Dwyer UFC User Manual download pdf (Page 46)

6: Troubleshooting

6.1 Overview

If you have a problem with your flow monitoring system it can be due to any of the following:

Faulty instrument

Blank instrument display:

• Loss of power supply to the instrument.

• Internal power supply fuse ruptured.

Scrambled instrument display:

• Reboot the instrument by temporarily disconnecting its power supply.

Incorrect setup

A low, or zero, signal could be caused by incorrect set-up such as:

• Incorrect site data entered into the instrument.

• Incorrect or non-matching ultrasonic transducers selected for use.

• Incorrectly fitted transducers – lack of couplant applied, incorrect spacing, insecure attachment.

• Poor connections between the probes and the instrument.

Application problem

If you are certain that the instrument is healthy and suitably set-up for the current site; and the probes are

properly assembled and fitted correctly, there could be an application problem concerned with the site.

Check such conditions such as:

Poor pipe outer surface quality

• Uneven surface preventing good surface contact with the transducer.

• Flaking paint (should be removed).

• Variable air gap in concrete-covered pipes affecting the ultrasonic signal quality.

Poor internal pipe construction

• Rough internal pipe walls affecting fluid flow (see roughness factor).

• Internal welds positioned in the transducer signal path affecting the signal quality.

• The ‘drippings’ in galvanized-dipped pipes or other irregularities interfering with the signal path.

Incorrect probe location

• Transducers located too close to bends or valves, disturbing the flow profile.

• Transducers located too close to insertion probes, disturbing the flow profile.

• For horizontal pipework, transducers should not be positioned on the top of the pipe.

Poor fluid conditions within the pipe

• Fluid contains bubbles, high particle density or sludge.

• Air in the top of the pipe.

Low fluid flow within the pipe

• Pipe obstructions.

• Malfunctioning valve not opening fully (or closed inadvertently).

Liquid content problems

• Multiple liquid contents do not comply accurately to expected sound speed criteria.

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Dwyer UFC User Manual Page 46