{"operation":"document","citation":"ERG 2024, ERG2024 Glossary","title":"ERG2024 Glossary","source_type":"guidance","agency":"U.S. DOT / Transport Canada / SICT","status":"guidance","official":true,"published_on":"2024-04-04","effective_on":null,"summary":"Official ERG2024 erg2024 glossary guidance, pages 371-381.","machine_formats":{"json":"https://regulus.evalyn.ai/document/phmsa-erg-2024-glossary.json","markdown":"https://regulus.evalyn.ai/document/phmsa-erg-2024-glossary.md"},"app_url":"https://regulus.evalyn.ai/document/phmsa-erg-2024-glossary","source_url":"https://www.phmsa.dot.gov/sites/phmsa.dot.gov/files/2024-04/ERG2024-Eng-Web-a.pdf#page=371","body":"GLOSSARY\nAdsorbed gas A gas which sticks (adsorbs) to the surface of a solid and porous\nmaterial (such as activated charcoal) contained within a metal\ncylinder. This results in an internal cylinder pressure of less than\n101.3 kPa at 20°C (14 psi at 68°F) and less than 300 kPa at 50°C\n(43 psi at 122°F). These pressures are much lower than those of\nconventional cylinders containing compressed or liquefied gases.\nAEGL(s) Acute Exposure Guideline Level(s), AEGLs represent threshold\nexposure limits for the general public after a once-in-a-lifetime,\nor rare, exposure and are applicable to emergency exposure\nperiods ranging from 10 minutes to 8 hours. Three levels AEGL-\n1, AEGL-2 and AEGL-3 are developed for each of five exposure\nperiods (10 and 30 minutes, 1 hour, 4 hours, and 8 hours) and\nare distinguished by varying degrees of severity of toxic effects;\nsee AEGL-1, AEGL-2 and AEGL-3.\nAEGL-1 AEGL‑1 is the airborne concentration (expressed as parts\nper million or milligrams per cubic meter [ppm or mg/m3]) of a\nsubstance above which it is predicted that the general population,\nincluding susceptible individuals, could experience notable\ndiscomfort, irritation, or certain asymptomatic, non‑sensory\neffects. However, the effects are not disabling and are transient\nand reversible upon cessation of exposure.\nAEGL-2 AEGL‑2 is the airborne concentration (expressed as ppm or mg/\nm3) of a substance above which it is predicted that the general\npopulation, including susceptible individuals, could experience\nirreversible or other serious, long‑lasting adverse health effects\nor an impaired ability to escape.\nAEGL-3 AEGL‑3 is the airborne concentration (expressed as ppm or mg/\nm3) of a substance above which it is predicted that the general\npopulation, including susceptible individuals, could experience\nlife‑threatening health effects or death.\nAir-Reactive See “Pyrophoric”.\nAlcohol-resistant foam A foam that is resistant to polar chemicals such as ketones and\nesters which may break down other types of foam.\nBLEVE Boil over Boiling Liquid Expanding Vapor Explosion\nA sudden increase in fire intensity associated with the expulsion\nof burning flammable liquid caused by the boiling of water that\nhas accumulated in the bottom of a tank car.\nPage 369\n\nGLOSSARY\nBurn Refers to either a chemical or thermal burn, the former may\nbe caused by corrosive substances and the latter by liquefied\ncryogenic gases, hot molten substances, or flames.\nCarcinogen A substance or mixture which induces cancer or increases its\nincidence.\nCategory A An infectious substance that poses a high risk to the health of\nindividuals and/or animals or public health. These substances can\ncause serious disease and can lead to death. Effective treatment\nand preventative measures may not be available.\nCategory B An infectious substance that poses a low to moderate risk\nto individuals and/or animals and/or public health. These\nsubstances are unlikely to cause serious disease. Effective\ntreatment and preventative measures are available.\nCBRN Chemical, biological, radiological or nuclear agent.\nCO2 Carbon dioxide gas.\nCold zone Area where the command post and support functions that\nare necessary to control the incident are located. This is also\nreferred to as the clean zone, green zone or support zone in\nother documents. (EPA Standard Operating Safety Guidelines,\nOSHA 29 CFR 1910.120, NFPA 472).\nCombustible In this guidebook, a solid or liquid capable of burning but\ndoes not catch fire as easily as a flammable liquid. See\n“Combustible Liquid”.\nCombustible liquid Liquids which have a flash point greater than 60°C (140°F) and\nbelow 93°C (200°F). U.S. regulations permit a flammable liquid\nwith a flash point between 38°C (100°F) and 60°C (140°F) to be\nreclassed as a combustible liquid.\nPage 370\n\nGLOSSARY\nCompatibility Group Control temperature Letters identify explosives that are deemed to be compatible.\nThe definition of these Compatibility Groups in this Glossary are\nintended to be descriptive. Please consult the transportation of\nhazardous materials/dangerous goods or explosives regulations\nof your jurisdiction for the exact wording of the definitions. Class\n1 materials are considered to be “compatible” if they can be\ntransported together without significantly increasing either the\nprobability of an incident or, for a given quantity, the magnitude\nof the effects of such an incident.\nA Substances which are expected to mass detonate very\nsoon after fire reaches them.\nB Articles which are expected to mass detonate very soon\nafter fire reaches them.\nC Substances or articles which may be readily ignited and\nburn violently without necessarily exploding.\nD Substances or articles which may mass detonate (with\nblast and/or fragment hazard) when exposed to fire.\nE & F Articles which may mass detonate in a fire.\nG Substances and articles which may mass explode and\ngive off smoke or toxic gases.\nH Articles which in a fire may eject hazardous projectiles\nand dense white smoke.\nJ Articles which may mass explode.\nK Articles which in a fire may eject hazardous projectiles\nand toxic gases.\nL Substances and articles which present a special risk and\ncould be activated by exposure to air or water.\nN Articles which contain only extremely insensitive\ndetonating substances and demonstrate a negligible\nprobability of accidental ignition or propagation.\nS Packaged substances or articles which, if accidentally\ninitiated, produce effects that are usually confined to the\nimmediate vicinity.\nThe maximum temperature at which a temperature-controlled\nsubstance can be safely transported. Above this temperature,\nself-accelerating decomposition or polymerization may occur.\nPage 371\n\nControl zones Criticality safety\nindex (CSI)\nCryogenic liquid Decomposition\nproducts\nDecontamination Dry chemical Edema ERPG(s) ERPG-1 ERPG-2 Page 372\nGLOSSARY\nDesignated areas at hazardous materials/dangerous goods\nincidents, based on safety and the degree of hazard. Many terms\nare used to describe control zones; however, in this guidebook,\nthese zones are defined as the hot/exclusion/red/restricted zone,\nwarm/contamination reduction/yellow/limited access zone, and\ncold/support/green/clean zone. (EPA Standard Operating Safety\nGuidelines, OSHA 29 CFR 1910.120, NFPA 472).\nA number value assigned to packages and overpacks containing\nfissile materials that limits the number of packages containing fissile\nmaterials during transportation.\nA refrigerated, liquefied gas that has a boiling point colder than\n-90°C (-130°F) at atmospheric pressure or is handled or transported\nat a temperature equal to or less than -100°C (-148°F).\nProducts of a chemical or thermal break-down of a substance.\nThe removal of hazardous materials/dangerous goods from\npersonnel and equipment to the extent necessary to prevent\npotential adverse health effects. For more information, consult the\n“Decontamination” section.\nA preparation designed for fighting fires involving flammable\nliquids, pyrophoric substances and electrical equipment.\nCommon types contain sodium bicarbonate or potassium\nbicarbonate.\nThe accumulation of an excessive amount of watery fluid in\ncells and tissues. Pulmonary edema is an excessive buildup of\nwater in the lungs, for instance, after inhalation of a gas that is\ncorrosive to lung tissue.\nEmergency Response Planning Guideline(s). Values intended\nto provide estimates of concentration ranges above which one\ncould reasonably anticipate observing adverse health effects;\nsee ERPG-1, ERPG-2 and ERPG-3.\nThe maximum airborne concentration below which it is believed\nnearly all individuals could be exposed for up to 1 hour without\nexperiencing more than mild, transient adverse health effects or\nwithout perceiving a clearly defined objectionable odor.\nThe maximum airborne concentration below which it is believed\nnearly all individuals could be exposed for up to 1 hour without\nexperiencing or developing irreversible or other serious health\neffects or symptoms that could impair an individual’s ability to\ntake protective action.\n\nGLOSSARY\nERPG-3 The maximum airborne concentration below which it is believed\nnearly all individuals could be exposed for up to 1 hour without\nexperiencing or developing life-threatening health effects.\nEvacuate Evacuate aims to protect as many people as possible by\nremoving persons from inside a zone safely. If removal is too\nrisky, sheltering-in-place can also be considered in this zone.\nFlammable liquid Flash point A liquid that has a flash point of 60°C (140°F) or lower.\nLowest temperature at which a liquid or solid gives off vapor in\nsuch a concentration that, when the vapor combines with air near\nthe surface of the liquid or solid, a flammable mixture is formed.\nHence, the lower the flash point, the more flammable the material.\nFlooding quantities Hazard zones\n(Inhalation Hazard\nZones)\nMinimum of 1900 L/min (500 US gal/min) of water.\nHAZARD\nGases: LC50 of less than or equal to 200 ppm,\nZONE A:\nLiquids: V equal to or greater than 500 LC50 and\nLC50 less than or equal to 200 ppm.\nHAZARD\nZONE B:\nGases: LC50 greater than 200 ppm and less\nthan or equal to 1000 ppm, Liquids: V equal to\nor greater than 10 LC50; LC50 less than or equal\nto 1000 ppm and criteria for Hazard Zone A are\nnot met.\nHAZARD\nLC50 greater than 1000 ppm and less than or\nZONE C:\nequal to 3000 ppm.\nHAZARD\nLC50 greater than 3000 ppm and less than or\nZONE D:\nequal to 5000 ppm.\nPlease note: even though the term “zone” is used, hazard zones\nare not an actual area or distance. How zones are assigned is\nstrictly a function of the lethal concentration 50 (LC50) of the\nproduct. For example, TIH Zone A is more toxic than Zone D.\nHigh expansion foam Foams that have a high expansion ratio (over 1:200) with a low\nwater content.\nHot zone Area immediately surrounding a hazardous materials/dangerous\ngoods incident which extends far enough to prevent adverse\neffects from the released product to personnel outside the zone.\nThis zone is also referred to as exclusion zone, red zone or\nrestricted zone in other documents. (EPA Standard Operating\nSafety Guidelines, OSHA 29 CFR 1910.120, NFPA 472).\nIED See “Improvised Explosive Device”.\nImmiscible In this guidebook, means that a material does not mix readily\nwith water.\nPage 373\n\nImprovised\nExplosive Device\nIsolate Large spill LC50 Mass explosion MAWP mg/m3 Miscible mL/m3 Mutagen Narcotic n.o.s. Noxious Page 374\nGLOSSARY\nA bomb that is manufactured from commercial, military or\nhomemade explosives.\nIsolate indicates a zone of no entry that applies to the public and\nfirst responders who are not equipped, trained, and prepared to\nmitigate the incident.\nA spill that involves quantities that are greater than 208 liters (55\nUS gallons). This usually involves a spill from a large package,\nor multiple spills from many small packages.\nLethal concentration 50. The concentration of a material\nadministered by inhalation that is expected to cause the death\nof 50% of an experimental animal population within a specified\ntime. (Concentration is reported in either ppm or mg/m3).\nExplosion which affects almost the entire load virtually\ninstantaneously.\nMaximum Allowable Working Pressure: The maximum allowable\ninternal pressure that the tank may experience during normal\noperations.\nMilligrams of a material per cubic meter of air.\nIn this guidebook, means that a material mixes readily with water.\nMilliliters of a material per cubic meter of air. (1 mL/m3 equals\n1 ppm).\nAn agent giving rise to an increased occurrence of mutations\nin populations of cells and/or organisms. Mutation means a\npermanent change in the amount or structure of the genetic\nmaterial in a cell.\nA substance which acts as a central nervous system depressor\nproducing effects such as drowsiness, narcosis, reduced\nalertness, loss of reflexes, lack of coordination, and vertigo.\nThese effects can also be manifested as severe headache or\nnausea, and can lead to reduced judgment, dizziness, irritability,\nfatigue, impaired memory function, deficit in perception and\ncoordination, reaction time, or sleepiness.\nThese letters refer to “not otherwise specified”. The entries\nwhich use this description are generic names such as “Corrosive\nliquid, n.o.s.” This means that the actual chemical name for that\ncorrosive liquid is not listed in the regulations; therefore, a generic\nname must be used to describe it on shipping papers.\nIn this guidebook, means that a material may be harmful or\ninjurious to health or physical well-being.\n\nGLOSSARY\nOrganic peroxide An organic (carbon-containing) compound having two oxygen\natoms joined together. Organic peroxides are thermally\nunstable chemicals. They may have one or more of the following\nproperties: be liable to explosive decomposition; burn rapidly;\nbe sensitive to impact or friction; react dangerously with other\nsubstances.\nOxidizer A chemical which supplies its own oxygen and which helps other\ncombustible material burn more readily.\nP See “Polymerization”.\nPacking Group The Packing Group (PG) is assigned based on the degree of\ndanger presented by the hazardous material/dangerous good:\nPG I : Great danger\nPG II : Medium danger\nPG III : Minor danger\nPG See “Packing Group”.\npH pH is a value that represents the acidity or alkalinity of a water\nsolution. Pure water has a pH of 7. A pH value below 7 indicates\nan acid solution (a pH of 1 is extremely acidic). A pH above 7\nindicates an alkaline solution (a pH of 14 is extremely alkaline).\nAcids and alkalies (bases) are commonly referred to as corrosive\nmaterials.\nPIH Polar Poison Inhalation Hazard. See “TIH”.\nA molecule in which one side of the molecule has a partial\npositive charge while another side has a partial negative charge.\nExamples includes alcohols and ketones.\nPolymerization A chemical reaction that often produces heat and pressure.\nOnce initiated, the reaction is accelerated by the heat that it\nproduces. The uncontrolled buildup of heat and pressure can\ncause a fire or an explosion, or can rupture closed containers.\nThe letter (P) following a guide number in the yellow and blue\nsections identifies a material that may polymerize violently\nunder high temperature conditions or contamination with other\nproducts during a transportation incident. It is also used to identify\nmaterials that have a strong potential for polymerization in the\nabsence of an inhibitor due to depletion of this inhibitor caused\nby accident conditions.\nppm Parts per million. (1 ppm equals 1 mL/m3).\nPage 375\n\nProtective clothing Pyrophoric Radiation Authority Radioactivity Refrigerated liquid Refrigerated liquefied\ngas\nRespiratory sensitizer Right-of-way Self-heating material Page 376\nGLOSSARY\nIn this guidebook, protective clothing includes both respiratory\nand physical protection. One cannot assign a level of protection\nto clothing or respiratory devices separately. These levels were\naccepted and defined by response organizations such as U.S.\nCoast Guard, NIOSH, and U.S. EPA.\nLevel A: SCBA plus totally encapsulating chemical resistant\nclothing (permeation resistant).\nLevel B: SCBA plus hooded chemical resistant clothing (splash\nsuit).\nLevel C: Full or half-face respirator plus hooded chemical\nresistant clothing (splash suit).\nLevel D: Coverall, including structural firefighters’ protective\nclothing (SFPC), with no respiratory protection.\nSCBA: Self-contained breathing apparatus.\nFor more information, consult the “Protective Clothing” section.\nA material which ignites spontaneously upon exposure to air\n(or oxygen).\nAs referred to in GUIDES 161 through 166 for radioactive\nmaterials, the Radiation Authority is either a Federal, state/\nprovincial agency or state/province designated official. The\nresponsibilities of this authority include evaluating radiological\nhazard conditions during normal operations and during\nemergencies. If the identity and telephone number of the authority\nare not known by emergency responders, or included in the local\nresponse plan, the information can be obtained from the agencies\nlisted on the inside back cover. They maintain a periodically\nupdated list of radiation authorities.\nThe property of some substances to emit invisible and potentially\nharmful radiation.\nSee “Refrigerated liquefied gas”.\nA gas which when packaged for transport is made partially liquid\nbecause of its low temperature. See “Cryogenic liquid”.\nA substance that induces hypersensitivity of the airways following\ninhalation of the substance.\nA defined area on a property containing one or more high-\npressure natural gas pipelines.\nMaterial that may spontaneously ignite or generate heat on\ncontact with oxygen (in air) after long periods of time (hours or\ndays).\n\nSelf-reactive material Shelter-in-place Skin corrosion Skin irritation Skin sensitizer Small spill Specific gravity Spontaneously\ncombustible material\nGLOSSARY\nMaterial that is thermally unstable and produces heat upon\ndecomposition, even without participation of air.\nPeople should seek shelter inside a building and remain inside\nuntil the danger passes. Sheltering-in-place is used when\nevacuating the public would cause greater risk than staying\nwhere they are, or when an evacuation cannot be performed.\nDirect the people inside to close all doors and windows and to\nshut off all ventilating, heating and cooling systems. In-place\nprotection (shelter-in-place) may not be the best option if (a) the\nvapors are flammable; (b) if it will take a long time for the gas to\nclear the area; or (c) if buildings cannot be closed tightly. Vehicles\ncan offer some protection for a short period if the windows are\nclosed and the ventilating systems are shut off. Vehicles are not\nnearly as effective as buildings for in-place protection.\nThe production of irreversible damage to the skin following the\napplication of a test substance for up to 4 hours.\nThe production of reversible damage to the skin following the\napplication of a test substance for up to 4 hours.\nA substance that will induce an allergic response following skin\ncontact.\nA spill that involves quantities that are 208 liters (55 US gallons)\nor less. This generally corresponds to a spill from a single small\npackage (for example, a drum), a small cylinder, or a small leak\nfrom a large package.\nWeight of a substance compared to the weight of an equal volume\nof water at a given temperature. Specific gravity less than 1\nindicates a substance is lighter than water; specific gravity greater\nthan 1 indicates a substance is heavier than water.\nIn this guidebook, a spontaneously combustible material means\na pyrophoric (air-reactive) material or self-heating material. Refer\nto each term in the glossary.\nPage 377\n\nGLOSSARY\nStraight or solid streams Method used to apply or distribute water from the end of a\nhose. The water is delivered under pressure for penetration.\nIn an efficient stream, approximately 90% of the water passes\nthrough an imaginary circle 38 cm (15 inches) in diameter at\nthe breaking point. Hose solid streams are typically created by\npassing water through a non-adjustable bore tip. On the other\nhand, hose straight streams originate from fog nozzles that are\ndialed into a straight stream. Hose (solid or straight) streams are\nfrequently used to cool tanks and other equipment exposed to\nflammable liquid fires, or for washing burning spills away from\ndanger points. However, these streams will cause a spill fire to\nspread if improperly used or when directed into open containers\nof flammable and combustible liquids.\nThermal runaway A chain reaction that leads to a violent release of stored energy\nand flammable gas. This reaction can spread to other batteries\nor combustible materials that are nearby, which could lead to a\nlarge-scale thermal event with severe consequences.\nTIH Toxic Inhalation Hazard. Term used to describe gases and\nvolatile liquids that are toxic when inhaled (same as PIH). These\nmaterials pose a known hazard to human health during transport\nor is presumed to be toxic to humans because of animal-based\nstudies.\nV Saturated vapor concentration in air of a material in mL/m3 (ppm)\nat 20°C and standard atmospheric pressure.\nVapor density Weight of a volume of pure vapor or gas (with no air present)\ncompared to the weight of an equal volume of dry air at the same\ntemperature and pressure. A vapor density less than 1 (one)\nindicates that the vapor is lighter than air and will tend to rise.\nA vapor density greater than 1 (one) indicates that the vapor is\nheavier than air and may travel along the ground.\nVapor pressure Pressure at which a liquid and its vapor are in equilibrium at a\ngiven temperature. Liquids with high vapor pressures evaporate\nrapidly.\nViscosity Measure of a liquid’s internal resistance to flow. This property is\nimportant because it indicates how fast a material will leak out\nthrough holes in containers or tanks.\nPage 378\n\nGLOSSARY\nWarm zone Water insoluble Water-Reactive Material Water-sensitive Water soluble Water spray (fog) Area between Hot and Cold zones where personnel and\nequipment decontamination and hot zone support take place. It\nincludes control points for the access corridor and thus assists\nin reducing the spread of contamination. Also referred to as\nthe contamination reduction corridor (CRC), contamination\nreduction zone (CRZ), yellow zone or limited access zone in\nother documents. (EPA Standard Operating Safety Guidelines,\nOSHA 29 CFR 1910.120, NFPA 472).\nA substance that does not easily dissolve in water.\nIn this guidebook, a material which produces a large amount of\ntoxic gas when it comes in contact with water.\nSubstances which may produce flammable, toxic and/or corrosive\ndecomposition products upon contact with water.\nA substance that easily dissolves in water. Polar substances are\ngenerally soluble in water.\nMethod or way to apply or distribute water. The water is finely\ndivided to provide for high heat absorption. Water spray patterns\ncan range from about 10 to 90 degrees. Water spray streams can\nbe used to extinguish or control the burning of a fire or to provide\nexposure protection for personnel, equipment, buildings, etc. This\nmethod can be used to absorb vapors, knock-down vapors\nor disperse vapors. Direct a water spray (fog), rather than a\nstraight or solid stream, into the vapor cloud to accomplish\nany of the above.\nWater spray is particularly effective on fires of flammable liquids\nand volatile solids having flash points above 37.8°C (100°F).\nRegardless of the above, water spray can be used successfully\non flammable liquids with low flash points. The effectiveness\ndepends particularly on the method of application. With proper\nnozzles, even gasoline spill fires of some types have been\nextinguished when coordinated hose lines were used to sweep\nthe flames off the surface of the liquid. Furthermore, water\nspray carefully applied has frequently been used with success\nin extinguishing fires involving flammable liquids with high flash\npoints (or any viscous liquids) by causing frothing to occur only\non the surface, and this foaming action blankets and extinguishes\nthe fire.\nPage 379","truncated":false,"body_characters":23027}