September 2024 | AIChE

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September 2024

Audit Trail

The proof that systematic documentation of activities was performed in a way that allows an auditor to confirm compliance with required or desired organizational behavior.

Audit (process safety audit)

An inspection of a plant or process unit, drawings, procedures, emergency plans, and/or management systems, etc., usually by an independent, impartial team. (See "Safety Review" for contrast.)

Audit

A systematic, independent review to verify conformance with prescribed standards of care using a well-defined review process to ensure consistency and to allow the auditor to reach defensible conclusions.

Atmospheric Turbulence

Random and rapid fluctuations in wind components, which determine the rate of turbulent dispersion or spread of the cloud. Typically expressed by the turbulent velocity (averaging about 1 m/s), which is the standard deviation of rapid fluctuations in wind speed.

Atmospheric Transport and Dispersion model

A model that follows the movement and dilution of a pollutant after it is released into the atmosphere (Hanna et al., 1982).

Atmospheric Tank

A storage tank that has been designed to operate at pressures from atmospheric through 0.5 psig measured at the top of the tank. (NFPA30)

Atmospheric Stability

A measure of the degree of atmospheric turbulence commonly defined in terms of the vertical temperature gradient. In neutral stability the gradient is equivalent to the Adiabatic Lapse Rate (ALR). Stable atmospheric conditions refer to a gradient less than the ALR (ultimately to a temperature...

Atmospheric Dispersion

The mixing of a gas or vapor with air at atmospheric conditions ((1 atm, 77 F)

Atmospheric Boundary Layer

The layer about 1000 m deep next to the ground that is strongly affected by diurnal variations in surface conditions such as ground temperature.

Assumed Risk

A risk that has been identified, analyzed, and accepted at the appropriate management level, unanalyzed or unknown risks fall under oversight and omissions by default.

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