Short-Term Ventilation Design

[Hydronican]

Hello Everyone:


From time to time I'm involved with the ventilation design for assembly hall, which is usually for events. ASHRAE 62.1-2007 has description on this kind of ventilation design under short-term condition and provides two equations to calculate time period for average

T = 3*V/Vbz (6-9a)
T = 50*V/Vbz (6-9b)

My question is why there are two time period definitions?Does anybody know how to apply these two equations?

Thanks

 

[bigAlittlee]

6-9a is IP
6-9b is SI

 

[Hydronican]

Thank you, bigAlittlee.

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