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.
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-1131A50300 | 33mm |
| FR-1131A50300C | 48mm |
| FR-1131A50300A | 70mm |
| FR-1131A50300B | 85mm |
Note: Probe with 100 or 300ft of cable also available
Readout Unit and Magnet model
| READOUT UNIT (probe and reel) | ||
| Model No. | Cable length | Resolution |
| FR-1013E50100A | 30m | 1 mm |
| FR-1013E50100B | 50m | 1 mm |
| FR-1013E50100C | 100m | 1 mm |
| FR-1013E50100D | 150m | 1 mm |
| LEAF SPRING MAGNET | |||
| Model No. | Min. borehole diameter | Released Outside diameter | Casing |
| FR-1131A50100 | 101 mm | 222 mm | 33 mm |
| FR-1131A50100C | 101 mm | 254 mm | 48 mm |
| FR-1131A50100A | 127 mm | 279 mm | 70 mm |
| FR-1131A50100B | 152 mm | 305 mm | 85 mm |
| PLATE MAGNET | |
| Model No | Casing |
| FR-1131A50200 | 33 mm |
| FR-1131A50200C | 48 mm |
| FR-1131A50200A | 70 mm |
| FR-1131A50200B | 85 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
