Common Pumping Mistakes
by Jim Elsey
September 12, 2017

19. Vibration limits for the pump as measured on the bearing frame must meet ANSI /HI 9.6.4 limits no matter where the pump is operated on the curve.
A) True
B) False

20. The pump allowable operating range (AOR):
A) Can be anywhere on the published curve the operator forces the pump to operate
B) Must be within 20 percent of the best efficiency point (BEP)
C) Must be no greater than 120 percent of BEP
D) Cannot be less than minimum flow, where min flow is per table 7.1.6-1 in the standard
E) None of the above
F) Answers C and D above

21. With the pump operating in the AOR:
A) There is no consideration for minimum thermal flow considerations
B) The pump expected life range will be the same no matter where the pump is on the curve.
C) Vibration levels will be near zero
D) You never need to calculate NPSHr or critical submergence.

22. Pursuant to the ANSI specification B73.1, it is perfectly acceptable for any portion of the motor to hang over the base plate on the sides and back (non-coupling end) by any amount.
A) True
B) False

23. There are circumstances where the NPSHr for the pump may be less than the NPSH3.
A) True
B) False

24. Published performance curves shall be based on tests conducted in accordance with ANSI/HI 14.6.
A) The accuracy of the curves shall be that 90 percent of pumps purchased untested when operated between minimum flow and BEP will meet published head points within plus or minus 5 percent and efficiency within plus zero percent and minus 5 percent.
B) The accuracy of the head and efficiency curves shall be within 10 percent if operating within 10 percent of BEP.
C) The accuracy of the published curves shall be 100 percent, with no deviations 100 percent of the time regardless of owners’ instrumentation accuracy or the product being pumped and at any temperature below 450 F.
D) The accuracy of the published curves is governed and regulated by ANSI P&J-S 8717.
E) None of the above are true.

25. When NPSHr tests are required and conducted:
A) The temperature of the water does not need to be factored into the test criteria.
B) The vapor pressure of the water is not to be considered and is irrelevant.
C) The absolute pressure on the suction side of the system does not need to be added to the calculation if the test is being conducted at elevations 5000 feet above sea level or higher.
D) Answers A, B and C
E) Unless otherwise agreed to by the purchaser and supplier, the test shall be a type II test, which is solely for determination of NPSH3 at the rated flow point only.

Bonus Question
For metallic pumps. All casings, seal chambers (stuffing boxes) and jackets MUST be hydrostatically tested: (This test should be a witnessed and documented test.)

A) For 5 minutes at 100 PSIG, except if the material is cast iron then it is 10 minutes
B) For 10 minutes at 100 PSIG regardless of material or expected temperatures
C) For 10 minutes at 150 percent of the maximum design pressure for that material and expected operating temperature maximum
D) For 10 minutes at 150 percent of the maximum design pressure for that material rating at 100 F (38 C).

Click here for the answer key to see how you did.


To read other articles in the 'Common Pumping Mistakes' column, go here.

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