Accuracy And Measurement Range Specifications; Figure 2-5: Upper Transition Zone Length And Minimum Blocking Distance High (Bdh) And Minimum Blocking Distance Low (Bdl) For Coax Probes In Water - Honeywell SLG 700 User Manual

installations where build-up or large ambient temperature swings over 30°C are expected.
For example: where large (>25 deg C, >45 deg F).

2.4.3 Accuracy and measurement range specifications

The available probe lengths for each probe type are summarized in Figure 3-3
'These accuracy specifications are defined under reference conditions, at other ambient
temperatures the accuracy specifications are increased by +/- 0.2 mm/deg C or +/- 15
ppm/deg C whichever is greater.
The measurement accuracy over the probe length is the larger of ±3mm or ±0.03% of probe
length. At the top and bottom of the probe the measurement performance can deviate from
the ±3mm or ±0.03% accuracy specification.
The zones at the top and the bottom of the probe at which the accuracy deviates from the
accuracy spec is called upper and lower transition zones respectively.
As the level rises or falls in the upper and lower transition zone a point may be reach were the
transmitter cannot provide a level reading or the accuracy is worse than ±30mm, at this point
we have reach the minimum blocking distance that can be set in the transmitter.
Figure 2-7 to Figure 2-6 summarize the accuracy as a function of length for the available
probe types in addition Table 3-4 provides a tabular summary of the minimum blocking
distances and the transition zones. In order to meet the accuracy specifications near the end of
the probe (lower transition zone and minimum blocking distance low), the correct probe type
and probe length need to be configured.
Note that for a wire probe with an end weight or with a looped end the minimum blocking
distance low is measured from the top of the weight or the top of the loop's crimp.
When the transmitter is installed in a nozzle then the distances are measured from the bottom
on the nozzle, i.e. where the nozzle transitions to the tank. In addition when using a nozzle
the guidance provided in Section 3.2.9.2 needs to be followed.
For the following four figures in this section, T and T are upper and lower transition
up low
zones respectively.
Figure 2-5: Upper transition zone length and minimum blocking distance high (BDH)
SLG 700 SmartLine Level Transmitter User's Manual
Revision 7 Page 21