7
Protocols
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¬Velocities in ductwork calibrated to achieve velocities consistent with typical air flows and isokinetic air sampling. 
t
tTypical air flows in commercial buildings:  10-20% Outdoor Air/80-90% Recirculating Air
wFlowrates Achieved:  22% Outdoor Air/88% Recirculating Air
t
tIsokinetic Sampling:  “equal-velocity” sampling
wnozzle tip opening area (An) and sample volumetric flowrate (Qm) must be adjusted     to obtain a velocity Vn = Qm/An equal to the                                      gas stream velocity (Vs) at the point of sampling