September 2024 | AIChE

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September 2024

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.

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...

Endothermic Chemical Reaction

A reaction involving one or more chemicals resulting in one or more new chemical species and the absorption of heat.

Endothermic

A physical or chemical change that requires or is accompanied by the absorption of heat.

End-of-Line Flame Arrester

A deflagration flame arrester that is installed on atmospheric pressure tank vent nozzles, having only one pipe connection. It is also called a tank vent deflagration flame arrester.

Enabling Event

An event that makes another event possible. Sometimes used for enabling condition. The term enabling condition is preferred, since enabling conditions are not generally events but rather conditional states.

Enabling Condition

A condition that is not a failure, error or a protection layer but makes it possible for an incident sequence to proceed to a consequence of concern. It consists of a condition or operating phase that does not directly cause the scenario, but that must be present or active in order for the scenario...

Emergency Trip Button

A hard-wired push button that, when pushed, will maintain the trip position and place selected final control elements in a safety position.

Emergency Shutdown System

The safety system which overrides the action of the basic control system when predetermined conditions are violated.

Emergency Shutdown Device

A device that is designed to shutdown the system to a safe condition on command from the emergency shutdown system.

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