Chemical Engineering Archives

4271. Pressure drop due to pipe fittings can be estimated by the equation, , 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 (dimensionless) for 45° elbow and 180° close return bends would be respectively around

5 and 10

45 and 75

180 and 300

300 and 500

✅ The correct answer is option B.

4272. In a bag filter, the pressure drop increases directly as the

density of the gas, but is independent of the viscosity of the gas.

density of the gas and inversely as viscosity of the gas.

viscosity of the gas and inversely as density of the gas.

none of these.

✅ The correct answer is option B.

4273. Any shell opening greater than 5 cms for a storage tank must be reinforced for reason of

preventing the local overstressing of the shell around the opening.

reduction of discontinuity in shape at the junction.

making the joint leak proof.

none of these.

✅ The correct answer is option A.

4274. A pipe is generally made of circular cross-section, because a circular cross-section has the

higher structural strength.

lowest surface area requirement for a given volume.

both (a) & (b).

none of these.

✅ The correct answer is option C.

4275. Which of the following factors affect the pressure drop in a co-current gas-liquid absorption packed tower ?

Size, shape, orientation and surface of the packing particles.

Density and viscosity of fluids.

Fluid flow rates.

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

✅ The correct answer is option D.

4276. Circumferential (hoop) stress in a thin cylindrical vessel under internal pressure is __________ the longitudinal stress.

half

equal to

twice

eight times

✅ The correct answer is option C.

4277. for fully open gate valves would be

much more than that for fully open globe valves.

much less (say 2% than that for fully open globe valves).

around 7.

both (b) and (c).

✅ The correct answer is option D.

4278. Vapor velocity in a distillation column for non-foaming mixture is in the range of __________ times the flooding velocity.

0.1 to 0.3

0.6 to 0.7

0.85 to 0.95

1.5 to 2

✅ The correct answer is option B.

4279. Ratio of tube length to shell diameter for a shell and tube heat exchanger is

8 : 1 to 12 : 1 for both liquid-liquid and gas-gas heat exchangers.

4 : 1 to 8 : 1 for liquid-liquid exchanger.

< 4 : 1 for gas-gas exchangers.

both(b) & (c).

✅ The correct answer is option D.

4280. In perforated plate towers, the

hole sizes may be around 1/8″ or 3/16″.

total hole area may be around 6 to 15% of tower cross-sectional area.

pressure drop is less compared is similar bubble cap towers.

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

✅ The correct answer is option D.