Borehole Extensometers is used to monitor displacement or deformation in soil, rock and concrete structure at various depths using rods of different material and lengths with reference to the instrument head.

The Borehole Extensometer of PMT consists of anchors, rods, protective tubes and a VW displacement sensor. The VW sensor measures the settlement or heave as movement in layers change. The anchors coupled to the rod are installed in the borehole. The anchors and anchor rods referenced to stable ground, move up or down as movement in borehole occurs. This changes tension of the vibrating wire inside the VW transducer which is transmitted through a cable to the readout unit.

•Cable: 4-wire, shielded, polyurethane jacket

Specifications
Model: 1401V-BEX
Sensor Type: Vibrating wire
Sensor range: 25, 50, 100,150, 200mm
Resolution: 0.02% F.S.
Accuracy: ±0.1% F.S.
Nonlinearity: <0.5% F.S.
Temperature Range: -20 to 80° C
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BOREHOLE EXTENSOMETER (VW)

Borehole Extensometers is used to monitor displacement or deformation in soil, rock and concrete structure at various depths using rods of different material and lengths with reference to the instrument head.

The Mechanical Borehole Extensometer of PMT is designed to be installed in 2-3 points suitable for a 76 mm borehole and 4-6 points suitable for a 100 mm borehole. Movement of rods attached to the anchors is measured manually with caliper/micrometer depth gauge with a resolution of 0.01mm relative to the head of the extensometer anchored at the mouth of the borehole to reveal the magnitude of the deformation between the anchors.

Specifications
Model: 4401M-BEX
Sensor range: 25, 50, 100mm
Resolution: 0.01mm
Accuracy: ±0.1% F.S.
Temperature Range: -20 to 80° C
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BOREHOLE EXTENSOMETER (MECHANICAL)

Electro-mechanical Borehole Extensometers provides both mechanical & electrical output and is used to monitor displacement or deformation in soil, rock and concrete structure at various depths using rods of different material and lengths with reference to the instrument head in two forms i.e. Mech.

The Electro-mechanical Borehole Extensometer of PMT has been designed to measure the deformation in soil, rock and concrete structure at various depths by mechanical readout as well as electrical readout simultaneously. It consists of anchors, rods, protective tubes and a potentiometer sensor. The anchors coupled to the rod are installed in the borehole. The anchors and anchor rods referenced to stable ground, move up or down as movement in borehole occurs. The head of the extensometer can be configured for manual reading using a depth gauge and electronic reading using electrical readout unit.

Specifications | Electrical
Sensor Type: Potentiometer
Sensor range: 25, 50, 100,150, 200mm
Resolution: 0.01mm
Accuracy: ±0.1% F.S.
Temperature Range: -20 to 80° C
Cable: 4-wire, shielded, polyurethane jacket
Specifications | Mechanical
Model: 1401PM-BE1–6
Sensor Type: Mechanical
Sensor range: 25, 50, 100mm
Resolution: 0.01mm
Accuracy: ±0.1% F.S.
Temperature Range: -20 to 80° C
Material: Stainless Steel
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ELECTRO-MECHANICAL BOREHOLE EXTENSOMETER

The Magnetic Ring Extensometer is used to measure settlement or heave of soft ground under the influence of loading or unloading due to the construction of embankments, fills, buildings, foundations, and structures.

The Magnetic Ring Extensometer of PMT comprises of access tube, magnet assemblies and a portable magnetic probe with reed switch. A probe is lowered inside a telescoping guide tube to detect and measure the position of magnetic anchors located around the guide tube at various depths along the borehole or within the fill. Plate anchors are used in fill and spider anchors in boreholes.

Specifications
Model: 4401M-BE-MR
Range: Unlimited (Preferably 200m)
Borehole Diameter: Not less than 54mm
Sensitivity:  1mm (Normal), 0.1mm (Optional)
Accuracy: ±1mm (Normal), ±0.5mm (Optional)
Temperature Range: -20 to 80° C
Material (Probe): Stainless Steel
Access Tube: 25 – 30mm PVC Pipe
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MAGNETIC RING EXTENSOMETER

Tell Tale/Wire Extensometers are used to measure the movement occurring in Rock bolted tunnel or mine roadways by the help of colour bands.

The Tell Tale Extensometer designed by PMT consist of a strata movement indicator (with coloured bands and/or graduations) positioned in the mouth of a drilled hole and attached to an anchor installed up to the hole. They are capable of resolving roof strata movement within two horizons i.e. within the bolted roof horizon and above the roof bolts. The sum of these gives the total roof displacement.

Specifications
Model: 4401M-BE-TTW
No. of Anchors: 1 to 4
Measuring range: 100, 150mm
Accuracy: ±1mm
Hole depth: 1 to 10m (more if required)
Diameter of hole: 37mm – 57mm
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TELL TALE WIRE EXTENSOMETER (MECHANICAL)

Tell Tale Extensometers are used to measure the movement occurring in Rock bolted tunnel or mine roadways by the help of colour bands.

The Rotary Tell tale Extensometer of PMT overcomes the problems with Mechanical Tell tales installed in the roadway roof which has difficulty in reading the graduated scale in high roadways. This instrument converts roof movement into rotation of a pointer round a dial and magnifies the movement.

Specifications
Model: 4401M-BE-TTR
No. of Anchor: 1
Measuring range: Upto 30mm
Accuracy: ±1mm
Hole depth: 1 to 10m (more if required)
Diameter of hole: 37mm – 57mm
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TELL TALE EXTENSOMETER (ROTARY)

Auto Warning Tell Tale Extensometers are used to provide a highly visible immediate warning of excessive movement occurring in Rock bolted tunnel or mine roadways with the help of colour bands.

The Auto Warning Tell Tale Extensometer of PMT has two LED lights that are provided in the body of housing. The deformation gap can be adjusted from 5mm to 25mm. The adjusting arrangement is provided in the bottom of the scale pipe assembly. When the deformation of roof reaches its preset value the LED will start flashing continuously which can be adjusted upto 30 days on demand. The tri clolour scale is also visible to actual deformation, hence the actual roof convergence can be seen everyday.

Specifications
Model: 4401M-BE-TTA
No. of Anchors: 1 to 4
Measuring range: 5mm to 30mm
Trigger level: 5mm to 10mm (adjustable)
Accuracy: ±1mm
Hole depth: 1 to 10m (more if required)
Diameter of hole: 37mm – 57mm
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TELL TALE (AUTO WARNING)