TECHNICAL DESCRIPTION
ULTRAFLOW
®
54 DN150-250
5512-876 GB/04-2012/Rev. F1
37
8.9
Pulse emission
Pulses are emitted at intervals of 1 sec. The number of pulses to be emitted is calculated every second. Pulses are
emitted in bursts with a pulse duration of 2…5 ms and pauses depending on current pulse frequency. The duration
of the pauses between the individual bursts is approx. 30 ms.
The transmitted pulse signal is the average determination of a series of flow measurements. This means that there
will be a transient phenomenon until correct flow signal has been obtained during start-up. Furthermore, this
brings about a pulse tail of up to 8 sec. in case of sudden hold.
8.10
Accuracy
ULTRAFLOW
®
54 has been developed as a volume flow rate sensor for energy meters according to DS/EN 1434.
The permitted tolerances of DS/EN 1434 for flow sensors with a dynamic range of 1:100 (q
i
:q
p
) are shown in the
diagram below (
Diagram 14
). The tolerances are defined for class 2 and class 3 with following formulas:
Class 2:
q
q
p
×
+
02
.
0
2
but max. 5%
Class 3:
q
q
p
×
+
05
.
0
3
but max. 5%
DS/EN 1434 defines following dynamic ranges (q
i
:q
p
): 1:10, 1:25, 1:50, 1:100 and 1:250.
In connection with accuracies the range from q
p
to q
s
is defined as max. flow short-term, where tolerances are
adhered to. There are no requirements as to the relation between q
p
and q
s
. See
Table 1
for information on q
s
for
ULTRAFLOW
®
.
To render probable that the sensors meet the tolerance requirements, DS/EN 1434-5 specifies calibration
requirements in connection with verification of sensors. It is required that flow sensors are tested at following 3
points:
q
i
…1.1 x q
i
, 0.1 x q
p
..0.11 x q
p
and 0.9 x q
p
…q
p
During test the water temperature must be 50°C ±5°C.
Further requirements are that the tolerance of the equipment used to perform the test must be less than 1/5 MPE
(Max. Permissible Error) to permit the acceptance limit to be equal to MPE. If the equipment does not observe 1/5
MPE, the acceptance limit must be reduced by the tolerance of the equipment.
ULTRAFLOW
®
54 will typically do better than half of the permitted tolerance according to DS/EN 1434 cl. 2.
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