Clamp-On Transducer Problems - GE DigitalFlow DF868 Service Manual

Chapter 3. Diagnostics
3.5.1 Wetted Transducer Problems (cont.)
3. INTERNAL DAMAGE: An ultrasonic transducer consists of a ceramic crystal bonded to the transducer case. The
bond between the crystal and the case, or the crystal itself, may be damaged by extreme mechanical shock and/or
temperature extremes. Also, the internal wiring can be corroded or shorted if contaminants enter the transducer
housing.
4. PHYSICAL DAMAGE: Transducers may be physically damaged by dropping them onto a hard surface or striking
them against another object. The transducer connector is the most fragile part and is the one most subject to
damage. Minor damage may be repaired by carefully bending the connector back into shape. If the connector
cannot be repaired, the transducers must be replaced.
IMPORTANT:
Transducers must be replaced in pairs. Refer to Chapter 2, Initial Setup, of the Startup Guide to
program the replacement transducer data into the meter.
If the instructions in this section fail to resolve the problem, contact the factory for assistance.

3.5.2 Clamp-on Transducer Problems

1. POOR COUPLING TO PIPE: Clamp-on transducers must be in close contact with the pipe. Make sure the pipe
wall is smooth and generally free of paint. The couplant material must fill voids between the transducer and the
pipe, and must be firmly coupled or bonded to both the pipe and the transducer. The pipe and transducer must be
clean and dry for permanent couplant, such as grease or epoxy, to adhere properly. Enough pressure must be
applied to the transducer by its clamp to hold it firmly against the pipe.
2. MISALIGNMENT: The transducer transmits relatively narrow beams of ultrasound; therefore, transducer
alignment is critical to assure that the beam can travel from one transducer to the other without undue attenuation.
Be sure to exactly follow the instructions that came with your transducers and clamping fixtures. Also, be sure that
the transducer spacing agrees with the calculated spacing (S).
3. INTERNAL DAMAGE: Ultrasonic transducers consist of a ceramic "crystal" bonded to the transducer case. The
bond between the crystal and the case may be damaged by extreme shock and by temperature extremes. The crystal
itself can also be damaged by the same conditions. The internal wiring can be corroded or shorted if contaminants
enter the transducer housing.
4. PHYSICAL DAMAGE: Transducers may be physically damaged by dropping them onto a hard surface or striking
them against another object. Usually the connector on the transducers is the part that is damaged, as it is the most
fragile. Minor damage may be repaired by carefully bending the connector back into shape. If the connector cannot
be repaired, replace the transducers.
IMPORTANT:
Transducers must be replaced in pairs. Refer to Chapter 2, Initial Setup, of the Startup Guide to
program the replacement transducer data into the meter.
5. CYCLE SKIP CONDITION: A cycle skip is usually caused by a distorted or altered signal due to poor couplant,
bad wall or unusual fluid disturbances. To resolve a cycle skip, recouple both transducers with proper couplant.
Check your couplant for temperature ranges. In addition, make sure the pipe wall is free of paint and rust.
Contact the factory if you cannot solve a transducer-related problem.
26 DigitalFlow™ Multipurpose Ultrasonic Liquid Flowmeter Service Manual