Amplification Display During Measurement; Filter Settings And Adjustment Of Limit Frequencies; Filter Selection In Practice; Muting Key - Trotec LD5000 Manuel D'utilisation

The volume of the headphones is set with the two keys
and . A bar at the side of the two keys on the
display shows the selected volume setting. At the start
of the measurement, a medium volume (3 scale units)
should be selected.
The amplification of the microphone signal is adjusted
with the soft keys and . The selected amplification
is shown by a horizontal bar above the two soft keys. The
amplification values from 1 to 8 are displayed.above this
bar.
At the start of measurement, a medium setting should
also be selected here, e.g. 3 to 4. Altering the amplification
results in a change in the level bars and the headphone
volume.
7.2.2 Amplification display during
measurement
The bar indicator (figure D) shows the current value
of the recorded and amplified noise. The lower, thicker
bar shows the minimum measured value
the nature of a leak sound, which can be understood to
be a continuous noise, the representation of this value
provides a much better result and is much less prone to
impulse-type background noise. This minimum value
is recalculated when the muting key
7.2.3 Filter settings and adjustment
of limit frequencies
Filter setting is very simple on the LD5000. In the main
menu , use the soft key to access the filter setting
function. As illustrated in figure E, 9 vertical bars for the
levels can be seen in the centre of the display. Under these
there is a horizontal bar which represents the selected
filter range. The upper and lower limits are shown on the
left and right sides of the bar graph respectively.
The following nine limit frequencies can be set: 70, 106,
160, 240, 360, 540, 800, 1200, 1800 Hz
Adjustment of the limit frequencies (figure F)
To adjust the lower limit frequency, use the two soft keys
and (figure F, ). The adjustment of the upper limit
frequency is carried out in the same way with the two
soft keys and (figure F, ). You can set the nine
limit frequencies listed above for both limits, and thus very
easily determine a particular filter range for each meas-
urement. After correctly setting the filter range, return to
the main menu via the "ESC" command by pressing the
soft key .

7.2.4 Filter selection in practice

The decision regarding filter settings is left open to the
user. Generally it can be said that, for measurements with
ground microphones, a lower frequency range should be
selected, and for measurements directly on the pipe or
valve with the probe arm, a higher frequency range should
be selected. Should a measurement be unsuccessful, a
broadband setting is recommended to ensure that parts
of the leak noise are not being filtered out.
Filter selection A (Ground microphone PAM W-1,
PAM-U with tripod)
As a standard setting, a filter from 240 Hz - 540 Hz should
be set. Especially in the case of plastic piping and low-
pressure piping, lower frequencies may also occur.
Filter selection B: Probe arm (PAM-U with tip)
When measuring directly on the pipe with the probe arm,
a frequency range from 540 Hz - 1200 Hz should be set.
B - 03

7.2.5 Muting key

To relocate the ground microphone, the muting key
must first be pressed. In this case, the headphones will
be muted and the current level will be "frozen". This
protects your ears, since the loud noise of the microphone
being placed on the ground is not reproduced. After select -
ing a new position for the ground microphone, the muting
key must be pressed again. The headphones will then be
switched on again, the level display will be updated and
the minimum value will be recalculated.

7.2.6 Histogram function

The "Histogram" function is used to compare a series of
measurements recorded one after another. This can be
done when isolating a leak with the probe arm microphone
as well as during the actual leak detection. The LD5000
can display a maximum of nine measurement values.
In the main menu
histogram function. After pressing the key, the LCD display
will be switched to histogram display mode and the first
. Based on
histogram display will be activated.
Each histogram display is composed of a double-seg -
ment display (DSD), which displays the current value and
the minimum value. This DSD is shown in figure G. The
narrow segment shows the current value
is pressed.
wide segment shows the minimum value
particular importance for leak detection.
When the muting key
is stored and displayed at the same time. In this way, nine
values can be stored, one after another. If more than nine
values are measured, the first stored values will be deleted
and all the other values will be shifted one place to the
left. As a result, the last nine readings only are always
available.
The histogram measurement depicted in figure G shows
very different current values. On the other hand, the fifth
DSD shows a definite maximum of the minimum values.
Based on this, the leak will be located near to the fifth
measurement position. Exit histogram measurement via
the "ESC" command, by pressing the soft key

7.2.7 Continuous measurement

This function is used to record noises over a programmable
time period and to display them in the form of a graph.
With this method, for instance, the identity of a water pipe
can be confirmed by recording the noise of water flowing
through a valve. The microphone is placed on the pipe
and continuous measurement is started. After this, the
valve is closed for a certain time (at least 2 minutes) and
afterwards opened again. If the pipe at the listening position
is identical with the pipe whose valve was closed, this
must be visible in the sound level graph. Such a sound
level graph is depicted in figure H.
To access the continuous measurement menu, press the
soft key in the main menu
pressed, the LCD display is switched to continuous meas-
urement display as illustrated in figure H.
To program the time period, press the soft key
until the desired measurement time, shown in the top
right-hand corner of the display, is set. Recording times
of 3, 10 and 30 minutes are available. After programming
the time, measurement is started by pressing the soft key
(Start). Measurement now begins and can be prematurely
ended by pressing the soft key

7.2.8 Pipe location mode

Besides the possibility of locating leaks, the LD5000 can
also be used to locate pipework, for instance to determine
the routing of a pipeline.
Operating manual LD5000
, use the soft key to access the
and the
, which is of
is first pressed, the current value
.
. After the key has been
repeatedly
(Stop) again.
To switch the LD5000 to pipe loca -
tion mode, the soft key
neath the impulse symbol (see
graphic) must be pressed after switching on, whilst
the welcome screen is being displayed.
The equipment is now in pipe location mode, which is in-
dicated by the impulse symbol at the top edge of the
display. This operating mode is particularly suitable for
displaying impulse noises, such as, for instance, the tapping
of the impulse generator RSP-3.
The horizontal bar is now particularly sensitive to impulses,
the maximum value becomes significantly higher and is
displayed with a longer delay, and the filters are set to
low frequencies. Of course, the filters frequencies can be
altered in the usual manner if necessary.
The LD5000 will remain in pipe location mode until it is
switched off. After switching on again, it will be in normal
mode.

7.3 Troubleshooting

Switch-on is not possible
Possibly the headphones are not plugged in, or headphones
not belonging to the equipment system are being used.
Battery check does not react
One or more batteries are inserted incorrectly. Open the
baseplate and check the polarities of the batteries. See
figure C. If the polarity of all the batteries is correct, check
the condition of each battery.
No audible sound
If the equipment is functioning, there are two possibilities:
The headphones are not plugged in or not correctly plugged
in. The muting key is activated and the headphones
are switched off. By pressing the muting key, the signal
is audible once again.
Crackling noises in the headphones
The cause is usually a bad contact, so check all the plugged
connections.

8. Maintenance and care

Clean the unit as necessary with a moist cloth. Use only
clear water to moisten the cloth, do not use any cleaning
agents.
If the equipment is not to be used for a longer period of
time, it is recommended that you remove the batteries
during this time.
under -