KROHNE ALTOSONIC III EN - Manual (Page 8)

ALTOSONIC III 8
Gas inclusion
To avoid measuring errors due to gas inclusion, adequate measures have to
be taken. Gas inclusion should be limited to the lowest possible value and
shall be < 1 vol. % according to OIML R117 for accurate measuring.
Particle inclusion
To avoid measuring errors due to particle inclusion, adequate measures
have to be taken. Particle inclusion should be limited to the lowest possible
value and shall be < 5 % for accurate measurement.
Cavitation
In order to prevent cavitation in the following formula should be applied to
calculate the minimum required back pressure:
Pb ≥ 2.65 10E-5 ρL* vL
2 + 1.25 Pv
Pb Back
pressure [bar]
ρL Liquid density [kg/m3]
vL Liquid velocity [m/s]
Pv Vapour pressure [bar] (at operational temperature)
2.3 Accessibility and
environmental
precautions
If required the position of the signal converter can be modified by turning the
display through 90° or 180°.
In case of direct sunlight, we recommend installation of a sunshield to
prolong the life of the meter. No direct damage will occur without a sunshield.
Do not expose the signal converter to excessive vibration. For this, support
the pipeline on either side of the flowmeter.
Ambient temperature: -40°C to +70°C/ -40°F to +158°F
Product temperature: -25°C to +180°C/ -13°F to +356°F
Storage temperature: -40°C to +80°C/ -40°F to +176°F
Keep a minimum distance between pipe centerline and adjacent wall of at
least 0.5 m (1.6 ft).
2.4 Special installation
requirements
To avoid measuring errors and malfunctioning of the flowmeter due to gas or
air inclusions or an empty pipe, please observe the following precautions:
Since gas will collect at the highest point of a pipe, installation of the
flowmeter at that location should be avoided at all times. Also installation in a
down going pipe should be avoided since a completely filled pipe may not be
guaranteed due to cascading affects. Additionally flow profile distortion is
possible.
Long horizontal pipes
Install in slightly ascending pipe section. If not possible, ensure adequate
velocity to prevent air, gas or vapor from collecting in upper part of flow tube
As a partially filled meter will report higher than actual flow rates, or not
measure (as transducer pairs become non-wetted).
Mixing different fluid products
Install the flowmeter upstream of mixing point or at minimum distance of 30
D (D = flowmeter diameter) downstream of the mixing point, otherwise the
flow measurement may be unstable.