MRG
MRG
MRG
MRG----10
10
10
10
Configuration
Configuration
Configuration
Configuration
5-11
5.9.3 Parameter setting
5.9.3.1 Antenna Type
（
Menu code:[1-1]
）
Use actual antenna type. (ex. 4inch cone antenna)
5.9.3.2 Span calibration
• As the speed of microwaves propagated inside of pipes differ from the speed of
microwaves when propagated in free spaces, a compensating coefficient must be input in
the “Span Calibration” parameter (Menu code, [4-4]).
• “Span Calibration” values are
derived from the inner diameter of the pipe.
The following table is one example.
Inner Pipe Dia [mm]
Span Calibration
107
0.9507
• When span calibration value (‘F’) is unknown, ‘F’ can be calculated from two points -
reference level value (X) and measured level value (Y) - using the following equation.
F =
（
Y
High
- Y
Low
）
/
（
X
High
- X
Low
）
F : Span calibration value
X
High
: High reference level value
X
Low
: Low reference level value
Y
High
: High measured level value
Y
Low
: Low measured level value
5.9.3.3 Offset compensation
・
Offset setting may be required using Menu code: [4-3].
・
Offset value is
derived from the difference in measured level and reference level at 1 point.
5.9.4
Considerations
• Pipe material should be metal.
In cases of existing pipes of concrete or PVC material instead of metal, span calibration may
not be required as their low dielectric constants allow transmission of microwaves. However
when wet, such pipe materials exhibit high reflectivity characteristics from wetted surfaces.
This affects accuracy and span calibration becomes necessary. Because of such changes
in characteristics under wet conditions, non-metal pipe applications are not recommended.
• Air vents (10mm dia.) for pressure release should be incorporated and located above the tip
of the antenna.
