Interview Questions with Answers

1. What is priming?

- Pump casing must be filled with liquid before the pump is started, or the pump will not be able to function. If the pump casing becomes filled with vapors or gases, the pump impeller becomes gas-bound and incapable of pumping.

2. Types of pumps?

- Positive Displacement

       - rotary lobe pump, progressive cavity pump, rotary gear pump, piston pump, diaphragm pump, screw pump, gear pump, Hydraulic pump, vane pump

- Centrifugal Pumps

        - end suction pumps, in-line pumps, double suction pumps, vertical multistage pumps, horizontal multistage pumps, submersible pumps, self-priming pumps, axial-flow pumps, regenerative pumps.

3. What is octane number in fuel?

- The octane rating of Gasoline is measured in a test engine, and is defined by comparison with the mixture of 2,2,4-trimethylpentane (iso-octane) and heptane which would have the same anti-knocking capacity as the fuel under test: the percentage, by volume, of 2,2,4-trimethylpentane in that mixture is the octane number of the fuel. For example, petrol with the same knocking characteristics as a mixture of 90% iso-octane and 10% heptane would have an octane rating of 90.

4. What is added in LPG to detect leakage?

- Methyl Mercaptan 

5. Pascal law ? Applications?

- Pascal's law or the Principle of transmission of fluid-pressure states that "pressure exerted anywhere in a confined incompressible fluid is transmitted equally in all directions throughout the fluid such that the pressure ratio (initial difference) remains the same.

Application- Hydraulic jacks, Car lifts, Fork Lifts

6. Can you transfer the heat energy from cold body to hot body?

- Yes, with external work. Eg : Air conditioner

7. What is hogging and sagging?

- Hogging and sagging describe the shape of a beam or similar long object when loading is applied. Hogging describes a beam which curves upwards in the middle, and sagging describes a beam which curves downwards.

8. What Bernoulli’s Principle?

- In fluid dynamics, Bernoulli's principle states that for an inviscid flow, an increase in the speed of the fluid occurs simultaneously with a decrease in pressure or a decrease in the fluid's potential energy.

9. Difference between single acting and double acting pump?

- In single-acting machines the compression takes place on only one side of the piston; double-acting machines use both sides of the cylinder for compression. The flow is continuous in double acting and in single acting the flow is not continuous unless there is a surge vessel.

10. What is VSD?

- Variable Speed Drive

11. What is conduction, convection and radiation? Give Examples?

- Conduction or diffusion

The transfer of energy between objects that are in physical contact

Convection

The transfer of energy between an object and its environment, due to circular fluid motion

Radiation

The transfer of energy to or from a body by means of the emission or absorption of electromagnetic radiation

12. Mention flow measuring devices?

- Venturimeter, Rotameter etc.

13. Classify Carbon Steels on basis of carbon content?

Low-carbon steels contain up to 0.30% C. The largest category of this class of steel is flat-rolled products (sheet or strip), usually in the cold-rolled and annealed condition. The carbon content for these high-formability steels is very low, less than 0.10% C, with up to 0.4% Mn. Typical uses are in automobile body panels, tin plate, and wire products.
For rolled steel structural plates and sections, the carbon content may be increased to approximately 0.30%, with higher manganese content up to 1.5%. These materials may be used for stampings, forgings, seamless tubes, and boiler plate.
Medium-carbon steels are similar to low-carbon steels except that the carbon ranges from 0.30 to 0.60% and the manganese from 0.60 to 1.65%. Increasing the carbon content to approximately 0.5% with an accompanying increase in manganese allows medium carbon steels to be used in the quenched and tempered condition. The uses of medium carbon-manganese steels include shafts, axles, gears, crankshafts, couplings and forgings. Steels in the 0.40 to 0.60% C range are also used for rails, railway wheels and rail axles.
High-carbon steels contain from 0.60 to 1.00% C with manganese contents ranging from 0.30 to 0.90%. High-carbon steels are used for spring materials and high-strength wires.
Ultrahigh-carbon steels are experimental alloys containing 1.25 to 2.0% C. These steels are thermomechanically processed to produce microstructures that consist of ultrafine, equiaxed grains of spherical, discontinuous proeutectoid carbide particles.

14. Draw a possible isometric view for the object that has the following plan and elevation views?