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Endothermic Chemical Reaction
A reaction involving one or more chemicals resulting in one or more new chemical species and the absorption of heat.
Endpoint
The furthest extent in an incident sequence to which a Layer of Protection Analysis (LOPA) or Quantitative Risk Analysis (QRA) scenario evaluation is taken in the scenario analysis. Depending on the approach used, the endpoint could be a material/energy release magnitude, a qualitative category of potential loss and harm impacts, an order-of-magnitude impact category with or without conditional modifiers, or fully quantified loss and harm impacts.
Engineered control
A specific hardware or software system designed to maintain a process within safe operating limits, to safely shut it down in the event of a process upset, or to reduce human exposure to the effects of an upset.
Episodic Event
An unplanned event of limited duration, usually associated with an accident.
Episodic Release
A release of limited duration usually associated with an accident.
Equipment
A piece of hardware which can be defined in terms of mechanical, electrical or instrumentation components contained within its boundaries.
Equipment Class
A grouping of individual equipment items with similar design and operation, such that facilities should perform similar ITPM activities on all of the items.
Equipment Deficiency
A condition that does not meet the acceptance criteria.
Equipment Failure Analysis
A systematic approach for analyzing equipment failures to determine the failure mechanism(s) and the root cause(s) that resulted in the failure.
Equipment Reliability
The probability that, when operating under stated environment conditions, process equipment will perform its intended function adequately for a specified exposure period.
Essential Criteria
Criteria defining the required content or conduct of a PHA based upon company or regulatory requirements.
Essential Personnel
Personnel with specific work activities that require them to be located in buildings in or near a process area for logistical and response purposes.
Event
An occurrence involving a process that is caused by equipment performance or human action or by an occurrence external to the process.
Event Sequence
A specific unplanned sequence of events composed of initiating events and intermediate events that may lead to an incident. See also Incident Sequence.
Event Tree
A logic model that graphically portrays the combinations of events and circumstances in an accident sequence.
Event Tree Analysis
A method used for modeling the propagation of an initiating event through the sequence of possible incident outcomes. The event is represented graphically by a tree with branches from the initiating cause through the success or failure of independent protection layers.
Evidence
Data on which the investigation team will rely for subsequent analysis, testing, reconstruction, corroboration, and conclusions.
Evidence gathering
the collection of data on which the investigation team will rely for subsequent analysis, testing, reconstruction, corroboration, and conclusions.
Exothermic
A physical or chemical change accompanied by the evolution of heat.
Exothermic Chemical Reaction
A reaction involving one or more chemicals resulting in one or more new chemical species and the evolution of heat.
Explosibility
The ability of a dust to take part in a closed explosion when dispersed in air at a suitable concentration and in the presence of an effective ignition source.
Explosibility Index
A numerical measure of the explosion hazard potential of a dust as determined by multiplying the dust Ignition Sensitivity Index by its Explosion Severity Index.
Explosion (CCPS)
External - A release of energy that causes a pressure discontinuity or blast wave.
Internal - The bursting or rupture of an enclosure or container due to the development of internal pressure from a deflagration.
Explosion (NFPA)
The bursting or rupture of an enclosure or container due to the development of internal pressure from a deflagration.
Explosion Efficiency, e
The ratio of the mechanical energy released in an explosion to the heat of combustion times the flammable mass in a vapor cloud (net efficiency). Alternately, the ratio of the mechanical energy released in an explosion to the heat of combustion times the total mass of fuel in a vapor cloud (gross efficiency).
Explosion Overpressure
Any pressure above atmospheric caused by a blast.
Explosion Vent
An intentionally weakly supported panel in the wall of an enclosure designed to give way in the event of an explosion in order to reduce the explosion overpressures and thereby protect the rest of the structure.
Explosions
A release of energy that causes a pressure discontinuity or blast wave.
Explosive
A chemical that causes a sudden, almost instantaneous release of pressure, gas, and heat when subjected to sudden shock, pressure, or high temperature. OSHA 1994
External Event
Event caused by (1) a natural hazard-earthquake, flood, tornado, extreme temperature, lighting, etc.; or (2) man-induced events-aircraft crash, missile, nearby industrial activity, sabotage, etc., or (3) an interruption of facilities such as electric power or process air.
Facility
The physical location where a management system activity is performed. In early life-cycle stages, a facility may be the company's central research laboratory, pilot plant, or the engineering offices of a technology vendor. In later stages, the facility may be a typical chemical plant, storage terminal, distribution center, or corporate office. In the context of this document, a facility is a portion of or a complete plant, unit, site, complex or offshore platform or any combination thereof.
Fail-Safe
A feature incorporated for automatically counteracting the effect of an anticipated possible source of failure. A system is fail-safe if failure of a component, signal, or utility, initiates action that return the system to a safe condition.
Fail-Safe Control
A system of remote control for preventing improper operation of the controlled function in event of circuit failure.
Fail-Safe Operation
An electrical system so designed that the failure of any component in the system will prevent unsafe operation of the controlled equipment.
Failure
An unacceptable difference between expected and observed performance.
Failure Frequency
The number of failure events that occur divided by the total elapsed calendar time during which those events occur or by the total number of demands, as applicable.
Failure Mode
Manner in which failure occurs. A failure mode might be identified as loss of function; spurious operation (function without demand); an out-of-tolerance condition; or a simple physical characteristic such as a leak observed during inspection.
Failure Mode and Effects Analysis
A hazard identification technique in which all known failure modes of components or features of a system are considered in turn and undesired outcomes are noted.
Failure Modes, Effects, and Criticality Analysis (FMECA)
A variation of FMEA that includes an estimate of the potential severity of consequences of a failure mode.
Failure Probability
The probability - a value from 0 to 1 - that a piece of equipment will fail on demand (not to be confused with fractional dead time) or will fail in a given time interval.
Failure Rate
The number of failure events that occur divided by the total elapsed operating time during which these event occur or by the total number of demands, as applicable.
Fatal Accident Rate (FAR)
A measure of individual risk expressed as the estimated number of fatalities per 108 exposure hours (roughly 1000 employee working lifetimes).
Fault Event
A failure event in a fault tree that requires further development.
Fault Tolerant
A system where some parts may fail but the system will still execute properly. A control system configuration that inherently provides auto selection of alternate or redundant signal paths to effect uninterrupted operations.
Fault tree
A logic model that graphically portrays the combinations of failures that can lead to a specific main failure or accident of interest.
Fault Tree Analysis
A method used to analyze graphically the failure logic of a given event, to identify various failure scenarios (called cut-sets), and to support the probabilistic estimation of the frequency of the event.
Feedback Control
A method by which one or more controlled variables (i.e., pressure, temperature, current, speed, power) are made to obey a common signal, whether constant or varying, according to a prescribed law, as a result of the measurement of the variable(s) in questions.
Final Element
Process control or safety device that implements the physical action necessary to achieve or maintain a safe state; e.g., valves, switch gear, and motors, including their auxiliary elements (such as the solenoid valve used to operate a valve).
Finding
A conclusion reached by the audit team based on data collected and analyzed in response to a specific audit question which indicates a need for improvement in the PSM program design or implementation. Findings are sometimes also referred to exceptions. Although strictly speaking a finding can be a positive or negative conclusion, common custom and terminology in auditing is to refer to the deficiencies identified as the findings. Findings include both the basis for the conclusion, i.e., an audit question or criteria, as well as the explanatory conclusion and the evidence that substantiates the conclusion.
Fire
A combustion reaction accompanied by the evolution of heat, light, and flame.