Navigating Fuel Flow Meters: A Technical Q&A

Jamie Jones, Senior Systems Engineer at Sentronics, discusses the measurement principles employed by Sentronics Ultrasonic Flow Meters, the different fuel flow meters available in the market, and what gives Sentronics the edge when it comes to selecting a flow meter for fuel systems.

How do Sentronics Ultrasonic Flow Meters operate? 


Sentronics Ultrasonic Flow Meters employ the principle of time-of-flight (TOF) measurement, utilising sound waves to accurately determine fluid flow velocity. Our system consists of two transducers, both capable of emitting and receiving ultrasonic pulses though a flowing medium. The TOF difference between upstream and downstream ultrasonic firings is directly proportional to the flow velocity, which can then be used to calculate the volumetric flow rate. If temperature is also accurately measured, then mass flow can be calculated too (provided the density vs temperature relationship is known). 

Sentronics Article Time of Flight Theory Illustration

What are the key advantages of implementing a fuel flow meter into a fuel system? 

When a fuel flow meter is incorporated into a fuel system there are a plethora of benefits, one of the most important being the potential for enhanced fuel efficiency. By accurately monitoring fuel consumption, fuel usage can be optimised to reduce fuel expenses and reduce environmental impact. Flow meter data can also be utilised for precise engine calibration by delivering valuable insights to powertrain engineers working on engine calibration and ensuring optimal engine performance and emissions compliance. Specifically in the automotive industry, fuel flow meters are crucial for regulatory compliance. It ensures vehicles are capable of demonstrating compliance to emissions regulations and allows customers to perform a fair and unbiased comparison between vehicle manufacturers.

What are the different types of flow meters used in fuel consumption metering?

The world of flow meters is diverse and encompasses a wide range of technologies tailored for specific applications:

Positive Displacement Flow Meters:
These meters employ mechanical elements to sweep a known volume of fluid per rotation, providing high accuracy and repeatability. Due to moving parts in the flow, the technology typically has high pressure drop and calibration drift.

Turbine Flow Meters:
These meters have an impeller inside the flow that rotates at a speed roughly proportional to the flow-rate. Due to the inertia of the impeller, these flow meters don’t respond well to rapidly responding or pulsing flow and commonly struggle with impeller stiction at low flows. Calibration drift is also common due to the bearings becoming worn.

Sentronics Article Turbine Flow Meter Illustration

Coriolis Flow Meters:
Used commonly for fuel consumption in engine test cell applications, the technology directly measures mass flow. It can also measure density which allows it to double as a volume flowmeter. Unfortunately, it’s not suitable for use on-vehicle due to the principle of operation being detrimentally impacted by vehicle borne vibration.

Sentronics Article Coriolis Flow Meter Illustration

Ultrasonic Flow Meters:
As showcased by Sentronics, ultrasonic flow meters utilize high frequency sound waves to measure fluid velocity, offering exceptional accuracy, reliability, and compatibility with wide range of fluid types.

Sentronics Article Ultrasonic Flow Meter Illustration

Are Sentronics flow meters suitable for diesel applications? 

Yes, Sentronics flow meters are ideal for demanding diesel applications. Our flow meters excel in handling fuels safely and have been designed to withstand the corrosive nature of hydrocarbon fuels, ensuring long-term performance and leak-free operation. With large flow-rate variation, Sentronics fuel flow meters are capable of measuring rapid changes in flow with extreme accuracy, across a wide turndown range (1:1000), catering to both passenger vehicles and heavy-duty engines. Implementing a flow meter assists vehicle manufacturers in meeting diesel consumption fuel regulations, and with calibration to ISO 17025 standards, our instruments ensure traceability of measurement back to national standards (NIST, UKAS). Sentronics ultrasonic flow meters are also extremely robust and reliable. Designed to withstand harsh environments and perform reliably over extended periods, the flow meters are ideal for demanding applications such as within diesel fuel systems.

What sets Sentronics apart from other manufacturers? 

Our devices incorporate cutting-edge proprietary technology for advanced features, such as self-calibration and diagnostic capabilities, offering enhanced performance and plug-and-play capability. With best-in-class measurement rates of 2.2kHz, Sentronics flow meters permit exceptional accuracy and repeatability, ensuring reliable flow rate measurements even in the toughest of conditions. In contrast to other technologies, our flow meter is extremely compact and designed with lightweight construction to facilitate easy integration into compact engine bays and fuel metering systems.

Our FlowSonic® LF installed directly within the engine bay of a vehicle.

Where do you see this technology evolving? 

The demand for solid-state electronic flowmeters appears to be on the increase, we see emerging requirements from almost every industry and market looking to move away from traditional mechanical measurement flowmeters (Turbine, PD). The opportunities for ultrasonic flow metering are vast and we look forward to developing the flowmeters of the future!

For more information, discover how we deliver fuel consumption measurement.