Pump Effeciency in Affinity Law

[Mahil]

Using the pump affinity laws, why does the given pump efficiency disregarded on the calculation of head#2?

 

[Dean Agnostic]

Using the pump affinity laws, why does the given pump efficiency disregarded on the calculation of head#2?

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Deat @Mahil:

Great Question! The answer choices - they all make logical sense. 

Let's examine each answer choice:

(A) 8.5    (19.60 ft * .75 Pump efficiency = 14.7 ft. Note: The probability of an examinee choosing Choice A is about 25%)

(B) 11      (19.60 ft * .75 Pump efficiency = 14.7 ft. Note: The probability of an examinee choosing Choice B is about 80%)

(C) 20

(D) 34    (19.60 ft * 1.75 Pump efficiency = 34.3 ft. Note: The probability of an examinee choosing Choice B is about 95%)

To Answer your question: Using the pump affinity laws, why does the given pump efficiency disregarded on the calculation of head#2?

This particular question requires understanding the theory/principle.  According to Affinity laws of centrifugal pumps it is assumed that the efficiencies of the larger and smaller pumps are the same and therefore efficiency is considered constant.  Hope this helps and good luck on your studying.

Very respectfully yours,

Dean