Tell Tale/Wire Extensometer 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 consists 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.
- - Reliable, low cost, accurate
- - High accuracy and simplicity in readings
- - Portability of probes
- - Versatility in component assemblies
|No. of Anchors||1 to 4|
|Measuring range||100, 150mm|
|Hole depth||1 to 10m (more if required)|
|Hole diameter||37mm – 57mm|
|Access Tube||25 – 30mm PVC Pipe|