Endress+Hauser FMR 231 - Accuracy; Measuring range

A linearisation function, based on a manually or semi-automatically entered table, can
be activated locally at the display unit or via the foreign system interface. This allows
measurement in customer units and provides a linear output current for spherical vessels,
horizontal cylinders and tanks with conical outlet.
AccuracyThe accuracy of Micropilot FMR 231 is dependent upon the set measuring range and
material being measured, see Technical Data. Under reference conditions it is capable
of measuring to an accuracy of ±15 mm up to a measuring range of 10 m and ±0.15%
of the range end-value of measuring ranges from 10 m to 20 m..
Measuring rangeThe measuring range depends upon the conditions in the tank and the product to be
measured. Table 1.2 describes the product classes, Table 1.3 the measuring range as
a function of the application and measuring conditions.
In order to ensure the highest accuracy for Class B, we recommend that
•
the empty distance "E" should be 30 cm above the tank bottom.
Class A products can be measured in bypass pipes using the FMR 230V horn antenna,
see operating manual BA 197F.
Product class Examples
A Non-conducting liquids, e.g. propane, buthane etc.
Dielectric constant ε
r.
1.4...1.9
B Non-conducting liquids, e.g. petrochemicals, benzine, oil, toluol, etc.
Dielectric constant ε
r
approx. 1,9...4
C E.g. concentrated acids, organic solvents, analine, esters, alcohols, acetone, etc.
oil/water mixtures
Dielectric constant ε
r
approx. 4...10
D Conducting liquids, watery solutions, dilutte acids and alkalis,
Dielectric constant ε
r
> 10 or electrical conductivity σ >10mS/cm
Table 1.2
Selection of product class
Product
Class
Strorage tank Buffer tank Stilling well or bypass pipe
Measuring range
Measuring range Measuring range
DN 50 DN 80
B
10 m 33 ft 5 m 16 ft 10 m 33 ft 20 m 67 ft
C
15 m 50 ft 8 m 25 ft 10 m 33 ft 20 m 67 ft
D
20 m 67 ft 10 m 33 ft 10 m 33 ft 20 m 67 ft
Table 1.3
Measuring range as a function of
application
Micropilot FMR 231 Chapter 1 Introduction
Endress+Hauser 7