TECHNICAL DESCRIPTION
ULTRAFLOW
®
54 DN150-250
5512-876 GB/04-2012/Rev. F1
44
9.3
Optimization in connection with calibration
To make a rational test of ULTRAFLOW
®
it is important that results obtained in connection with tests can be
reproduced. This is also very important if the tested sensors are to be adjusted.
Experience has shown that ULTRAFLOW
®
operates with standard deviations of 0.3…0.4% at q
i
and 0.2…0.3% at q
p
.
This is standard deviations for 300…500 pulses at q
i
, 3000…5000 at q
p
, and flying start/stop.
In connection with optimization of calibration the following sub-components can be considered:
Pressure:
Optimal working pressure is 4…6 bar of static pressure. This minimizes the risk of air and cavitation.
Temperature:
Calibration temperature according to DS/EN 1434-5 is 50°C ±5°C.
Water quality:
No requirements
Installation - mechanical conditions:
To avoid flow disturbances the inlet pipes and distance pieces must have the same nominal diameter as the
sensors. There should be min. 5 x DN between the sensors. In connection with calibration, a code of practice for
distance pieces has been made on the basis of many years' experience:
The lengths of the distance pieces must be 10 x DN.
With bends etc. there should be a min. distance of 10 x DN. If tests are made at low flow with a bypass at right
angles to the pipe, it will be an advantage to mount an absorber of pressure fluctuations due to the perpendicular
inlet. This can be a flexible tube on the bypass. In addition, it will be an advantage to mount a flow straightener
before the first distance piece. Flow disturbances such as pulsations, e.g. pump fluctuations must be minimized.
Installation - electrical conditions:
To avoid external disturbances and achieve an electrical interface like MULTICAL
®
we recommend the use of a
PULSE TESTER.