


American Conference of Governmental Industrial Hygienists (ACGIH)
A professional society of individuals responsible for full-time industrial hygiene programs, who are employed by official governmental units. Its primary function is to encourage the interchange of experience among governmental industrial hygienist and to collect and make information available of value to them. ACGIH promotes standards and techniques in industrial hygiene and coordinates governmental activities with community agencies.

American National Standards Institute (ANSI)
Serves as a clearinghouse for nationally coordinated voluntary safety, engineering, and industrial consensus standards developed by trade associations, industrial firms, technical societies, consumer organizations, and government agencies.

API-ASME Container (or tank)
A container constructed in accordance with the pressure vessel code jointly developed by the American Petroleum Institute and the American Society of Mechanical Engineers.

Items connected to a container opening needed to make a container gas tight. These include pressure relief devices, shut-off, backflow, excess flow, internal valves, liquid level gauging devices, pressure relief devices, pressure gauges, and plugs.

The Boiler and Pressure Vessel Code (Section VIII, "Rules for the Construction of Unfired Pressure Vessels") of the American Society of Mechanical Engineers.

Association of American Railroads (AAR)
Professional trade association which coordinates technical information and research within the United States railroad industry. Publisher of emergency response guidebooks.



Boiling Liquid Expanding Vapor Explosion (BLEVE)
A container failure with a release of energy, often rapidly and violently, which is accompanied by a release of gas to the atmosphere and propulsion of the container or container pieces due to an overpressure rupture.

Boiling Point
The temperature at which a liquid changes its phase to a vapor or gas. The temperature where the vapor pressure of the liquid equals atmospheric pressure. Significant property for evaluating the flammability of a liquid, as flash point and boiling point are directly related. A liquid with a low flash point will also have a low boiling point, which translates into a large amount of vapors being given off.

That organizational level within the Incident Management System having functional /geographic responsibility for major segments of incident operations (e.g., Hazmat Branch). The Branch level is organizationally between Section and Division/Sector/Group.

Buddy System
A system of organizing employees into work groups in such a manner that each employee of the work group is designated to be observed by at least one other employee in the work group [per OSHA 1910.120 (a)(3)].

Bulk Packaging
Bulk packaging has an internal volume greater than 119 gallons (450 liters) for liquids, a capacity greater than 882 pounds (400 kg) for solids, or a water capacity greater than 1,000 pounds (453.6 kg) for gases. It can be an integral part of a transport vehicle (e.g., cargo tank truck, railroad tank car, and barges), packaging placed on or in a transport vehicle (e.g., portable tanks, intermodal portable tanks, ton containers), or fixed or processing containers.

Bulk Plant or Terminal
A facility with the primary purpose of distribution of gas that receives propane by tank car, tank truck, or piping, and distributes this gas to the end user by portable container delivery, by tank truck, or through gas piping. Such plants have bulk storage of at least 2,000 gallons (7.6 m3) water capacity or more and have container filling and truck loading facilities on the premises.



Cargo Tanks
Tanks permanently mounted on a tank truck or tank trailer which is used for the transportation of liquefied and compressed gases, liquids and molten materials. Examples include MC-306, DOT-406, MC-307/DOT-407, MC-312/DOT-412, MC-330/331, and MC-338. May also be any bulk liquid or compressed gas packaging, not permanently attached to a motor vehicle, which because of its size, construction, or attachment to the vehicle can be loaded or unloaded without being removed from the vehicle.

Chemical Manufacturers Association
Professional trade association of the United States chemical industry. The parent organization that operates CHEMTREC.

Chemical Protective Clothing (CPC)
Single or multipiece garment constructed of chemical protective clothing materials designed and configured to protect the wearer's torso, head, arms, legs, hands, and feet. Can be constructed as a single or multipiece garment. The garment may completely enclose the wearer either by itself or in combination with the wearer's respiratory protection, attached or detachable hood, gloves, and boots.

Chemical Safety and Hazard Investigation Board
Federal board under the auspices of the Environmental Protection Agency charged with responsibility for investigating serious accidents and emergencies involving chemical emergencies.

Chemical Transportation Emergency Center (CHEMTREC)
The Chemical Transportation Center, operated by the Chemical Manufacturers' Association (CMA), can provide information and technical assistance to emergency responders (phone number: 1-800-424-9300).

As used in NFPA 70&emdash;The National Electric Code, used to describe the type of flammable materials that produce the hazardous atmosphere. There are three classes:

Class I Locations - Flammable gases or vapors may be present in quantities sufficient to produce explosive or ignitible mixtures.

Class II Locations - Concentrations of combustible dusts may be present (e.g., coal or grain dust).

Class III Locations - Areas concerned with the presence of easily ignitible fibers or flyings (e.g., cotton milling).

Clean Air Act (CAA)
Federal legislation which resulted in EPA regulations and standards governing airborne emissions, ambient air quality, and risk management programs.

Clean Water Act (CWA)
Federal legislation which resulted in EPA and state regulations and standards governing drinking water quality, pollution control, and enforcement. The Oil Pollution Act (OPA) amended the CWA and authorized regulations pertaining to oil spill preparedness, planning, response and clean-up.

Closed Container
A container as herein defined, so sealed by means of a lid or other device that neither liquid nor vapor will escape from it at ordinary temperatures. The container is not allowed to have any vents, either automatic, fixed, or pressure operated.

Code of Federal Regulations (CFR)
A collection of regulations established by federal law. Contact with the agency that issues the regulation is recommended for both details and interpretation.

Cold Zone
The control zone of a hazmat incident that contains the command post and other support functions as are deemed necessary to control the incident. This zone may also be referred to as the clean zone or the support zone.

The act of directing, ordering, and/or controlling resources by virtue of explicit legal, agency, or delegated authority.

Command Staff
The command staff consists of the Information Officer, the Safety Officer, and the Liaison Officer, who report directly to the Incident Commander.

Community Awareness and Emergency Response (CAER)
A program developed by the Chemical Manufacturers Association (CMA) to provide guidance for chemical plant managers to assist them in developing integrated hazmat emergency response plans between the plant and the community.

Comprehensive Environmental Response, Compensation and Liability Act (CERCLA)
Known as CERCLA or SUPERFUND, it addresses hazardous substance releases into the environment and the clean-up of inactive hazardous waste sites. It also requires those who release hazardous substances, as defined by the Environmental Protection Agency (EPA), above certain levels (known as "reportable quantities") to notify the National Response Center.

Compressed Gas
Any material or mixture having an absolute pressure exceeding 40 psi (276 kPa) in the container at 70 F (21.1 C), having an absolute pressure exceeding 104 psi (717 lPa) at 130 F (54.4 C).

Confined Space
A space that (1) is large enough and so configured that an employee can bodily enter and perform assigned work; (2) has limited or restricted means for entry or exit (e.g., tanks, vessels, silos, storage bins, hoopers, vaults, and pits are spaces that may have limited means of entry); and (3) is not designed for continuous employee occupancy.

Confined Space (Permit Required)
Has one or more of the following characteristics:

1) Contains or has the potential to contain a hazardous atmosphere. A hazardous atmosphere would be created by any of the following, including:

a) Vapors exceed 10% of the lower flammable limit (LEL)

b) Airborne combustible dust exceeds its LEL

c) Atmospheric oxygen concentrations below 19.5% or above 23.5%

d) Atmospheric concentration of any substance for which a dose or PEL is published and which could result in employee exposure in excess of these values

e) Any other atmospheric condition which is immediately dangerous to life or health (IDLH)

2) Contains a material that has the potential for engulfing an entrant.

3) Has an internal configuration such that a person could be trapped or asphyxiated by inwardly converging walls or by a floor which slopes downward and tapers to a smaller cross section.

4) Contains any other recognized serious safety or health hazard.

Any vessel, including cylinders, tanks, and portable tanks, used for transporting, or storing of LP-Gases.

Controlled Burn
Defensive or nonintervention tactical objective by which a fire is allowed to burn with no effort to extinguish the fire.

Narrow split or break in the container metal which may penetrate through the container metal (may also be caused by fatigue). It is a major mechanism which could cause catastrophic failure.

Critical Pressure
Critical pressure is the pressure that must be applied to bring a gas to its liquid state. (See critical temperature.) Both critical temperature and critical pressure terms relate to the process of liquefying gases. A gas cannot be liquefied above its critical temperature. The lower the critical temperature, the less pressure required to bring a gas to its liquid state.

Critical Temperature
Critical temperature is the minimum temperature at which a gas can be liquefied no matter how much pressure is applied. (See critical pressure.) Both critical temperature and critical pressure relate to the process of liquefying gases. A gas cannot be liquefied above its critical temperature. The lower the critical temperature, the less pressure required to bring a gas to its liquid state.

An element of incident termination which examines the overall effectiveness of the emergency response effort and develops recommendations for improving the organization's emergency response system.

A container constructed in accordance with U.S. Department of Transportation specifications under Title 49 CFR.



Damage Assessment
The process of gathering and evaluating container damage.

An element of incident termination which focuses on the following factors:

1) Informing responders exactly what hazmats they were (possibly) exposed to, and the signs and symptoms of exposure

2) Identifying damaged equipment requiring replacement or repair

3) Identifying equipment or supplies requiring specialized decontamination or disposal

4) Identifying unsafe work conditions

5) Assigning information-gathering responsibilities for a post-incident analysis

Popular abbreviation referring to the process of decontamination.

The physical and/or chemical process of reducing and preventing the spread of contamination from persons and equipment used at a hazardous materials incident. (Also referred to as "contamination reduction").

Defensive Tactics
These are less aggressive spill and fire control tactics where certain areas may be "conceded" to the emergency, with response efforts directed toward limiting the overall size or spread of the problem.

Degree of Solubility
An indication of the solubility and/or miscibility of the material.

Negligible&emdash;less than 0.1%

Slight & 0.1 to 1.0%

Moderate & 1 to 10%

Appreciable & greater than 10%

Complete & soluble at all proportions

Deformation of the tank head or shell. It is caused from impact with a relatively blunt object (e.g., railroad coupler, vehicle). If the dent has a sharp radius, there is the possibility of cracking.

Application of water to water-miscible flammable liquids to reduce to safe levels the hazard they represent. It can increase the total volume of liquid which will have to be disposed of. In decon applications, it is the use of water to flush a hazmat from protective clothing and equipment and the most common method of decon.

As used in NFPA 70&emdash;The National Electric Code, describe the types of location that may generate or release a flammable material. There are two divisions:

Division I - Location where the vapors, dusts, or fibers are continuously generated and released. The only element necessary for a hazardous situation is a source of ignition.

Division II - ;Location where the vapors, dusts, or fibers are generated and released as a result of an emergency or a failure in the containment system.

Circular fixture on the top of a pressurized railroad tank car containing valves, pressure relief valve, and gauging devices.



Pure substance that cannot be broken down into simpler substances by chemical means.

Emergency Medical Services (EMS)
Functions as required to provide emergency medical care for ill or injured persons by trained providers.

Emergency Operations Center (EOC)
The site where government agency officials or senior managers from organizations provide central direction and control of a major emergency. The EOC usually deals with the political, governmental, legal, insurance, community, and public affairs issues related to the emergency. The operational aspects of the emergency are managed by the on-scene Incident Command Post (ICP). See Incident Command Post.

Emergency Response Organization
An organization that utilizes personnel trained in emergency response. This would include fire, law enforcement, EMS, and industrial emergency response teams.

Emergency Response Personnel
Personnel assigned to organizations that have the responsibility for responding to different types of emergency situations.

Emergency Response Plan
A plan that establishes guidelines for handling flammable liquids incidents as required by regulations such as SARA, Title III, and HAZWOPER (29 CFR 1910.120).

Emergency Response Team (ERT)
Crews of specially trained personnel used within industrial facilities for the control and mitigation of emergency situations. May consist of both shift personnel with ERT responsibilities as part of their job assignment (e.g., plant operators) or volunteer members. ERTs may be responsible for both fire, hazmat, medical, and technical rescue emergencies, depending upon the size and operation of the facility.

Emergency Shut-Off Valve
A shut-off valve incorporating thermal and manual means of closing that also provides for remote means of closing.

Environmental Protection Agency (EPA)
The purpose of the EPA is to protect and enhance our environment today and for future generations to the fullest extent possible under the laws enacted by Congress. The Agency's mission is to control and abate pollution in the areas of water, air, solid waste, pesticides, noise, and radiation. EPA's mandate is to mount an integrated, coordinated attack on environmental pollution in cooperation with state and local governments.

(See Environmental Protection Agency.)

Excess Flow Valve (Excess-Flow Check Valve)
A device designed to close when the liquid or vapor passing through it exceeds a prescribed flow rate as determined by pressure drop.

Excess Flow Valve (Internal)
An excess flow valve constructed and installed so that the seat remains in the container so that damage to the valve parts exterior to the container will not prevent effective seating to the valve.

Expansion Ratio
The amount of gas produced by the evaporation of one volume of liquid at a given temperature. Significant property when evaluating liquid and vapor releases of liquefied gases and cryogenic materials. The greater the expansion ratio, the more gas that is produced and the larger the hazard area. The expansion ratio of propane is 1 to 270.

Explosion-Proof Construction
Encases the electrical equipment in a rigidly built container so that (1) it withstands the internal explosion of a flammable mixture, and (2) it prevents propagation to the surrounding flammable atmosphere. Used in Class I, Division 1 atmospheres at fixed installations.



Failure of Container Attachments
Attachments which open up or break off the container, such as pressure relief valves, frangible discs, fusible plugs, discharge valves, or other related appliances.

Fire Entry Suits
Suits which offer complete, effective protection for short-duration entry into a total flame environment. Designed to withstand exposures to radiant heat levels up to 2,000 F. Entry suits consist of a coat, pants, and separate hood assembly. They are constructed of several layers of flame-retardant materials, with the outer layer often aluminized.

First Responder
The first trained person(s) to arrive at the scene of a hazardous materials incident. May be from the public or private sector of emergency services.

First Responder, Awareness Level
Individuals who are likely to witness or discover a hazardous substance release who have been trained to initiate an emergency response sequence by notifying the proper authorities of the release. They would take no further action beyond notifying the authorities of the release.

First Responder, Operations Level

Flammable Limits
(Note to reader: The terms flammable limits and explosive limits are often used interchangeably. Within the propane industry, the term flammable limits is used most often in technical literature. Within the emergency services, the term explosive limit is most common. Both terms have the same meaning.) Flammable limits are the range of gas or vapor concentration (percentage by volume in air) that will burn or explode if an ignition source is present. Limiting concentrations are commonly called the "lower flammable limit" and the "upper flammable limit." Below the lower flammable limit, the mixture is too lean to burn; above the upper flammable limit, the mixture is too rich to burn. If the gas or vapor is released into an oxygen-enriched atmosphere, the flammable range will expand. Likewise, if the gas or vapor is released into an oxygen-deficient atmosphere, the flammable range will contract.

Controlled burning of a high vapor pressure liquid or compressed gas in order to reduce or control the pressure and/or dispose of the product.

Flash Point
Minimum temperature at which a liquid gives off enough vapors that will ignite and flash-over but will not continue to burn without the addition of more heat. Significant in determining the temperature at which the vapors from a flammable liquid are readily available and may ignite.

Full Protective Clothing
Protective clothing worn primarily by firefighters which includes helmet, fire retardant hood, coat, pants, boots, gloves, PASS device, and self-contained breathing apparatus designed for structural fire fighting. It does not provide specialized chemical splash or vapor protection.



Reduction in the thickness of the tank shell. It is an indentation in the shell made by a sharp, chisel-like object. A gouge is characterized by the cutting and complete removal of the container or weld material along the track of contact.

A method of controlling ignition hazards from static electricity. The process of connecting one or more conductive objects to the ground; it is done to minimize potential differences between objects and the ground.

As used in NFPA 70 - The National Electric Code, are products within a Class. Class I is divided into four groups (Group A-D) on the basis of similar flammability characteristics. Class II is divided into three groups (Groups E-;G). There are no groups for Class III materials.



Refers to danger or peril. In hazmat operations, the term usually refers to the physical or chemical properties of a material.

Hazard and Risk Evaluation
Evaluation of hazard information and the assessment of the relative risks of a hazmat incident. Evaluation process leads to the development of Incident Action Plan.

Hazard Class
The hazard class designation for the material as found in the Department of Transportation regulations, 49 CFR. There are currently 9 DOT hazard classes, which are divided into 22 divisions.

Hazard Communication (HAZCOM)
OSHA regulation (29 CFR 1910.1200) which requires hazmat manufacturers to develop MSDSs on specific types of hazardous chemicals and provide hazmat health information to both employees and emergency responders.

Hazard Control Zones
The areas at a hazardous materials incident that are designated based upon the degree of hazard. Many terms are used to describe these zones; however, for the purposes of this text, these zones are defined as the Hot, Warm and Cold zones.

Hazardous Chemicals
Any chemical that would be a risk to employees if exposed in the workplace (U.S. Occupational Safety and Health Administration, 29 CFR 1910).

Hazardous Materials
Any substance or material in any form or quantity capable of posing an unreasonable risk to safety and health and property when transported in commerce (U.S. Department of Transportation, 40 CFR 171).

Hazardous Materials Response Team (HMRT)
An organized group of trained response personnel operating under an emergency response plan and appropriate standard operating procedures who handle and control actual or potential leaks or spills of hazardous substances requiring possible close approach to the material. The team members respond to releases or potential releases of hazardous materials for the purpose of control or stabilization of the incident. An HMRT may be a separate component of a fire brigade or a fire department or other appropriately trained and equipped units from public or private agencies.

Hazardous Materials Specialists
Individuals who respond and provide support to Hazardous Materials Technicians. While their duties parallel those of the Technician, they require a more detailed or specific knowledge of the various substances they may be called upon to contain. Would also act as a liaison with federal, state, local and other governmental authorities in regard to site activities.

Hazardous Materials Technicians
Individuals who respond to releases or potential releases of hazardous materials for the purposes of stopping the leak. They generally assume a more aggressive role in that they are able to approach the point of a release in order to plug, patch, or otherwise stop the release of a hazardous substance.

Hazardous Substances
Any substance designed under the Clean Water Act and the Comprehensive Environmental Response, Compensation and Liability Act (CERCLA) as posing a threat to waterways and the environment when released (U.S. Environmental Protection Agency, 40 CFR 302). Hazardous substances as used within OSHA 1910.120 refer to every chemical regulated by EPA as a hazardous substance and by DOT as a hazardous material.

Heat-Affected Zone
Area in the undisturbed tank metal next to the actual weld material. This area is less ductile than either the weld or the steel plate due to the effect of the heat of the welding process. This zone is most vulnerable to damage as cracks are likely to start here.

High-Temperature Protective Clothing
Protective clothing designed to protect the wearer against short-term high-temperature exposures. Includes both proximity suits and fire entry suits. This type of clothing is usually of limited use in dealing with chemical exposures.

Hot Tapping
An offensive technique used by highly qualified specialists for welding on and cutting holes through liquid and/or compressed gas vessels and piping for the purposes of relieving the internal pressure and/or removing the product. Hot tapping is not performed on MC-330/331 cargo tank trucks.

Hot Zone
At a hazardous materials incident, the control zone immediately surrounding the hazard that presents the highest level of risk and extends far enough to minimize the adverse effects to unprotected personnel outside the zone. This zone is also referred to as the exclusion zone or the restricted area in other documents.

Compounds primarily made up of hydrogen and carbon. Examples include LPG, gasoline, and fuel oils.



Ignition (Autoignition) Temperature
Minimum temperature required to ignite gas or vapor without a spark or flame being present. Significant in evaluating the ease with which a flammable material may ignite.

Immediately Dangerous to Life or Health (IDLH)
An atmospheric concentration of any toxic, corrosive or asphyxiant substance that poses an immediate threat to life or would cause irreversible or delayed adverse health effects or would interfere with an individual's ability to escape from a dangerous atmosphere.

Impingement Event
As the hazmat and/or its container engulf an area, they will impinge on, or come in contact with exposures. They may also impinge upon other hazmat containers, producing additional problems.

A release or potential release of a hazardous material from its container into the environment.

Incident Action Plan
The strategic goals, tactical objectives, and support requirements for the incident. All incidents require an action plan. For simple incidents (Level I) the action plan is not usually in written form. Large or complex incidents (Level II or III) will require that the action plan be documented in writing.

Incident Command Post
The location from which all incident operations in the field are directed and planning functions are performed. The communications center is often incorporated into the command post.

Incident Commander (IC)
The person responsible for the management of all incident operations. The IC is in charge of the incident site. May also be referred to as the On-Scene Incident Commander as defined in 29 CFR. 1910.120.

Incident Management System (IMS)
An organized system of roles, responsibilities, and standard operating procedures, or guidelines, used to manage and direct emergency operations. May also be referred to as Incident Management System (ICS).

Industrial Occupancy
Includes factories that manufacture products of all kinds and properties devoted to operations such as processing, assembling, mixing, packaging, finishing or decorating, and repairing.

Industrial Plant
An industrial facility that utilizes gas incidental to plant operations, with LPG-Gas storage of 2,000 gallons (7.6 m3) water capacity or more that receives gas by means of tank car, truck transport, or truck lot.

Inert Gas
A nonreactive gas, such as argon, helium, and neon. Also called nobel gases.

Information Officer
The individual responsible interface with the media or other appropriate agencies requiring information direct from the incident scene. Member of the Command Staff.

The introduction of a chemical or toxic products of combustion into the body by way of the respiratory system. Inhalation is the most common exposure route and often the most damaging. Toxins may be absorbed into the bloodstream and carried to other internal organs, or they may affect the upper and/or lower respiratory tract. Resulting respiratory injuries include pulmonary edema and respiratory congestion.

Internal Valve
A container's primary shut-off valve where the seat and seat disc remain inside the container so that damage to the parts exterior to the container or mating flange will not prevent effective seating of the valve. An internal valve closes when flow through the valve exceeds its rated excess-flow capacity or when pump actuation differential pressure drops to a predetermined point.

Intrinsically Safe Construction
Equipment or wiring is incapable of releasing sufficient electrical energy under both normal and abnormal conditions to cause the ignition of a flammable mixture. Commonly used in portable direct-reading instruments for operations in Class I, Division 2 hazardous locations.

Isolating the Scene
The process of preventing persons and equipment from becoming exposed to a actual or potential hazmat release. Includes establishing isolation perimeter and control zones.

Isolation Perimeter
The designated crowd control line surrounding the Hazard Control Zones. The isolation perimeter is always the line between the general public and the Cold Zone.



Liaison Officer
The point of contact for assisting or coordinating agencies. Member of the Command Staff.

Liquefied Petroleum Gas
Any material having a vapor pressure not exceeding that allowed for commercial propane composed predominantly of the following hydrocarbons, either by themselves or as mixtures: propane, propylene, butane (normal butane or isobutane), or butylenes.

Local Emergency Planning Committee (LEPC)
A committee appointed by a State Emergency Response Commission, as required by SARA Title III, to formulate a comprehensive emergency plan for its region.



Material Safety Data Sheet
A document which contains information regarding the chemical composition, physical and chemical properties, health and safety hazards, emergency response, and waste disposal of the material as required by 29 CFR 1910.1200.

Mechanical Harm Events
Those harm events resulting from direct contact with fragments scattered because of a container failure, explosion, or shock wave.

Mechanical Stress
The result of a transfer of energy when one object physically contacts or collides with another. Indicators include punctures, gouges, breaks, or tears in the container.

Any offensive or defensive action to contain, control, reduce, or eliminate the harmful effects of a hazardous materials release.

Mobile Containers
Containers that are permanently mounted on a vehicle and are connected for uses other than engine fuel.

The act of systematically checking to determine contaminant levels and atmospheric conditions.

Monitoring Instruments
Monitoring and detection instruments used to detect the presence and/or concentration of contaminants within an environment. They include:

Combustible Gas Indicator (CGI): Measures the concentration of a combustible gas or vapor in air.

Oxygen Monitor: Measures the percentage of oxygen in air.

Colorimetric Indicator Tube: Measures the concentration of specific gases and vapors in air.

Specific Chemical Monitor: Designed to detect a large group of chemicals or a specific chemical. Most common examples include carbon monoxide and hydrogen sulfide.

Flame Ionization Detector (FID): A device used to determine the presence of organic vapors and gases in air. Operates in two modes&emdash;survey mode and gas chromatograph.

Gas Chromatograph: An instrument used for identifying and analyzing specific organics compounds.

Photoionization Detector (PID): A device used to determine the total concentration of many organic and some inorganic gases and vapors in air.

Radiation Monitor: An instrument used to measure accumulated radiation exposure. Include both alpha, beta, and gamma survey detectors.

Radiation Dosimeter Detector: An instrument which measures the dose of radiation to which a person has been exposed.

Corrosivity (pH) Detector: A meter, paper, or strip that indicates the relative acidity or alkalinity of a substance, generally using an international scale of 0 (acid) through 14 (alkali-caustic). (See pH.)

Indicator Paper: Special chemical indicating papers which test for the presence of specific hazards, such as oxidizers, organic peroxides, and hydrogen sulfide. Are usually part of a hazmat identification system.

Mounded Container
An ASME container designed for underground service installed above the minimum depth required for underground service and covered with earth, sand, or other material, or an ASME container designed for aboveground service installed above grade and covered with earth, sand, or other material.



National Fire Protection Association (NFPA)
An international voluntary membership organization to promote improved fire protection and prevention, establish safeguards against loss of life and property by fire, and write and publish national voluntary consensus standards (e.g., NFPA 472&emdash;Professional Competence of Responders to Hazardous Materials Incidents).

National Institute for Occupational Safety and Health (NIOSH)
A Federal agency which, among other activities, tests and certifies respiratory protective devices, and air sampling detector tubes, and recommends occupational exposure limits for various substances

National Interagency Incident Management System (NIIMS)
A standardized systems approach to incident management that consists of five major subdivisions collectively providing a total systems approach to all-risk incident management.

National Response Center (NRC)
Communications center operated by the U.S. Coast Guard in Washington, D.C. It provides information on suggested technical emergency actions and is the federal spill notification point. The NRC must be notified within 24 hours of any spill of a reportable quantity of a hazardous substance by the spiller. Can be contacted at (800) 424-8802.

National Transportation Safety Board (NTSB)
Independent federal agency charged with responsibility for investigating serious accidents and emergencies involving the various modes of transportation (e.g., highway, pipeline, air), as well as hazardous materials. Issues investigation reports and nonbinding recommendations for action.

Nonbulk Packaging
Any packaging having a capacity meeting one of the following criteria:

Liquid&emdash;internal volume of 119 gallons (450 L) or less;

Solid&emdash;capacity of 882 lb. (400 kg) or less; and

Compressed Gas&emdash;water capacity of 1,001 lb. (454 kg) or less.

Non-intervention Tactics
Essentially "no action." It is useful at certain fire emergencies where the potential costs of action far exceed any benefits (e.g., violent container failure scenario).



Occupational Safety and Health Administration (OSHA)
Component of the United States Department of Labor; an agency with safety and health regulatory and enforcement authorities for most United States industries, businesses, and states.

Odor Threshold (TLVOdor)
The lowest concentration of a material's vapor in air that is detectable by odor. If the TLVodor is below the TLV/TWA, odor may provide a warning as to the presence of a material.

Offensive Tactics
Aggressive leak, vapor control, and fire control tactics designed to quickly control or mitigate the problem. Although increasing risks to emergency responders, offensive tactics may be justified if rescue operations can be quickly achieved, if the spill can be rapidly confined or contained, or if the fire can be quickly extinguished.

Off-Site Specialist Employee A
Those persons who are specially trained to handle incidents involving chemicals and/or containers for chemicals used in their organization's area of specialization. Consistent with the organization's response plan and standard operating procedures, the Off-Site Specialist Employee A shall have the ability to analyze an incident involving chemicals within the organization's area of specialization, plan a response to that incident, implement the planned response within the capabilities of the resources available, and evaluate the progress of the planned response.

Off-Site Specialist Employee B
Those persons who in the course of their regular job duties work with or are trained in the hazards of specific chemicals and/or containers for chemicals used in their individual area of specialization. Because of their education, training, or work experience, the Off-Site Specialist Employee B may be called upon to gather and record information, provide technical advice, and provide technical assistance (including work within the hot zone) at an incident involving chemicals consistent with their organization's emergency response plan and standard operating procedures and the local emergency response plan

Off-Site Specialist Employee C
The Off-Site Specialist C should be able to provide information on a specific chemical or container and have the organizational contacts needed to acquire additional technical assistance. This individual need not have the skills or training necessary to conduct control operations. This individual is generally found at the command post ,providing the IC or their designee with technical assistance.

On-Scene Incident Commander
(See Incident Commander.)

Operations Section
Responsible for all tactical operations at the incident. The Hazmat Branch falls within the Operations Section.

Overpressure Shut-Off Device
A device that shuts off the flow of LP-Gas vapor when the outlet pressure of the regulator reaches a predetermined maximum allowable pressure.

Oxygen-Deficient Atmosphere
An atmosphere which contains an oxygen content less than 19.5 % by volume at sea level.

Oxygen-Enriched Atmosphere
An atmosphere which contains an oxygen content great-er than 23.5% by volume at sea level.



Permissible Exposure Limit (PEL)
The maximum time-weighted concentration at which 95% of exposed, healthy adults suffer no adverse effects over a 40-hour work week and are comparable to ACGIH's TLV/TWA. PELs are used by OSHA and are based on an eight-hour, time-weighted average concentration.

Personal Protective Equipment (PPE)
Equipment provided to shield or isolate a person from the chemical, physical, and thermal hazards that may be encountered at a hazardous materials incident. Adequate personal protective equipment should protect the respiratory system, skin, eyes, face, hands, feet, head, body, and hearing. Personal protective equipment includes: personal protective clothing, self-contained positive pressure breathing apparatus, and air purifying respirators.

Physical State
The physical state or form (solid, liquid, gas) of the material at normal ambient temperatures (68 F to 77 F)

Planning Section
Responsible for the collection, evaluation, dissemination and use of information about the development of the incident and the status of resources. Includes the Situation Status, Resource Status, Documentation, and Demobilization Units as well as Technical Specialists.

A vapor, liquid, dust, or gaseous cloud formation which has shape and buoyancy.

Portable Container
A container designed to be moved readily, as distinguished from containers designed for stationary installations. Portable containers, designed for transportation, filled to their maximum filling limit, include cylinders, cargo tanks, and portable tanks, all three of which are defined separately under NFPA 58. Containers which are designed to be "readily" moved from one usage to another, but substantially empty of product, are defined under NFPA 58 as portable storage containers.

Portable Storage Container
container similar to but distinct from those designed and constructed for stationary installation, designed so that it can be moved readily over the highways, substantially empty of liquid, from one usage to another. Such containers either have legs or other supports attached, or are mounted on running gear (such as a trailer or semitrailer chassis) with suitable supports of the fold-down type, allowing them to be placed or parked in a stable position on a reasonably firm and level surface. For large volume, limited duration product usage (such as construction sites and on site normally 12 months or less), portable storage containers function in lieu of permanently installed stationary containers.

Pressure Relief Valve
A type of pressure relief device designed to open and close to maintain internal fluid pressure. Pressure relief valves are divided into the following types: External Pressure Relief Valve, Flush Type Full Internal Pressure Relief Valve, Full Internal Pressure Relief Valve, Internal Spring-Type Pressure Relief Valve, and Sump-Type Full Internal Pressure Relief Valve.

Process Safety Management (PSM)
The application of management principles, methods and practices to prevent and control releases of hazardous chemicals or energy. Focus of both OSHA 1910.119&emdash;Process Safety Management of Highly Hazardous Chemicals, Explosives and Blasting Agents and EPA Part 68&emdash;Risk Management Programs for Chemical Accidental Release Prevention.

Protective Clothing
Equipment designed to protect the wearer from heat and/or hazardous materials contacting the skin or eyes. Protective clothing is divided into four types:

Structural firefighting protective clothing

Liquid splash chemical protective clothing

Vapor chemical protective clothing

High-temperature protective clothing

Public Protective Actions
The strategy used by the Incident Commander to protect unexposed people from the hazardous materials release by evacuating or protecting-in-place. This strategy is usually implemented after the IC has established an isolation perimeter and defined the Hazard Control Zones for emergency responders.

Totally enclosed electrical equipment is protected with an inert gas under a slight positive pressure from a reliable source. The inert gas provides positive pressure within the enclosure and minimizes the development of a flammable atmosphere. Used in Class I, Division 1 atmospheres at fixed installations.



Rail Burn
Deformation in the shell of a railroad tank car. It is actually a long dent with a gouge at the bottom of the inward dent. A rail burn can be oriented circumferentially or longitudinally in relation to the tank shell. The longitudinal rail burns are the more serious because they have a tendency to cross a weld. A rail burn is generally caused by the tank car passing over a stationary object, such as a wheel flange or rail.

Reporting Marks and Number
The set of initials and a number stenciled on both sides and both ends of railroad cars. These markings can be used to obtain information on the contents of the car from either the railroad or the shipper.

Respiratory Protection
Equipment designed to protect the wearer from the inhalation of contaminants. Respiratory protection is divided into three types: positive pressure self-contained breathing apparatus (SCBA), positive pressure airline respirators (SARs), and air purifying respirators.

Risk Analysis
A process to analyze the probability that harm may occur to life, property, and the environment and to note the risks to be taken to identify the incident objectives.

Risk Management Programs
Required under EPA's proposed 40 CFR Part 68, risk management programs consist of three elements: (1) hazard assessment of the facility; (2) prevention program; and (3) emergency response considerations.

The probability of suffering a harm or loss. Risks are variable and change with every incident.

Runaway Cracking
Cracking occurring in closed containers under pressure, such as liquid drums or pressure vessels. A small crack in a closed container suddenly develops into a rapidly growing crack which circles the container. As a result, the container will generally break into two or more pieces.



To perform the assigned tasks without injury to self or others, to the environment, or to property.

Safety Officer
Responsible for monitoring and assessing safety hazards and unsafe conditions and developing measures for ensuring personnel safety. Member of the Command Staff. The Safety Officer is a required position at a hazmat incident based upon the requirements of OSHA 1910.120.

Saturated Hydrocarbons
A hydrocarbon possessing only single covalent bonds. All of the carbon atoms are saturated with hydrogen. Examples include methane (CH4), propane (C3H8), and butane (C4H10).

(See Self-Contained Breathing Apparatus.)

Reduction in the thickness of the container shell. It is an indentation in the shell made by a relatively blunt object. A score is characterized by the reduction of the container or weld material so that the metal is pushed aside along the track of contact with the blunt object.

That organization level within the Incident Management System having functional responsibility for primary segments of incident operations, such as Operations, Planning, Logistics and Administration/Finance. The section level is organizationally between the branch and the Incident Commander.

Is either a geographic or functional assignment. Sector may take the place of either the Division or Group or both.

Self-Contained Breathing Apparatus (SCBA)
A positive pressure, self-contained breathing apparatus (SCBA) or combination SCBA/supplied air breathing apparatus certified by the National Institute for Occupational Safety and Health (NIOSH) and the Mine Safety and Health Administration (MSHA) or the appropriate approval agency for use in atmospheres that are immediately dangerous to life or health (IDLH).

A person, company, or agency offering material for transportation.

Shipping Documents/Papers
Generic term used to refer to documents that must accompany all shipments of goods for transportation. These include Hazardous Waste Manifest, Bill of Lading, and Consists. Shipping documents should provide the following:

Proper shipping name

Hazard classification

Four-digit identification number(s), as required

Number of packages or containers

Type of packages

Total quantity by weight, volume, and/or packaging

Shipping Name
The proper shipping name or other common name for the material; also any synonyms for the material.

Site Management and Control
The management and control of the physical site of a hazmat incident. Includes initially establishing command, approach and positioning, staging, establishing initial perimeter and hazard control zones, and public protective actions.

The rapid yet deliberate consideration of all critical scene factors.

Skilled Support Personnel
Personnel who are skilled in the operation of certain equipment, such as cranes and hoisting equipment, and who are needed temporarily to perform immediate emergency support work that cannot reasonably be performed in a timely fashion by emergency response personnel.

The ability of a solid, liquid, gas, or vapor to dissolve in water or other specified medium. The ability of one material to blend uniformly with another, as in a solid in liquid, liquid in liquid, gas in liquid, or gas in gas. Significant property in evaluating the selection of control and extinguishing agents, including the use of water and firefighting foams.

Specialist Employee
Employees who, in the course of their regular job duties, work with and are trained in the hazards of specific hazardous substances and who will be called upon to provide technical advice or assistance to the incident Commander at a hazmat incident

Specific Gravity
The weight of the material as compared with the weight of an equal volume of water. If the specific gravity is less than one, the material is lighter than water and will float. If the specific gravity is greater than one, the material is heavier than water and will sink. Most insoluble hydrocarbons are lighter than water and will float on the surface. Significant property for determining spill control and clean-up procedures for water-borne releases.

The point in an incident at which the adverse behavior of the hazardous materials is controlled.

The management of committed and uncommitted emergency response resources (personnel and apparatus) to provide orderly deployment.

Staging Area
The safe area established for temporary location of available resources closer to the incident site to reduce response time.

Standard Transportation Commodity Code (STCC)
A number which will be found on all shipping documents accompanying rail shipments of hazmats. A seven-digit number assigned to a specific material or group of materials and used in determination of rates. For a hazardous material, the STCC number will begin with the digits ''49." Hazardous wastes may also be found with the first two digits being "48." The STCC will also be found when intermodal containers are changed from rail to highway movement.

Street Burn
Deformation in the shell of a highway cargo tank. It is actually a long dent that is inherently flat. A street burn is generally caused by a container overturning and sliding some distance along a cement or asphalt road.

The degree to which a corrosive ionizes in water. Those that form the greatest number of hydrogen ions are the strongest acids (e.g., pH < 2), while those that form the hydroxide ion are the strongest bases (pH > 12).

Stress Event
An applied force or system of forces that tend to either strain or deform a container (external action) or trigger a change in the condition of the contents (internal action). Types of stress include thermal, mechanical, and chemical.

Structural Firefighting Protective Clothing
Protective clothing normally worn by firefighters during structural firefighting operations. It includes a helmet, coat, pants, boots, gloves, PASS device, and a hood to cover parts of the head not protected by the helmet. Structural firefighting clothing provides limited protection from heat but may not provide adequate protection from harmful liquids, gases, vapors, or dusts encountered during hazmat incidents. May also be referred to as turnout or bunker clothing.

Superfund Amendments & Reauthorization Act (SARA)
Created for the purpose of establishing Federal statutes for right-to-know standards and emergency response to hazardous materials incidents, reauthorized the Federal Superfund program and mandated states to implement equivalent regulations/requirements.



Tactical Objectives
The specific operations that must be accomplished to achieve strategic goals. Tactical objectives must be both specific and measurable. Tactical level officers are Division / Group / Sector.

Technical Information Specialists
Individuals who provide specific expertise to the Incident Commander or the HMRT either in person, by telephone, or through other electronic means. They may represent the shipper, manufacturer, or be otherwise familiar with the hazmats or problems involved.

That portion of incident management where personnel are involved in documenting safety procedures, site operations, hazards faced, and lessons learned from the incident. Termination is divided into three phases: debriefing, postincident analysis, and critique.

Thermal Stress
Hazmat container stress generally indicated by temperature extremes, both hot and cold. Examples include fire, sparks, friction or electricity, and ambient temperature changes. Extreme or intense cold, such as that found with cryogenic materials, may also act as a stressor. clues of thermal stress include the operation of pressure relief devices or the bulging of containers.

The point where a physiological or toxicological effect begins to be produced by the smallest degree of stimulation.

Threshold Limit Value/Ceiling (TLV/C)
The maximum concentration that should not be exceeded, even instantaneously. The lower the value, the more toxic the substance.

Threshold Limit Value/Short Term Exposure Limit (TLV/STEL)
The 15-minute, time-weighted average exposure which should not be exceeded at any time, nor repeated more than four times daily with a 60-minute rest period required between each STEL exposure. The lower the value, the more toxic the substance.

Threshold Limit Value/Skin (Skin)
Indicates a possible and significant contribution to overall exposure to a material by absorption through the skin, mucous membranes, and eyes by direct or airborne contact.

Threshold Limit Value/Time-Weighted Average (TLV/TWA)
The airborne concentration of a material to which an average, healthy person may be exposed repeatedly for 8 hours each day, 40 hours per week, without suffering adverse effects. The young, old, ill, and naturally susceptible will have lower tolerances and will need to take additional precautions. TLVs are based upon current available information and are adjusted on an annual basis by organizations such as the American Conference of Governmental Industrial Hygienists (ACGIH). As TLVs are time-weighted averages over an eight-hour exposure, they are difficult to correlate to emergency response operations. The lower the value, the more toxic the substance.

Toxic Products of Combustion
The toxic by-products of the combustion process. Depending upon the materials burning, higher levels of personal protective clothing and equipment may be required.

The ability of a substance to cause injury to a biologic tissue. Refers to the ability of a chemical to harm the body once contact has occurred.

The process of physically moving a liquid, gas or some forms of solids either manually, by pump or by pressure transfer, from a leaking or damaged container. The transfer pump, hoses, fittings and container must be compatible with the hazardous materials involved.



UN/NA Identification Number
The four-digit identification number assigned to a hazardous material by the Department of Transportation; on shipping documents may be found with the prefix "UN" (United Nations) or "NA" (North American). The ID numbers are not unique and more than one material may have the same ID number.

Unified Command
The process of determining overall incident strategies and tactical objectives by having all agencies , organizations, or individuals who have jurisdictional responsibility, and in some cases those who have functional responsibility at the incident, participate in the decision-making process.

Universal Cylinder
A cylinder constructed and fitted with appurtenances in such a manner that it can be connected for service with its longitudinal axis in either the vertical or the horizontal position, and so that its fixed maximum liquid level gauge, pressure relief device(s), and withdrawal appurtenance will function properly in either position.



An air dispersion of molecules in a substance that is normally a liquid or solid at standard temperature and pressure.

Vapor Density
The weight of a pure vapor or gas compared with the weight of an equal volume of dry air at the same temperature and pressure. The molecular weight of air is 29. If the vapor density of a gas is less than one, the material is lighter than air and may rise. If the vapor density is greater than one, the material is heavier than air and will collect in low or enclosed areas. Significant property for evaluating exposures and where hazmat gas and vapor will travel.

Vapor Dispersion
Use of water spray to disperse or move vapors away from certain areas or materials. Note that reducing the concentration of a material through the use of a water spray may bring the material into its flammable range.

Vapor Pressure
The pressure exerted by the vapor within the container against the sides of a container. This pressure is temperature dependent; as the temperature increases, so does the vapor pressure. Consider the following three points:

1) The vapor pressure of a substance at 100 F is always higher than the vapor pressure at 68 F.

2) Vapor pressures reported in millimeters of mercury (mm Hg) are usually very low pressures. 760 mm Hg is equivalent to 14.7 psi or 1 atmosphere. Materials with vapor pressures greater than 760 mm Hg are usually found as gases.

3) The lower the boiling point of a liquid, the greater vapor pressure at a given temperature.

Vent and Burn
The use of shaped explosive charges to vent the high pressure at the the top of a pressurized container and then, with additional explosive charges, release and burn the remaining liquid in the container in a controlled fashion. This is a highly sophisticated technique that is only used under very controlled conditions.

The controlled release of a liquid or compressed gas to reduce the pressure and diminish the probability of an explosion. The method of venting will depend upon the nature of the hazmat.

Violent Rupture
Associated with chemical reactions having a release rate of less than one second (i.e., deflagration). There is no time to react in this scenario. This behavior is commonly associated with runaway cracking and overpressure of closed containers.

The ease with which a liquid or solid can pass into the vapor state. The higher a material's volatility, the greater its rate of evaporation. Significant property in that volatile materials will readily disperse and increase the hazard area.



Warm Zone
The control zone at a hazardous materials incident where personnel and equipment decontamination and hot zone support takes place. It includes control points for the decontamination corridor, thus helping reduce the spread of contamination. This is also referred to as the "decontamination," "contamination reduction," "yellow zone," or "limited access zone" in other documents.

Wheel Burn
Reduction in the thickness of a railroad tank shell. It is similar to a score, but is caused by prolonged contact with a turning rail car wheel.