Control Systems and Instrumentation Quiz

Process Flow Diagram (PFD)

• PFDs are small diagrams, limiting stream information.
• They include crucial data around reactors and towers.
• Flags are used to track data.
• Full stream data is not typically included.

Basic Control Loops

• PFDs display control strategies for normal operations.
• Key elements include basic control loops.

Piping and Instrumentation Diagram (P&ID)

• P&IDs graphically represent the hardware and software necessary for process operation.
• Include piping, equipment, and instrumentation.
• Synonyms include Engineering Flow Diagram (EFD), Utility Flow Diagram (UFD), and Mechanical Flow Diagram (MFD).

Basic Loop (P&ID)

• A basic loop in a P&ID includes a process, a sensing element, measuring element, transmitter, and a final control element.
• This loop tracks the variable being monitored and controls the process.

Sensors (Sensing Element)

• Sensors detect, measure, and convert physical quantities into signals.
• Specific examples include photoelectric cells and mercury thermometers.
• Calibration against known standards is necessary for accuracy.

Temperature Sensor (Thermocouple)

• A thermocouple is a junction of two different metals that produce a voltage proportional to temperature difference.
• Thermocouples accurately measure temperature and convert heat energy into electrical energy.

Resistance Temperature Detector (RTD)

• RTDs are temperature sensors that measure temperature by correlating resistance with temperature.
• RTD elements are typically made of coiled wire wrapped around a ceramic or glass core.
• Their resistance changes predictably with temperature.

Flow Sensor (Magnetic Flow Meter)

• Magnetic flow meters measure fluid flow without obstructing it.
• They are unaffected by viscosity, density, temperature, pressure, and fluid turbulence.
• The principle of Faraday's Law of Induction utilizes the movement of an electrical conductor perpendicular to a magnetic field.

Flow Sensor (Orifice Meter)

• Orifice meters create a pressure drop to measure fluid flow.
• A nozzle, venturi, or orifice can be used to restrict the flow.
• Empirical calibration is needed for accurate measurements.

Flow Sensor (Venturi Meter)

• Fluid flow is measured by the pressure drop caused by a venturi tube constriction.
• This flow measurement device was invented by Clemens Herschel.

Transmitter

• Transmitters convert input signals, from sensors, into standardized transmission signals.

Controller

• Controllers monitor and adjust process operational conditions by altering input variables to control output variables.

Final Control Element

• Final control elements (e.g., control valves, pumps, heaters) directly control the value of a manipulated variable in a control loop.

Instrumentation Symbology (Field Mounted)

• Field-mounted instruments are connected to the process plant.
• Specific examples include sensors connected to pipelines or process equipment.

Instrumentation Symbology (Board Mounted)

• Board-mounted instruments are connected to the control panel.
• They are typically located on control boards.

Instrumentation Symbology (Invisible)

• Invisible instruments are located behind control panel boards.
• These instruments are not directly visible but still connected to the system.

Distributed Control System (DCS)

• DCS instruments are distributed throughout a manufacturing system or process.
• They use networks for communication and monitoring.

Instrumentation Numbering

• Examples of instrumentation numbering.

P&ID Examples

• Various examples of P&IDs illustrating control loops and process functions.

Exercise 1 (P&ID Example)

• The pH adjustment diagram illustrates control loop functionality.

Exercise 2 (P&ID Example)

• Diagram showing control loop to control level in a tank using valves and transmitters.
• Failure modes are also included.

Signal Lines

• Various signal line types are illustrated.
• They include pneumatic, hydraulic, and electrical signals, etc.