Description

HMA’s Model 4500HD Heavy Duty Piezometer is designed for direct burial in fills and dam embankments. The 4500HD is used in conjunction with heavily armoured cable to withstand earth movements during construction. Recommended for use in earth dams. The transducer utilises a pressure sensitive diaphragm with a vibrating wire attached to it. The diaphragm is welded to a capsule which is evacuated and hermetically sealed. Fluid pressures acting upon the outer face of the diaphragm causes deflections of the diaphragm and changes in tension and frequency of the vibrating wire. The changing frequency is sensed and transmitted to the readout device by an electrical coil acting through the walls of the capsule. Piezometers incorporate a porous filter stone ahead of the diaphragm, which allows the fluid to pass through but prevents soil particles from impinging directly on the diaphragm. HMA’s vibrating wire piezometers have outstanding long-term stability and reliability, with low thermal zero shift. The all-stainless-steel construction allows for a high level of corrosion resistance. However, VWP’s are not suitable for the measurement of rapidly changing pressures. Additionally, the piezometer features an inbuilt thermistor which allows for the measurement of temperature at the piezometer’s location.