Section 5

Question 1

__________ tower is the most suitable gas-liquid contacting device involving highly corrosive fluids.

Answer 1

Packed

Question 2

At equal mass velocities, the values of film co-efficients for gases as compared to that for liquids are generally.

Answer 2

lower

Question 3

The ratio of the largest load in a test to the original cross-sectional area of the test specimen is called the __________ stress.

Answer 3

ultimate

Question 4

The wall thickness of thin cylindrical shell with hemispherical ends is __________ that of the spherical ends.

Answer 4

more than

Question 5

A ‘rupture disc’ is provided in chemical equipments as an accessory meant for

Answer 5

relieving excess pressure.

Question 6

In a vertical short tube evaporator (Calendria type), the
A. tube dia of 2.5-7.5 cms, tube length of 75-200 cms and cylinderical drum dia of 1-6 metres are normally used.
B. area of central downtake is equal to 40 to 100% of total cross-sectional area of the surrounding tube.
C. liquor is inside the tube while the steam is outside the tube.
D. all (a), (b) & (c).

Answer 6

D. all (a), (b) & (c).

Question 7

In a shell and tube heat exchanger, the shortest centre to centre distance between the adjacent tubes is

Answer 7

called tube pitch.

Question 8

Any shell opening greater than 5 cms for a storage tank must be reinforced for reason of

Answer 8

preventing the local overstressing of the shell around the opening.

Question 9

Minimum tube pitch recommended for shell and tube heat exchangers is about __________ times the outside diameter of the tube.

Answer 9

1.25

Question 10

Liquid redistribution should be done in a packed tower packed with raschig rings every 6 metres or __________ times the column diameter, whichever is lower.

Answer 10

2.5-3.0

Question 11

Slope of countercurrent flow rotary drier is in the range of __________ meter/metre.

Answer 11

0 to 0.08

Question 12

In case of saddle packing (e.g., berl and intralox saddles), the maximum size of the packing should not exceed __________ of the column diameter.

Answer 12

l/15th

Question 13

The thermal stress in a metallic bar does not depend upon the

Answer 13

cross-sectional area.

Question 14

The minimum baffle height should be

Answer 14

twice the impeller diameter.

Question 15

For turbulent flow (NRe > 2100) of low viscosity fluid (μ > 20cp) in steel pipes, the optimum inside pipe diameter is given by(where, Q = fluid flow rate, ft3/sec.ρ = fluid density, lb/ft3 μ = fluid viscosity, centipoise Di = optimum inside pipe diameter, inches)

Answer 15

Di, opt = 3.9 Q^(0.45) ρ^(0.13)

Question 16

To avoid the tearing off the plate of an edge, the margin (i.e., the minimum distance from the centre of the rivet hole to the nearest edge of the plate) should be equal to

Answer 16

1.5 d

Question 17

The normal range of velocity of water in pipes is __________ m/sec.

Answer 17

1-2

Question 18

Baffles are provided in a shell and tube heat exchanger to increase the turbulence and velocity of the shell side fluid. Which of the following shaped baffles does not fall in the category of transverse baffle ?

Answer 18

Flat plate extending across the wall

Question 19

A certain pressure vessel manufacturer avoids doing reinforcements calculations for openings by always providing a reinforcing pad extending upto double the diameter of the opening and of the same material and thickness as that of the shell wall. If area compensation is accepted as a code guideline, his approach leads to safe design

Answer 19

irrespective of the shape of the vessel.

Question 20

In a __________ rivetted joint, the number of rivets decreases from the innermost row to the outermost row.

Answer 20

diamond

Question 21

Large process vessels operating under extreme temperature and pressure conditions are normally clad/ lined with materials like stainless steel, aluminium, nickel & its alloys, copper & its alloys and titanium. The cladding thickness is generally about __________ percent of the total thickness.

Answer 21

10 to 20

Question 22

Heat transfer co-efficient for a horizontal condenser as compared to a vertical condenser operating under similar conditions is

Answer 22

about 3 times

Question 23

Pick out the wrong statement pertaining to the design of the distillation column.
A. Generally, a skirt clerance of 0.5” to 1.5’ is recommended to prevent plugging of the slots by residue build up.
B. The purpose of the slot is to disperse the gas into the liquid in the form of small bubbles.
C. If sufficient slot area is not provided, the gas may pass through the skirt clearance.
D. none of these.

Answer 23

D. none of these.

Question 24

The longitudinal stress induced in a thin walled cylinderical vessel under internal pressure is

(Eqn)

Answer 24

pd/4t

Question 25

The buckling tendency of compression members is always in the direction of the

Answer 25

least radius of gyration.

Question 26

In case of plain carbon steel, butt welded joints are used for shell plate thickness ≤ __________ cms.

Answer 26

3.8

Question 27

The average velocity in the tubes of a 1-4 heat exchanger is __________ times that in 1-1 heat exchanger having the same size & number of tubes and operated at same liquid flow rate.

Answer 27

4

Question 28

Hoop (circumferential) stress induced in a thin walled ‘Horton Sphere’ used for the storage of liquid ammonia under pressure is

Answer 28

pD/(2t)

Question 29

When one of the fluids is highly corrosive and has fouling tendency, it should

Answer 29

preferably flow inside the tube for its easier internal cleaning.

Question 30

The ratio, propeller agitator diameter to tank dia is normally taken as

Answer 30

0.15-0.30

Question 31

A/an __________ is used for changing the direction of a pipeline.

Answer 31

elbow

Question 32

Maximum plate efficiency is achieved in case of __________ flow.

Answer 32

cross

Question 33

The LMTD correction factor (FT) is defined as the

Answer 33

ratio of true temperature difference to the LMTD.

Question 34

The clearance between two tubes in a shell and tube heat exchanger is known as ‘ligament’, whose minimum value is __________ the outside diameter of the tube, but in no case it should be less than 4.5 mm.

Answer 34

one fourth

Question 35

The ratio for the rate of washing to the final rate of filtration in a washing type of plate and frame filter is

Answer 35

0.25

Question 36

Normally, the length to diameter ratio of rotary dryers varies form 4 to 10 and for its economic operation, the number of transfer units (NTU) for such dryers varies from

Answer 36

1.5-2.5

Question 37

Value of Peclet number = 0, is the representative of

Answer 37

complete back mixing.

Question 38

Poisson’s ratio of a material is the ratio of unit lateral strain to the unit axial elongation within its elastic limit. The value of Poisson’s ratio for structural and pressure vessel steel may be taken as

Answer 38

0.3

Question 39

Removable connection of tubes to tube sheet is called

Answer 39

ferrule

Question 40

Typical static submergence for bubble cap plate column operating at atmospheric pressure may be around

Answer 40

0.5”

Question 41

In the allocated cap area, bubble caps are generally arranged on equilateral triangular pitch. Number of caps fixed on a plate is with a
A. clearance of 25-75 mm.
B. cap pitch of 1.3-2 times the cap diameter.
C. either ‘a’ or ‘b’.
D. neither ‘a’ nor ‘b’.

Answer 41

C. either ‘a’ or ‘b’.

Question 42

The length of straight rectangular weir used on cross-flow trays is generally __________ the column diameter.

Answer 42

0.6-0.8 times

Question 43

Le/D for couplings and unions would be

Answer 43

negligible

Question 44

What is the slope of the operating line in the rectifying section of a distillation coloumn ?

Answer 44

<1

Question 45

Stage efficiency for packed tower varies with the
type & size of packing.
fluid rates and fluid properties.
operating pressure and column diameter.
all (a), (b) and (c).

Answer 45

all (a), (b) and (c).