Fan Engineering — Fan Law — Speed Change
Fan Law — Speed Change for mine and tunnel fan systems.
The cube law is the kindest physics in mining: 14% less speed costs 14% of quantity but returns 36% of the power bill. Ventilation-on-demand systems are this calculator attached to a VFD and a tag-reader — the savings arithmetic is exactly what you see here.
Formula
Note: Mine ventilation is statutory and life-safety territory: airflow quantities, gas limits and re-entry times must be set by the registered ventilation engineer/manager under your jurisdiction's mining regulations — this calculator is a planning and training aid.
Fan Law — Speed Change for mine and tunnel fan systems. A free mine ventilation & air quality tool — no sign-up, no upload, instant results in your browser.
About Fan Engineering — Fan Law — Speed Change
Fan Engineering — Fan Law — Speed Change computes the governing relationship Q∝N · p∝N² · P∝N³ [fan affinity laws] live as you type. The cube law is the kindest physics in mining: 14% less speed costs 14% of quantity but returns 36% of the power bill. Ventilation-on-demand systems are this calculator attached to a VFD and a tag-reader — the savings arithmetic is exactly what you see here. Defaults are pre-filled with realistic values for this exact scenario, and the worked example substitutes your numbers step by step so the math is never a black box.
How to use Fan Engineering — Fan Law — Speed Change
- 1Enter your values — Current quantity, Current pressure, Current input power, Current speed and more (sensible defaults are pre-filled).
- 2Read the live results: New quantity, New pressure, New power.
- 3Check the "with your numbers" line to see Q∝N · p∝N² · P∝N³ [fan affinity laws] substituted step by step.
- 4Adjust inputs until the scenario matches yours, then copy or share the result.
Why use Fan Engineering — Fan Law — Speed Change?
- ✓Instant, free and private — every calculation runs client-side in your browser; nothing is uploaded
- ✓Built on the stated formula Q∝N · p∝N² · P∝N³ [fan affinity laws] with authoritative sources cited on the page (McPherson, M.J., Subsurface Ventilation and Environmental Engineering; Hartman et al., Mine Ventilation and Air Conditioning, 3rd ed.)
- ✓The cube law is the kindest physics in mining: 14% less speed costs 14% of quantity but returns 36% of the power bill.
- ✓SI ⇄ Imperial toggle converts your inputs in place, so you can work in the units your drawings use
Frequently asked questions
What formula does the fan engineering — fan law — speed change use?+
It evaluates Q∝N · p∝N² · P∝N³ [fan affinity laws], exactly as published. Sources: McPherson, M.J., Subsurface Ventilation and Environmental Engineering; Hartman et al., Mine Ventilation and Air Conditioning, 3rd ed.. The substituted worked example on the page lets you verify every step against the textbook.
How should I read the result — and how far can I trust it?+
The cube law is the kindest physics in mining: 14% less speed costs 14% of quantity but returns 36% of the power bill. Mine ventilation is statutory and life-safety territory: airflow quantities, gas limits and re-entry times must be set by the registered ventilation engineer/manager under your jurisdiction's mining regulations — this calculator is a planning and training aid.
When is this calculator the right tool for the job?+
Fan Law. Ventilation-on-demand systems are this calculator attached to a VFD and a tag-reader — the savings arithmetic is exactly what you see here. For neighbouring scenarios, the related tools below cover the same engine with different presets.
Does it support both metric and imperial units?+
Yes — the SI ⇄ Imperial toggle converts the values already in the fields, preserving the physical quantity, so you can flip mid-calculation without re-entering anything.
Related tools
- Fan Engineering — Density Correction (Altitude/Temp)
- Fan Engineering — Fans in Parallel
- Fan Engineering — Series / Booster Fan
- Fan Engineering — Natural Ventilation Pressure
- Fan Engineering — Auxiliary Duct Leakage
- Fan Engineering — Auxiliary Duct Sizing
- Fan Engineering — Operating Point (Quadratic Estimate)
- Truck Fleet — Regional Haul
- Bolting — M24 Gr 10.9 Installation Torque
Related Manufacturing tools
Spindle Speed Calculator — Aluminum 6061
Carbide starting RPM for milling Aluminum 6061: n = 1000·Vc/(π·D) with a handbook cutting speed preset.
● LiveSpindle Speed Calculator — Mild Steel 1018
Carbide starting RPM for milling Mild Steel 1018: n = 1000·Vc/(π·D) with a handbook cutting speed preset.
● LiveSpindle Speed Calculator — Stainless 304
Carbide starting RPM for milling Stainless 304: n = 1000·Vc/(π·D) with a handbook cutting speed preset.
● Live