Process Control Questions PDF

1. Which of the following is NOT a component of a basicprocess control loop? A) Sensor b) Controller c) Actuator d) Final product 2. A temperature control system in a chemical reaction vessel is anexample of a process loop for controlling which variable? A) Flow rate b) Temperature c)...

1. Which of the following is NOT a component of a basicprocess control loop? A) Sensor b) Controller c) Actuator d) Final product 2. A temperature control system in a chemical reaction vessel is anexample of a process loop for controlling which variable? A) Flow rate b) Temperature c) Pressure d) Level 3. The current flowing through a transmitter in a process loop can beconsidered a: a) Process variable b) Manipulated variable c) Controlled variable d) Setpoint 4. In P&ID diagrams, a square box with a diagonal line represents: a. Sensor b. Controller c. Valve d. Control room 5. Instruments located in the physical process area (near theequipment) are represented by symbols in the:  a. Top half of the P&ID (CORRECT) b. Bottom half of the P&ID c. Left side of the P&ID d. Right side of the P&ID 6. The standard 4-20mA current loop is used in process controlbecause it is: a. Easy to generate b. Less susceptible to noise c. Both a) and b) d. Requires less power 7. In a pressure transmitter, a “live zero” calibration refers to adjusting the output signal when the: a. Pressure is at its maximum value b. Pressure is at its minimum value c. Transmitter is powered on but no pressure applied d. Pressure is at the desired setpoint 8. Which of the following statements about dead zero is INCORRECT? a. It is used to adjust the zero output of the transmitter. b. It is performed with no pressure applied. c. It does not affect the transmitter’s span. d. It should be done frequently during operation. 9. Why are transmitters used in process control systems? a. To directly control actuators b. To convert sensor signals into a standard format for easy transmission c. To generate power for the control loop d. To display process measurements in the control room 10. Which of the following term indicates the main difference between a two-wire and a four-wire transmitter? a. Accuracy b. Power supply c. Measurement range d. Output signal type 11. Which of the following is NOT a typical feature of a transmitter? a. Linear output signal b. Internal diagnostics c. Remote calibration capability d. Flow control valve 12. An electronic capacitive differential pressure transmitter (DPT) canbe used for level measurement. How does this work? a. By directly measuring the weight of the liquid b. By measuring the pressure difference between the top andbottom of a tank c. By measuring the electrical conductivity of the liquid d. By measuring the vibration of the tank walls 13. What is the purpose of zero elevation and suppression in a DPT? a. To adjust the span of the transmitter b. To compensate for static pressure and adjust measurable range c. To improve the accuracy of the high-pressure range d. To increase the power consumption of the transmitter 14. How does a SMART transmitter differ from a conventionaltransmitter? a. It uses a different type of sensor b. It offers digital communication capabilities c. It has a higher accuracy rating d. It requires a separate power supply 15. Identify the important element of a SMART Ttransmitter with reference to conventional transmitter a. control valve b. Sensor c. ADC d. power supply 16. What is the "error" in a control system? a. The desired output of the controller b. The actual output of the process c. The difference between the desired output (setpoint)and the actual output d. The time it takes for the process to reach the setpoint 17. What is the variable range in a control system? a. The range of the control signal b. The range of values of the process variable c. The accuracy of the measurement sensor d. The maximum error allowed in the system 18. What is cycling in a control system? a. A gradual change in the process variable b. Rapid on-off switching of the final control element c. A steady state condition at the setpoint d. A large deviation from the setpoint 19. Differentiate between direct acting and reverse actingcontrol actions. a. controller output increases with increase in controlled variable w.r.to SP. b. controller output increases with decrease in controlled variable w.r.to SP. c. controller output decreases with increase in controlled variable w.r.to SP. d. controller output remains constant with increase in controlled variable w.r.to SP. 20. Two-position control is also known as: a. Proportional control b. Integral control c. Floating control mode d. On/off control 21. What is the advantage of using a multi-position controlmode over a two-position control mode? a. Faster response time b. precise control with multiple discrete output levels c. Reduced energy consumption d. Improved stability 22. In floating control mode, the final control element can assume any position within its range. This mode is typicallyused with: a. Two-position valves b. Linear valves like globe valves c. Rotary valves like butterfly valves d. On/off actuators 23. Proportional control (P) adjusts the control signal based onthe: a) Rate of change of the error b) Magnitude of the error (proportional to the error) c) Accumulation of past errors d) Setpoint value 24. What is the drawback of using only proportional control? a. Slow response to large errors b. Requires a complex controller c. Prone to cycling d. Steady-state error (the process variable may not reach the setpoint) 25. Integral control (I) eliminates the steady-state error of aproportional controller by considering: a) The instantaneous error b) The rate of change of the error c) The accumulation of past errors d) The setpoint value 26. What is the potential issue with using only integralcontrol? a. Slow response for large integral time b. Prone to overshoot c. Decreases bandwidth d. Increase offset 27. Derivative control (D) anticipates future changes in theerror by considering the: a. Accumulation of past errors b. Rate of change of the error c. Magnitude of the current error d. Setpoint value 28. What is the effect of adding derivative control to a PIcontroller ? a) Improves response time and reduces overshoot b) Reduces steady-state error c) Makes the system unstable d) All of the above 29. Reset windup occurs in a PI controller when the integrator accumulates a large error signal due to: a. A malfunctioning sensor b. A sudden change in the setpoint c. A sustained process disturbance that the controller cannot fully compensate for d. A saturated actuator 30. What is the purpose of "rate before reset" in a PIcontroller? a) To limit the integrator output b) To increase the derivative gain c) To prevent reset windup by temporarily stopping the integrator during large errors d) To improve the response time to setpoint changes 31. What is the purpose of tuning a PID controller? a. To optimize controller performance b. To reduce overshoot c. To improve setpoint tracking d. All of the above 32. Which of the following methods is NOT commonly used fortuning PID controllers? a. Ziegler-Nichols method b. Relay tuning method c. Root locus method d. Genetic algorithm method 33. What is the main drawback of the Ziegler-Nichols tuning method? a. It may cause instability in the system b. It requires excessive trial and error c. It does not work well for complex systems d. It is time-consuming 34. Which parameter of a PID controller is typically adjusted first during tuning? a. Proportional gain b. Integral gain c. Derivative gain d. Setpoint 35. Why is it important to tune a PID controller for aspecific application?  a. To ensure optimal system performance b. To prevent system oscillations c. To reduce energy consumption d. To improve system reliability. 36. Which type of converter is used to convert currentsignals into pressure signals? a. Current to voltage converter b. Pressure to current converter c. Current to pressure converter d. Pressure to voltage converter 37. What is the necessity of final control elements in acontrol system? a. To regulate the flow of fluids b. To maintain process parameters within desired limits c. To convert signals between different forms d. To provide feedback to the controller 38. Which of the following is not a part of a controlvalve? a. Valve body b. Actuator c. Flow meter d. Valve trim 39. Which type of actuator is powered by compressedair and is commonly used in control valves? a. Pneumatic actuator b. Electric actuator c. Hydraulic actuator d. Handwheel  40 What does the term "rangeability" refer to in controlvalve terminology? a. The range of pressure that the valve can handle b. The range of flow rates the valve can handle c. The ability of the valve to withstand hightemperatures d. The precision and accuracy of the valve control 41. What does the term "fail-safe action" refer to incontrol valve terminology? a. The valve automatically closing in case of a systemfailure b. The valve staying in its last known position during apower outage c. The valve opening fully in case of a power failure d. The valve adjusting to a default position whencontrol signals are lost 42. What is the purpose of a control valve sizingcoefficient CV? a. To indicate the size of the valve body b. To determine the flow capacity of the valve c. To calculate the rangeability of the valve d. To measure the pressure drop across the valve 43. What is the advantage of using an electric actuator over apneumatic actuator? a. Requires less maintenance b. Faster response time c. Needs a constant air supply d. More powerful for high-pressure applications 44. What is the purpose of a handwheel actuator? a. To control the valve remotely b. To manually operate the valve during maintenance oremergencies c. To provide position feedback to the controller d. To convert electrical signals to pressure 45. How are control valves classified based on the number ofpositions they can achieve? a. Linear and rotary b. Globe and butterfly c. On/off and throttling d. Two-position and multi-position (Two-position for on/offcontrol, multi-position for specific flow rates) 46. Which type of control valve is best suited for high-pressureapplications? a. Butterfly valve b. Globe valve c. Gate valve (Due to their simple design) d. Diaphragm valve 47. Turndown is another term for: a. Rangeability (These terms are often used interchangeably) b. Valve capacity c. Valve position d. Fail-safe action  48. What does AO stand for in control valve terminology? a. Air Open b. Air to Open c. Automatic open d. Always open 49. What does AC stand for in control valve terminology? a. Air Close b. Automatic Close c. Air to Close d. Always Close 50. Control valve characteristics are plotted as a. % stem opening and % flowrate b. stem opening and flowrate c. stem opening and time d. Flowrate and time 51. What type of valve uses a disc that moves vertically to regulateflow? a) Butterfly valve b) Globe valve c) Ball valve d) Gate valve 52. Differentiate between a single-seated and a double-seatedglobe valve. a) Single-seated has higher flow capacity, double-seated hasbetter shutoff. b) Single-seated is for throttling, double-seated is for on/offcontrol. c) Single-seated experiences unbalanced forces, double-seated is more balanced. d) Single-seated requires higher pressure to operate, double-seated needs less. 53. What is the advantage of a 3-way globe valve? a) Higher pressure rating b) Controls flow direction in addition to flow rate c) More precise throttling capability d) Suitable for high-viscosity fluids 54. What is a disadvantage of using a gate valve for controlapplications? a) More complex construction b) Prone to cavitation c) Limited throttling capability d) Requires high actuator force 55. What is the primary function of an angle valve? a) Regulates high-pressure applications b) Changes flow direction (similar to an elbow with control capability) c) Provides superior shutoff compared to globe valves d) Offers a wider rangeability 56. A butterfly valve features a disc that rotates on a shaft tocontrol flow. What is an advantage of this design? a. High pressure rating b. Compact and lightweight c. Excellent throttling characteristics d. Ideal for viscous fluids 57. Why is a positioner used with a control valve? a) To increase the flow capacity of the valve b) To convert electrical signals to pneumatic signals c) To improve the accuracy and stability of the valveposition d) To provide fail-safe functionality 58. How does a positioner improve the performance of a controlvalve? a) By increasing the actuator force b) By reducing the rangeability of the valve c) By making the valve response faster d) By compensating for pressure drops and friction in the actuator 59. What is cavitation in a control valve, and what effect doesit have? a) Build-up of pressure due to a closed valve b) Rapid formation and collapse of vapor bubbles due topressure drop, causing vibration and erosion c) Internal leakage through the valve seat d) Excessive noise generated by the actuator 60. How can cavitation and flashing be prevented in a controlvalves? a) Using a larger valve size b) Selecting a valve with a higher pressure rating c) Reducing the pressure drop across the valve d) Increasing the actuator force