TSI Instruments 3079A, Руководство по эксплуатации и обслуживанию, Страница: 30 / 39

Chapter 7
7-4 Model 3079A
Model II:
LAF
AG room
room
AG
ATM
LAF
room AG
test
V
) V V ( C V C
V
N N
C












(3)
Aerosols Produced by the Aerosol Generator (no dilution)
Particle/cm
3
Particle/cf
Number concentration (total) >10
8
2.8

10
12
Number concentration
(fractions 0.3 … 0.5µm):
5

10
5
1.4

10
10
Number concentration
(fractions 0.5 … 1.0µm):
3

10
5
8.5

10
9
Example
Laminar flow box type II
V
LAF
= 600 m
3
/h
V
LAF
= 70% V
total
= 0.7 V
total
V
room
= 30% V
total
= 0.3 V
total
C
room
(0.5 µm)= 3.5 Particle/cm
3
(cleanroom standard 100000

US-Fed.Std. 209D or in Germany: VDI2083)
C
AG
(0.5 … 1.0µm) = 3

10
5
Particle/cm
3
V
AG
= 250 L/h = 250

10
3
cm
3
/h
Considering the allowed particle number concentration in the surrounding air, the particle
concentration in the produced aerosol will be calculated as follows:
LAF
AG total
room
AG
AG
LAF
room AG
test
V
) V V (0.3 C V C
V
N N
c












h
cm
10 600
h
cm
) 10 250 10 600 (0.3
cm
Particle
3.5
h
cm
10 250
cm
Particle
10 8
test
C
3
6
3
3 6
3
3
3
3
6

      

cf
Particle
10 9.4
cm
Particle
3334 C
7
3
test
  
If the surrounding air is considered, the produced test aerosol concentration is calculated as
126 Particles/cm
3
(3.6

10
6
Particles/cf); whereas, without it, the concentration is 125 Particles/cm
3
.
This example shows that it is acceptable to neglect the particle number concentration in the
surrounding air and apply formula (1).