DENSITY OPTION
Part No.: 4417340 Revision 1 Service Manual 277
954 SmartServo FlexLine
Principle of operation
The 954 can be used for density measurement if the servo level gauge
is equipped with the optional software. In addition to the software a
density displacer with an increased volume (200 cm
3
) must be used.
Two standard stainless-steel density displacers, with 43 mm and 90 mm
outer diameter, are available. They are applicable for a maximum
working pressure of 20 bar (290 psi).
To obtain the average observed density, the displacer is positioned at
up to 50 different positions, equally divided over a specified measuring
height. The apparent weight of the displacer is measured. Knowing the
volume and the weight of the displacer, the observed density can be
calculated. An average density will be calculated over all measured
densities. The density data is transferred via the Honeywell Enraf field
bus.
10.2 Commissioning
Installation on the tank
Correct installation and calibration of the 954 is essential to obtain
maximal accuracy of the density measurements.
Check if the gauge is correctly installed and commissioned.
Check the stability of the mounting of the 954. As all position changes of
the 954 perpendicular on the shaft axes will introduce a density
deviation, the horizontal angle should not exceed ± 0.5 °.
Check whether the installed software supports density measurement.
This can be done by checking entity [Functional licensed options] on the
Miscellaneous tab in Engauge. Field 01 must be set to True.
Calibration of the 954 level gauge
Perform a balance test to check the unbalance of the measuring drum.
Refer to section 9.1.3.
Note:
The drum unbalance should be within 3 grams. If the drum unbalance is
more, check the drum for contamination. If the unbalance is still more
than 3 grams, replace the drum bearings and check again. For details
refer to section 9.1.2, 9.1.3 and 0.
Calibrate the force transducer. This is required for the most accurate
density measurement result. Refer to section 9.5.
Check the displacer weight after the calibration of the force transducer.
Refer to sections 9.1.2 and 9.1.3.
It is recommended to weigh the displacer with the balance test and then
check the average unbalanced weight.
To Next Page
Loading...
Need help?
General
