SL1188P Ultrasonic transit-time flowmeter
Revision
：
2.0.0
Page
14
of
81
4.1.4.
Z Method
The signal transmitted in a Z method installation has less attenuation than a signal transmitted with the V method.
This is because the Z method utilizes a directly transmitted (rather than reflected) signal which transverses the
liquid only once.
The Z method is able to measure on pipe diameters ranging from 100mm to 3000mm (4
”
~120
”
) approximately.
Therefore, we recommend the Z method for pipe diameters over 300mm (12
”
).
Downstream Transducer
Upstream Transducer
Flow
Transducer Spacing
Flow
Side View
Top View
Section
Pipe Strap
Transducer
4.1.5.
N Method (not commonly used)
With the N method, the sound waves traverse the fluid twice and bounce three times off the pipe walls. It is
suitable for small pipe diameter measurement.
The measurement accuracy can be improved by extending the transit distance with the N method (uncommonly
used).
Downstream Transducer
Upstream Transducer
Flow
Transducer Spacing
Flow
Side View
Top View
Section
Pipe Strap
Transducer
4.2.
Transducer Mounting Inspection
Check to see if the transducer is installed properly and if there is an accurate and strong enough ultrasonic signal
to ensure proper operation and high reliability of the transducer. It can be confirmed by checking the detected
signal strength, total transit time, delta time as well as transit time ratio. These checks are explained below.
The
“
mounting
”
condition directly influences the flow value accuracy and system reliability. In most instances,
apply a wide bead of sonic coupling compound lengthwise on the face of the transducer and stick it to the outside
pipe wall to get good measurement results. However, the following inspections still need to be carried out in order
to ensure a high reliability of the measurement and long-term operation of the instrument.
4.2.1.
Signal Strength
Signal strength (displayed in menu 90) indicates a detected strength of the signal both from upstream and
downstream directions. The relevant signal strength is indicated by numbers from 00.0~99.9. 00.0 represents no
signal detected while 99.9 represent maximum signal strength.
Normally, the stronger the signal strength detected, the better the measurement.
Adjust the transducer spacing to the best position and check to ensure that enough sonic coupling compound is
applied during installation in order to obtain the maximum signal strength. This is essentially fine tuning the
calculated spacing shown in menu 25 (transducer spacing). It may be slightly different.
System normal operation requires signal strength over 60.0, which is detected from both upstream and
downstream directions. If the signal strength detected is too low, the transducer installation position and the
