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Very near-field
The area very close to the source where the specific geometry of one or two individual obstacles influence the flow and dispersion.
Viscous Nonconductive Liquid
Nonconductive liquid having a kinematic viscosity above 30-100 cS and a very slow rate of charge dissipation, equivalent to a conductivity of about 0.02 pS/m and a relaxation time of about 1000 s.
Volume-Source Explosion Models
Models that predict explosion characteristics based on the volumetric portion of the flammable cloud involved in the explosion (that portion of the flammable cloud that is influenced by congested and/or confined volumes in a plant).
Voluntary Risk
Risk that is consciously tolerated by someone seeking to obtain the benefits of the activity that poses the risk.
Water-Compatible
A material that is neither reactive with water nor incompatible with water and consequently can be extinguished with a water-based extinguishing system.
Water-Incompatible
A material that does not chemically react with water but undergoes a change of phase or state upon mixture with water that renders it permanently changed or incompatible with the remainder of the process.
Water-Reactive
A material that will react upon contact with water under normal ambient conditions. Includes materials that react violently with water and other materials that react slower but can generate heat or gases that can result in elevated pressure if contained.
What-If Analysis
A scenario-based hazard evaluation procedure using a brainstorming approach in which typically a team that includes one or more persons familiar with the subject process asks questions or voices concerns about what could go wrong, what consequences could ensue, and whether the existing safeguards are adequate.
What-If/Checklist Analysis
A What-If Analysis that uses some form of checklist or other listing of broad categories of concern to structure the what-if questioning.
Wind Rose
A plan view diagram that shows the percentage of time the wind is blowing in a particular direction.
Witness
A person who has facts related, directly or indirectly, to the accident or incident.
Work force
A general term used to refer to employees and contractors at a facility. This term is often, but not exclusively, used to refer to operators, maintenance employees, and other employees or contractors who are not in a supervisory or technical role.
Workforce Involvement
CCPS RBPS Element 04: This Element is a system that includes operations, maintenance, and contractor personnel in the design, development, application, and evolution of the facility's process safety efforts.
Workforce involvement
A PSM program element that consists of a series of work activates that (1) solicit input from the entire work force (including contractors), (2) foster a consultative relationship between management and workers at all levels of the organization, and (3) help sustain a strong process safety culture.
Worst Case
A conservative (high) estimate of the consequences of the most severe incident identified.
Worst Case Consequence
A conservative (high) estimate of the consequences of the most severe accident identified. For example, the assumption that the entire contents of a contained volume of toxic material is released to the most vulnerable area in such a way (all at once or continuous) as to have the maximum effect on the public or employees in that area. The contained volume could be chosen as the containers and pipes between shutoff valves or the entire process unit but probably not the entire plant.
Worst Credible Case
The most severe consequences, considering all scenarios and their outcomes, that is considered plausible or reasonably believable.
Worst Credible Incident
The most severe plausible or reasonably believable incident, considering only incident outcomes and their consequences, of all identified incidents and their outcomes.
Worst Possible Incident
The most severe incident, considering only incident outcomes and their consequences of all identified incidents and their outcomes.
Worst-Case Scenario (WCS)
A release involving a hazardous material that would result in the worst (most severe) off-site consequences.
Written program
A description of a management system that defines important aspects such as purpose and scope, roles and responsibilities, tasks and procedures, necessary input information, anticipated results and work products, personnel qualifications and training, activity triggers, desired schedule and deadlines, necessary resources and tools, continuous improvement, management review, and auditing.
Zone
Classification system for electrical and electronic equipment and wiring for all voltages in locations where fire or explosion hazards may exist, as defined in Article 505 of NFPA 70 National Electrical Code.