MSHA HANDBOOK SERIES - PH13-V-1 - Mine Safety and Health ...

GENERAL COAL MINE INSPECTION PROCEDURES AND
INSPECTION TRACKING SYSTEM HANDBOOK CHAPTER 5
STEP 4: CALCULATING AIR QUANTITY
Air quantity can now be determined by using the formula Q = VA
Where:
Q = air quantity in cfm
V = air velocity in fpm
A = airway cross-sectional area in square feet.
(height x width (in feet) = area in square feet.
Therefore: V = 81.0 fpm
A = 74 sq. ft.
Q = 6053 cfm
Using Air Velocity Table - The Air Velocity Table (Figure 5-3, MSHA Form 7000-10F) can
be used as an alternative for calculating air velocity. When the final average time has
been calculated (6.6 seconds in Step 1 above), locate the air velocity on the table.
Example:
Find 6.6 seconds in the “TIME SEC” column. For a measured distance of 10 ft., the air
velocity equals 82 fpm.
Release 1 (February 2013) 5-10