Page 240 - Industrial Ventilation Design Guidebook

5,2 HUMAN RESPIRATORY TRACT PHYSIOLOGY 20 I

TABLE S.5 Representative Conducting Airway Dimensions Based
on the Weibel "A" Model

Reynolds number

Minute ventilation
Cross- Equivalen Airway
sectional t segment
area diameter length 8 16 30
Airway region (cm) (cm) (cm) L/min L/min L/min

Nasal vestibule 1.3 67 0.9 1515 3029 5679
Nasal cavity 2.4 0.61 1.8 1664 3327 6238
Nasal turbinates 2.3 0.44 1.3 2306 46,12 8648
Nasal turbinates 2.6 0.36 4.4 2819 5637 10570
Nasal turbinates 3 1.18 0.6 860 1720 3225
Proximal nasopharynx 3.9 2.03 2 500 1000 1875
Distal nasopharynx 2.9 1.45 3 700 1400 2624
Proximal oropharynx 2.8 1.26 1.7 805 1611 3020
Distal oropharynx 3 1.3 1.3 781 1561 2927
Proximal hypo pharynx 2.3 1.5 2.4 676 1353 2537
Distal hypopharynx 1,9 1 .3 1.3 781 1561 2927
Larynx 1.8 1.5 1.1 676 1353 2537
Proximal trachea 2.1 1.6 2.7 634 1268 2378
Distal trachea 2.8 1.9 9.3 534 1068 2003
Bronchii gen. 1 3.4 1.47 4.8 345 689 1292
Bronchii gen. 2 3.9 1.11 1.9 227 454 851
Bronchii gen. 3 3.9 0.79 0.8 161 323 605
Bronchii gen. 4 3.9 0.56 1.3 114 229 429
Bronchii gen. 5 4 0.4 1.1 80 159 299
Bronchii gen. 6 4.3 0.29 0.9 54 107 202
Bronchii gen. 7 4.7 0.22 0.8 37 75 140
Bronchii gen. 8 5.4 0.16 0.6 24 47 89
Bronchii gen. 9 6.7 0.13 0.5 15 31 58
Bronchii gen. 10 8 0.1 0.5 10 20 37
Bronchii gen. J 1 19.6 0.11 0.4 4.4 8.9 .1 7
Bronchii gen. 12 28.8 0.1 0.3 2.8 5.5 1 0
Bronchii gen. 13 44.5 0.08 0.3 1.4 2.9 5,4
Bronchii gen. 14 69.4 0.07 0.2 0.8 1.6 3
Bronchii gen. 15 113 0.07 0.2 0.5 1 1.9
Bronchii gen. 16 180 0.06 0.2 0.3 0.5 1
Bronchii gen. 17 300 0.05 0.1 0.1 0.3 0.5
Note that turbulent flow (Reynolds number > 3000 is predicted only
in the extrathoracic airways at flow rates < 30 L/min,