Long term stability is ensured in the model EPP-50V (MTI.EWS.ER.M-EPP50V) pore pressure meter by:
• Pressure and thermal cycling
• Unique method of wire clamping
• By generating a vacuum of around 1/1000 Torr inside the sensor by electron beam welding. This results in effect of oxidation, moisture, environmental conditions and any ingress of water being completely eliminated.
The vibrating wire pressure sensing capsule is sealed under high vacuum. The capsule and coil magnet assembly is housed in a stainless steel body. The model EPP-50V vibrating wire push-in piezometer has a pointed cone at one end and drill rod threads (EW drill or M28) at the other end. When threaded into a drill rod, the piezometer can be pushed into soft soil directly. The cable attached to the piezometer is passed through the drill rod. The piezometer must be monitored to ensure that the pressure created during installation does not exceed the maximum rated pressure. The piezometer model EPP-50V is supplied with the required length of cable attached. The pore pressure meter is individually temperature compensated making the requirement of a thermistor for temperature correction redundant. However a thermistor is provided for monitoring temperature.
Piezometer Model EPP-50V
• Sensor Type: Vibrating wire
• Parameter: Pore pressure
• Range: 0.35, 0.5, 0.7, 1.0, 2.0 MPa
• Protection (Waterproofing): IP-68, water resistant up to its full range
• Accuracy: ± 0.25 % fs normal; ± 0.1 % fs optional
• Dimension (mm): 35 Ø x 166 L
• Key Testing / Calibration:
- Thermal cycling (-20 to +80°C)
- Pressure cycling (2000 cycles), individually temperature compensated, reverse pressure test, individually calibrated providing high accuracy & repeatability
• Key Feature/Advantage: Hermetically sealed with electron beam welding
• Non linearity: ± 0.5 % fs
• Temperature limit Operational: -20 to 80°C
• Over range limit: 150 % of range
• Thermistor: YSI 44005 or equivalent