Low-Flow AdBlue Consumption Successfully Measured using FlowSonic Flow Meter

Sentronics Ltd has successfully and accurately recorded the flow rate of Diesel Exhaust Fluid (DEF), commonly known as AdBlue®, at flow rates as low as 2ml/min using the FlowSonic LF ultrasonic flow meter.

The successful test was conducted at a leading independent automotive test house in the UK, and marks a significant step forward for vehicle development engineers’ understanding of DEF consumption. Until now it has been widely accepted that no commercial solid-state solution exists for the accurate measurement of DEF at the low flow rates typically experienced on commercial, industrial and off-highway vehicles.

The FlowSonic Ultrasonic Flow Meter installed on a flow test rig

While flow meters capable of measuring DEF do exist, none of the solutions more widely available offer the benefits of solid state technology.

Sentronics were approached with a requirement to measure DEF flow on an industrial vehicle. DEF flow rates in this type of application tend to be approximately 3-5% of the fuel consumption rate per minute. So with peak fuel consumption of approximately 100kg/hr, the maximum DEF flow rate is approximately 44ml/min, with flow rate dropping to as little as 2ml/min at idle.

While the Sentronics FlowSonic flow meter had not been previously tested with DEF, it was a natural candidate for the application. Originally designed to measure fuel consumption in passenger and commercial vehicles, where flow rate can be as low as 10ml/min, FlowSonic not only has the technical ability to measure very low flow rates accurately, but the mechanical construction necessary to make it fully compatible with DEF.

Initial test preparation involved plumbing the FlowSonic into a specially developed gravity-fed flow rig capable of delivering a reliable, adjustable flow of DEF of a known quantity. At the lowest flow rates of circa 2ml/min, DEF consumption is merely a drip every few seconds! With the meter installed, flow tests were conducted firstly to confirm that the device was indeed capable of measuring DEF flow, and secondly to allow calibration of the device and to quantify measurement uncertainty.

Initial test results were extremely encouraging, with plots of the sensor output vs measured ‘consumed’ DEF quantity correlating well.

Further, more detailed testing by the advanced research engineers involved is ongoing, with results expected within the coming weeks.

Neville Meech, Managing Director at Sentronics said: “With ever-tightening vehicle emissions legislation it is clear the need for more advanced technologies to assist in the measurement of media such as DEF in real vehicle applications is growing. Allowing engineers to optimise its usage helps drive efficiency and minimise harmful NoX emissions polluting the environment.”