Instrumentation Engineering Interview Questions and Answers
Question - 1 : - What is the instrumentation Engineering?
Answer - 1 : -
Instrumentation engineering is the engineering specialization deals with principle and operation of measuring devices used in electrical, pneumatic, etc. design and configuration of automated systems.
Instrumentation engineers work with automated processes, such as chemical or manufacturing plants, for industries to enhance system efficiency, reliability, health, optimization and stability.
Question - 2 : - What are the primary control variables?
Answer - 2 : -
The level is excluded, which is not a primary control variable because the level is controlled by manipulating flow to tank.
Question - 3 : - What is the instrumentation measurement?
Answer - 3 : -
Instrumentation can be used to measure certain field parameters (physical values):
- Pressure, either differential or static
- Flow
- Temperature measurement
- Level Measurement
- Density
- Viscosity
- Radiation
- Current
- Voltage
- Inductance
- Capacitance
- Frequency
- Resistivity
- Conductivity
- Chemical composition
- Chemical properties
- Various physical properties
Question - 4 : - What are the different flow meters?
Answer - 4 : -
Based on the working principle, there are 5 types of flow meters:
- Differential pressure(DP) flow meter - example: Orifice plate, Venturi meter, Flow nozzle, Rotameter.
- Velocity Flowmeter: Electromagnetic flowmeter, Ultrasonic flowmeter, Turbine flowmeter, Paddlewheel flow meter.
- Positive displacement flowmeter: Nutating disk, Rotary vane, Gear, Diaphragm flowmeter.
- Mass flowmeter: - Coriolis flowmeter , Thermal dispersion meter,
Question - 5 : - What are the different types of temperature measuring instruments?
Answer - 5 : -
- Thermometer
- Thermister
- RTD
- Pyrometer
- Thermometers, Infrared thermometer
Question - 6 : - What are different pressure measuring gauges?
Answer - 6 : -
Liquid column elements:
- Barometer
- Manometer –u tube, enlarge leg well-inclined leg
Elastic element gauge:
- Bourdon tube
- Bellows
- Diaphragm
- Capsule
Electrical transducers:
- Resistance and inductance type
Force –balanced devices:
- Deadweight gauge
- Ring gauge
- Bell gauge
Question - 7 : - What is Flow compensation?
Answer - 7 : -
In steam or gas flow measurement, the density of the steam or gas changes as pressure and temperature change. This change in density can affect the accuracy of the measured flow rate if it is uncompensated. Temperature, pressure compensated flow control is a mathematically adjusted flow control with one or more additional variables.
Question - 8 : - Why 4-20mA signal is prefered over a 0-10v?
Answer - 8 : -
If the instrument is faulty, it can be detected easily. If the output is 0 ma, it will be hard to determine whether it is a defective signal or a good signal.
20 ma is used as maximum because the human heart can withstand up to 30 ma of current only. For safety reason 20 ma chosen as the maximum value.
Question - 9 : - What is Ultrasonic flowmeter?
Answer - 9 : -
Ultrasonic flowmeters pass high-frequency sound wave to the fluid path to measure the fluid velocity. The ultrasonic method uses the change in the moving fluid’s propagation time. There are two main types of ultrasonic flowmeters: Doppler and form of transit time.
Question - 10 : - What are the options to measure the temperature of an object without contact?
Answer - 10 : -
Pyrometer: Pyrometry tests surface temperature without touching it. Each object above absolute zero(-273.15 ° C) emits radiation. This emission is radiation from the heat and depends on the temperature. The term infrared radiation is also used because most of this radiation’s wavelengths are in the infrared domain in the electromagnetic spectrum over a visible red light.