Water Level Instruments

Models 6541C, 6547B and 6547S

  • Overview

    The 6541 precision water level instrument is a high accuracy float and pulley based shaft encoder instrument for measuring the level of water in many different applications. Float-operated instruments can be the most accurate way to monitor water levels, and they are the most common method to measure river levels. The Unidata 6541 precision water level instrument can achieve operating accuracy and resolution of 0.2mm with high stability and minimum drift.

    This accuracy is maintained for the service life of the instrument without calibration or maintenance, apart from battery changes. The 6541 has the range to monitor surface and underground waters and the precision to monitor rainfall and evaporation.
    The water level instrument is normally connected to the surface of the water by a float system. As the water level changes, the input shaft rotates. An optical encoder is mounted on the input shaft. On installation, the instrument is set to display the water level.

    The encoder is continuously monitored as the instrument tracks water level changes. These changes update the LCD display and the readings can be recorded by an associated datalogger.
    The very low mechanical friction and inertia of the instrument mean that it can produce data with high precision and accuracy. A replaceable battery pack powers the instrument for more than twelve months. Practical design and rugged construction ensure easy operation and long service life.

    The 6547 radar water level sensor is 4-20mA two-wire instrument that provides continuous water level measurement of water in rivers, streams, open wastewater channels, stormwater overflow tanks and pump stations. The 6547 is a radar sensor which provides accurate long term measurements of water level up to 8m range from the sensor.

    The radar sensor emits extremely short microwave pulses through the antenna. The emitted signal is reflected by the medium/water and then received as an echo by the antenna. The time between the emitted and received signal is proportional to the distance and is outputted as the measured value. The sensor is normally mounted vertically with a bracket mounted on a structure with the sensor pointing downwards. The 6547 is almost maintenance-free due to non-contact measuring principle and is protected by an IP 68 housing.

    The radar SDI-12 version 6547S that provides accurate long term measurements of water level up to 15m range from the sensor is available as well.

    Radar readings are unaffected by the change in temperature and pressure making this instrument ideal for use in difficult process conditions.

    When used with a companion Unidata IP data logger, collected data is transmitter to a central Neon server where data can be viewed on the Neon Web server in near real time from any browser. Same data can be reported to other systems using email, ftp, and web services.

    water monitoring precision water level instrument 6541C
    6547 Radar Water Level Sensor

  • Specifications

    6541C Precision Water Level Instrument

    Physical specifications

    Material: Powder coated aluminium mounting with Polycarbonate Enclosure IP66
    Size: 180mm x 140mm x 275mm (LxWxH)
    Weight: 2.7kg (including battery)
    Operating temperature: -10°C to 60°C

    Electrical specifications

    Battery: 6 x 1.5V industrial grade D size Alkaline battery pack 6910A (non-rechargeable)
    Battery life: up to 1 year (based on daily schedule)
    External power: External battery power 7-15VDC may be connected
    Range: Standard 0m-65.5m or -199.999m to 199.999m
    Accuracy: 1mm, 0.2mm or 0.1inch depending on the chosen float pulley size
    Resolution: 1mm, 0.2mm or 0.1inch depending on the chosen float pulley size
    I/O: 2 x HSIO bi-directional channels, Up to eight instruments can be daisy chained
    Optional 4-20mA
    SDI-12: SDI-12V 1.3 recorder (1200 baud smart instrument channel)
    LCD Type: Reflective grey no backlight
    Display Format: One line x 6 Characters, 7 segments
    Optimum Viewing: 6 o’clock
    Cable: 5m 8 core data cable

    Integrated logger specifications – optional

    Storage memory: Low power CMOS RAM 512k standard
    RAM Back up battery: Lithium Battery 3V, 950mAh
    Time clock: Crystal regulated, +/- 10 seconds/month
    Scan rates: Programmable from 5 seconds to 5 minutes
    Log intervals: Programmable from 5 seconds to 24 hours
    CPU: 80C552 microcontroller, 14.7456 MHz

    6547B 4-20mA two-wire Radar Water Level Sensor

    Physical specifications

    Material: PVDF Enclosure IP68
    Size: Diameter 76mm, Length 109mm
    Weight: ~1.5kg
    Operating temperature: -40°C to 60°C

    Electrical specifications

    External power: 12V-35VDC
    Range: Standard 0m-8m
    Accuracy: ±5mm
    Frequency Range: W-band (80GHz technology)
    I/O: 4-20mA two wire
    Cable: 10m or more if required of 2 core + Kevlar relief wire

    6547S SDI-12 Radar Water Level Sensor

    Physical specifications

    Material: PVDF Enclosure IP68
    Size: Diameter 76mm, Length 109mm
    Weight: ~1.5kg
    Operating temperature: -40°C to 80°C

    Electrical specifications

    External power: 9V-32VDC
    Range: Standard 0m-15m
    Accuracy: ±2mm
    Frequency Range: 80Ghz
    I/O: SDI-12
    Cable: 5m or more if required of 2 core + Kevlar relief wire

  • Ordering Information

    Model Description
    6541C-­10 Water Level Instrument with 500mm Pulley
    6541C-­11 Water Level Instrument with
    500mm Pulley and 6910A Alkaline Battery Pack
    6541C-11-C Water Level Instrument with MicroLogger 8010C, 500mm Pulley and 6910A Alkaline Battery Pack
    6541C-­30 Water Level Instrument with 100mm Pulley
    6541C-­31 Water Level Instrument with 100mm Pulley and 6910A Alkaline Battery Pack
    6541C-31-C Water Level Instrument with MicroLogger 8010C
    100mm Pulley and 6910A Alkaline Battery Pack
    6541C-CL Additional parts for 4-20mA option
    6541D-M Metric Beaded Floatline, 125mm spaces fits 500mm Pulley
    6541E Unbeaded Floatline, 0.4mm dia fits 100mm Pulley
    6541F-115 Float Assembly 115mm Cylinder
    6541F-90 Float Assembly 90mm Ovoid
    6547B 4-20mA Radar Water Level Sensor
    6547S SDI-12 Radar Water Level Sensor

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