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:
  • 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:
  • 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


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

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


  • 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