12
8011952/YWL2/3-0/2016-08| SICK
O P E R A T I N G I N S T R U C T I O N S | DUSTHUNTER C200
Subject to change without notice
2
PRODUCT DESCRIPTION
Transmission, opacity, relative opacity:
Transmission, opacity and relative opacity are usually specified in percent.
Extinction:
Dust concentration:
Based on the Beer-Lambert law, the dust concentration is derived from the extinction as
follows:
Extinction is directly proportional to dust concentration for constant particle size and
uniform dust distribution.
Particle size, dust density and dust distribution during differing load states influence trans-
mission and extinction values and therefore the measuring system must be calibrated
using a gravimetric comparison measurement for exact dust concentration measurement.
The calibration coefficient determined can be entered directly in the measuring system as
c = cc2
·
E² + cc1
·
E + cc0
(Entry
see “Calibration for dust concentration measurement”, page 76
; standard factory
setting: cc2 = 0, cc1 = 1, cc0 = 0).
2.1.1.2
Scattered light measurement
A laser diode beams the dust particles in the gas flow with modulated light in the visual
range (wavelength approx. 650 nm). A highly sensitive receiver registers the light scattered
by the particles, amplifies the light electrically and feeds it to the measuring channel of a
microprocessor as central part of the measuring, control and evaluation electronics. The
measuring volume in the gas duct is defined through the intersection of the sender beam
sent and the receive aperture.
In the same manner as for transmission measurement, continuous monitoring of the
sender output registers smallest changes in brightness of the light beam sent which then
serves to determine the measurement signal.
T
N
I
meas
I
mon
------------
•
=
O
1 T
–
=
ROPA
1 e
E
D
Do
2 D
meas
•
-----------------------
•
–
=
N
=
scaling constant
I
meas
= light received
I
mon
= monitor signal
D
Do
= stack diameter at the top end
D
meas
= active measuring path
E
1
T
---
log
=
c
2 31
,
E
•
k L
•
---------------------
K E
•
=
=
k= extinction constant
L = 2x active measuring path (due to double beam path)
