Environmental Engineering Questions and Answers – Selection of Pumping Units

This set of Environmental Engineering Questions and Answers for Aptitude test focuses on “Selection of Pumping Units”.

1. The plot of total dynamic head and discharge of a pump is called ____________
a) Dynamic head curve
b) System head curve
c) Pump curve
d) Discharge curve
View Answer

Answer: b
Explanation: The plot of total dynamic head and discharge of a pump is called system head curve and each point on it denotes the head which consists of total static head, head loss in suction and delivery pipe.

2. _______ is the point of intersection of system head curve with the characteristic curve of the pump.
a) Discharge point
b) Operating point
c) Velocity head
d) Pumping point
View Answer

Answer: b
Explanation: The operating point is the point of intersection of system head curve with the head – discharge characteristic curve of the pump. It is also called as operating range.

3. Which of the following is not included in the friction head?
a) Head Loss in entire length of piping
b) Total static head
c) Head Loss in bend tees
d) Head Loss in valves
View Answer

Answer: b
Explanation: The friction head is the sum of head Loss in the entire length of piping, head Loss in bend tees and head Loss in valves.
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4. When the pumps are in parallel operation?
a) H = H1 + H2
b) 1/H = 1/H1 +1/ H2
c) Q = Q1 + Q2
d) 1/Q = 1/Q1 + 1/Q2
View Answer

Answer: c
Explanation: When the pumps are in parallel operation, then the total discharge is equal to the sum of the discharges by each pump i.e Q = Q1 + Q2.

5. When the pumps are in series operation?
a) H = H1 + H2
b) 1/H = 1/H1 +1/ H2
c) Q = Q1 + Q2
d) 1/Q = 1/Q1 + 1/Q2
View Answer

Answer: a
Explanation: When the pumps are in series operation, then at a given discharge, total head is equal to the sum of heads added by each pump i.e H = H1 + H2.
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6. The efficiency of the pump at half load is ____________
a) 50%
b) 70%
c) 80%
d) 100%
View Answer

Answer: b
Explanation: The efficiency of a pump depends on the amount of load. At half load, the efficiency of the pump is 70%.

7. The efficiency of the pump at quarter load is ____________
a) 50%
b) 70%
c) 80%
d) 100%
View Answer

Answer: a
Explanation: The efficiency of the pump at quarter load is 50% and at full load, the efficiency of the pump is 80%.
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8. The installed capacity of the pump does not depend on which of the following?
a) The maximum rate of hourly demand
b) Balancing storage
c) Power of pump
d) Operation schedule
View Answer

Answer: c
Explanation: The installed capacity of the pump depends on three factors, namely- balancing storage, the maximum rate of hourly demand and the operation schedule. The installed capacity of the pump is kept larger than the maximum rate of demand.

9. If the diameter of pumping mains decreases, then the total dynamic head will increase.
a) True
b) False
View Answer

Answer: a
Explanation: If the diameter of pumping mains decreases, then the velocity of flow will increase for a given fixed discharge resulting in the increase of friction head loss and velocity head and ultimately increases the total dynamic head.
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Sanfoundry Global Education & Learning Series – Environmental Engineering.

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Manish Bhojasia - Founder & CTO at Sanfoundry
Manish Bhojasia, a technology veteran with 20+ years @ Cisco & Wipro, is Founder and CTO at Sanfoundry. He lives in Bangalore, and focuses on development of Linux Kernel, SAN Technologies, Advanced C, Data Structures & Alogrithms. Stay connected with him at LinkedIn.

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