Ignitable Mixture
A flammable gas, mist, or dust mixture or any combination of these that can be ignited by a specified ignition source such as a static spark.
Ignition
Self-sustained flame propagation caused by a static discharge in a flammable mixture.
Ignition Energy
Energy in Joules stored in a capacitor which upon discharge is just sufficient to effect ignition of a given fuel mixture under specified test conditions (Methods: ASTM 582 for Gas Mixtures)
Ignition Sensitive
Easily ignitable gases or dusts meeting the following criteria: a gas whose LMIE in air is small compared with the 0.2 mJ value typical of common fuel and solvent vapors, or a dust whose MIE in air is small compared with that of Lycopodium. In practice, ignition sensitive gases have LMIEs ? 0.1 mJ and ignition sensitive dusts have MIEs ?10 mJ. Examples of ignition sensitive gases are acetylene and hydrogen. Ignition sensitive dusts include finely divided bisphenol-A (BPA) and butylated hydroxy toluene (BHT).
Ignition Sensitivity Index
An overall measure of the ignitability of a particulate material.
Ignition Source Density
The number of ignition sources per unit area (of plant).
Image (I/O Image, Image Register)
A portion of memory where I/O status (the image) is maintained.
Immediately Dangerous to Life or Health
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. [29 CFR* 1910.120]
Immune Response
The reaction of the immune system to foreign organisms.
Immunity
Measured by the presence of antibodies in the blood, a natural or acquired resistance to a specific disease, whether partial or complete, specific or nonspecific, lasting or temporary.
Immunodeficiency (also immunosuppression)
Condition in which the normal immune response is weakened or diminished from the effects of disease or drugs.
Impact
A measure of the ultimate loss and harm of a loss event.
Note: Impact may be expressed as the number of injuries and/or fatalities, the extent of the environmental damage, or the magnitude of the loss, such as property damage, material loss, production loss, market share loss, and recovery costs.
Impedance
Frequency-dependent counterpart of resistance in AC circuits, comprising both inductive and resistive components.
Implementation
Completion of an action plan associated with the outcome of the process of resolving audit findings, incident investigation team recommendations, risk analysis team recommendations, and so forth. Also, the establishment or execution of PSM program element work activities.
Implementation Design
A phase in the development of computerized systems in which hardware and software components are selected and implementation, operation, and maintenance procedures are developed.
Importance
The contribution from a subsystem or a component to the complete system.
Impulse
The area under the overpressure-time curve for explosions. The area can be calculated for the positive phase or negative phase of the blast.
In Vitro
Literally within glass, an activity taking place in a controlled environment outside of a living organism
In Vivo
Literally within the living, an activity taking place within a living organism
In-Line Flame Arrester
A flame arrester which is fitted with two pipe connections, one on each side of the flame arrester element. An in-line flame arrester may be either a deflagration or a detonation flame arrester. An in-line arrester that is installed on a vessel vent nozzle with a short length of pipe attached to the discharge (atmospheric) side is sometimes also called a "pipe-away" flame arrester.
Incendive
Ability of an energy source, such as a static discharge, to cause ignition in a given system.
Incestuous Data
Data in two or more data sets which is derived from a common origin and may be inadvertently "double-counted" when aggregated.
Incident
An event, or series of events, resulting in one or more undesirable consequences, such as harm to people, damage to the environment, or asset/business losses.
Note: Such events include fires, explosions, releases of toxic or otherwise harmful substances, runaway reactions, etc.
Incident Enumeration
The identification and tabulation of incidents without regard to significance or other biases.
Incident investigation
A systematic approach for determining the causes of an incident and developing recommendations that address the causes to help prevent or mitigate future incidents. See also Root cause analysis and Apparent cause analysis.
Incident Investigation Management System
A written document that defines the roles, responsibilities, protocols, and specific activities to be carried out by personnel performing an incident investigation.
Incident Investigation Team
a group of qualified people who examine an incident in a manner that is timely, objective, systematic, and technically sound to determine that factual information pertaining to the event is documented, probable cause(s) are ascertained, and complete technical understanding of such an event is achieved.
Incident Outcome
The physical manifestation of the incident: for toxic materials, the incident outcome is a toxic release, while for flammable materials; the incident outcome could be a boiling liquid expanding vapor explosion (BLEVE), flash fire, vapor cloud explosion (VCE), etc. For example, the incident outcome for a leak of chlorine from a railcar is a toxic release.
Incident Outcome Case
The quantitative definition of a single result of an incident outcome through specification of sufficient parameters to allow distinction of this case from all others for the same incident outcome.
Incident Sequence
A series of events composed of an initiating event and intermediate events leading to an undesirable outcome.
Incident Stereotype
A fixed or general pattern of incident causation. From a review of historical incident data it can be possible to identify "classes of incidents," each with certain features (or typical, repeated patterns) in common; i.e., incident stereotypes are defined.
Incident Warning Sign
An indicator of a subtle problem that could lead to an incident.
Incipient failure
An imperfection in the state or condition of hardware such that a degraded or catastrophic failure can be expected to result if corrective action is not taken.
Incompatible
The term can refer to any undesired results occurring when substances are combined. In the context of this publication, it refers to incompatible substances giving an undesired chemical reaction when combined, posing a chemical reactivity hazard under a defined scenario.
Independent
Give events A and B, A is independent of B if, and only if, the probability of A is unchanged by the occurrence of B. Also, if A is independent of B, B i likewise independent of A.
Independent Protection Layer (IPL)
A device, system, or action that is capable of preventing a scenario from proceeding to the undesired consequence without being adversely affected by the initiating event or the action of any other protection layer associated with the scenario.
Note: There are specific functional criteria for protection layers that are designated as "independent." A protection layer meets the requirements of being an IPL when it is designed and managed to achieve the following seven core attributes: Independent; Functional; Integrity; Reliable; Validated, Maintained and Audited; Access Security; and Management of Change.
Individual Hazard Index (IHI)
The Fatal Accident Rate (FAR) for a particular hazard, with the exposure time defined as the actual time that a person is exposed to a hazard of concern.
Individual Risk
The risk to a person in the vicinity of a hazard. This includes the nature of the injury to the individual, the likelihood of the injury occurring, and the time period over which the injury might occur.
Induction Charging
This is the process of momentarily grounding a conductor which has been polarized by an electric field, then removing the conductor from the electric field so that it gains a net charge.
Induction Period/Time
Time interval (starting at operating conditions) after which a runaway shows its maximum effects.
Inductive Approach
Reasoning from individual cases to a general conclusion by postulating that a system element has failed in a certain way. An attempt is then made to find out what happens to the whole system or process.
Inert
A chemical that does not react chemically with other substances. (Cambridge online)
Inert Gas
A nonflammable, nonreactive gas that can be used to render the combustible material in a system incapable of supporting combustion.
Inerting
A technique by which a combustible mixture is rendered non-ignitable by addition of an inert gas or a noncombustible dust. See Oxidant Concentration Reduction.
Infectious agents
Organisms (such as bacteria, viruses, and fungi) that cause disease.
Infrastructure
The basic facilities, services, and installations needed for the functioning of a site such as transportation and communications systems, water and power lines, and public institutions including emergency response organizations.
Ingestion
The taking of a substance through the mouth. Importance: A route of exposure to a hazardous material.
Ingredients
A listing of chemicals that are in a mixture. Importance: Knowing exactly what chemicals and how much of each is in a mixture helps you to understand the potential hazard a mixture represents.
Inhalation
The breathing in of a substance in the form of gas, vapor, fume, mist, or dust. Importance: A route of exposure to a hazardous material.
Inhalation Reference Concentration
The estimated continuous inhalation exposure concentration (mg/m3) that is likely to be without appreciable risk of deleterious non-cancer effects during a human lifetime.