Practice Test: Question Set - 17
1. Pressure drop due to pipe fittings can be estimated by the equation,
∆P/ρ = 4f, (Le/D) (V2/2gc) where, Le = equivalent length of straight pipeline which will incur the same frictional loss as the fitting and D = diameter of the fitting. The value of (Le/D) (dimensionless) for 45° elbow and 180° close return bends would be respectively around
- (A) 5 and 10
- (B) 45 and 75
- (C) 180 and 300
- (D) 300 and 500
2. The thickness of segmental baffles (25 -35% cut truncated plates usually) is generally _________ the tube wall thickness.
- (A) Equal to
- (B) Twice
- (C) Four times
- (D) Half
3. In a distillation column, the minimum residence time for liquid in the downspout is about _________ seconds.
- (A) 1
- (B) 8
- (C) 80
- (D) 180
4. In a double pipe concentric heat exchanger, the equivalent diameter of annulus for heat transfer would be (where, D1 and D2 are I.D. of inner and outer pipes)
- (A) (D22 - D12)/D12
- (B) D2 - D1
- (C) (D22 - D12)/D22
- (D) None of these
5. In a multipass shell and tube heat exchanger, the baffles on shell side is primarily provided for
- (A) Reducing scale deposition
- (B) Increasing pressure drop
- (C) Fixing the tubes
- (D) Creating turbulence
6. A head comprises of straight flange section, corner torus, section and central dished section. Crown radius and knuckle radius in a head is related respectively to the
- (A) Central dished section and corner torus section
- (B) Corner torus section and central dished section
- (C) Central dished section and straight flange section
- (D) Straight flange section and corner torus section
7. _________ dished head is the strongest of all.
- (A) Hemispherical
- (B) Elliptical
- (C) Torispherical
- (D) None of these
8. _________ of water makes it a widely used coolant in heat exchangers.
- (A) Low corrosiveness
- (B) Low dirt factor
- (C) High specific heat
- (D) Low viscosity
9. Speed of industrial paddle agitator ranges from _________ rpm.
- (A) 1 to 5
- (B) 20 to 100
- (C) 500 to 750
- (D) 1000 to 2000
10. Hold up of material in a operating rotary drier is in the range of
- (A) 0.05 to 0.15
- (B) 0.25 to 0.50
- (C) 0.5 to 0.8
- (D) 0.8 to 0.9
11. In a shell and tube heat exchanger having triangular pitch, the shell side equivalent diameter is given by
- (A) 4(0.86P2 - πd2/4)/πd
- (B) (P2 - πd2/4)/πd
- (C) 4(0.86P2 - πd2)/πd
- (D) (4P2 + πd2/4)/πd
12. Generally, elliptical dished heads
- (A) Are manufactured on 2:1 ratio of major to minor axis and is
recommended to be used for pressure vessels operating above a pressure of 1.5
MN/m2
- (B) Resist half the pressure rating compared to hemi spherical head
provided on the cylindrical shell of the same thickness and diameter
- (C) Are approximately as strong as seamless cylindrical shell having the
corresponding I.D and O.D
- (D) All (a), (b) and (c)
13. A pressure vessel is said to be made of 'thick' shell, if the ratio of its diameter to wall thickness is
- (A) < 10
- (B) > 10
- (C) > 20
- (D) < 20
14. For given number of passes, pitch & tube diameter, the maximum number of tubes that can be accommodated in a shell of tripled inside diameter will be _________ times.
- (A) About 9
- (B) Considerably more than 9
- (C) Considerably less than 9
- (D) About 3
15. In case of a continuous distillation column, increase in reflux ratio may result in the
- (A) Lower fixed charges for the column
- (B) Greater cost for the reboiler heat supply
- (C) Greater cost for the condenser coolant
- (D) All (a), (b) and (c)
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