Centrifugal Compressor - Fan Laws

This application uses the affinity laws to calculate the volume capacity, head when the speed of the impeller is changed. Understanding the ratio of specific heat for the gas being used in the compressor may present challenges.

Gas volume flow is proportional to the impeller rotation speed:

Head is proportional to the square of the impeller rotation speed:

Brake horsepower is proportional to the cube of the impeller rotation speed:

𝑄₁ − Initial Flow[𝑀𝑀𝑆𝐶𝐹𝐷]

𝑄₂ − Final Flow[𝑀𝑀𝑆𝐶𝐹𝐷]

𝐻₁ − Initial Compressor head[ft • lb_f / lb_m]

𝐻₂ − Final Compressor head[ft • lb_f / lb_m]

𝐵𝐻𝑃₁ − Initial Brake Horsepower[HP]

𝐵𝐻𝑃₂ − Final Brake Horsepower[HP]

𝑛₁ − Initial Rotational Speed[rpm]

𝑛₂ − Final Rotational Speed[rpm]

Input Parameters

1. To create a new case, click the “Add Case” button
2. Select the Centrifugal Compressor – Fan Laws application from the Pipeline Compressor module.
3. Enter Case Name, Location, Date and any necessary notes.
4. Fill out all required fields.
5. Make sure the values you are inputting are in the correct units.
6. Click the CALCULATE button.

• Q1 – Initial Flow Rate(MMSCFD)
• H1 – Initial Compressor Head (ft lbf/lbm)
• BHP1 – Initial Shaft Horsepower(HP)
• N1 – Initial Impeller Rotational Speed(rpm)
• N2 – Final Impeller Rotational Speed(rpm)

Outputs/Reports

1. View the results.
2. If an input parameter needs to be edited be sure to hit the CALCULATE button after the change.
3. To SAVE, fill out all required case details then click the SAVE button.
4. To rename an existing file, click the SAVE As button. Provide all case info then click SAVE.
5. To generate a REPORT, click the REPORT button.
6. The user may export the Case/Report by clicking the Export to Excel/PowerPoint icon.
7. To delete a case, click the DELETE icon near the top of the widget.

• Q2 – Final Flow Rate (MMSCFD)
• H2 – Final Compressor Head (ft lbf/lbm)
• BHP2 – Final Shaft Horsepower(HP)

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