### Translate

Technical Interview Questions - 8 Contains following Questions

81. Pressure drop equation for horizontal pipe line in laminar flow condition?
82. What is application of atomizer in Spray dryer?
83. What are the units of Dynamic Viscosity?
84. What is Elutriation ?
85. What is jigging and where it is used ?
86. What is Intensive and Extensive properties of material?
87. What are differences between pipe and tube?
88. What is liquid and its properties?
89. Convert 1 atm pressure terms to other units?

### 81. Pressure drop equation for horizontal pipe line in laminar flow condition?

In fluid dynamics, the Hagen–Poiseuille equation is a physical law that gives the pressure drop in a fluid flowing through a long cylindrical pipe.

The assumptions of the equation are that the flow is laminar viscous and incompressible and the flow is through a constant circular cross-section that is substantially longer than its diameter.

The equation is als known as the Hagen–Poiseuille law, Poiseuille law and Poiseuille equation.

The governing equation is,

### 82. What is application of atomizer in Spray dryer?

Atomizer converts liquid in tiny droplets.

### 83. What are the units of Dynamic Viscosity?

Dynamic viscosity has the units of cP (Centi Poise), Poise(P) or in M.K.S units it has the units Kg/m.s.

### 84. What is Elutriation ?

Elutriation: It is a separation method, which depends on the settling velocity of the particles in the fluid.

In this process of separation, the material is placed in a rising fluid having a fixed upward velocity,
particles whose normal falling velocity is less than the velocity of the fluid will be carried upward and out of the vessel.

If fractions obtained from a series of fluid velocities are collected and weighed, a complete size analysis may be obtained.

### 85. What is jigging and where it is used ?

Jigging:

Jigging is a separation method in which the particle are separated by using the density difference between them.

Jigging is a method of gravitational preparation of natural resources, based on separation of mineral mixture on density in vertically oscillating water stream.

Usually it is used to separate metal slag form metals.

### 86. What is Intensive and Extensive properties?

Intensive property:

It is defined as one which doesn't depends on the quantity of matter present in the system.

Examples:
Temperature, pressure,Molar enthalpy, molar volume

Extensive property:

Is defined as one which depends on quantity of matter specified in the system.

Examples:
Total mass, volume, Energy, enthalpy,

### 87. What are differences between pipe and tube?

Pipes and tubes are specified in terms of their diameter and wall thickness.

Pipes:

Heavy walled
Relatively large in diameter
comes in moderate lengths (20 to 40 ft)
Pipe walls are rough
Lengths of pipes are joined by screwed, flanged and welded fittings
Made by welding , casting, or piercing a billet in a piercing mill
The wall thickness of the pipe is indicated using schedule number
Size of the pipe is indicated as nominal diameter

Tubes:

Thin walled
Less diameter
available in the form of coils also, several hundred meters
Tube walls are smooth
These are joined by compression fittings, flare fittings, or soldered fittings
These can be cold drawn
Tube thickness is indicated using BWG (Birmingham wire gauge)
Size of the tube is indicated as outside diameter

### 88. What is liquid and its properties?

Liquid is defined as a material which will take the shape of the container. It is one of the three classical states of matter.

Examples:

water, ethanol, most of the organic solvents.

Properties:

Liquids tend to have better thermal conductivity than gases, and the ability to flow makes a liquid suitable for removing excess heat from mechanical components.

The heat can be removed by channelling the liquid through a heat exchanger, such as a radiator, or the heat can be removed with the liquid during evaporation

Liquid is the primary component of hydraulic systems, which take advantage of Pascal's law to provide fluid power.

Devices such as pumps and waterwheels have been used to change liquid motion into mechanical work since ancient times.

Oils are forced through hydraulic pumps, which transmit this force to hydraulic cylinders. Hydraulics can be found in many applications, such as automotive brakes and transmissions, heavy equipment, and air-plane control systems.

Various hydraulic presses are used extensively in repair and manufacturing, for lifting, pressing, clamping and forming

Mechanical properties:

Volume: Commonly liquids are measured in the units of volume. SI units for volume are m3.

Pressure:
Hydrostatic head is the main property of the liquid. This hydrostatic head is calculated as P= h*rho*g. h = height of the liquid column, rho = density of the liquid, g = acceleration due to gravity.

### 89. Convert 1 atm pressure terms to other units?

1 atm pressure

= 760 torr
= 760 mmHg
= 101.325 kPa
=101.325 kN/m2
= 1.103 bar
= 1.103 kg/cm2
= 14.7 psi ( pressure per square inches)