TDS-100H Handhold Ultrasonic Flowmeter Ver.8.08 - 14 -
§2.8.5 N-method Installation
Rarely used method.
§2.9 Installation Checkup
Through the checkup of the installation, one can: check the receiving signal strength, the
signal quality Q value, the traveling time difference of the signals, the estimated liquid speed,
the measured traveling time of the signals and the calculated traveling time ratio. Therefore,
optimum measurement result and longer running time of the instrument can be achieved.
§2.9.1 Signal Strength
Signal strength indicates the amplitude of receiving ultrasonic signals by a 3-digit number.
[000] means there is no signal detected, and [999] refers to the maximum signal strength that
can be received.
Although the instrument works well if the signal strength ranges from 500 to 999, stronger
signal strength should be pursued, because a stronger signal means a better result. The
following methods are recommended to obtain stronger signals:
(1) Relocate a more favorable location, if the current location is not good enough for a stable
and reliable flow reading, or if the signal strength is lower than 700.
(2) Try to polish the outer surface of the pipe, and apply more coupler to increase the signal
strength.
(3) Adjust the transducers both vertically and horizontally while checking the varying signal
strength, stop at the highest position, and then check the transducers spacing to make sure
the transducers spacing is the same as what the M25 shows.
§2.9.2 Signal Quality
Signal quality is indicated as the Q value in the instrument. A higher Q value would mean a
higher Signal and Noise Ratio (short for SNR), and accordingly a higher degree of accuracy
would be achieved. Under normal pipe condition, the Q value is in the range 600-900, the
higher the better.
Causes for a lower Q value could be:
(1)
Interference of other instruments and devices such as a powerful transverter working
nearby. Try to relocate the flow meter to a new place where the interference can be
reduced.
(2)
Bad sonic coupling for the transducers with the pipe. Try to apply more coupler or clean
the surface, etc.
(3)
Pipes are difficult to be measured. Relocation is recommended.
§2.9.3 Total Transit Time and Delta Time
The numbers displayed on menu window M93 are called total transit time and delta time
