January 10, 2013 – Flow Monitoring
SFE Global has been providing sewer, drainage, and industrial effluent flow monitoring services for over 20-years. Over this time, technology has developed and so have our internal processes and QA/QC procedures that have allowed SFE to continually deliver the excellent services and quality data we’re known for. As much as technology has changed, the fundamentals of open channel flow monitoring have remained relatively consistent. Flow rates are generally calculated a few different ways:
- Area/Velocity Flow Meters – Uses an application specific flow meter that measures velocity and liquid depth through a known geometric shape. (i.e. an open channel round pipe sewer; or box culvert) Once the user has programmed all pertinent information into the meter, it will then record these velocity/depth measurements and calculate a flow rate.
- Primary Devices –Weirs and Flumes are common examples of primary devices used in open channel flow monitoring. These devices have known head (liquid level) vs. flow relationships and thus measuring velocity is not required. Primary devices can transform unfavorable hydraulic conditions into consistent predictable conditions. In these cases a secondary device is used to rough a known geometric shape. (i.e. an open channel round pipe sewer; or box culvert) Once the user hameasure the liquid depth upstream of the weir or flume and based on the specific head vs. flow relationship, a flow rate is recorded.
- Hydrologic / Hydrometric / Stage-Discharge Monitoring – There are applications when there’s neither a defined channel nor accessible pipe to measure; and it is not feasible to install a primary device. Typically in these scenarios the channel bed is profiled at a good stage area in the flow channel and a depth sensor with data logger is used to measure/record level. Then, over time and at various levels of flow, velocity is manually measured. (using industry standard equipment) The result is that a stage-discharge curve is developed, allowing for flow rates to be derived from all information gathered.
SFE is not a manufacturer of equipment or instrumentation. We use the most appropriate technology for the specific application at hand. Detectronic, HACH/Sigma, Nivus, Isco, ADS, Telog, Campbell Scientific, and Sutron are just some of the flow meter and data logger brands used in our monitoring programs.
Now that you’ve got your flow data recorded in your flow meter or data logger… what’s next? Stay tuned for next month’s News Update with insights on data acquisition and data management.
For feedback and/or general inquiries about Open Channel Flow Monitoring, please contact Mike Lemmen at 1.866.332.9876 or firstname.lastname@example.org