Weekly Q/A List :


Q1 : Which of the following is not a primary function of the pump casing?
  • a. Transmit torque from the driver to the impeller
  • b. To convert kinetic energy into pressure energy
  • c. To develop dynamic head
  • d. Directing flow into and out of impeller
  • e. Provide support to the bearing bracket
  • f. Incorporate nozzles to connect suction & discharge piping.
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Q2 : A pump develops 100 m head while handling kerosene with specific gravity of 0.8. What head will the pump develop if the liquid handled is water:
  • a. 120m
  • b. 100m
  • c. 80m
  • d. 60m
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Q3 : A pump lifts water from a sump. Static height of the pump center line from the water level in the sump is 5m. Friction loss in the suction pipe line 0.5m, vapor pressure at pumping temperature is 0.5m and the atmospheric pressure is 10.3m of water column. What is the approximate NPSH available at this installation?
  • a. 14.3 m
  • b. 4.3 m
  • c. 4.8 m
  • d. 14.8 m
Details

Q4 : Which of the following statements about cavitation is not true?
  • a. Cavitation occurs when NPSH available is less than the NPSH required by the pump.
  • b. Cavitation is caused by the collapse of air bubbles in the suction side of the pump.
  • c. Cavitation does not occur during part flow operation since available NPSH is high.
  • d. Cavitation occurs only on the suction side of the impellers.
  • e. Cast Iron impellers have the least ability to resist cavitation damage.
Details

Q5 : The following diagram shows pump performance curve superimposed on system characteristics. Can you identify the various terms in the table?
Design

Description

  • a. System Resistance Curve
  • b. Friction Head
  • c. Static Head
  • d. Total Dynamic Head
  • e. Head Capacity Curve
  • f. Operating Point
  • A. (a) - 2 (b) - 5 (c) - 4 (d) - 6 (e) - 1 (f) - 3
  • B. (a) - 1 (b) - 4 (c) - 6 (d) - 5 (e) - 2 (f) - 3
  • C. (a) - 2 (b) - 6 (c) - 4 (d) - 5 (e) - 1 (f) - 3
  • D. (a) - 1 (b) - 4 (c) - 5 (d) - 6 (e) - 2 (f) - 3
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Q6 : For each of the following duties which is the most appropriate type of impeller:
  • a. Radial flow
  • b. Francis Vane
  • c. Mixed Flow
  • d. Axial Flow
Table
  • 1. c - b - a - d
  • 2. a - d - b - c
  • 3. d - a - b - c
  • 4. b - a - d - c
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Q7 : In a pumping system where the major component of the total head is friction, which of the following three methods of flow control is the most energy efficient? The flow through a pump can be controlled by:
  • a) Throttling
  • b) Connecting or disconnecting pump running in series or parallel
  • c) Speed control
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Q8 : Which of the following properties are important for selecting the material of construction of an impeller:
  • a) Endurance Limit
  • b) Corrosion Resistance
  • c) Abrasive Wear Resistance
  • d) Cavitation Resistance
  • e) Casting and machining properties
  • f) Tip speed
  • g) Cost
  • h) Working Pressure
  • i) Galling Characteristics
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Q9 : According to American Standard NFPA20 for fire pumps, pumps are generally provided with gland packing and mechanical seals are not used. What is the main reason for using gland packing in place of mechanical seals for these pumps?
  • a) Gland Packing is easily installed.
  • b) Gland Packing is cheaper than mechanical seal.
  • c) Leakage tends to increase gradually giving early indication of impending failure.
  • d) Gland Packing is less sensitive to the axial movement of shaft compared to mechanical seal.
  • e) Gland Packing is easily replaced when the gland is split.
Details

Q10 : The following is a list of some of the Quality Assurance checks carried out by a pump manufacturer:
  • a) Shaft Ultrasonic test
  • b) Casing UTS, hardness test, chemical test
  • c) Impeller - chemical analysis
  • d) Impeller – dynamic balancing
  • e) Casing - hydrostatic pressure test
  • f) Pump - Performance test
  • g) Pump - dimensional check
  • h) NPSH test

The following is a list of the Test Reports as required by a user:

Please identify the QA document which contains the appropriate test report from the following options:

A.  B.
C.  D.
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Q11 : Which of the following impeller types has the highest efficiency potential?
  • a) Radial flow impeller
  • b) Francis Vane impeller
  • c) Mixed flow impeller
  • d) Axial flow impeller
Details

Q12 : The following are four End Suction ISO 2858 pumps. Pump efficiencies are
  • 1. 72%
  • 2. 75%
  • 3. 81%
  • 4. 83%

Can you place the correct efficiencies in the appropriate boxes?

Pump Size Best efficiency duty point at 1480 rpm Efficiency
A. 125x80-400 140 m3/hr, 50m
B. 125x100-400 190 m3/hr, 50m
C. 150x125-400 300 m3/hr, 50m
D. 200x150-400 450 m3/hr, 50m
  • a) A-1 B-2 C-3 D-4
  • b) A-4 B-3 C-2 D-1
  • c) A-3 B-1 C-2 D-4
  • d) A-2 B-4 C-3 D-1

All the pumps generate the same head and impeller diameters are identical (400mm) - Why are the efficiencies different?

Details

Q13 : Select the Pumps for the given duty points:
S/N SPEED (RPM) HEAD (m) FLOW (Litre Per Sec)
1 1480 20 100 LPS
2 1480 22 140 LPS
3 1000 80 564 LPS
4 1480 100 564 LPS
  • a) 1: 6HS14 2: 8HS10 3: 16HS32 4: 12HS23
  • b) 1: 8HS12 2: 8HS12 3: 14HS32 4: 14HS26
  • c) 1: 6HS12 2: 8HS12 3: 16HS32 4: 12HS23
  • d) 1: 6HS10 2: 10HS12 3: 18HS25 4: 10HS22
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Q14 : 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 both run at 1500 rpm. You would expect both the pumps to have:
  • a) Same design capacity, head and impeller diameter
  • b) Identical foot-print and installation interface dimensions
  • c) Same materials of construction
  • d) None of the above
Details

Q15 : 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 which of the following is required?
  • a) Optimum pump efficiency is wanted
  • b) Lowest life cycle cost for the installation
  • c) Highest reliability in a critical application
  • d) Lowest environmental impact
Details

Q16 : A double suction split-case pump is sometimes preferred over an end suction pump because of?
  • a) Smaller installation dimensions
  • b) Ease of maintenance
  • c) Absence of radial thrust load
  • d) All of the above
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Q17 : 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?
  • a) B is likely to be more efficient than A at the best efficiency point (design point)
  • b) Shaft deflection at the stuffing box will be higher for B
  • c) A will have lower axial thrust load
  • d) B will have lower radial thrust load at part flow operation
Details

Q18 : There are two axially split-case pumps with the following description:
Parameters Pump model- 6x8-21 Pump model- 8x10-14
Rated capacity 450 m3/hr. 750 m3/hr.
Rated head 90 m 36 m
Impeller diameter 540 mm 360 mm
Impeller width at outlet (including shrouds) 40 mm 76 mm
Speed 1480 rpm 1480 rpm
Type of casing Single volute Single volute
Type of impeller Double entry Double entry
Which of the following statements is true?
  • a) Axial thrust of 8x10-14 is likely to be greater than that of 6x8-21
  • b) 6x8-21 is likely to be more efficient than 8x10-14
  • c) Radial thrust at 50% flow will be more in case of 6x8-21
  • d) None of the above
Details

Q19 : Which of the following statement is not true for a two stage axially split-case pump with two back-to-back single-entry impellers?
  • a) Protect the shaft from abrasion and wear
  • b) Increase the stiffness of the rotating element (shaft to be more precise)
  • c) Reduce leakage losses through the stuffing box
  • d) None of the above
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Q20 : Which of the following statement is not true for a two stage axially split-case pump with two back to back single-entry impellers?
  • a) Total head developed by the pump is the sum of heads developed by each stage.
  • b) The pump axial thrust is balanced because of two opposed single-entry impellers.
  • c) The pump radial thrust is balanced because the volutes of two stages are at 1800 to each other.
  • d) The total capacity of the pump is the sum of the flow through each stage.
Details