User guide

Rev. 12/97 -38- D77X
PART 4 - TROUBLE SHOOTING
Stability of flow readings are
unsatisfactory
? Increase the DAMP constant from keypad.
? Move transducers to a location further
from piping tees, elbows, valves, filters,
etc.
Erroneous Reading
? Transducer mounted incorrectly or not
true to the pipe.
? Another local ultrasonic instrument is
operating at about the same frequency
[ consult the Dynasonics factory].
? Presence of large amounts of suspended
solids or aeration. Use CAL constant to
compensate.
? Sources of radiated interference are
present. Apply appropriate shielding.
? An electrically noisy power supply is
powering the D77. Power the meter with
a circuit that does not power motors,
ballasts or switching supplies.
The D77 display indicates flow, when
true fluid velocity is zero.
? Verify that residual leakage and flow is not
present. [I.e. leaking check valves]
? Verify that GAIN control (R13 on the Main
PCB) is not adjusted too high. With
nominal flow running through the pipe,
adjust GAIN control till the display zeros
with no flow.