For calculating the supply air requirement either of the
formulas shown below, may be used.
Formula 1
where
|
q
|
= |
required
outdoor air, m3/s
|
|
F
|
= |
pollution,
mg/s |
|
k
|
= |
exposure
limit value, mg/m3
|
|
a
|
= |
dilution
factor (see paragraph 6)
|
|
b
|
= |
pollution
content of the outdoor air |
For the purposes of calculation it is understood that there
is a complete mixture of air and pollutant.
The pollution
content of the outdoor air (b) is assumed to be 1/40 of the exposure
limit value - in the absence of any other information.
Formula 2
where
|
C
|
= |
concentration
of contaminant |
|
G
|
= |
rate
of generation of contaminant, or rate per car times the number of
cars in motion during the specified period |
|
e
|
= |
2.71828 |
|
Q'
|
= |
effective
rate of ventilation, or actual rate (Q) divided by a safety factor
of 3 |
|
t
|
= |
time
in minutes |
|
V
|
= |
volume
of ventilated space |