Flow Data Scatter And Damping; Fug1010Gcn Damping And Slewing Controls; Time Average; Smartslew - Siemens SITRANS FUG1010 IP65 NEMA 4X Instruction Manual

1010GCNFM-3C
Section 6

6.3.2 FLOW DATA SCATTER AND DAMPING

The transit-time flowmeter's ability to respond to the extremely fast flow fluctuations that characterize
"real" flow may surprise you. Most conventional flowmeters cannot detect these rapid flow fluctuations
since they are subject to unavoidable mechanical inertia. FUG1010GCN's response speed is ideal for
tracking fast flow transients. However, if this performance is unnecessary, FUG1010GCN includes con-
trols to smooth its response time to suit any application.

FUG1010GCN Damping and Slewing Controls

FUG1010GCN can detect and display minute flow fluctuations that are always present, though not usu-
ally detectable by typical flowmeters. This rapid response accommodates applications that require the
tracking of fast flow transients.
Time Average is a filter that controls the output damping (the number of samples averaged together to
produce the instrument's primary rate output). It allows you to enter a value in seconds that the flowme-
ter uses to integrate its response to flow changes. Do not confuse this with the update speed of analog
outputs. This occurs every 0.1 seconds, regardless of the time average that you select. One practical
application is to set the time average damping so that the meter maintains a smooth output, when it is
installed downstream from devices (e.g., a positive displacement pump) that may cause regular surges
in the fluid flow.
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 - resulting in very smooth data output. However, SmartSlew instantaneously reduces
the time constant whenever the trend of flow changes, even for a short duration. This permits the flow
output to quickly follow the slewing of actual flow. SmartSlew thus provides excellent data without sacri-
ficing the fast response required for precise flow control. Feel free to experiment with time average
damping and slewing factors to discover which settings optimize the collected data. With SmartSle en-
abled, you can create very smooth output graphs without losing the ability to respond to fast flow tran-
sients that may be undetectable with the fixed time average filter enabled.

6.3.3 NOTES ON FLUID CONDITIONS

Successful transit-time flow measurement depends on sonic transmit signals traveling through the fluid
and arriving at the receive transducer without excessive attenuation. Receive signals can be scattered by
fluids carrying dispersed particulate matter, either of a solid, non-homogeneous or gaseous nature (for
liquid flow). This is especially apparent if the dispersed material is of different sonic impedance than the
base fluid.

6.3.4 ERRONEOUS FLUID PARAMETER SPECIFICATION

The viscosity of the fluid is an important factor. It governs the degree of Reynolds Number compensation
that the flowmeter applies to the final rate output. Therefore, flow data errors could result if you enter an
inaccurate viscosity value. The Technical Service Dept. can provide reliable viscosity data for most fluids.

6.3.5 TURBULENCE

Gases, having very low sonic impedance or large quantities of water vapor, may cause sonic beam
scattering. In large quantities, they can reduce the sonic signal strength and cause rapid variations in the
receive signal amplitude. This rapid amplitude variation is related to the "Turbulence" variable, where
100% represents the maximum level of turbulence. FUG1010GCN can operate successfully with a
larger amount of turbulence than any other transit-time flowmeter.
6-3