Network — Controlled Recirculation Fraction
Controlled Recirculation Fraction for ventilation network design and surveying.
The counterintuitive theorem of controlled recirculation: steady-state contaminant levels depend ONLY on fresh air — recirculated air adds velocity, cooling and capture, not dilution. Done with monitoring and filters it is legitimate engineering; done by accident it is the classic ventilation violation.
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.
Controlled Recirculation Fraction for ventilation network design and surveying. A free mine ventilation & air quality tool — no sign-up, no upload, instant results in your browser.
About Network — Controlled Recirculation Fraction
Network — Controlled Recirculation Fraction computes the governing relationship steady state: C_face = C_in + G/Q_fresh — recirculation raises velocity, NOT steady-state dilution live as you type. The counterintuitive theorem of controlled recirculation: steady-state contaminant levels depend ONLY on fresh air — recirculated air adds velocity, cooling and capture, not dilution. Done with monitoring and filters it is legitimate engineering; done by accident it is the classic ventilation violation. 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 Network — Controlled Recirculation Fraction
- 1Enter your values — Fresh air into district, Recirculated quantity, Contaminant in fresh air, District generation (sensible defaults are pre-filled).
- 2Read the live results: Recirculation fraction, Face concentration.
- 3Check the "with your numbers" line to see steady state: C_face = C_in + G/Q_fresh — recirculation raises velocity, NOT steady-state dilution substituted step by step.
- 4Adjust inputs until the scenario matches yours, then copy or share the result.
Why use Network — Controlled Recirculation Fraction?
- ✓Instant, free and private — every calculation runs client-side in your browser; nothing is uploaded
- ✓Built on the stated formula steady state: C_face = C_in + G/Q_fresh — recirculation raises velocity, NOT steady-state dilution 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 counterintuitive theorem of controlled recirculation: steady-state contaminant levels depend ONLY on fresh air — recirculated air adds velocity, cooling and capture, not dilution.
- ✓Niche-specific defaults give a meaningful worked answer the moment the page loads
Frequently asked questions
What formula does the network — controlled recirculation fraction use?+
It evaluates steady state: C_face = C_in + G/Q_fresh — recirculation raises velocity, NOT steady-state dilution, 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 counterintuitive theorem of controlled recirculation: steady-state contaminant levels depend ONLY on fresh air — recirculated air adds velocity, cooling and capture, not dilution. 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?+
Controlled Recirculation Fraction for ventilation network design and surveying. A free mine ventilation & air quality tool. Done with monitoring and filters it is legitimate engineering; done by accident it is the classic ventilation violation. For neighbouring scenarios, the related tools below cover the same engine with different presets.
Do I need to install anything or create an account?+
No. The tool is pure client-side JavaScript: open the page and it works, offline once loaded, with no account, no quota and no data leaving your device.
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