Fluid Model Experiments
Experiments carried out at small scale in wind tunnels and water channels.
Force Majeure
An event or effect that cannot reasonably be anticipated or controlled.
Forensic Engineering
The art and science of professional practice of those qualified to serve as engineering expects in matters before the courts of law or in arbitration proceedings.
Form Prototype
A device that is of the correct physical size and general appearance, and can be mechanically installed or interconnected with other devices or components that constitute a system. A form prototype is not necessarily functional electrically or optically. A "mock-up".
Formula
The conventional scientific designation for a material (water is H2O, sulfuric acid is H2SO4, Sulfur dioxide is SO2, etc.) Importance: Chemical formulas identify specific materials.
Fractional Dead Time (FDT)
The mean fraction of time in which a component or system is unable to operate on demand.
Fractional Dead Time (FDT)
A probability representing the mean proportion of the total relevant time that a component, equipment, or system, is incapable of providing protection. Also called average unavailability or average probability of being in a failed state. Dimensionless. The mean fraction of time in which a component or system is unable to operate on demand. (Also know as Unavailability.) The measure of the fractional time that the system is likely to be in a non-working state.
Free stream or geostrophic wind speed
Wind speed at the top of the boundary layer.
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.
Friction Velocity, u*
The fundamental scaling velocity, equal to the square root of the surface stress, to, divided by the air density. The surface stress can be observed by special instruments that directly observe the drag at the surface, or by fast response turbulence instruments using the definition: to = r(-u'w') = ru*2 where u' is the longitudinal wind speed fluctuation, w' is the vertical wind speed fluctuation, and the average is over about a one-hour time period. The variable u* can also be estimated from wind observations. A rough rule of thumb is that the ratio u*/u is about 0.05 to 0.1, where u is the wind speed at a height of about 10 m, which is the standard measurement height at airports around the world. u* has typical values ranging from about 0.05 m/s in light winds to about 1 m/s in strong winds.
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.
Froth-Over
When water is present or enters a tank containing hot viscous oil, the sudden conversion of water to steam causes a portion of the tank contents to overflow.
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.
Full Volume Deflagration (FVD)
A deflagration explosion developed from a flammable cloud of gas, aerosol, or dust that occupies the entire volume in a confined space.
Full-scale Field Experiments
Field experiments of flow and dispersion around full sized obstacles (e.g., buildings, storage tanks, nuclear reactor structures, street canyons, isolated hills).
Fully Developed Flow
Flow in a long, constant area pipe in which the mean velocity profiles are independent of position along the pipe. In the pipe the surface shear stress is balanced by the longitudinal gradient of static pressure in the pipe (the pressure gradient).
Functional Deficiencies
Failures from a system that works as designed but are inadequate for the task at hand.
Functional Design
A phase in the development of computerized systems which produces detailed descriptions of the system that are independent of particular hardware and software. This includes all flows of information, timing diagrams, and state transition diagrams.
Functional Prototype
A device that is electrically and optically workable, used to demonstrate the operating function of the device or interconnected system. It may not have a size or shape that is considered usable in an operating environment. A "breadboarded" device.
Functional Requirements
A phase in the development of computerized systems in which all inputs to and outputs from the system and transfer functions that produce the outputs from the inputs are identified and described in detail.
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.
Fungus (plural fungi)
occurring as single-celled forms such as yeast and complex forms such as mushrooms, fungi can cause infections from mild skin infections such as ringworm and athlete's foot to life-threatening conditions such as cryptococcal meningitis, histoplasmosis, and clastomycosis.
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].
General Exhaust
A system for exhausting air containing contaminants from a general work area. See also, "Local Exhaust". Importance: Adequate ventilation is necessary to prevent adverse health effects from exposures to hazardous materials and vapor accumulations that can be a fire hazard.
Generic Data
Data which is typical for a system. Such data will not have been collected for the particular system but will have been collected, estimated or aggregated from many generally similar systems.
Genome
An organism's complete set of genetic material.
Go-Devil
See "Surface Streamer".
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.
Graceful Degradation
A computer program technique the purpose of which is to prevent catastrophic system failure by permitting the machine to operate, although in a degraded mode, in spite of failures of malfunctions in several integral units or subsystems.
Gradient Transport or K theory
The eddy diffusivity coefficient K is used to solve the mass conservation equation for the pollutant. The solution can be obtained analytically for some simple cases but must be solved numerically for more general cases. This model is most useful when the size of the cloud is greater than the dominant turbulent length scales.
Grassroots
Totally new facility that may be built upon a greenfield or brownfield site.
Gravitational Settling Velocities
Downward velocity of particles due to gravity (about 10 cm/s for an aerosol diameter of about 50 microns and about 100 cm/s for an aerosol diameter of about 200 microns, assuming an aerosol density approximately equal to the density of water, or about 1000 kg/m3).
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)
Grooved and Shouldered Joint
Type of pipe connection that might result in electrical isolation by gasket and which may require jumper cable across joint.
Ground Indicator
Commercially available device which automatically senses the presence of ground continuity and which may be equipped with alarms or interlocks to prevent operations such as flammable liquid transfers unless equipment is grounded.
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.
Hard Wired Interlock
An interlock accomplished by electro-relays and/or wires. An interlock not accomplished through a PES (see software interlock).
Hardware
Physical equipment directly involved in performing industrial process measuring and controlling functions, as opposed to computer programs, procedures, rules, and associated documentation.
Hardwired
That portion of the logic which is executed by electrical circuits comprised exclusively of H/W. That portion of the logic which is executed by electrical circuits devoid of S/W or firmware.