CCPS Process Safety Glossary | AIChE

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CCPS Process Safety Glossary

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Fire Point

The minimum temperature at which a flammable or combustible liquid, as herein defined, and some volatile combustible solids will evolve sufficient vapor to produce a mixture with air that will support sustained combustion when exposed to a source of ignition, such as a spark or flame.

Fire Protection

Methods of providing for fire control or fire extinguishment. (NFPA 850)

Fire Triangle

Three basic conditions are required for fire to take place. These are fuel, oxygen, and heat.

Fitness for service (FFS)

A systematic approach for evaluating the current condition of a piece of equipment in order to determine if the equipment item is capable of operating at defined operating conditions (e.g., temperature, pressure).

Flame

A region in which chemical interaction between gases occurs, accompanied by the evolution of light and heat

Flame Arrester

A device fitted to the opening of an enclosure or to the connecting piping of a system of enclosures and whose intended function is to allow flow but prevent the transmission of flame from either a deflagration or detonation.

Flame Barrier

A device that prevents transmission of a flame from a source to a receptor.

Flame Front

That portion of the flame reaction zone moving into the unburned gas where the bulk of the reaction occurs and the medium reaches its ignition temperature

Flame Propagation

The movement of a flame front in piping or equipment.

Flame Speed

The speed of a flame front relative to a fixed reference point. Flame speed is dependent on turbulence, the equipment geometry, and the fundamental burning velocity.

Flame Temperature

Theoretical temperature achieved based on chemical equilibrium with the assumption of Gibbs free energy minimization

Flame Trap

Another name for a flame arrester, commonly used in the United Kingdom.

Flame Velocity

See Flame Speed

Flammability Limits

The range of gas or vapor amounts in air that will burn or explode if a flame or other ignition source is present. Importance: The range represents an unsafe gas or vapor mixture with air that may ignite or explode. Generally, the wider the range the greater the fire potential. See also Lower Explosive Limit / Lower Flammable Limit and Upper Explosive Limit / Upper Flammable Limit.

Flammable

A gas that can burn with a flame if mixed with a gaseous oxidizer such as air or chlorine and then ignited. The term flammable gas includes vapors from flammable or combustible liquids above their flash points.

Flammable Gas (NFPA 55)

A gas that is flammable in a mixture of 13 percent or less (by volume) with air, or the flammable range with air is wider than 12 percent regardless of the lower limit, at atmospheric temperature and pressure.

Flammable Limits

The minimum and maximum concentration of fuel vapor or gas in a fuel vapor or gas/gaseous oxidant mixture (usually expressed in percent by volume) defining the concentration range (flammable or explosive range) over which propagation of flame will occur on contact with an ignition source. See also Lower Flammable Limit and Upper Flammable Limit.

Flammable Limits (Dusts)

The minimum and maximum concentration of a particulate solid (dust) in a dust/gaseous oxidant mixture (usually expressed in percent by volume) defining the concentration range (flammable or explosive range) over which propagation of flame will occur on contact with an ignition source. See also Lower Flammable Limit and Upper Flammable Limit.

Flammable Liquids

Any liquid that has a closed-cup flash point below 100 F (37.8 C), as determined by the test procedures described in NFPA 30 and a Reid vapor pressure not exceeding 40 psia (2068.6 mm Hg) at 100 F (37.8 C), as determined by ASTM D 323, Standard Method of Test for Vapor Pressure of Petroleum Products (Reid Method). Class IA liquids shall include those liquids that have flash points below 73 F (22.8 C) and boiling points below 100 F (37.8 C). Class IB liquids shall include those liquids that have flash points below 73 F (22.8 C) and boiling points at or above 100 F (37.8 C). Class IC liquids shall include those liquids that have flash points at or above 73 F (22.8 C), but below 100 F (37.8 C). (NFPA 30)

Flammable Mass

The mass of fuel in a vapor cloud that is in the flammable range, mf.

Flammable Range

The range of concentrations between the lower and upper flammability limits.

Flammable Vapor

A vapor that is above its lower flammable limit (LFL) concentration. A zone of flammable vapor will exist in equilibrium with a flammable or combustible liquid any time it is above its flash point.

Flash Fire

A fire that spreads by means of a flame front rapidly through a diffuse fuel, such as a dust, gas, or the vapors of an ignitable liquid, without the production of damaging pressure.

Flash Point

The minimum temperature at which a liquid gives off sufficient vapor to form an ignitable mixture with air within the test vessel used (Methods: ASTM 502). The flash point is less than the fire point at which the liquid evolves vapor at a sufficient rate for indefinite burning.

Flashback

Undesired flame propagation opposite to the direction of flow. It is also used to describe failure of a flame arrester element.

Flashpoint

The temperature at which a liquid develops sufficient vapor pressure to form a vapor/air mixture capable of undergoing combustion after ignition from an external energy source. (Fire point is the temperature at which the reaction will be sustained).

Force Majeure

An event or effect that cannot reasonably be anticipated or controlled.

Frequency

Number of occurrences of an event per unit time (e.g., 1 event in 1000 yr. = 1 x 10-3 events/yr.).

Frequency Data

The data required to generate accident and non-accident rates, the probability of a release following an accident, the range of release sizes to be considered, and the probabilities of various outcomes of release (i.e., toxic, flammable, explosive).

Frequency modeling

Development of numerical estimates of the likelihood of an event occurring.

Front-line Personnel

The personnel who perform tasks that produce the output of the work group. Front-line personnel include operations and maintenance personnel, engineers, chemists, accountants, shipping clerks, etc.

Fuel

the reducer; any combustible material, solid, liquid or gas. Most solids and liquids must vaporize before they will burn.

Fuel Gas

Gaseous fuels consisting of natural gas and various manufactured or by-product gases.

Fugitive Emissions

Those emissions which could not reasonably pass through a stack, chimney, vent or other functionally-equivalent opening.

Fundamental Burning Velocity (Su).

The burning velocity is the rate of flame propagation relative to unburned gas ahead of the flame front. The fundamental burning velocity is the burning velocity of a laminar flame under stated conditions of composition, temperature and pressure in the unburned gas. The reported Su is usually the maximum value measured for the fastest burning composition at 25 C and 760 mmHg.

Galloping Detonation

A detonation that periodically fails and reinitiates during propagation. This type of detonation is typically observed in near-limit mixtures. Since it reinitiates via DDT, a galloping detonation is periodically overdriven and results in large overpressures at periodic distances along a pipe.

Gantt chart

A manner of depicting multiple, time-based project activities (usually on a bar chart with a horizontal time scale).

Gas

The state of matter characterized by complete molecular mobility and unlimited expansion at standard temperature and pressure

Gas Enrichment

The addition of another flammable gas to a gas-air mixture to raise the concentration above the upper flammable limit.

Gaussian Models

A class of transport and dispersion model which assumes that the distribution of pollutant concentration has a Gaussian or normal shape [e.g., exp(-y2/2σy 2), where y is the lateral crosswind distance from the center of the plume or puff and σy is the lateral dispersion component].

Glossary Term

IT Download
May 13, 2024

Glossary Term

IT Download May 13, 2024

Good Engineering Practices

Engineering, operating, or maintenance activities based on established codes, standards, published technical reports, or recommended practices.

Good industry practice (GIP)

In PSM, a best or common practice that a facility or company has found to be a useful addition to its PSM program, or a useful but non-mandatory solution to a PSM issue.

Grassroots

Totally new facility that may be built upon a greenfield or brownfield site.

Gravity Slumping

The decrease in cloud height of a flowing dense gas due to the effects of gravity (negative buoyancy).

Greenfield

Undeveloped property that is being considered as a site for construction. (Dictionary.com)

Ground-level releases

Source emissions from near ground level.

Grounding

The process of connecting one or more conductive objects to ground so that each is at the same potential as the earth. By convention, the earth has zero potential. In practice, grounding is the process of providing a sufficiently small resistance to ground so that a static hazard cannot be created at the maximum credible charging current to a system. Grounding may be referred to as earthing in Europe.

Hardware

Physical equipment directly involved in performing industrial process measuring and controlling functions, as opposed to computer programs, procedures, rules, and associated documentation.