Suction Specific Speed

Contents

Introduction

Pump specific speed when running, calculates increases in unit of volume in a unit of time through a unit of head pressure. The characteristics of the suction side of the impeller determine the efficiency. : S = \frac{N \sqrt{Q_{bep}}}{NPSH_{req}^{3/4}}

S = \frac{N \sqrt{Q_{bep}}}{NPSH_{req}^{3/4}}

Where:
𝑆 − Suction Specific Speed
𝑁𝑃𝑆𝐻_𝑟𝑒𝑞 − Net Positive Suction Head Required (ft)
𝑄_𝑏𝑒𝑝 − Capacity at Best Efficiency Point (gpm)
𝑁 − Pump Rotational Speed (rpm)

Case Guide

Part 1: Create Case

Select the Suction Specific Speed application from the Pump Module
To create a new case, click the “Add Case” button
Enter Case Name, Location, Date and any necessary notes.
Fill out all required Parameters.
Make sure the values you are inputting are in the correct units.
Click the CALCULATE button to overview results.

Input Parameters

Pump Speed (rpm)
Capacity at the Best Efficiency Point (gpm)
Net Positive Suction Head Required (ft)

Part 2: Outputs/Reports

If you need to modify an input parameter, click the CALCULATE button after the change.
To SAVE, fill out all required case details then click the SAVE button.
To rename an existing file, click the SAVE As button. Provide all case info then click SAVE.
To generate a REPORT, click the REPORT button.
The user may export the Case/Report by clicking the Export to Excel icon.
To delete a case, click the DELETE icon near the top of the widget.

Results

Suction Specific Speed

References

ASME B31.4 – 1998 Edition “Pipeline Transportation Systems for Liquid Hydrocarbons and other Liquids”, Art. 404.1
API 1117 – Movement of In-Service Pipelines
API 5L, API 5LS and API 5LX – Specification of Pipe Grade
ASTM – Various – Weld Joint Factor
CFR Code Part 192
MMS Regulations
USDA-SCS Modified (Permissible Velocity of Water and Soil Erodibility)
Pipeline Rules of Thumb Handbook

Updated on December 26, 2023

Tagged: Calculations Pipeline Pumps

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