Pressure drop due to pipe fittings can be estimated by the equation, ΔP/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______________________?

Related Mcqs:

1. Le/D) for 90° elbow (medium radius) and 90°square elbow would be respectively around___________________?

   A. 25 and 60
   B. 3 and 5
   C. 100 and 250
   D. 250 and 600

2. A cylindrical pressure vessel of volume 6 πm3 has to be designed to withstand a maximum internal pressure of 10 atm. The allowable design stress of the material is 125N/mm2 and corrosion allowance is 2 mm. The thickness of the vessel for a length/diameter ratio of 3 will be close to________________?

   A. 5 mm
   B. 6 mm
   C. 8 mm
   D. 10 mm

3. For annular flow of a fluid, the ratio of the equivalent diameter for pressure drop calculation to the equivalent diameter for heat transfer calculation is_________________?

   A. d1/(d1 + d2)
   B. d2/(d1 + d2)
   C. (d1 + d2)/d1
   D. (d1 + d2)/d2

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

   A. 0.6-0.8 times
   B. Equal to
   C. Twice
   D. 2 ft irrespective of (for column > 3 ft diameter)

5. Multiple blade paddle agitator is used for mixing high viscosity liquids/paste in which the paddle diameter is commonly 0.8 times the tank diameter. However, the width of the blade is in the range of ______________ times the paddle diameter?

   A. 0.1 to 0.25
   B. 0.3 to 0.5
   C. 0.5 to 0.6
   D. 0.65 to 0.80

6. In a shell and tube heat exchanger for a given heat transfer surface area, smaller diameter tubes are favoured as compared to larger diameter ones; because the smaller diameter tubes ______________?

   A. Are easier to clean
   B. Are less prone to fouling
   C. Can be fitted into a smaller shell diameter hence the cost of the heat exchanger would be less
   D. None of these

7. The equivalent diameter for pressure drop is _______________ that for heat transfer?

   A. Smaller than
   B. Greater than
   C. Equal to
   D. Not related with

8. If a single tube pass heat exchanger is converted to two passes; for the same flow rate, the pressure drop per unit length in tube side will _____________ times?

   A. Increase by 1.8
   B. Decrease by 22
   C. Increase by 21.6
   D. None of these

9. Tube wall thickness depends on the corrosiveness of the fluids and their operating pressure & temperature and is specified by Birmingham wire gauge (B.W.G)-a number which varies from 8 to 18 with the numbers 14 and 16 being more commonly used. Outside diameter of tubes varies from about 15 to 50 mm; however a tube of less than _____________ mm outside diameter is generally not recommended for fouling fluids ?

   A. 16
   B. 19
   C. 28
   D. 38

10. Overall distillation column efficiency for most of the refinery columns can be given by (for μ = 0.07 – 1.4 cp and relative volatility < 4) (where ε = overall column efficiency, % μ = molal average viscosity of feed at average column temperature and pressure, cp Δp = pressure drop per tray, psi) ?

    A. η = 17 – 61.1 log μ
    B. η = 24.6 (Δp/μ)
    C. η = 1.66 – 0.25 log μ
    D. η = 0.25 log μ – 1.67