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PUMP
 QUIZ

 

 

  
 
 
 
 
 
1.11. Types, Construction and Standards
Qs1 You have two pumps conforming to ISO 2858 standard, one from Europe (KSB) and the other from Australia (TKL). Both have the same designation - 100x80-315 and run at 1500 rpm. You would expect both the pumps to have Answers
  • Same design capacity, head and impeller diameter
  • Identical foot-print and installation interface dimensions
  • Same materials of construction
  • None of the above
Qs2 American Petroleum Institute Standard API 610 (10th edition) is a process pump standard for petrochemical plants and refineries. A user will insist on pumps complying to this standard when he wants to achieve:
 Answers
  • Optimum pump efficiency
  • Lowest life cycle cost for the installation
  • Highest reliability in a critical application
  • Lowest environmental Impact
Qs3 A double suction split-case pump is sometimes preferred over an end suction pump because of:
 Answers
  • Smaller installation dimensions
  • Ease of maintenance
  • Absence of radial thrust load
  • All of the above
Qs4 There are two identical end suction pumps A and B of designation 200x150-500. Both A and B have identical impellers and shafts, the only difference between these two pumps being that A has a single volute casing while B uses a double volute casing. Which of the following statements is true? Answers
  • B is likely to be more efficient than A at the best efficiency point (design point)
  • Shaft deflection at the stuffing box will be higher for B
  • A will have lower axial thrust load
  • B will have lower radial thrust load at part flow operation
Qs5

There are two axially split-case pumps with the following description: Which of the following statement is true?

Parameters
Pump model- 6x8-21
Pump model- 8x10-14
Rated CApacity 450m3/hr 750m3/hr
Rated Head 90m 36m
Impeller Diameter 540mm 360mm
Impeller width at Outlet ( including Shrouds) 40mm 76mm
Speed 1480 rpm 1480 rpm
Type of Casing Single Volute Single Volute
Type of Impeller Double Entry Double Entry

 

Answers
  • Axial Thrust of 8x10-14 is likely to be greater than that of 6x8-21
  • 6x8-21 is likely to be more efficient than 8x10-14
  • Radial thrust at 50% flow will be more in case of 6x8-21
  • None of the above
Qs6 Primary function of the shaft sleeve is to: Answers
  • Protect the shaft from abrasion and wear
  • Increase the stiffness of the rotating element
  • Reduce leakage losses through the stuffing box
  • None of the above
Qs7 Which of the following statement is not true for a two stage axially split-case pump with two back-to-back single entry impellers: Answers
  • Total head developed by the pump is the sum of heads developed by each stage
  • The pump axial thrust is balanced because of two opposed single entry impellers
  • The pump radial thrust is balanced because the volutes of two stages are at 1800 to each other
  • The total capacity of the pump is the sum of the flow through each stage.
Qs8 Which of the following statements is not true about packed gland pumps: Answers
  • Packed gland pumps are preferred over mechanical seal fitted pumps in services such as fire protection where catastrophic failure of seals cannot be tolerated
  • Compared to a mechanical seal fitted pump, mechanical efficiency of a packed gland pump is lower
  • iii) It's possible to reduce leakage to zero through a packed gland stuffing box
  • Packed gland pumps generally have shaft sleeves to protect the shafts from abrasive wear at the stuffing box
Qs9 Which of the following statements about pump shaft is not true : Answers
  • Diameter of the pump shaft depends mainly on the power absorbed (kW), speed of the pump and the permissible shear stress for the shaft material selected
  • Shaft stiffness factor (L3/D4) where L is the bearing span and D is the average shaft diameter is one of the measures of the shaft deflection
  • Keyways, threads and sharp changes of section are stress raisers in a pump shaft
  • A double volute pump needs shaft of larger diameter compared to a single volute pump
Qs10 Which of the following statements about pump casings is not true : Answers
  • Pump casing plays as important a role in the generation of dynamic head as the pump impeller
  • Thickness of the pump casing depends on the yield strength of the material used, permissible deflection, corrosion allowance required and the maximum test pressure
  • Single volute casing is easier to cast compared to a double volute casing
  • Casings are vulnerable to leakage, during pressure test, in areas where there are sharp changes of section