Checkline TI-UMX2 - Manual (Page 27)

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8.0 addITIonal feaTures & oPTIons
8.1 Power off
The TI-UMX2 will power off automatically after approximately 4 minutes without
receiving an echo (measurement). It should be noted that if the transducer face is not
wiped clean, there’s a chance an echo can continuously be detected. If that happens, the
gauge will remain on until the battery life is exhausted. As a result, the TI-UMX2 can
also be powered down manually as follows:
Manual Power Off
1. Press and hold the single TI-UMX2 button, located on the top end cap. Once the
TI-UMX2฀is฀approaching฀power฀off฀status,฀“POWER”…”OFF”,฀will฀be฀displayed฀
in a loop on the alpha display, and the TI-UMX2 will shut down. This takes
approximately 10 seconds. Once the gauge is off, the button can be released.
8.2 Gain
The฀gain฀feature฀will฀only฀be฀displayed฀as฀a฀menu฀option฀if฀a฀‘dual฀element’฀style฀
transducer฀has฀been฀connected,฀and฀the฀TI-UMX2฀is฀in฀either฀‘pulse-echo฀(P-E)฀or฀
‘pulse-echo฀coating฀(PECT)’฀modes.฀Multiple฀echo฀modes,฀which฀include฀both฀single฀
and฀dual฀style฀probes,฀are฀equipped฀with฀‘automatic฀gain฀control฀(AGC)฀that฀optimizes฀
the gain setting automatically in the hardware of the TI-UMX2..
Gain, or amplification of the return echoes, can be adjusted in the TI-UMX2 to
accommodate a variety of applications. The setting of the gain is crucial in order to
obtain valid readings during the measurement process. Too much gain may result in
erroneous measurements, by detecting on noise rather than the actual material back wall
itself. Not enough gain may result in intermittent detection. It may also result in lack
of detection on internal flaws, pits, or porosity. The gain can easily be compared to the
volume control of a home stereo system. If you turn it up too much, you can’t hear the
music clearly. If it’s turned down too much, you can’t hear it at all.
The฀TI-UMX2฀has฀three฀gain฀settings฀(VLOW,฀LOW,฀MED,฀HI,฀VHI).฀The฀gain฀range฀is฀
42dB฀–฀50dB฀in฀2dB฀increments.฀Note:฀The฀TI-UMX2฀has฀been฀optimized฀for฀the฀MED฀
gain setting for all common applications. It should be operated in this mode as standard.
However,฀some฀applications฀may฀require฀the฀lower฀or฀higher฀gain฀settings.฀
When?฀The฀low฀settings฀may฀be฀necessary฀for฀noisy฀or฀granular฀cast฀materials.฀How฀do฀
I know when to lower the gain? If the reading becomes sporadic and won’t settle down
or resolve on a thickness value, the user can assume that the material is either very noisy
aluminum, or granular cast iron. This would be a good time to change the TI-UMX2 to
lower gain setting and see if the reading settles down and become stable.
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9.0 THru-PaInT MeasureMenT TeCHnIQue
9.1 Introduction to Thru Paint Measurement (dual element Probes)
The principle behind thru paint measurement is by measuring the time between two
back wall echoes returning from the test material. Since both of these back wall
echoes travel the same path through the paint or coating, the thickness of the coating
is subtracted out of the measurement so that only the actual material thickness can be
measured. This feature saves the user a great deal of time scraping and removing the
coating from tanks and pipes during the inspection process.
The primary purpose of thru paint measurement is to determine actual or overall
material thickness by eliminating the coating thickness. Thru paint mode cannot be
used for flaw or pit detection. Therefore, inspectors may need to use echo-echo thru
paint mode in conjunction with the standard pulse-echo flaw detection mode for some
applications. Pipe and tube inspectors will use the echo-echo mode for pipes with
powder coatings, and pulse-echo mode for pipes without coating. The combination of
using both modes is ideal for the advanced inspectors needs.
noTe: The procedure to select the measurement mode in the TI-UMX2 is located at
the end of this chapter.
9.2 Triple echo (TCG) – single element Probes
The TCG mode was added to include single element membrane style transducers, and
operates using three individual return echoes. Each echo is then adjusted, in terms of
‘gain’,฀to฀provide฀suficient฀signal฀amplitude฀for฀each฀individual฀echo.฀This฀is฀needed฀
because, if you’re standing at the edge of a canyon and scream hello there, each return
echo becomes weaker than the first until the sound in gone.
Similar to echo-echo mode, the measurement is made between the first two return
echoes,฀eliminating฀the฀paint/coating฀and฀measuring฀only฀the฀based฀material.฀However,฀a฀
second measurement is made between the second and third echoes, and compared to the
first measurement. If both measurements are the same, the stability indicator will fully
light up, and a stable measurement will be displayed.
Advantages:
The primary advantage using a single element transducer is linearity. Since only one
crystal is used, and perfectly flat, a correction curve is not needed to compensate for
focusing issues. A second advantage would be the comparison made between two
different sets of echoes.