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8012426/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 SP100
Subject to change without notice
PRODUCT DESCRIPTION
2
2
Product Description
2.1
Measuring principle, measured variables
2.1.1
Functional principle
The measuring system works according to the scattered light measurement principle
(forward dispersion). 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 detector registers
the light scattered by the particles, amplifies the light electrically and feeds it to the mea-
suring channel of a microprocessor as central part of the measuring, control and evalu-
ation electronics. The measuring volume in the gas duct is defined through the intersection
of the sender beam sent and the receive aperture.
Continuous monitoring of the sender output registers the smallest changes in brightness of
the light beam sent which then serves to determine the measurement signal.
Fig. 1: Measuring principle
Determining the dust concentration
Measured scattered light intensity (SI) is proportional to dust concentration (c). Scattered
light intensity not only depends on the number and size of particles but also on the optical
characteristics of the particles and therefore the measuring system must be calibrated
using a gravimetric comparison measurement for exact dust concentration measurement.
The calibration coefficients determined can be entered directly in the measuring system as
c = cc2
·
SI² + cc1
·
SI + cc0
(Entry
see “Calibration for dust concentration measurement”, page 69
; standard factory
setting: cc2 = 0, cc1 = 1, cc0 = 0).
Approx. 15°
Sender/receiver unit
Gas duct
Receiver
Measuring volume
Sender