Endress+Hauser promag 31, Operating Manual

Page: 54 / 60

6.5 Conceptual definitions
Temperature ranges for cold water: 0...30 °C
Metrological Classes
A+B
Indicate the range from Q
max
(full scale value) down to Q
min
in which
the approved fiscal meter can measure. Within this complete range,
the maximum error as defined by the metrology office shall not be
exceeded.
Limiting values of flow rate
Q
max
Highest flow rate without damaging the measuring unit and without
exceeding the maximum permissible error.
Q
n
The nominal flow rate is half the value of the highest flow rate Q
max
and is to characterize the measuring unit.
Q
min
Lowest flow rate from which the measuring unit shall not exceed
the maximum permissible error. It is dependent on Q
n
and the
metrological class.
Q
t
Is the transition flow rate, which separates the lower and the upper
maximum permissible range from each other with different error values.
Q
t
is dependent on Q
n
and the metrological class.
Error limits
Q
min
…
Q
t
lower range:
±
5%
Q
t
…
Q
max
upper range:
±
2%
Metrology classes
Class Q
n
<15 m
3
/h >15 m
3
/h
Class A
range of Q
min
range of Q
t
0.04 Q
n
0.10 Q
n
0.08 Q
n
0.30 Q
n
Class B
range of Q
min
range of Q
t
0.02 Q
n
0.08 Q
n
0.03 Q
n
0.20 Q
n
b
a
028y
t8
±
Error [%]
5
2
Q
min
Q
t
Q
n
flow rate
[m
3
/h]
Q
max
upper range
∆
2 = 2% lower range
∆
1 = 5%
Flow range and fiscal metering error values
for cold water
Fig. 52
6. Technical Data Promag 31
54 Hauser