15 Instruction Manual
2.8.1 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.
2.8.2 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.
2.8.3 Total Transit Time and Delta Time
The numbers displayed on menu window M93 are called total transit time and delta time
respectively. They are the primitive data for the instrument to calculate the flow rate inside
the pipe. So the flow rate indication will vary accordingly with the total time and delta time.
The total transit time should remain stable or vary little.
If the delta time fluctuates higher than 20%, it means there are certain kinds of problems
with the transducer installation.
