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R-4 – Magnetic Probe Extensometer / Settlement

VERSATILE

EASY TO USE

MAGNETIC REED SWITCH PROBE

The R-4 is used to manually measure settlement or heave of soils at various depths, allowing the end user to create settlement/heave.

Description

The R-4 consists of a magnetic reed switch mounted on a graduated tape and reel. The switch is activated by magnetic targets installed at different elevations along an access pipe in a borehole or within an embankment or fill.

The R-4 detects the position of the magnetic anchors outside the riser pipe when it is lowered down the access pipe. The probe is suspended by a single graduated tape that incorporates the electrical leads. The tape graduation is used to determine the probe’s precise position relative to the magnets. Comparison of these locations allows heave and settlement determination.

The magnetic anchors are available in three configurations: leaf spring anchor for borehole installation, plate anchor for embankment or fill installation and datum magnet that is fixed directly to the bottom section of access pipe. The leaf spring anchor can be pushed in place or lowered with the access pipe and released with an external draw wire.
The plate magnet is a plate with a central hole. The plate magnets are installed over the riser pipe and between the layers of placed fill, as the filling operation proceeds.

Telescoping couplings are used where deformations exceeding 1% are expected.TheR-4system is compatible with standard inclinometer casings. The use of a probe centralizer is recommended for repeatable readings.

Specifications
Probe:  Stainless steel, 14.3 x 227mm
Cable:  Epoxy coated steel tape with medium density polyethylene jacket

Metric cables have 1mm graduations and imperial cable have 0.01ft graduation

Reel:  263 or 300mm in diameter depending on cable length
Battery:  The readout operates on with one 9-Volt alkaline cell.
Material: Magnet body in  PVC
Temperature range: -30°C to +80°C
Plate magnet dimensions: 200 x 200 x 9.5 mm standard, 300 x 300 x 9.5 mm optionnal
Access tube:   -Standard 1’’ pipe sch.80 flush-coupled PVC pipe (33mm)

(telescoping sections available if large settlementss are anticipated)

– 70mm or 85mm inclinometric casing

– optional 1.5” pipe sch.80 flush-coupled PVC pipe (48mm)

DATUM RING MAGNET
Model No.Casing
FR-1131A5030033mm
FR-1131A50300C48mm
FR-1131A50300A70mm
FR-1131A50300B85mm

Note: Probe with 100 or 300ft of cable also available

Readout Unit and Magnet model

READOUT UNIT (probe and reel)
Model No.Cable lengthResolution
FR-1013E50100A30m1 mm
FR-1013E50100B50m1 mm
FR-1013E50100C100m1 mm
FR-1013E50100D150m1 mm

 

 

LEAF SPRING MAGNET

Model No.Min. borehole diameterReleased

Outside diameter

Casing
FR-1131A50100101 mm222 mm33 mm
FR-1131A50100C101 mm254 mm48 mm
FR-1131A50100A127 mm279 mm70 mm
FR-1131A50100B152 mm305 mm85 mm

 

PLATE MAGNET
Model No.Casing
FR-1131A5020033 mm
FR-1131A50200C48 mm
FR-1131A50200A70 mm
FR-1131A50200B85 mm

 

 

Ordering Info

Please specify:

  • Borehole diameter and depth
  • Access tube model and length (For more information about 70 and 85 mm O.D. access tube, please refer to standard inclinometer casing data sheets)
  • Telescoping section
  • Anchor model number
  • Readout instrument model no.

Optional accessories:

  • Probe centralizer
  • Collar tape guide
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