MODEL TW-6 PIPE AND
|The Model TW-6 "Two-Box" metal-detector finds underground pipes, cables,
manhole covers, vaults, valve boxes and other metallic objects. Like earlier
models, the TW-6 is used primarily by water departments, telephone companies,
power companies, gas companies and petroleum pipe line companies when
making repairs and rearranging lines.
The TW-6 shows where to dig, as well as where NOT to dig, an important consideration when working near gas lines. To increase the instrument's sensitivity, Fisher engineers removed all unnecessary metallic parts on the TW-6, replac ing them with durable ABS molded plastic. Newly designed coil wind ings, completely upgraded electronics and nonmetallic parts have boosted the trac ing distance of the TW-6 by 50-100 percent.
With the TW-6, longer tracing distances, which used to require expensive high-powered fault locator/tracers, can now be accomplished economically.
Many underground locators can only trace an underground pipe or cable from a known starting point, such as an exposed line, hydrant or water faucet (conductive trace). However, the "two-box" M-Scope metal detector invented by Dr. Gerhard Fisher in 1931 can locate and trace an underground pipe or cable when no starting point is known (inductive trace). Today's TW-6 is a direct descendant of that first M-Scope metal detector invented by Dr. Fisher and is capable of conducting a "blind" search of an area for an underground pipe or cable that has no known starting point. Nonmetallic pipes may be located inductively or conductively if tracer tape or wire is placed in the trench above the line.
Using a 4-foot handle, position the Transmitter Box behind while the Receiver Box is ahead. Walk a grid pattern to discover the location of buried metallic objects. Watch the meter on the TW-6 Transmitter Box and listen for the signal tone to discover the location of a metallic object, such as a pipe, cable or vault box. Mark the pavement with chalk for each signal location. Soon a pattern will emerge that shows the location of underground linear objects, such as pipes and cables, or nonlinear items, such as a buried manhole cover.
When one point of an underground linear conductor (such as a pipe or cable) is known, place the Transmitter Box of the TW-6 over it and trace in either direction. Walk out the path of the line and swing the TW-6 Receiver Box left and right over the line while listening for the audio signal tone. As you walk away from the Transmitter Box, tracing farther down the line, the Transmitter signal will become faint, but the Transmitter Box can be moved closer to you so that tracing can continue to the end of the line.
This is the preferred method for tracing because the Transmitter makes a direct physical hookup with the line to be traced. Plug the TW-6 Ground Plate Assembly into the Transmitter with one wire going to an alligator clamp that is attached to the pipe, non-energized wire or conduit. This concentrates the signal on the known line to be traced, and there is less chance of the signal being induced to a nearby or adjacent line. Tracing distances are increased 25-50 percent over the Inductive method. Nonmetallic pipes may be traced Conductively if the Ground Plate Assembly is attached to a plumber's "snake" or electrician's "fish tape" running inside the pipe.
TW-6 SHOWN WITH OPTIONAL ACCESSORIES
Operating Frequency 81.92 kHz+/-.005%
Batteries ......... 8 each, AA
Weight ............ 2 1/2 lbs. (1.1 kg)
Sensitivity ....... N/A
Signal-to-noise ratio ...... N/A
Headset Impedance .......... N/A
Dimensions 11.5"x9"x3" (29x23x7.6 cm)
Operating Temperature -10 to +120F
(-23 to +48C) depending on batteries
Total Weight 5 1/2 lbs. (2.5 kg) - (without handle of accessories, ground plate assembly or operating manual).
Total Shipping Weight 6 3/4 lbs. (3 kg) - (including only ground plate assembly and operating manual.)
Total Shipping Volume 0.69 cu ft
81.92 kHz +.005%
8 each, AA (NEDA 15)
3 lbs. (1.36 kg)
Normal: 400 uV/High: 8 uV
600 ohms (mono)
8 ohms (stereo)
11.5"x9x3") (29x23x7.6 cm)
FAX 952-926-5498 / EMAIL:firstname.lastname@example.org