Siemens CD 3002 - Manual (Page 5)

LDS 3000
Air blower Purging of CD 3002 using air blower
1
1. Purging of CD 3002 using air blower
1.1 General
In application with high dust load and ash build-up in front of the lens in
CD 3002 very high purging flows may be necessary. For these applica-
tions an air blower producing flow rates in the 1000 ltr/min. range can be
used. A typical application where this is preferable is in MWI (municipal
waste incineration). This manual relates to the installation and operation
of the air blower set supplied by Siemens Laser Analytics.
1.2 Installation
An important issue is the counter pressure build up at the output of the
air blower. It is vital to keep this as low as possible since the air flow is
decreasing when the counter pressure increases – se the graph below.
Flow rate vs counter pressure.
A large cross section of the air blower output and a short tube is param-
eters that affects this in a positive direction. If a long tube must be used
– make sure it has a large diameter. The following diagram illustrates the
flow changes with different output tubes and may serve as a guide when
the set-up is designed. If the air blower is serving two sensors it is very
important that the lengths of the tubes to the two sensors are equal. This
ensures that the air is split 50/50 between the two.
0 200 400 600 800 1000
0
40
80
120
160
200
Flow rate [ltr/min]
Counter pressure [mbar]
Flow rate vs counter pressure