Micronics Portaflow 222, Руководство пользователя

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Micronics Portaflow 222 & 333 User Manual
Issue 3.1 Feb 20 Page 39
8 TROUBLESHOOTING
8.1 Overview
If you have a problem with your flow monitoring system it can be due to any of the following:
Faulty
instrument
If you suspect the instrument is faulty you can check it out using a test block as described on page 44.
This will establish that the instrument is functional and receiving a healthy signal from the connected
transducers.
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 galvanised
-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.

Very hot pipe almost turns water to steam and therefore exhibits the wrong speed characteristics
–
could be due to reduced pipe pressure.

Flashover
–
liquid turns into a gas because of lower than required pressure.
Automatic signal loss recovery

If the signal is lost or the Quality falls below 40% then the set up procedure, normally invoked by
Read Flow in the main menu, is automatically run until a good quality signal is found.