HCLTech Interview Questions and Answers

Nucleonic type radar level transmitter uses radioactive sources to measure level of liquids or solids in tanks. It is commonly used in industries like oil and gas, chemical, and power plants.

• Uses radioactive sources to emit gamma rays towards the material being measured

• The gamma rays are then reflected back to the detector, with the time taken for the reflection used to calculate the level of the material

• Suitable for measuring level of liquids or solids in tanks where other t...read more

Designing tools and drawings required for setting up a chemical plant include P&IDs, PFDs, equipment layouts, and instrumentation diagrams.

• Process and Instrumentation Diagrams (P&IDs) are essential for showing the interconnection of process equipment and the instrumentation used to control the process.

• Piping and Instrumentation Diagrams (P&IDs) show the piping of the process flow together with the installed equipment and instrumentation.

• Equipment layouts are necessary to plan...read more

The liquid filled in pressure gauge is typically glycerin or silicone oil.

• Common liquids used are glycerin and silicone oil

• The liquid helps dampen the effects of vibration and pulsation on the gauge

• It also helps lubricate the internal components of the gauge

• The choice of liquid depends on the application and operating conditions

A bourdon type pressure gauge is a mechanical device used to measure pressure in a system.

• Consists of a curved tube that straightens with pressure, causing a pointer to move on a dial

• Commonly used in industrial applications for measuring pressure in pipelines, tanks, and machinery

• Available in various designs such as C-type, spiral, and helical bourdon tubes

Final control elements are classified based on their action, type of motion, and type of signal.

• Based on action: On-off control, proportional control, PID control

• Based on type of motion: Linear motion, rotary motion

• Based on type of signal: Pneumatic, hydraulic, electric

• Examples: Control valves, actuators, solenoid valves

Float type level measurement works by using a float that rises or falls with the liquid level, activating a switch or transmitter.

• Float rises or falls with the liquid level

• Float activates a switch or transmitter

• Commonly used in tanks and vessels for level control

• Examples: magnetic float level switch, displacer level transmitter

Transducers can be classified based on various criteria such as principle of operation, electrical output, and application.

• Classification based on principle of operation: resistive, capacitive, inductive, piezoelectric

• Classification based on electrical output: analog, digital

• Classification based on application: temperature, pressure, level, flow

• Other classifications: active vs. passive, contact vs. non-contact

A solenoid valve is an electromechanically operated valve that is commonly used to control the flow of liquids or gases.

• Solenoid valves use an electromagnetic coil to open or close the valve mechanism.

• They are commonly used in applications such as controlling water flow in irrigation systems, gas flow in HVAC systems, and fluid control in industrial processes.

• When the coil is energized, it creates a magnetic field that moves the valve mechanism to either open or close the flo...read more