Endress+Hauser Levelflex FMP54 - Gas Phase Compensation with Reference Signal (Option for FMP54)

Levelflex FMP51, FMP52, FMP54
Endress+Hauser 41
Gas phase compensation
with reference signal (option
for FMP54)
Under high pressure the propagation speed of microwave signals is reduced in the steam (polar
media) above the liquid to be measured. As a result, the Levelflex indicates the level too low
→  40.
As an option Levelflex is available in a version with automatic gas phase correction, which corrects
this error (feature 540 "Application Package", option EF: "Gas Phase Compensation L
ref
= 300 mm" or
EG: "Gas Phase Compensation L
ref
= 550 mm"). This version of the Levelflex generates a reference
reflection in the distance L
ref
from the flange by a diameter step of the probe rod. The reference
reflection must be at least 150 mm (6") above the highest level. By means of the shift of the
reference reflection the actual propagation speed is measured and the level value will be
automatically corrected.
Dref
iD
max
min
150mm
6inch
LN
Lref
max
min
150mm
6inch
LN
Lref
(300/550mm)
(300/550mm)
A0014534
Coax probes with reference reflection can be installed in any tank (free in the tank or into a
bypass). Coax probes are completely mounted and adjusted ex works. After mounting they are
ready for use, additional settings are not necessary.
Rod probes are only recommended if the installation of a coax probe is not possible (e.g. if the
bypass diameter is too small).
Rod probes with reference reflection are only suited for mounting in stilling wells and side
gauges (bypasses). The diameter D
ref
of the probe rod in the range of the reference distance L
ref
must be chosen depending on the pipe inner diameter iD, see table below. In the range of the
reference distance L
ref
the pipe has to be cylindrical; changes of the cross section, for example at
flanged connections, are only allowed up to 5% of the inside diamter iD.
Additionally, the settings must be checked by an expert person after mounting and corrected if
necessary.
Inner diameter iD of the stilling well/bypass Diameter D
ref
of the rod probe within the reference distance
L
ref
40 mm (1.57") ≤ iD < 45 mm (1.77") 22 mm (0.87")
45 mm (1.77") ≤ iD < 70 mm (2.76") 25 mm (0.98")
70 mm (2.76") ≤ iD < 100 mm (3.94") 30 mm (1.18")