18 Questions
What is one major problem when dissimilar pumps are arranged in series?
The smaller pump may be forced to operate beyond its free delivery flow rate.
Why might the smaller pump in a series arrangement act like a head loss?
It is unable to handle the large head imposed on it.
What happens if two very dissimilar pumps are connected in series?
Problems may arise due to mismatched performance curves.
When centrifugal pumps are connected in series, what is the relationship between the discharge of one pump and the suction side of the second pump?
The discharge is connected to the suction side.
What could happen if dissimilar pumps in a parallel arrangement are not sized properly?
The smaller pump may not handle the large head imposed on it.
In what scenario would connecting similar pumps in series or parallel be more suitable?
When minimizing wasted power is important.
What is the result of connecting two pumps in series?
The resultant head is the sum of the individual heads
What must be ensured about the casing of the second pump in a series connection?
It must be strong enough to resist higher pressure
Why should you start the second pump after the first pump is running in a series connection?
To ensure both pumps are filled with liquid
What happens to the head when two identical pumps are arranged in series?
The head is twice the head of a single pump at the same flow rate
Where does the combined head and flow rate move when two pumps are connected in series?
Along the system curve to a new point
What is required to overcome larger system head loss than one pump can handle alone?
Centrifugal pumps in series
What is the relationship between the head for each pump when two pumps with equal performance curves are running in series?
The head for each pump equals half the head at point 3.
Why are multistage centrifugal pumps more often used than single stage pumps when operating in series?
Multistage pumps deliver higher energy and are more suitable for series operation.
How is the water head added by a centrifugal pump typically measured?
By calculating the difference in heads at the pump's inlet and outlet.
What is the formula for calculating the water head added by a centrifugal pump?
$Hp = pd - ps vd^2 - vs^2 + (zd - zs) \gamma/2g$
What does the combined/equivalent head formula represent for n pumps connected in series?
The sum of all individual pump heads in series.
How does the combined/equivalent flowrate (QE) for n pumps connected in Series compare to that of an individual pump?
$QE = n * Q1$
Test your knowledge on connecting two similar pumps in series to operate as a two-stage centrifugal pump. Learn about considerations such as maintaining the same speed, ensuring casing strength, and protecting the stuffing box.
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