Chapter_12_abridged

Process Diagrams

Symbology

Graphical representations used to identify equipment, lines, instrumentation, or process configurations.

P&ID

Piping and Instrumentation Diagram; contains detailed piping and instrumentation details and the entire control system.

PFD

Process Flow Diagram; a pictorial description of an actual process including the major equipment and process information.

BFD

Block Flow Diagram; shows the flow scheme in a simple sequential block form.

Legend

An explanation of what the symbols and codes on a drawing represent.

ISA

International Society of Automation; a nonprofit technical society developing standards for automation and instrumentation.

Control Loop

A system that regulates the performance of a process variable.

Balloon

The basic instrumentation symbol used in process diagrams to represent an instrument.

Basic Equipment Symbol

Symbols representing common equipment such as pumps, towers, furnaces, etc.

Instrumentation

Control systems used to monitor, maintain, and manipulate process variables.

Instrument Tag Number

A unique identifier for an instrument that includes the measured variable and function.

Flow Rate

The quantity of fluid that moves through a system over a period of time.

Differential Pressure

The difference in pressure between two points in a system, often used for flow measurement.

Control Valve

A valve used to control the flow rate and pressure of a fluid.

Final Control Element

The last device in a control loop that directly affects the process variable.

Instrumentation Sketching

The process of drawing relationships of instrumentation in a P&ID.

Process Variables

Parameters like flow, temperature, pressure, and level that are controlled in a process.

Signal Line Symbols

Symbols used to depict the type of signal transmitted between instruments.

Soft Link

A connection in a digital control system, showing the flow of information.

Analog Signal

A continuous signal used to represent varying values.