Siemens SITRANS LR250 Operating Instructions Manual page 122

Parameter reference
Propogation Factor (2.5.3.)
Note
• When operating in a stillpipe, values for CLEF Range (2.5.7.4.), and for the propagation
factor, should be set according to the pipe size. See the table below.
• For reliable results, the antenna size must be close to the pipe size.
Compensates for the change in microwave velocity due to propagation within a metal stillpipe
instead of in free space.
Values
Nominal Pipe Size
Propagation Factor
CLEF Range (2.5.7.4.)
Since pipe dimensions may vary slightly, the propagation factor may also vary.
a)
CLEF range covers the whole measurement range except first 700 or 1000 mm from unit
b)
reference point (see A in graphic below)
①
②
A
Note
Flanged encapsulated antenna
For Flanged encapsulated antenna (7ML5432) match the process connection size to the pipe
diameter whenever possible (for example, mount a DN80/3" flange on DN80/3" pipe).
120
a)
sensor reference point
air gap
700 or 1000 mm
Range: 0.3 to 1.0 depending on pipe size.
Default: 1.0000
40 mm (1.5") 50 mm (2")
0.9844 0.988
Low calibration Low calibration
point - 700 mm point - 700 mm
(2.29 ft) (2.29 ft)
b) b)
③
④
80 mm (3")
0.9935
Low calibration
point - 1000
mm (3.28 ft)
b)
low calibration point
CLEF range 2.5.7.4.
SITRANS LR250 (PROFIBUS PA)
Operating Instructions, 08/2014, A5E32221386-AC
100 mm (4")
0.9965
Low calibration
point - 1000 mm
(3.28 ft)
b)