22
8024493/AE00/V1-0/2020-09| SICK
O P E R A T I N G I N S T R U C T I O N S | DUSTHUNTER SP100 Ex-2K
Subject to change without notice
3
PRODUCT DESCRIPTION
3.3.1
Functional principle
●
The measuring system works according to the principle of scattered light measurement
(forward scattering), the measuring volume in the gas duct is defined by the intersection
of the sender beam and receive aperture.
●
To maintain measuring reliability, a permanent gas flow (purge gas) keeps the optics free
from dust particles as well as condensate.
Determining the dust concentration
Fig. 6: Measuring principle
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 77
; standard factory
setting: cc2 = 0, cc1 = 1, cc0 = 0).
Sender/receiver unit
Gas duct
Receiver
Measuring volume
Sender