AUF610 Series Operation Manual
OP610.1.1.5R1ENG
15
Examples of optimum locations:
Guidelines for selection of optimum mounting locations:
(1)
Install the transducers on a longer length of the straight pipe.
(2) Make sure that the temperature at the selected location does not exceed the range of the
transducers. Generally speaking, the closer to the room temperature, the better.
(3)
Consider the possibility that the pipe has coated over time.
(4) Select a straight length of a relatively newer pipe. If the conditions are not optimum, consider the
coating as part of the liner for a better result.
(5)
Some pipes are dual walled with a plastic line or with air in between. The system may not work in the
latter case. Also the thickness between the outer pipe and the liner may vary. This can prevent or disrupt
ultrasonic wave propagation. Avoid this kind of pipe. Alternately, consider permanently installed through
the pipe, hot tap type transducers as available from Alia.
2.9 Transducers Installation
The transducers used by the AUF610 series ultrasonic flow meter are made of piezoelectric crystals both
for transmitting and receiving ultrasonic signals. Measuring the traveling time difference of the upstream
verses downstream ultrasonic signals travelling in the pipe makes the measurement. Since the measured
time difference is very small, the spacing, alignment and acoustic coupling of the transducers are factors
critical for the specified measurement performance of the system. Great care should be taken when
installing the transducers.
Here are some guidelines:
•
Locate an optimum position where the straight pipe length is sufficient, and where pipes are in a
favorable condition, e.g., newer pipes with no rust and ease of operation.
•
Clean any dust and rust. For a better result, polishing the pipe with a sander is recommended.
•
Apply adequate coupling grease to the spot where the transducers are to be installed and leave no
gap between the pipe surface and the transducers.
•
Extra care should be taken to avoid any sand or dust particles left between the pipe outer surface
and the transducers.
•
To avoid gas bubbles inside the upper part of the pipe, the transducers should be installed on the
side of the pipe at the 2:00/10:00, 3:00/9:00 or 4:00/8:00 o’clock positions.
2.9.1 Transducers Spacing
The spacing value shown on menu window M25 refers to the distance of inner spacing between the
transducers. It is
calculated based on the preliminary pipe data, sonic path info (see 2.9.2 below) and
process information entered by the user in the previous menu items. If the spacing does not sound right
(i.e. spacing of 2” on a 10” pipe then checks the setup figures. Data can get entered incorrectly especially
with inexperienced users. The spacing is important
，
and should be measured from the indicator which is an
integral part of each transducer assembly.
As important as the Transducer spacing is the ‘bounce pattern’ of the Ultra sonic signal. This is described
below.
