20+ Senior Instrumentation Technician Interview Questions and Answers

The question is asking about your experience with calibration, loop checking, P&ID interpretation, control valve simulation, installation, termination, and pre-commissioning.

• Discuss your experience with calibration procedures and equipment

• Explain your process for loop checking and troubleshooting

• Demonstrate your ability to interpret P&ID diagrams

• Describe your experience with control valve simulation and installation

• Discuss your experience with pre-commissioning activities

• Prov...read more

4-20 mA is commonly used because it allows for a minimum value of 4 mA to indicate a fault condition, while 0-20 mA does not have this capability.

• 4-20 mA provides a clear indication of a fault condition by having a minimum value of 4 mA.

• Using 4-20 mA allows for a wider range of measurement values compared to 0-20 mA.

• Many instruments and control systems are designed to work with 4-20 mA signals.

• 4-20 mA signals are less susceptible to noise and interference compared to 0-20 mA ...read more

To check level transmitter at 0%, disconnect the transmitter from the process and verify the output signal is at 4mA.

• Disconnect the transmitter from the process

• Verify the output signal is at 4mA

• Check the wiring and connections

• Ensure the transmitter is properly configured for 0% level

• Perform a loop check to confirm the transmitter is functioning correctly

Calibration of various types of instruments including electronic, pneumatic, electrical, loop check, troubleshooting, termination, and installation.

• Calibration involves adjusting an instrument to ensure it is accurate and reliable.

• Electronic instruments require calibration to maintain precision in measurements.

• Pneumatic instruments use air pressure for operation and need calibration for accuracy.

• Loop checks involve verifying the communication between instruments and control s...read more

There are several types of process elements in instrumentation.

• Process elements in instrumentation can include sensors, transmitters, controllers, and final control elements.

• Sensors are used to measure physical quantities such as temperature, pressure, flow, and level.

• Transmitters convert the sensor signals into standardized electrical signals for further processing.

• Controllers receive the signals from transmitters and make adjustments to maintain desired process conditions.

• F...read more

The principal thermocouple working is based on the Seebeck effect.

• The Seebeck effect is the phenomenon where a temperature difference between two dissimilar metals or semiconductors generates an electric voltage.

• The voltage generated is proportional to the temperature difference and can be measured to determine the temperature.

• Common types of thermocouples include Type K (chromel-alumel), Type J (iron-constantan), and Type T (copper-constantan).

The mass flow meter should be calibrated by a qualified technician using a traceable standard.

• Calibration should be performed by a qualified technician with experience in calibrating mass flow meters.

• The calibration should be performed using a traceable standard, such as a NIST-traceable calibration device.

• The calibration should be performed at regular intervals to ensure accurate readings.

• The calibration process should be documented and the results should be recorded.

• If the ...read more

Flow rate is the amount of fluid passing through a point per unit time, while volumetric rate is the volume of fluid passing through a point per unit time.

• Flow rate is measured in units like liters per minute, while volumetric rate is measured in units like cubic meters per hour.

• Flow rate is dependent on the area of the pipe or channel, while volumetric rate is not.

• For example, a flow rate of 10 liters per minute means that 10 liters of fluid are passing through a point in th...read more

The question is asking for the name of a loop in the context of instrumentation.

• The name of the loop could refer to a control loop in a process control system.

• It could also refer to a feedback loop in a measurement or control system.

• Examples of loop names could be PID loop, cascade loop, or closed-loop system.

MOSFETs are used in various applications due to their high switching speed, low power consumption, and compact size.

• MOSFETs are commonly used in power electronics for switching applications.

• They are used in amplifiers and audio systems for signal amplification.

• MOSFETs are used in voltage regulators to maintain a stable output voltage.

• They are used in digital circuits for logic gates and memory storage.

• MOSFETs are used in motor control circuits for precise control of motor spe...read more

There are two types of loops in instrumentation: open loop and closed loop.

• Open loop: A control system where the output is not affected by the input.

• Closed loop: A control system where the output is affected by the input and feedback is used to make adjustments.

• Example: In a temperature control system, an open loop would simply turn on the heater without considering the actual temperature, while a closed loop would measure the temperature and adjust the heater accordingly.

Calibrating instruments involves adjusting and verifying their accuracy to ensure reliable measurements.

• Identify the instrument to be calibrated and gather necessary calibration standards and tools.

• Follow the manufacturer's instructions and guidelines for calibration procedures.

• Perform initial checks and adjustments to ensure the instrument is in a stable and suitable condition for calibration.

• Compare the instrument's readings to known reference standards and make necessary a...read more

RTD works on the principle of change in resistance with temperature.

• RTD stands for Resistance Temperature Detector.

• RTD works based on the principle that the electrical resistance of a metal changes with temperature.

• As the temperature increases, the resistance of the RTD increases.

• The change in resistance is measured and converted into temperature using a calibration curve.

• RTDs are commonly used in industrial applications for temperature measurement and control.

• Platinum is a c...read more

Cable glanding is the process of securing the end of a cable to a piece of equipment or a junction box to prevent strain on the cable and ensure safety.

• Select the appropriate size and type of cable gland based on the cable diameter and material

• Prepare the cable by stripping the outer sheath and any insulation to expose the conductors

• Insert the cable through the gland and tighten the gland nut to secure it in place

• Ensure that the cable is properly sealed to prevent ingress of ...read more

Cable testing involves checking the integrity and functionality of cables used in instrumentation systems.

• Use a multimeter to check for continuity in the cable

• Inspect the cable for any physical damage or wear

• Perform insulation resistance testing to ensure there are no shorts or faults

• Check for proper grounding and shielding of the cable

• Verify correct wiring connections at both ends of the cable

Control system monitoring involves ensuring proper functioning of instruments and equipment used in the control system.

• Regularly checking and calibrating instruments

• Identifying and troubleshooting issues in the control system

• Maintaining records of maintenance and repairs

• Collaborating with other technicians and engineers to optimize control system performance

Thermocouples are classified by letter codes. Common types are J, K, T, E, R, S, and B.

• Thermocouples are used to measure temperature in various industries.

• Type J is made of iron and constantan, and is commonly used in food industry.

• Type K is made of chromel and alumel, and is commonly used in industrial applications.

• Type T is made of copper and constantan, and is commonly used in low-temperature applications.

• Type E is made of chromel and constantan, and is commonly used in cr...read more

Hot loop check with DCS involves verifying the accuracy and functionality of temperature control loops using a distributed control system.

• Performing a hot loop check involves simulating a high temperature setpoint and verifying that the DCS responds correctly.

• Checking for proper communication between the DCS and temperature sensors/transmitters.

• Verifying that the DCS is accurately displaying and recording temperature readings.

• Ensuring that the control algorithm is functioning...read more

A capsule is a small container, typically made of gelatin, used for enclosing medicine or supplements.

• Capsules are commonly used in the pharmaceutical industry to encapsulate drugs or supplements for oral consumption

• There are two main types of capsules: hard capsules, which are typically made of two pieces that fit together, and soft capsules, which are made of a single piece of gelatin

• Capsules can be filled with powder, liquid, or pellets depending on the medication being en...read more