Verification Case 13

View Model    Problem Statement

PRODUCT: AFT Fathom

TITLE: FthVerify13.fth

REFERENCE: Ingersoll-Dresser Pumps, Cameron Hydraulic Data, 18th Ed., 1995, Published by Ingersoll-Dresser Pumps, Page 1-13, 14, Example 2

FLUID: Water at 68 deg. F

ASSUMPTIONS: N/A

RESULTS:

Parameter Cameron AFT Fathom
NPSHA (feet) 40.26 40.23
Suction Head (feet) 7.08 7.08

DISCUSSION:

The example in the book does not actually perform a flow calculation. To demonstrate how AFT Fathom determines NPSHA, a few unusual steps were taken.

  1. The head loss up the pump is given in Cameron as 2.92 feet. This was modeled in the valve J2, as a fixed pressure drop of 2.92 feet.

  2. All three pipes were modeled as frictionless so that all pressure loss comes from valve J2.

  3. A discharge pipe and reservoir were modeled to complete the system, even though the discharge piping does not affect the answer to the problem.

  4. The pump was modeled as an assigned flow at 100 gpm. Since the pressure drop is fixed at J2 as 2.92 feet, the flow rate in the pump (and piping for that matter) does not affect the answer. In typical system analysis, the flow in the piping affects the results because as the flow changes the pressure drop changes. In this model this did not occur because all pipes were frictionless.

The AFT Fathom NPSHA prediction is shown in the Pump Summary at the top of the Output window. The suction head is shown as the EGL inlet to the pump, J3.

Note this model uses fluid properties from the AFT Standard fluid library. The AFT Standard fluid library was updated in AFT Fathom 12, thus the AFT Fathom results will be slightly different for this verification case when compared to previous versions of AFT Fathom.

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