5-5
1010PVNFM-3A
Section 5
SmartSlew
™ is a digital signal processing method that generates a variable time constant
based on the real-time assessment of collected data. When the flow data exhibits a steady
trend, SmartSlew™ extends the time constant and the resulting output is smooth data.
5.4.3 NOTES ON LIQUID CONDITIONS
Successful transit-time flow measurement depends on sonic transmit signals traveling
through liquid and arriving at the receive transducer without excessive attenuation. Receive
signals can be scattered by liquids carrying dispersed particulate matter, either of a solid,
non-homogeneous or gaseous nature. This is especially true if the dispersed material is of
different sonic impedance than the base liquid. Liquids that contain an excess of gas bubbles
or mineral solids may prove to be unsatisfactory transit-time applications. However, these
liquids are perfectly suitable for Reflexor™ flowmetering. Liquids containing dissolved gas-
ses or dissolved organic solids will not cause any problems for transit-time operation.
Most liquids are excellent sonic conductors, regardless of their electrical or optical proper-
ties. Although highly viscous liquids exhibit a greater degree of sonic attenuation, System
1010 operates perfectly with the vast majority of these liquids. The
Valc %
(signal strength)
item on the Diagnostic Menu is a good indicator of this condition. A low value (under 30)
indicates a possible low liquid sonic conductivity, or improper transducer installation.
5.4.4 ERRONEOUS LIQUID PARAMETER SPECIFICATION
The viscosity of the liquid is an important factor. It governs the degree of Reynolds Number
compensation that the flow computer applies to the final rate output. Therefore, flow data
errors could result if you enter an inaccurate viscosity value. Controlotron’s Technical Service
Department can provide reliable viscosity data for most liquids.
5.4.5 LIQUID COMPATIBILITY
Since our clamp-on transducer systems never contact liquid, the issue of liquid compatibility
only applies to entrained gases or mineral solid content that might impair sonic signals Since
System 1010 is designed to measure flow using both transit-time and Reflexor™ techniques,
we can safely say that it will operate most successfully on virtually all liquids.
5.4.6 AERATION
Undissolved gases, having very low sonic impedance, may cause sonic beam scattering. In
large quantities, they can reduce the sonic signal strength. Small bubbles, caused by cavita-
tion, usually provoke more signal loss than an equal quantity of large gas bubbles. Usually, the
problem can be alleviated by eliminating the cause. Aeration may be caused by a mixing tank,
throttling valve cavitation, or air suction upstream of the transducer location.
System 1010 can operate successfully with a larger amount of aeration than any other
transit-time flowmeter.
It measures and reports the aeration level as the analog output,
Vaer %. This represents the relative degree of aeration detected within the flow stream. Its
computer reports the Vaer level until it impedes operation and forces a Fault Alarm. The
Vaer output accommodates applications requiring an aeration indicator. The Vaer % also ap-
pears on the display screen. The aeration percentage can be used as an alarm relay set-point.
You can set the aeration alarm setpoint such that it trips before aeration reaches a level that
impairs flow measurement.
Содержание 1010PVDN
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