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Sentinel™ User’s Manual 99
Chapter 5. Diagnostics
5.4.2 Pipe Problems
Pipe-related problems may result either from a failure to observe the installation instructions, as described in
Chapter 1, Installation , or from improper programming of the flowmeter. By far, the most common pipe problems are
the following:
• The collection of material at the transducer locations.
Accumulated debris at the transducer locations will interfere with transmission of the ultrasound signals. As a
result, accurate flow rate measurements are not possible. Refer to Chapter 1, Installation , for more details on
proper transducer installation.
• Inaccurate pipe measurements.
The accuracy of the flow rate measurements is no better than the accuracy of the programmed pipe
dimensions. For the Sentinel system, the flowcell dimensions are programmed at the factory prior to shipment
and the correct data is included in the documentation. Check the adjacent pipe for dents, eccentricity, weld
deformity, straightness and other factors that may cause inaccurate readings.
5.5 Transducer Problems
Ultrasonic transducers are rugged, reliable devices. However, they are subject to physical damage from mishandling
and chemical attack. The most common transducer problems are listed below:
• Leaks:
Leaks may occur around the transducer and/or the flowcell fittings. Repair such leaks immediately. If the
leaking gas is corrosive, carefully check the transducer and cables for damage, after the leak has been
repaired.
• Corrosion Damage:
If the transducer material was not properly chosen for the intended application, the transducers may suffer
corrosion damage. The damage usually occurs either at the electrical connector or on the transducer surface.
Any transducer damaged in this manner must be replaced. Contact Panametrics for information on
transducers in materials suitable for the application.
• 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.
• 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 transducer must be replaced.
Note: Transducers must be replaced in pairs. Refer to Chapter 6, Transducer Replacement , and Chapter 2, Initial
Setup , to program the replacement transducer data into the meter.
If the instructions in this section fail to resolve the problem, contact Panametrics for assistance.