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Stair pressurization: fan airflow and door force
Enter floors, doors per floor, door size and the pressure to hold. The tool gives airflow with doors closed and open, fan flow, and checks the door opening force.
Quick answer
Pressurization fan about 22,281 m³/h holding 50 Pa with doors closed; door force 81 N, door force OK.
Preliminary results
Fan airflow22,281m³/h
Doors closed2,105m³/h
Doors open19,375m³/h
Door force81N
| Step | Result | Basis |
|---|---|---|
| Leakage per closed door0,827 × 0.01 × √50 | 211 m³/h | EN 12101-6 ⚠ |
| Total leakage, doors closed10 × 0.0585 m³/s | 2,105 m³/h | EN 12101-6 ⚠ |
| With doors open2 × 1.89 × 1.3 + 8 × 0.0585 | 19,375 m³/h | QCVN 06:2022/BXD PL D ⚠ |
| Fan airflow (+15 % duct leakage)max × 1,15 | 22,281 m³/h | — |
| Door opening forceF = 30 + W·A·ΔP / (2(W − 0,06)) | 81 N ≤ 100 | EN 12101-6 ⚠ |
- Outdoor air intake at least 5 m from smoke discharge.
- Fit a pressure relief damper (or VFD) so pressure does not overshoot with all doors closed.
- Fan starts on fire alarm, on a priority power supply.
Sources and assumptions. Door leakage Q = 0.827·A·√ΔP, single leaf 0.01 m², double 0.03 m²; door force F = F_dc + W·A·ΔP/(2(W − d)) ≤ 100 N (EN 12101-6); pressure 20–150 Pa (MDS 41-1.99 cl. 2.2); open-door velocity per QCVN 06:2022/BXD Annex D ⚠. ⚠ = code table value to be checked against the original standard. Preliminary results for material selection and budgeting; not a substitute for an approved fire protection design.
Suggested materials
Pressurization fan ≥ 22,281 m³/h1
Pressure relief damper (or VFD + differential pressure sensor)1
Supply grilles, pressurization ductsper drawing
Frequently asked questions
What fan for a 20-storey stair?
Single-leaf doors 0.9 × 2.1 m, 50 Pa, 2 doors open at 1.3 m/s: about 2 × 0.9 × 2.1 × 1.3 = 4.9 m³/s plus leakage of 18 closed doors, fan about 24,700 m³/h (incl. 15 % duct leakage).
Why must pressure not be too high?
High pressure pushes the door force above 100 N so the elderly and children cannot open the escape door.