Water Depth Probes and Tipping Bucket Flow Gauge

Models 6506G, 6506H, 6542D and 6548A

  • Overview

    The 6542 hydrostatic water depth and temperature probe is a pressure sensor based instrument for measuring water depth in many applications. It has a cable with a vent tube for atmospheric pressure compensation. The 6542 Hydrostatic water depth and temperature probes provide accurate long term measurements of water depths of 3m to 50m in standard ranges, with an accuracy of 0.05% full scale. The sensor communicates via SDI-12 v1.3 or Modbus RTU RS485 protocol.

    The 6542 is fully sealed and temperature compensated. A hermetically sealed case with a protection type IP 68 allows the pressure sensor to be immersed down to a depth of 200m. The inner vented connection cable makes pressure compensation of the measuring cell against the atmosphere possible and thus hydrostatic pressure measurement. The pressure sensor is designed for submersible measurements and meets the electromagnetic compatibility (EMC) requirements to EN 61326.

    The mechanical fastening of the pressure sensor does not require any additional strain relief, as the construction of the cable is suitable to take a maximum tensile force of 1000 N. The cable’s individual signal wires are epoxy sealed into the casing to protect against water ingress. This probe is ideal for monitoring drainage, bore depth and river height. It can also be used to measure water with dissolved solids and other liquids.

    The 6506 tipping bucket flow gauge is used to measure small volumetric flows which exceed the capacity of standard rainfall gauges. Typical applications include monitoring rainfall under a tree canopy, leakage in water storage dams, seepage and runoff.

    Unidata 6506 tipping bucket flow gauge is sturdily constructed from polished stainless steel. The tipping mechanism is manufactured from stainless steel and is of solid construction, ensuring that tips are accurate and consistent in volume.

    The 6506 is supplied with a single-reed switch as a detector. This requires no power and is a simple two-wire connection and is usually the easiest to connect to dataloggers, including the Unidata Neon Remote Loggers. Tipping bucket is pre-calibrated to a 75ml/tip or a 130ml/tip but it can be calibrated to any volume from 75ml to 130ml per tip.

    The 6548 submersible level transmitter measures the height of liquid above the position in the tank, well or borehole, referenced to atmospheric pressure. The sensor has a slim body design, ideal for narrow space applications like boreholes. It has good chemical compatibility and lightning and surge protection.

    The transmitter has a piezoresistive sensing element, encased in stainless steel 316 housing. A bullet nose design protects the diaphragm from damage. The 6548 incorporates lightning and surge protection that utilises dual arrestor technology, grounded to case, which eliminates both power supply surges and lightning ground strike transients. Lightning and surge protection is not guaranteed and is not covered by warranty.

    When used with proper intrinsically safe Zener barrier the 6548 is UL approved intrinsically safe for use in hazardous locations. The level transmitter comes equipped with a strong tensile strength shielded and vented cable. The vent tube in the cable automatically compensates for changes in atmospheric pressure above the water level. The vent is protected with a maintenance-free filter that stops water droplets or vapour from entering the transducer.

    The 6542 Hydrostatic water depth and temperature probe
    water monitoring tipping bucket flow gauge 6506G&H
    The sensor in a slim body design, ideal for narrow space applications like bore holes. It has good chemical compatibility and lightning and surge protection.

  • Specifications


    Physical specifications

    Material: Marine Grade 316 Stainless Steel or titanium
    Size: Dia 19mm x 214mm long
    Weight: 400g
    Operating temperature: -15°C to 55°C

    Electrical specifications

    External power: 9-16VDC


    Range Gauge: 3.5m, 10.5m, 21m of water
    Accuracy: ±0.05% FS
    Resolution: ±0.0034% FS
    Max Operating Pressure: 1.1 x full scale


    Range: -15°C to 55°C
    Accuracy: ±0.5°C for 0° to 55°C and ±2.0°C for below 0°C
    Resolution: ±0.06°C

    Modbus: RS485 RTU, output = 32bit IEEE floating point
    SDI-12: SDI-12V 1.3 recorder (1200 baud smart instrument channel)
    Cable: Custom lengths of either polyurethane, polyethylene or ETFE cable

    6506G and 6506H

    Physical specifications

    Material: Marine Grade 316 Stainless Steel
    Size: 400mm x 300mm x 155mm (LxWxH)
    Weight: 2.7kg net
    Operating temperature: -20°C to 60°C
    6506G – up to 3 litres/minute
    6506H – up to 4 litres/minute
    Bucket Capacity:
    6506G – 75ml per tip
    6506H – 130ml per tip
    Signal Element: Single reed switch
    Cable: 5m of 2-way instrumentation screened cable – PVC


    Physical specifications

    Material: Stainless Steel 316 Enclosure IP68, bullet nose PVC
    Size: Diameter 25.40mm x Length 177mm
    Weight: ~1.00kg depending on cable length
    Operating temperature: -18°C to 60°C

    Electrical specifications

    External power: 12V-35VDC
    Depth Range: 3.5m, 5m and 10m
    Accuracy: ±0.25% FS
    Max Operating Pressure: 2 x full scale
    I/O: 4-20mA two-wire
    Cable: Custom lengths of 3 core + breather tube, submersible cable

  • Ordering Information

    Model Description
    6542D-A Water Depth Probe 3.5m Stainless Steel
    6542D-A Water Depth Probe 3.5m Stainless Steel
    6542D-B Water Depth Probe 10m Stainless Steel
    6542D-C Water Depth Probe 20m Stainless Steel
    6542D-CBL Water Depth Probe PU Cable/meter - cable length
    to be specified at the time of order
    6542D-T-A Water Depth Probe 3.5m Titanium
    6542D-T-B Water Depth Probe 10m Titanium
    6542D-T-C Water Depth Probe 20m Titanium
    6542D-T-CBL Water Depth Probe FEP Cable/meter - cable length
    to be specified at the time of order
    6506G Tipping Bucket Flow Gauge, 75ml per tip
    6506H Tipping Bucket Flow Gauge, 130ml per tip
    6548A-A Submersible Level Transmitter 3.5m
    6548A-B Submersible Level Transmitter 5m
    6548A-C Submersible Level Transmitter 10m
    6548A-CBL Submersible Level Transmitter Cable/meter - cable length
    to be specified at the time of order

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    • Documents