Accuracy Over Measuring Range - Emerson Rosemount 3308A Reference Manual

Specifications and Reference Data
August 2017
A.1.4 Accuracy over measuring range
The measuring range depends on probe type, dielectric
constant of the product and installation environment, and is
limited by the Blind Zones at the very top and bottom of the
probe. In the Blind Zones, the accuracy exceeds ±1.18 in.
(30 mm), and measurements may not be possible.
Measurements close to the Blind Zones will have reduced
accuracy.
The following conditions will impact the Blind Zones:
If the single lead probes or twin probes are installed in a
nozzle, the nozzle height shall be added to the specified
Upper Blind Zone.
The measuring range for the PTFE covered flexible single
lead probe includes the weight when measuring on a high
dielectric media.
Figure A-2, Figure A-3, Figure
the accuracy over measuring range at reference condition
using the Trim Near Zone function, with alternating probe
types and varying dielectric constant of the product.
Figure A-2. Accuracy over Measuring Range for Flexible Single Lead Probe
±
(6 mm)
3.2 in. (8 cm)
9.8 in. (25 cm)
5.1 in. (13 cm)
114
PRELIMINARY
A-4, and Figure A-5 illustrate
Water (DC = 80)
±
0.25 in. 1.18 in.
(30 mm)
Accuracy
Note
Measurements may not be possible in the Blind Zones, and
measurements close to the Blind Zones will have reduced
accuracy. Therefore, the alarm points should be configured
outside these zones.
Oil (DC = 2.2)
± ±
0.25 in. 1.18 in.
(6 mm) (30 mm)
4.3 in. (11 cm)
10.6 in. (27 cm)
2 in. (5 cm)
4.3 in. (11 cm)
Reference Manual
00809-0100-4308, Rev CA
Upper Blind Zone
Reduced accuracy
Reduced accuracy
Lower Blind Zone
Accuracy
Blind Zone
Specifications and Reference Data