Fisher Labs TW-6 User manual

TW-6
Operating Manual
Pipe and Cable Locator
F I S H E R R E S E A R C H L A B O R A T O R Y
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CONTENTS
Introduction ...............................................................................pg. 3
Receiver .....................................................................................pg. 4
Transmitter..................................................................................pg. 5
Component Descriptions .........................................................pg. 6
Modes of Operation .................................................................pg. 7
The Inductive Mode..................................................................pg. 7
How to Assemble ......................................................................pg. 7
How to Tune...............................................................................pg. 8
Inductive Locating (with handle)............................................pg. 10
High Power (with handle).........................................................pg. 11
Inductive Tracing (without handle) ........................................pg. 12
Inductive Locating When Only Approximate Position of a
Linear Conductor is Known......................................................pg. 13
Pinpointing Centering of the Pipeline.....................................pg. 13
Determining Conductor Depth by Triangulation ..................pg. 14
Locating Manhole Covers, Valves, Tees and Risers..............pg. 15
Locating Pipe When Other Lines are Close by......................pg. 15
Conductive Tracing (without handle)....................................pg. 16
Tracing Procedure ....................................................................pg. 18
The Tracer Probe .......................................................................pg. 18
The Coupling Clamp ................................................................pg. 19
Locating Non-Metallic Pipes....................................................pg. 20
Operating Hints .........................................................................pg. 21
Changing Batteries ...................................................................pg. 22
Specifications ............................................................................pg. 23
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INTRODUCTION
to set the standard of quality in the design and manufacture of
even greater speed and precision in locating underground pipes
and cables.
covers, manhole covers, or valves clearly visible at the surface of
the ground are excellent items to start locating. This way you will
3
WARNING: Batteries can contain hazardous materials and must
be disposed according to the laws in your country.
This Category II radiocommunication device complies with
Industry Canada Standard RSS-310.
Ce dispositif de radiocommunication de catégorie II respecte
la norme CNR-310 d’Industrie Canada.
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RECEIVER
1. Carrying Strap: Keeps one hand free for marking
ground or pavement while using Tracer Probe.
2. Meter: Indicates signal strength up to a point
from metallic conductors while locating or tracing.
Meter also gives a visual indication of battery
strength.
3. Accessory Input: Use this jack to plug in all
accessories except the headphones.
4. Sensitivity:
A. Toggle switch to select NORMAL or HIGH
range.
B. Knob to control sensitivity level within the
NORMAL or HIGH range.
5. Depth Level: This bubble indicates the angle of
the receiver to the ground. Use it to keep Receiver
and Transmitter level during Inductive Locating
and for making the 45-degree angle necessary in
depth determination.
6. Headphones: Use this jack to plug in
headphones only. It automatically silences
speaker. Use in particularly noisy areas.
7. Battery Test: Turn unit ON then press this red
button and observe battery strength on meter. If
meter reads below 80, replace receiver batteries.
Usually transmitter & receiver batteries are
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replaced at the same time.
8. Power: Pull out for ON, push in for OFF.
9. Speaker: Produces the audible signal, which
increases in volume and pitch as signal strength
increases. The volume and pitch increase even
after the meter has peaked at 100.
RECEIVER
TRANSMITTER
1. Battery Test Meter: Gives a visual indication of
battery strength. Battery test is activated
automatically when unit is turned ON.
2. Constant Signal/Warble Tone Switch:
A. When toggle switch is in left position a constant
signal is generated/transmitted.
B. When Toggle Switch is in right position, the TW6
generates a warble tone. This results in a pulsating
sound and an oscillation of the needle between
zero and 100.
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3. Accessory Output: The Ground Plate Assemblies
Coupling
Clamp or Ground Rod Assembly connects into
this jack for a Conductive Trace or Direct Induced
Trace.
TRANSMITER
COMPONENT DESCRIPTIONS
1. Ground Rod/Harness Assembly: Provides a
“ground” for greatest efficiency in CONDUCTIVE
TRACING. For hard ground, the accessory Ground-
Rod /Harness Assembly is recommended.
2. 3-Piece handle: For use in INDUCTIVE LOCATING.
3. Handle Carrying Strap: Allows you to lower handle
closer to the ground for greater depth penetration
and sensitivity in locating. The same strap is used for
carrying the receiver.
4. Handle Carrying Case: Protects 3 piece handle
and makes a neater bundle.
5. Carrying Case: Sturdy protection for your TW-
6 and storage for accessories, such as coupling
clamp, headphones, mini probe, and ground plate
assembly.
6. Headphones: Stereotype headphones are
available for the TW-6. They are switch selectable
from monaural to stereo and may not work with the
TW-6 when switched to mono. You may prefer to use
the stereo phones because volume is adjustable
separately to each ear. The VCO sound is shrill and
without a volume control on the mono headphones,
the sound may be uncomfortable.
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7
MODES OF OPERATION
and CONDUCTIVE. In the INDUCTIVE mode, the Transmitter
LOCATING and (2) Transmitter placed on the ground directly
above and in line with the conductor for TRACING and the path
of the conductor.
The CONDUCTIVE mode operates when you connect the
Transmitter directly to an exposed portion of the pipe or cable in
question with the Ground Plate Assembly, or with the Coupling
Clamp, or the Ground Rod Assembly.
THE INDUCTIVE MODE
HOW TO ASSEMBLE
1.
end sections into the central section and turn the
2. Place the Transmitter on its back and insert
3.
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8
HOW TO TUNE
1. Check batteries on both Transmitter and
Receiver.
2. Place the Receiver Sensitivity Switch in the
NORMAL position.
3. Turn SENSITIVITY knob to 7.
4. To turn ON, pull POWER switches on Receiver and
Transmitter.
5. Pick the unit up by the handle and balance it so
that it is level with the ground and at normal carrying
height (arms length). For a deeper search, hold with
the carrying strap which has been fully lengthened.
You will need to hold the instrument at this lower level
while tuning if you plan to use it lowered. On some
may not be able to use it with strap fully lengthened.
reaching a null can also indicate the presence of
nearby metal.
CAUTION: Never attempt to tune the TW-6 in the presence of metal
objects like cars, metal walls, roofs or heavy metal reinforcements
in any structure. Their presence will make proper balancing
impossible.
6.
lowest meter and speaker indications are reached.
in either direction results in an increase in sound and
meter reading. If at the lowest point there is still sound
MODES OF OPERATION
4. With the Transmitter still on its back, align the two
holes in the panel of the Receiver with the knobs.
5. Turn the lower knob of the two knobs until it is
spring is compressed and the panel is pulled within
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9
and meter reading, turn down sensitivity slowly until
without an increase in sound and meter reading,
turn the sensitivity knob up from 7 to 8 and try again,
going through the null area making sure it does not
balance.
CAUTION: Keep away from cars, fences and metal
objects during this procedure.
You are now ready to locate. Crossing over buried
metal causes an increase in sound and meter
reading.
MODES OF OPERATION
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INDUCTIVE LOCATING (with handle)
locate lost or unknown metal pipes and cables. Walk at a right
angle toward what you assume to be the conductor’s position. As
you near the conductor, the speaker sound and meter indication
will increase. They will reach maximum readings when you are
earlier models, the sound volume and pitch increases far higher
than when the meter peaks. This will allow you to do most of your
locating without several readjustments of the Sensitivity knob.
As you cross over, the indications will begin to decrease because
a mark at your feet when readings reach their maximum. Cross
over the pipe, turn around and come back. Make a second mark
when readings return to maximum. Measure between the two
marks and bisect the distance. That is where the conductor is.
three locations you should be able to draw a straight line (unless
pipe has turned). Careful additional locations may be necessary
if no prints of the area are available.
It may be necessary to reduce sensitivity with the knob when the
peaked and sound is at a high level, you will want to bring the
sensitivity down to see the peak of the needle at a point less than
your peak reading.
MODES OF OPERATION
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HIGH POWER (with handle)
and an earlier model is that you may prefer to use it in HIGH power,
no sound when balancing. As you approach a pipe or cable lying
beneath the ground, the signal may be slight, approximately 20
Now turn the Sensitivity knob up so the meter reading becomes
a peak on the meter. Mark the spot on the ground where you
have stopped, with both feet together. Then go on beyond the
conductor, turn around and approach the conductor in the same
way, stopping with feet together at the highest meter reading and
mark the spot on the ground. Measure between the two points,
bisect it and you have the centerline of the conductor.
Be aware that when you use HIGH power on the handle, you will
need to be further away from vehicles, metal buildings and metal
fences to avoid sensing them as well.
MODES OF OPERATION
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INDUCTIVE TRACING (without handle)
signal strength by having the bottom edge of the Transmitter
directly over and in line with the conductor you’re tracing. Placing
the conductor and a signal on either side.
If you place the transmitter and receiver too close together “direct
control down until you lose the air signal, or (2) simply move the
receiver further away until the air signal fades.
NOTE: With the SENSITIVITY knob on full and the Sensitivity Selection
Switch set to NORMAL, the two units should be at least 30 feet
apart to avoid air coupling. With HIGH SENSITIVITY, they must be
even further apart.
MODES OF OPERATION
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13
INDUCTIVE LOCATING WHEN ONLY APPROXIMATE POSITION
OF A LINEAR CONDUCTOR IS KNOWN
unit with its face towards him and parallel to the other’s instrument.
from the curb toward the opposite side of the street. When the
two operators are directly over the pipe, the receiver meter and
speaker will indicate the location. The pipe is directly below the
point at which the maximum signal occurs.
If only one operator is available, he should begin by placing the
transmitter over and in line with an assumed position of the buried
the transmitter, hold the receiver parallel to the other instrument
and begin to walk forward until the signal reads its maximum
move the transmitter several times in order to be precisely over
the buried conductor.
PINPOINTING CENTER OF THE PIPELINE
After determining the position of the pipe, set the transmitter down
on its bottom edge and in line with the indicated position. Then, at
down and begin moving the receiver from side to side over the
general location line of the conductor. This back and forth motion
will give a null directly over the position of the buried conductor.
MODES OF OPERATION
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DETERMININING CONDUCTOR DEPTH BY TRIANGULATION
This procedure is only accomplished when the transmitter is close
enough for the receiver to receive a strong and clear signal.
Once you have determined the exact centerline of the conductor
(either Inductively or Conductively), place the receiver above and
parallel to it. Hold the receiver as close to the ground as possible.
Now, tip the receiver back until the bubble inside the depth level
indicator rests between the outer edge of the center ring and the
black border of the level.
ground. Care should be taken at this point, as a few degrees of
conductor centerline. Now, back away slowly, at a right angle
to the conductor, keeping the bubble as steady as possible. The
meter indication should manually be adjusted by means of the
sensitivity control to stay on scale in order to observe the point
where the needle will fall to a minimum signal. After this point, the
signal begins to increase again.
Position the receiver at the minimum or null point. Measure the
of the fastener, which holds transmitter and receiver together. This
distance, minus the distance of the center of the locator loop
If the conductor is buried in sloping ground, make a depth
determination on each side of the conductor and average the
A tracer probe with its smaller receiver coil in the tip, is quicker
and easier to use, hence it yields greater accuracy in depth
when using the receiver or receiver with tracer probe.
MODES OF OPERATION
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15
LOCATING MANHOLE COVERS, VALVES, TEES AND RISERS
These jobs are best performed in the Inductive Mode using the
of the previously discussed methods, then, holding the center of
the handle with the receiver leading (face up), walk alongside the
main pipe. Be sure you’re far enough away from the centerline of
the pipe to have a low or no reading. When you cross the sought
after valve, tee or riser, the meter and speaker will signal a larger
mass of metal indicating the valve. At that point, you can cross
to pinpoint its location.
feet apart. Practice this grid technique with a visible cover so that
LOCATING PIPE WHEN OTHER LINES ARE CLOSE BY
method, set the transmitter vertically and parallel to the line to
tracing and away from the pipe not wanted.
Now, follow normal Inductive Tracing instructions. To locate the
feet away from the second pipe. In the second method, set up
the transmitter so that its plane points toward the pipe desired.
MODES OF OPERATION
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CONDUCTIVE TRACING (without handle)
The most satisfactory method of tracing when you need to trace
an individual pipe when another pipe is nearby is CONDUCTIVE
pipe through direct connection. Before attaching the ground rod
clamp to the conductor, clean the conductor with a wire brush
After cleaning, plug the jack into the transmitter and secure the
in an upright position and as far away from the pipe as possible to
the side opposite any other lines. As far away as possible means
If you are working in an area with several other conductors near
the pipe or cable you want to trace, place the ground plate as
close as possible to the point at which you fasten the clip to the
pipe or cable. This will reduce the signal strength and reduce the
amount of signal induced into another nearby conductor, giving
a more concentrated signal in the pipe or cable you are tracing.
Never stretch the ground plate across a conductor running parallel
to the pipe or cable you are tracing, because even if you are
not hooked up to the conductor you crossed over, the signal has
MODES OF OPERATION
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17
to cross back past the path of this conductor and will induce a
certain amount of signal into it. This signal can mislead you when
tracing it out.
Harness Assembly on its side, parallel to the conductor in
the direction of the tracing. Weighting it down with a rock or
someone standing on it makes it a better ground contact. If the
plate is weighted down in a puddle or at least if the pavement
is wet, tracing distance is improved. You may pour some water
on the pavement to improve ground contact.
MODES OF OPERATION
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TRACING PROCEDURE
Turn the transmitter ON and turn receiver SENSITIVITY knob all the
way up in NORMAL. Then, when the conductor is located, turn
SENSITIVITY down to get a precise indication of the location. Use
NORMAL for ordinary tracing, HIGH for extended tracing. In the
Conductive Mode, you can have Transmitter and
Receiver as near to each other as 20 feet apart and closer yet
if you use the Tracer Probe, without air coupling occurring. With
HIGH power, the distance increases.
With settings and connections completed, the operator need only
walk out his trace while paying attention to signal strength over
the conductor. As in the Inductive Mode, the receiver should be
carried vertically and parallel to the pipe or cable being traced.
However, once the position is discovered, you may turn the
its surface location on pavement with colored chalk or spray paint
as you locate it. Extra long yellow or white golf tees are very handy
markers when locating over turf or open ground.
Another tip...start tracing operations away from the congested
location. The pipe is then carefully traced into the desired area
with little chance of false indications. The Tracer Probe also helps
reduce spurious signals from nearby pipes and cables.
The Tracer Probe
As you trace out the pipe or cable, signal strength gradually
diminishes. When you reach the limit of NORMAL, switch to HIGH
sensitivity and adjust the sensitivity knob for a sharp null over the
conductor you are following.
than the earlier model and does not need a separate SENSITIVITY
Tracer Probe
tracing distance.
back away at right angles, dragging the tip of the Tracer Probe
on the ground and maintaining the level bubble centered in its
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circle. You need to be close enough to the transmitter for a strong
then resume again as you move backwards. You measure from
the middle of the null area back to the centerline of the pipe or
cable and that is its depth.
TRACING PROCEDURE
COUPLING CLAMP
using the ground rod assembly, so there is no advantage to using
prevents bare metal contact.
Begin by plugging the Clamp into ACCESSORY OUTPUT on the
transmitter. Place Clamp around cable or other conductor (make
sure jaws are completely closed). Turn receiver and transmitter ON
and precede using tracing techniques as described earlier. The
conductor must make a closed loop, or circuit, or be grounded
for best tracing results.
driven into the ground to be sure of the ground. Two Coupling
receiver ACCESSORY INPUT jack. Then, test different strands with
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the ground plate assembly. Attach the ground plate assembly
or receiver and tracer probe. B lockages in pipes can be
located this way too in that the tracing signal will stop where
is aluminum foil tape sandwiched in printed mylar is available
laid according to the tape manufacturer’s instructions, the tape
and hence pipe can be located Inductively or Conductively.
LOCATING NON-METALLIC PIPES
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