PFD

PFD is an acronym that can refer to several distinct concepts depending on the context.

Personal Flotation Device: A Personal Flotation Device (PFD) is a life jacket or buoyant garment designed to keep a wearer afloat in water. They are labeled by buoyancy and intended activity, commonly Type I, II, III, IV, and V, and are subject to regulatory standards in various jurisdictions.

Primary Flight Display: In aviation, the Primary Flight Display is the main cockpit instrument in modern glass cockpits. It visualizes essential flight data such as attitude, airspeed, altitude, vertical speed, and flight mode status, and is often paired with a Navigation Display.

Process Flow Diagram: In chemical and process industries, a Process Flow Diagram illustrates the major equipment and the flow of materials through a facility. PFDs are used during design and operation and are typically complemented by Piping and Instrumentation Diagrams (P&ID) for detailed instrumentation and piping.

Probability of Failure on Demand: In reliability engineering and safety instrumentation, the Probability of Failure on Demand represents the likelihood that a safety-related function will fail in a dangerous mode when demanded. It informs risk assessments and determines safety integrity levels under standards such as IEC 61508 and IEC 61511.

Context usually clarifies which PFD is meant, and the term may have additional specialized meanings in other fields.