Autocatalytic Reaction
Reaction of which the rate is increased by the catalyzing effect of its reaction products.
Autodecomposition
The sustained decomposition of a substance without introduction of any other apparent ignition source besides thermal energy and without air or other oxidants present. Autodecomposition is the result of a thermal self-decomposition reaction for given initial conditions (temperature, pressure, volume) at which the rate of heat evolution exceeds the rate of heat loss from the reacting system, thus resulting in an increasing reaction temperature and reaction rate. CCPS 1995b
Autodecomposition Temperature
The minimum temperature for a specified test method, test apparatus (including material of construction and test volume) and initial pressure required to initiate self-sustained decomposition of a solid, liquid or gaseous substance without any other apparent source of ignition and without air or other oxidants present. CCPS 1995b
Autoignition temperature
The lowest temperature at which a fuel/oxidant mixture will spontaneously ignite under specified test conditions.
Automated System
A control system beyond the scope of this standard in which PESs are incorporated by or for the user, but which also contains other components including their application programs.
Autoxidation
Also autooxidation or auto-oxidation. A slow, easily initiated, self-catalyzed reaction, generally by a free radical mechanism, between a substance and atmospheric oxygen. Initiators of autoxidation include heat, light, catalysts such as metals, and free radical generators. Davies (1961) defines autoxidation as interaction of a substance with molecular oxygen below 120 degrees C without flame. Possible consequences of autoxidation include pressure buildup by gas evolution, autoignition by heat generation with inadequate heat dissipation, and the formation of peroxides. CCPS 1995b
Availability
The fraction of time that the system is capable of performing its required functions. The fraction of time a system is fully operational.
Average Concentration
The concentration averaged over time and/or space.
Average Individual Risk
There are three Average Individual Risks; 1) Average Individual Risk (exposed population) is the individual risk averaged over the population which is exposed to risk from the facility, 2) Average Individual Risk (total population) is the individual risk averaged over a predetermined population, without regard to whether or not all people in that population are actually exposed to the risk, and 3) Average Individual Risk (Exposed hours/worked hours). The individual risk for an activity may be calculated for the duration of the activity or may be averaged over the working day.
Average rate of death
A measure of societal risk expressed as the average number of fatalities that might be expected per unit time from all possible incidents.
Averaging Time
The length of time in atmospheric dispersion testing over which concentration data are averaged to produce the concentration-time series.
Balanced scorecard
A management system that provides feedback on both internal business processes and external outcomes to continuously improve strategic performance and results.
Barrier
A control measure or grouping of control elements that on its own can prevent a threat developing into a top event (prevention barrier) or can mitigate the consequences of a top event once it has occurred (mitigation barrier). A barrier must be effective, independent, and auditable.
Barrier/Isolator
A sealed enclosure within which operations can be carried out without exposing the operators or the surrounding environment to contamination from the process materials inside it or vice versa.
Baseline Risk Assessment
a process to characterize the current and potential threats to human health and the environment that may be posed by contaminants migrating to groundwater or surface water; releasing to air; leaching through soil; remaining in the soil and bio-accumulating in the food chain. The primary purpose of the baseline risk assessment is to provide risk managers with an understanding of the actual and potential risks to human health and the environment posed by the site and any uncertainties associated with the assessment. This information may be useful in determining whether a current or potential threat to human health or the environment warrants remedial action.
Basic Event
An event in a fault tree that represents the lowest level of resolution in the model such that no further development is necessary (e.g., equipment item failure, human failure, or external event).
Basic Process Control System (BPCS)
A system that responds to input signals from the process and its associated equipment, other programmable systems, and/or from an operator, and generates output signals causing the process and its associated equipment to operate in the desired manner and within normal production limits.
Batch Reactor
Reactor in which all reactants and solvents are introduced prior to setting the reaction conditions (temperature, pressure). Products are only taken from the reactor upon conclusion of the reaction process. Both heat generation and concentrations in the batch reactor vary during the reaction process.
Batch Reactor
A reactor in which the reactants are added to the reactor at the start of the reaction. The reactants are allowed to react in the reactor for a fixed time. No feed is added or product withdrawn during this time. The reaction products are removed at the end of the batch.
Batch Sheet
Sometimes called batch instruction. The operating procedure for making a batch product. Primarily focuses on material quantities, as well as instructions for any mixing, reaction, heating, cooling, drying required for the process.
Battery Limit
The perimeter of a specific manufacturing process area. It is often defined by the roads around the perimeter. This area will include process equipment, and may include in-process tankage.
Baud
Unit of modulation speed corresponding to a unit interval testing one second. (IEV 5550 20)
Behavior-based safety program
A program designed to provide frequent feedback to personnel regarding their safety behaviors in the workplace.
Bench Scale
Technical laboratory scale (typically between 0.1 and 5 dm3), more specifically directed to process simulation and determination of technical plant facilities (cooling/heating capacities, temperature constraints, charging requirements, etc.)
Benchmark
A point of reference from which measurements may be made or from which other things can be measured. A program that is used to compare the operation of two or more systems is called a benchmark program.
Benchmarking
The comparison of current operating practices to internal or external company practices, industry best practices, and regulatory standards.
Benefit
Amount of expected risk reduction.
Beta Test Unit
A device or system that is comprised of preferably production components, but may use preproduction equipment if life cycle is satisfactory. The scale of the test is such that the equipment is installed in a real-life operating environment and its operation is monitored to determine performance against expectations.
Bidirectional Flame Arrester
An in-line flame arrester is considered to be bidirectional if: (a) the investigation (test) shows that the flame arrester performs its intended function with a detonation or deflagration approaching from either direction, or (b) the design of the flame arrester is symmetrical and each end is considered identical when approached by a detonation or deflagration from either direction.
Binary Character
Either of the "characters" of the "character set" consisting of two characters (e.g., a "binary digit").
Binary Code
A code consisting of the numbers 0 and 1. Can be easily represented in a computer by a series of on/off switches, the direction of a magnetic field, etc.
Binary Coded Decimal (BCD)
A numerical representation in which each decimal digital is represented by a group of four bits (binary digits). The bits are assigned the respective weights 8-4-2-1. If binary coded decimal, the number 14 is represented as 0001 0100.
Binary Digit (BIT)
Either of the "digits" 0 and 1 when it is used in the "pure binary numeration system."
Biological Oxygen Demand
The amount of dissolved oxygen in water, given in lbs. (kgs) or % that is consumed by biological oxidation of a chemical
Bioprocess engineering
the sub-discipline within biotechnology that is responsible for translating the discoveries of life science into practical products, processes, or systems that can serve the needs of society.
Bioprocessing
Bioprocessing makes use of microorganisms, cells in culture or enzymes to manufacture products.
Biosafety level
A specific combination of work practices, safety equipment, and facilities designed to minimize the exposure of workers and the environment to infectious agents.
BIT
An abbreviation for binary digit. A single character in a binary number. A single pulse in a group of pulses. A unit of information capacity of a storage device.
Blanketing
The technique of maintaining an atmosphere that is either inert or fuel-enriched in the vapor space of a container or vessel. Also called Padding.
Blast
A transient change in the gas density, pressure, and velocity of the air surrounding an explosion point. The initial change can be either discontinuous or gradual. A discontinuous change is referred to as a shock wave, and a gradual change is known as a pressure wave.
Blast Load
The load applied to a structure or object from a blast wave, which is described by the combination of overpressure and either impulse or duration.
Blast resistant buildings
Buildings that are structurally designed to withstand an explosion generated load (pressure and impulse) while sustaining a predetermined amount of damage.
Blast Wave
The overpressure wave traveling outward from an explosion point. (CCPS, 1996, no. 22)
Block Flow Diagram
A simplified drawing representing a process. It typically shows major equipment and piping and can include major valves.
Blowdown Drum
A separate collection vessel intended to receive a periodic or emergency discharge of liquids, liquid reaction mass, or slurries from a number of process vessels, reactors, or equipment items. Blowdowns may be initiated automatically, i.e., depressurizing a batch reactor, or manually for other applications. Blowdown drums are usually maintained at a low level or essentially empty. The collected liquids are pumped elsewhere for recovery, recycle, or disposal. Gases and any uncondensed vapors are vented through relief devices or an open line into a vent header system for appropriate treatment and disposal.
Blowdown Drums
Separators or accumulators used to separate liquids and vapors in pressure-relieving and emergency systems.
Boil-over
A violent expulsion of contents caused by a heat wave from the surface burning at the top of the tank reaching the water stratum at the bottom of the tank. Oils subject to boilover contain components having a wide range of boiling points, including both light ends and viscous residues. These characteristics are present in most crude oils. (Draft NFPA Understanding Fire Protection for Flammable Liquids)
Boiling-Liquid-Expanding-Vapor Explosion (BLEVE)
A type of rapid phase transition in which a liquid contained above its atmospheric boiling point is rapidly depressurized, causing a nearly instantaneous transition from liquid to vapor with a corresponding energy release. A BLEVE of flammable material is often accompanied by a large aerosol fireball, since an external fire impinging on the vapor space of a pressure vessel is a common cause. However, it is not necessary for the liquid to be flammable to have a BLEVE occur.
Bonding
The process of connecting two or more conductive objects together by means of a conductor so that they are at the same potential as each other but not necessarily at the same potential as the earth. 261
Boolean Algebra
That branch of mathematics describing the behavior of linear functions of variables which are binary in nature: on or off, open or closed, true or false. All coherent fault trees can be converted into an equivalent set of Boolean equations.