API 674 Evaluation

After the Pump RPM Evaluation is finished in the base scenario, child scenarios are created to evaluate the identified pump operating speeds. In each pump operating speed scenario API-674 evaluations are performed as follows:

1. For each pipe station Impulse performs a Fast Fourier Transform (FFT) on the static pressure results at that pipe station to find the frequency response

2. The pressure limit is calculated for each harmonic using equation C.2 from API-674American Petroleum Institute. 2010. API Standard 674 with Errata (May 2014) 3rd Edition. Positive Displacement Pumps-Reciprocating. Annex C, sections A.1 and A.2, pages 67-68 as is shown here:

   

   Where d is the inner diameter of the pipe, and f is the pulsation frequency which is defined as

   

   Where N is the pump speed in rpm and j is the harmonic multiple.

3. The FFT results are compared to the pressure limit results, and any pressures that exceed the pressure limits are reported in the Pulsation Summary in the Output window.