38
Reference Manual
00809-0100-4024, Rev CA
Mechanical Installation
March 2020
Mechanical Installation
2.8.4
Measurement in large pipes
When using standard cones in larger (8-in. or larger) still pipe installations, there is a risk for
measurement problems. When standard linear shaped cones are used in pipes, more than one
microwave mode is generated and each mode has a unique propagation speed. This is a radar physics
problem that is common to all radar gauges when linear shaped cones are used.
In larger pipes, the amplitude of echoes generated by the “unwanted” modes may become rather high,
and may result in loss of the surface echo at certain locations in the pipe. In addition, there may be
measurement errors associated with two closely spaced echoes where the gauge will not lock on a single
target.
The relative amplitude of the unwanted modes in a straight cone is proportional to the product of the
cone angle and the diameter in the cone opening. Therefore measurement error increases as pipe
diameter increases since the cone angle is the same for all the cones.
Due to this issue, Emerson Automation Solutions does not recommend using the Rosemount 5600
Series 8-in. cone antennas for larger pipe measurements. Instead, a special pipe antenna should be used.
Table 2-6. Recommendations
Pipe size
3-in. (76 mm)
4-in. (102 mm)
6-in. (152 mm)
Maximum measuring range
65 ft (20 m)
65 ft (20 m)
65 ft (20 m)
Maximum hole size (Ø)
0.24in. (6 mm)
0.28 in. (7 mm)
0.39 in. (10 mm)
Maximum number of holes per
meter
2
2
2
Deflection plate required
Yes
Yes
Yes
Summary of Contents for Rosemount 5600 Series
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Page 4: ...4 Reference Manual 00809 0100 4024 Rev CA Title Page March 2020 Title Page ...
Page 16: ...16 Reference Manual 00809 0100 4024 Rev CA Introduction March 2020 Introduction ...
Page 125: ...125 Reference Manual 00809 0100 4024 Rev CA Index March 2020 Index Strapping Table 71 ...
Page 126: ...126 Reference Manual 00809 0100 4024 Rev CA Index March 2020 Index ...
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