AutoSalt (AQAc™) – Base

Description

The automated salt injection system that does the work for you.

It can be difficult to obtain a full range of flow measurements for your hydrometric rating curve. Resources are often wasted visiting sites at similar flow conditions. At Fathom Scientific, we’ve been developing the Automated Q Acquisition (AQAc…a.k.a. AutoSalt™), since 2008 to address these and other challenges. The AutoSalt system consists of a control system, 300 litre brine tank and stand, Creek Pressure Transducer, 2x T-HRECS self-logging EC-T probes, and a proprietary salt injection system. Systems have been installed at >20 locations around the province of BC since 2008 and collected hundreds of automated discharge measurements.

How does it work?

The system works by first sensing the water level in the Creek. This is essentially a redundant water level sensor to support a Grade A Hydrometric record. The AQAc then decides to inject brine based on a combination of logical rules, preferably injecting brine on the falling limb of a hydrograph. Alternatively, a Regular Injection Interval can be set. Measurements can also be triggered via Telemetry. EC-T data is relayed back to the control module via LoRa radios, as well as logged continuously at the D/S Temperature – High Resolution Electrical Conductivity Serial (T-HRECS) device EC-T sites. Injected brine volume is measured by three independent methods. Due to the high resolution and sensitivity of the T-HRECS EC-T sensors (and the paired U/S T-HRECS) we can use very low salt doses and still achieve low SDIQ uncertainty. Typically we set the brine [NaCl] to 20%, and aim for 1 litre of brine per m³/s. Tanks come in 200 and 300 litre sizes. This implies we can measure between 200-300 cumulative m³/s per visit, i.e. 10 measurements of 20 m³/s (for the 200 l tank) or 200 measurements of 1m³/s. Of course, in reality it will be a range of flows.

Systems have been installed at numerous locations around the world including New Zealand, Germany, UK, and Canada for agencies such as NIWA, TUM, Helmholtz Institute, and WSC, along with several hydropower and mining operations.

Technical Documents + User Information

A requirement of any automated system is to either know the Calibration Factor – Temperature compensated (CF.T) or measure the CF.T in situ. We have partnered with academic institutions and other consultants to determine the variance of the CF.T in streams and rivers in B.C.  We’ve found this value to be relatively constant (+/-1.6% at 95% confidence) with calibrated instrumentation and careful calibration procedures.  Browse our recent presentations on the Derivation, Uncertainty, and Variance of the Calibration Factor used in Salt Dilution Flow Measurements (or read the associated post) and Quantifying and Controlling Error in Salt Dilution Flow Measurements (and the associated post).

Autosalt Manual

Install the latest version of RealTerm to communicate with AutoSalt, or use an older version.

AutoSalt brochure and Technical Datasheet.

Installation + Warranty

The AutoSalt system is a good value for $12,000 CAD.  We will install the system for $2000 CAD at most sites + transportation + disbursements.  We strongly recommend our assistance for the first installation.  AutoSalt has a 3 year limited warranty on parts and includes a subscription to WIT-HM to semi-automatically process SD Measurements, manage measurements, and develop a Maximum-Likelihood Hydraulically-Based Rating Curve.

We also offer a rental option of $1500/month.  For rentals, the same installation costs apply: $2000 CAD at most sites + transportation + disbursements.

For more information, please contact us.