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Chapter 1 Smoke control overview
4 BAS-APG001-EN
Table 2: Maximum allowable pressure differences across doors
Airflow method
The airflow method controls smoke in spaces that have barriers with one
or more large openings. It is used to manage smoke in subway, railroad,
and highway tunnels. The method employs air velocity across or between
barriers to control smoke movement (
Figure 2).
Figure 2: Sample airflow method
Door width
(in. [m])
32 (0.813) 36 (0.914) 40 (1.02) 44 (1.12) 46 (1.17)
Door closer force
(lb. [N])
Pressure difference
(In.w.c. [Pa])
6 (26.7) 0.45 (112.0) 0.40 (99.5) 0.37 (92.1) 0.34 (84.6) 0.31 (77.1)
8 (35.6) 0.41 (102.0) 0.37 (92.1) 0.34 (84.5) 0.31 (77.1) 0.28 (69.7)
10 (44.5) 0.37 (92.1) 0.34 (84.5) 0.30 (74.6) 0.28 (69.7) 0.26 (64.7)
12 (53.4) 0.34 (84.5) 0.30 (74.6) 0.27 (67.2) 0.25 (62.2) 0.23 (57.2)
14 (62.3) 0.30 (74.6) 0.27 (67.2) 0.24 (59.7) 0.22 (45.7) 0.21 (52.2)
Notes:
• Total door opening force is 30 lb. (133 N); door height is 80 in. (2.03 m). NFPA 101 (NFPA 2003, Life
Safety Code) recommends the door opening force.
• N is Newton.
• m is meter.
• In.w.c. is inches of water column.
• Pa is Pascal.
• The pressure difference values are based on recommendations in NFPA 92A (NFPA 2000,
Recommended Practice for Smoke Control Systems).