Piezoresistive level probe PIEZO HR

for water2-wire4-20 mA

Overview
The PIEZO HR piezometric probe (High Resistance) is a hydrostatic level sensor designed for continuous monitoring of water levels in aggressive environments (seawater, chemical applications). It can also be used for pump automation via a control relay. The probe converts hydrostatic pressure into a conditioned electrical signal on a 4-20 mA current loop.

Operating principle
The probe houses a piezoresistive sensing cell that measures the pressure exerted by the water column above the sensor. This pressure, proportional to the water column height, is converted into an electrical signal (4-20 mA loop) to provide continuous piezometric level readings.

Installation and wiring
The probe can be suspended by the cable sheath or mounted with a stainless-steel support cable fitted with a lifting eye. Use the FIX-CAB accessory to secure the cable at the desired depth. Avoid clamps or tight fittings that could damage the cable and cause capillary ingress. Electrical connections must be made in a non-pressurized junction box (internal pressure equal to atmospheric pressure) and the junction box must never be placed inside a tank. The cable and its capillary may be extended using a standard signal cable.

Recommended accessories

• FIX-CAB (cable attachment / fixing accessory)
• Junction box (for cable extension)
• Surge arrester (protection against overvoltages)

Documentation
Technical data sheet available (e.g., technical sheet - PIEZO ST hydrostatic probe indicated on the page; size example: pdf : 268.04 KB).

Specifications / technical data

• Water column range: configurable full scale from 2 mH2O to 20 m (full scale set at factory to requested value; 20 mA = full scale, 4 mA = 0 m).
• Output signal: 4-20 mA current loop (4 mA = 0 m, 20 mA = full scale).
• Electrical characteristics: DC supply 6 to 38 V.
• Housing material: Hastelloy C276.
• Sensing cell: Hastelloy C276.
• Hysteresis: 0.05%.
• Operating temperature: 0 °C to 40 °C.
• Consumption: loop current (4-20 mA).
• Cable: 2 conductors 0.22 mm²; standard 10 m PU cable supplied.
• Probe weight: 370 g.
• Dimensions: length 130 mm – diameter 25 mm.