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.

With a companion Unidata data logger or a telemetered Neon Remote Logger, the instrument can be programmed to compute flow rate and total flow in pipes and open channels of known dimensions.

The Unidata 6537 Starflow QSD SDI-12 and Modbus Instrument has a 4 electrode electro conductivity instrument (EC) included for measuring the quality of the water. Water quality is measured on an ongoing basis and this parameter can be recorded along with velocity and depth to better analyse the nature of the water in open channels and pipes. Conductivity is a very important water quality measure and any spike on the conductivity is a strong indicator of a pollution event.

The Unidata 6515 Barometric Reference is a barometric reference module which is used with the Starflow QSD instruments to correct the pressure sensor depth sensor readings for atmospheric pressure variations.

The 6515 barometric reference is a module which is installed in line with a Starflow QSD Instrument to monitor the barometric pressure in the geographical location of the instrument. With this module barometric compensation can be achieved for the depth sensor within the Starflow QSD Instrument, so the depth sensor provides pressure and derived depth readings which are corrected for differences in atmospheric pressure.
6515 barometric reference inbuilt electronic components communicate with the Starflow QSD instrument via a dedicated protocol providing regular atmospheric pressure readings. These values are then applied to the pressure sensor, allowing the Starflow QSD Instrument to report true atmospheric pressure compensated depth readings.

An alternative to using 6515 barometric reference can be any other electronic barometer, which is read and then the depth readings are corrected for atmospheric pressure in another system, such as another data logger or an RTU connected to the SCADA system.

Another alternative to this barometric reference could also be to consult the local weather service and obtain the current barometric pressure for the geographical location that the Starflow QSD Instrument is deployed and use those readings as a depth compensation factor in an end system where the velocity and depth data is being stored.