Airway Resistance — Flexible Duct (Force Fan)
Atkinson resistance and frictional pressure loss for a flexible duct (force fan) at its design airflow.
Layflat duct is smooth (k ≈ 0.003) but tiny — A³ punishes the small area mercilessly, which is why duct pressure dominates auxiliary fan selection. Every sag, dogleg and shoddy coupling adds shock losses this friction-only number ignores; field pressure typically runs 30–50% above the clean calculation.
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.
Atkinson resistance and frictional pressure loss for a flexible duct (force fan) at its design airflow. A free mine ventilation & air quality tool — no sign-up, no upload, instant results in your browser.
About Airway Resistance — Flexible Duct (Force Fan)
Airway Resistance — Flexible Duct (Force Fan) computes the governing relationship R = k·P·L/A³ · p = R·Q² [Atkinson] live as you type. Layflat duct is smooth (k ≈ 0.003) but tiny — A³ punishes the small area mercilessly, which is why duct pressure dominates auxiliary fan selection. Every sag, dogleg and shoddy coupling adds shock losses this friction-only number ignores; field pressure typically runs 30–50% above the clean calculation. 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 Airway Resistance — Flexible Duct (Force Fan)
- 1Enter your values — Friction factor k, Airway length, Cross-section area, Perimeter and more (sensible defaults are pre-filled).
- 2Read the live results: Resistance R, Pressure loss, Air velocity.
- 3Check the "with your numbers" line to see R = k·P·L/A³ · p = R·Q² [Atkinson] substituted step by step.
- 4Adjust inputs until the scenario matches yours, then copy or share the result.
Why use Airway Resistance — Flexible Duct (Force Fan)?
- ✓Instant, free and private — every calculation runs client-side in your browser; nothing is uploaded
- ✓Built on the stated formula R = k·P·L/A³ · p = R·Q² [Atkinson] 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.)
- ✓Layflat duct is smooth (k ≈ 0.003) but tiny — A³ punishes the small area mercilessly, which is why duct pressure dominates auxiliary fan selection.
- ✓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 airway resistance — flexible duct (force fan) use?+
It evaluates R = k·P·L/A³ · p = R·Q² [Atkinson], 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?+
Layflat duct is smooth (k ≈ 0.003) but tiny — A³ punishes the small area mercilessly, which is why duct pressure dominates auxiliary fan selection. 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?+
Atkinson resistance and frictional pressure loss for a flexible duct (force fan) at its design airflow. A free mine ventilation & air quality tool. Every sag, dogleg and shoddy coupling adds shock losses this friction-only number ignores; field pressure typically runs 30–50% above the clean calculation. 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.
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