7
Maintenance
96
6924-en_V1.3_09/20
7.5
Determining the factor for mass concentra-
tion
Objective
The aerosol spectrometer
Promo
works with a factor for the mass concentra-
tion. The factor has been set at the factory. It has to be checked or specified
anew occasionally. Each type of aerosol (saline or oil) has its own factor.
The two factors have to be determined one after the other and separately.
Apply the following formulas to the calculations:
Calculation formula 1
Factor
Mass, aerosol
= Factor for mass concentration
C
m,grav
= Gravimetrically determined mass concentration [mg/m
3
]
C
m,Promo
= Mass concentration of aerosol spectrometer Promo [mg/m
3
]
Calculation formula 2
C
m,grav
= Gravimetrically determined mass concentration [mg/m
3
]
m
2
= Mass of filter with load [mg]
m
1
= Mass of empty filter [mg]
Q = Volume flow [l/min]
t = duration of loading [min]
Materials required
• Round filter “Glass Microfiber Filter,” diameter 125 mm,
(Whatman no. 1820-125)
• Precision scale with four decimal places, weighing capacity up to 300 g
(Precisa 321 LX 320A)