ULTRAFLOW®54(H)/(J)
KamstrupA/S∙TechnicalDescription∙5512‐1554_J1_GB_04.2018
47
8.7 Pulse emission
Pulses are emitted at 1-sec. intervals. The number of pulses to be emitted is calculated every second. Pulses are
emitted in bursts with pulse duration 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 s. in case of sudden hold.
8.8 Accuracy
ULTRAFLOW
®
54 has been developed as a volume flow rate sensor for energy meters according to EN 1434. The
tolerances permitted according to EN 1434 for flow sensors with a dynamic range of 1:100 (q
i
:q
p
) and q
p
1.5 m
3
/h
are shown in Figure 43. The tolerances are defined for class 2 and class 3 with following formulas:
Class 2:
)%02.02(
q
q
p
but max. ±5 %
Class 3:
)%05.03(
q
q
p
but max. ±5 %
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, EN 1434-5 specifies calibration requirements
in connection with verification of sensors. It is required that flow sensors are tested at the 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±5) °C for ULTRAFLOW
®
as a heat meter.
Further requirement is 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
®
will typically do better than half of the permitted tolerance according to EN 1434 class 2.
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