Definitions
Explosive (Flammable) Limits - the lower explosive (flammable) limit (LEL) is the lowest concentration of vapor in air which will burn or explode upon contact with a source of ignition.
The upper explosive (flammable) limit (UEL) is the highest concentration of vapor in air which will burn or explode upon contact with a source of ignition.
Explosive (Flammable) Range - the range between the lower explosive limit (LEL) and the upper explosive limit (UEL).
www.setonresourcecenter.com /MSDS/define.htm   (2012 words)

  
 NCDOT, Safety & Loss Control, SPP Manual, Chapter 14, Ventilation SPP# 1910.94   (Site not responding. Last check: 2007-10-17)
If the flush and purge ventilation is not successful in lowering the toxicity, flammability and/or threshold limit values, then PPE with air supplied or self contained air respirators should be specified to match the hazard.
Exhausted air from the spraying operation shall dilute the solvent vapor to 25 percent of the lower explosive limit of the solvent being sprayed.
Appendix A presents the lower explosive limits of common solvents and a formula to determine the cubic feet air volume required to dilute a vapor to 25 percent of the lower explosive limit.
www.ncdot.org /doh/safety/sppmanual/Chapter14/191094.html   (1900 words)

  
 Rimbach Publishing - Industrial Hygiene News - Articles   (Site not responding. Last check: 2007-10-17)
For instance a coarse combustible dust such as coal may burn well but not explode depending on how fine the dust is. To produce a conflagration the dust must have a sufficient surface area ratio to weight to sustain the rapid oxidation to create and sustain an explosion.
Above this limit the concentration of dust is so high that there is insufficient oxygen to oxidize the fuel and the unburned fuel stops the spread of the flame front.
The water stream agitated dust and formed a cloud of dust that passed between the LEL and UEL and the fire in the hopper provided a detonation source and serious explosions have occurred in the hopper.
www.rimbach.com /scripts/Article/IHN/Number.idc?Number=50   (2224 words)

  
 Ritec.com - Gas & Flame Detection Solutions
It is designed to monitor combustible gases and vapors within the lower explosive limit (LEL) and provide status indication and alarm outputs.
The Model IR2100 Infrared Point Detector is a microprocessor-based hydrocarbon gas detector that continuously monitors combustible gases and vapors within the lower explosive limit (LEL)* and provides alarm indication.
These concentrations are indicated over the range 0-99% LEL (lower explosive limit).
www.ritec.com /content/gasflame/combustible.html   (446 words)

  
 The ORCBS - Chemical Safety - Programs & Guidelines - Right To Know - Lower Explosive Limit   (Site not responding. Last check: 2007-10-17)
Lower Explosive Limit (LEL) (Also known as Lower Flammable Limit-LFL) - The lowest concentration of a substance that will produce a fire or flash when an ignition source (flame, spark, etc.) is present.
It is expressed in percent of vapor or gas in the air by volume.
Below the LEL or LFL, the air/contaminant mixture is theoretically too "lean" to burn (See also UEL).
www.orcbs.msu.edu /chemical/programs_guidelines/right_to_know/gloss/lower_explosive_limit.htm   (81 words)

  
 International-different-nomendature for exposure limit   (Site not responding. Last check: 2007-10-17)
There is only a limited band of gas/air concentration which will produce a combustible mixture.
The flammable range therefore falls between the limits of the LEL and UEL for each individual gas or mixture of gases.
Outside the limits, the mixture is not capable of combustion.
www.lenntech.com /Air-purification/International-different-nomendature-for-explosive-limits.htm   (341 words)

  
 [No title]   (Site not responding. Last check: 2007-10-17)
Certain federal pipeline safety regulations require that combustible gases in pipelines be detectable at one-fifth of the lower explosive limit by a person with a normal sensor of smell, either by the natural odor of the gas or by means of artificial odorization [].
Federal pipeline safety regulations  require that combustible gases in certain pipelines be detectable at one-fifth the lower explosive limit by a person with a normal sensor of smell, either by the natural odor of the gas or by means of artificial odorization [].
Important points are to state which pipelines require odorization, the detectable limits of gas odor, odorants and odorizing considerations, and monitoring a pipeline system to ensure that the odorization program is meeting the regulatory requirements.
www.unileoben.ac.at /~fink/papers/software/w2ltest.doc   (1068 words)

  
 Chapter 296-304 Part 2 - Ship repairing, shipbuidling, and shipbreaking
Artificial cooling of the metal surrounding the heated area may be used to limit the size of the area required to be cleaned.
A substantial cleat shall be nailed to the lower section to form a support for the upper section except when bolted connections are used.
(f) In order to limit spreading, the top ends of the side rails of both the trestle ladder and of the base section of the extension trestle ladder shall be beveled, or of equivalent construction, and shall be provided with a metal hinge.
www.lni.wa.gov /wisha/rules/shiprepairbuildingbreaking/HTML/304-2.htm   (11176 words)

  
 California Code of Regulations, Title 8, Section 8355. Confined and Enclosed Spaces and Other Dangerous Atmospheres, ...
Section 8354 Definition of "Lower explosive limit." The terms lower flammable limit (LFL) and lower explosive limit (LEL) are used interchangeably in fire science literature.
Section 8354 Definition of "Upper explosive limit." The terms upper flammable limit (UFL) and upper explosive limit (UEL) are used interchangeably in fire science literature.
An atmosphere with a measurable concentration of a flammable substance below 10 percent of the LEL may be above the permissible exposure limit for that substance.
www.dir.ca.gov /Title8/8355a.html   (1195 words)

  
 St. Mary's County Department of Public Works and Transportation - County Recycling & Solid Wate Division - Landfill ...   (Site not responding. Last check: 2007-10-17)
Methane is potentially explosive and is also a greenhouse gas that is considered thirty (30) times more potent than carbon dioxide.
Owners or operators of all municipal solid waste landfills must implement a routine monitoring program to ensure that the concentration of explosive gases generated by the facility does not exceed 25% of the lower explosive limit in structures and the lower explosive limit for the gases at the property boundaries.
This is the lowest percent by volume of a mixture of explosive gases in air that will propagate a flare at 25°C and atmospheric pressure.
www.co.saint-marys.md.us /dpw/recycle/landfillgasmonitoring.asp   (277 words)

  
 1998 Inspection Guidelines for Solid Waste Landfills (part 10)
(d) For purposes of this section, "lower explosive limit" means the lowest percent by volume of a mixture of explosive gases in air that will propagate a flame at 25 degrees Celsius and atmospheric pressure.
The lower explosive limit (LEL) of a combustible gas is the lowest concentration of that gas by volume in air that will explode, ignite, or burn when there is an ignition source.
The upper explosive limit (UEL) is the highest concentration of gas that will explode, ignite, or burn with an ignition source present.
www.ciwmb.ca.gov /LEAadvisory/54/54part10.htm   (1978 words)

  
 1926.800 Underground construction.
Air quality limits and control requirements for construction are found in §1926.55, except as modified by this section.
(viii) Whenever 10 percent or more of the lower explosive limit for methane or other flammable gases is detected in the vicinity of welding, cutting, or other hot work, such work shall be suspended until the concentration of such flammable gas is reduced to less than 10 percent of the lower explosive limit.
This paragraph applies in addition to the requirements for blasting and explosives operations, including handling of misfires, which are found in subpart U of this part.
www.setonresourcecenter.com /29CFR/1926/800.asp   (7032 words)

  
 Requirements for Airflow Through a Spray Booth
In most cases, this limit does not correlate to breakthrough of solid paint particulates from the filter media.
Technically, there are three criteria that should be met; (i) the air velocity through the spray booth should not fall below 100 fpm, (ii) the vacuum created in the exhaust plenum of the spray booth should not be large enough to cause the duct work and sheet metal to collapse.
In addition to the requirements in paragraph (c)(6)(i) of this section, the total air volume exhausted through a spray booth shall be such as to dilute solvent vapor to at least 25 percent of the lower explosive limit of the solvent being sprayed.
www.ronjoseph.com /Q&A/L1002_airflow_requirements.htm   (1115 words)

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