Tape Extensometer is a portable instrument to take accurate distance measurements between pairs of reference points permanently installed.

The Tape Extensometer of PMT consists of a steel survey tape with punched holes loaded on a reel fixed to the body of the instrument. If incorporates a tensioning mechanism for the tape as well as dial/ digital indicator based distance measuring system. Two hooks are provided, one at the movable extremity on the tape and the others on the reel frame. Tensioning of the tape to a predetermined load is easily done by rotating large knurled collar until two reference lines are precisely aligned.

Model: 4101M-TE-M / Model: 4101M-TE-D
Tape length: 15,30m
Resolution: 0.01mm
Accuracy: ±0.05mm

Tunnel Convergence Meters are used to measure deformation in tunnels and underground caverns by measuring the contraction/elongation between two anchor points fixed in the wall of the tunnel cavern.

The Tunnel Convergence Meter of PMT consists of a spring tensioned vibrating wire sensor assembly, turnbuckle, 6/8mm diameter connecting rods of stainless steel/fiber glass, rod clamp and a pair of anchor points. Change in distance between the two anchors causes tension of the vibrating wire inside the VW transducer which is transmitted through a cable to the readout unit.

Model: 1101V-TE-T
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
Cable: 4-wire, shielded, polyurethane jacket

The Remote Convergence Meter is used for measuring the convergence between roof and floor of underground mines or cavity. Monitoring of the roof to floor convergence of these openings, particularly when driven through rocks showing a time-dependent behavior, provides essential information to assess the overall ground stability.

Remote Convergence Meter of PMT consists of either VW displacement sensor or Linear Potentiometer type displacement sensor with two telescopic tubes maintained together by a friction ring which prevents the system from collapsing under its own weight.  Both the tubes have anchoring flange at one end for fixing it with roof and floor where as free end moves in each other in perfect alignment. Remote type system is generally used where access is not easy.