MPBX - Multipoint Borehole Extensometers
The MPBX, also known as multi-point rod extensometer, is designed to monitor changes in the distance between downhole anchors, each
set at a specified depth in the borehole, and a measurement head at the surface. Rods extend upward from the anchors to the head, where measurements are made with a depth micrometer or displacement transducers. MPBX heads are sized to accommodate measurement ranges up to 100 mm (3.9”) or 200 mm (7.9”), the number of anchors (points) to be monitored, and the type of rod to be used.
| Measurement principle | vibrating wire with built-in thermistor | Linear potentiometer |
|---|---|---|
| Range | 10, 25, 50, 100, 150mm | 25, 50, 100, 150, 200mm |
| Accuracy Pol. MPE | < ±0.50% FS (10mm) < ±0.50% FS (25mm) < ±0.30% FS (50mm) < ±0.30% FS (100mm) < ±0.30% FS (150mm) |
< ±0.30% FS (25mm) < ±0.30% FS (50mm) < ±0.30% FS (100mm) < ±0.15% FS (150mm) < ±0.15% FS (200mm) |
| Output signal | frequency (displacement), Ohm (thermistor) | 4-20 mA current loop (displacement) |
| Resolution | <0.0066% FS | <0.0060% FS |
| Typical frequency range | 1500 - 2800 Hz | |
| Power supply | 12 - 24 V DC | |
| Operating temperature | - 20°C +80°C | - 20°C +80°C |
| Material | stainless steel | stainless steel |
| Thermal coefficient of expansion | 50 ppm / °C | 50 ppm / °C |
