6527 Starflow QSD

The Unidata 6527 Starflow QSD SDI-12 and Modbus Instrument is used to measure water velocity, depth and temperature of water flowing in rivers, streams, open channels and large pipes. When used with a companion Unidata IP data logger, flow rate and total flow can also be calculated.

The 6527 Instrument is robust, reliable and easy to use. It is completely sealed against water ingress, low maintenance, low power, no calibration and no fussy power arrangements required.

Ultrasonic Doppler Principle in Quadrature Sampling Mode is utilised to measure water velocity. The 6527 Instrument transmits ultrasonic energy through its epoxy casing into the water. Suspended sediment particles or small gas bubbles in the water reflect some of the transmitted ultrasonic energy back to the 6527 Instrument’s ultrasonic receiver instrument that processes this received signal and calculates the water velocity.

The 6527 Starflow QSD incorporates ultrasonic depth sensor and an absolute pressure depth sensor. An ultrasonic depth sensor measures the water depth using the ultrasonic principle and has a range of up to 5m. An absolute pressure sensor measures pressure forces applied to the strain gauge. The absolute, non-vented, sensor reports a value equal to the sum of the water pressure and the atmospheric pressure above the water. In order to compensate for the atmospheric (barometric) pressure fluctuation, the 6527 Starflow QSD should be connected to the 6515 Starflow QSD barometric reference. The absolute pressure sensor has a range of up to 10m. Having sensors using different depth measurement methods provides flexibility in-depth measurement.

The 6527 instrument’s low profile form factor minimises disturbance to the flow it’s measuring. Furthermore, 6527 instrument measures velocity in both directions and is suitable for use in a wide range of water qualities, from sewage to potable water, seawater too.

Velocity Range – 20mm/s to 0.8m/s
– 20mm/s to 1.6m/s in one direction (default)
– 20mm/s to 3.2m/s
– 20mm/s to 13.2m/s
– Bidirectional velocity capability, set using configuration tools
Velocity Accuracy ±1% typical
Depth Range Ultrasonic Sensor 20mm up to 5m above top surface of the instrument
40mm up to 5m from the base of the instrument
Depth Accuracy Ultrasonic Sensor Typical ± 1%
Depth Range Absolute Pressure Sensor 0 to 10m
Depth Accuracy Absolute Pressure Sensor Typical ± 0.19% for 0m to 5m range
Typical ± 0.38% for 0m to 10m range
Channel type Pipe, open channel, natural stream
Cable 15 metre, 6 way
Cable Options User specified up to 50 metres
Power Source Typical External Battery 12V – 24V DC



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