Reliably Detecting Volume Flows from 0.3 ml/min: World’s Smallest Gear Typ Flow Meter Wins in the “Test and Measurement” Category

16 Mar 2023  |
Measurement of minimum flow rates with media thinner than water

The Best of Industry Award 2022 acknowledged innovations in 24 different categories considered groundbreaking in the industry. When it comes to measuring and testing technology, one participant – even though small in size – was able to prevail against all its “big” competitors: the world’s smallest gear type flow meter from KRACHT. No comparable measuring equipment, such as that used on test benches for testing fuel injectors, has been able to measure such low volume flows reliably and reproducibly until now. Low-viscosity media is a particular challenge. KRACHT is an expert medium-sized company for fluid measurement technology and world market leader in the field of flow measurement technology. It has now been recognised for its special micro flow meter, which can determine volume flows very precisely (less than 0.5 ml – that’s just three drops per minute) So for example, this micro-quantity meter can now test fuel injectors four times faster.

The company’s original development objective was to design a gear type flow meter that could reliably measure volume flows of at least 0.5 ml/min, even for media with viscosities of just 1 mm²/s. Experts at KRACHT chose extremely corrosion-resistant stainless steel as the material to achieve this objective, and fundamentally reworked all functionally relevant components: gear geometry and gear design were both optimised using special ball bearings in the highest accuracy class. This was necessary to meet the strict requirements for tightness as well as ensuring the measuring mechanism ran smoothly.

A particularly high-resolution sensor system was required to output the measured values at the targeted minimum flow rates at a sufficiently high frequency. KRACHT worked together with a parameter monitoring partner to develop a sensor element specially tailored to the needs of the gear type flow meter. This means the required frequencies in a compact installation space can be detected, and with completely smooth scanning. The result of this comprehensive redesign is now a gear type flow meter that can determine volume flows of 0.3 ml/min at viscosities from 0.8 mm²/s with high precision, reliability and reproducibility.

Component production and assembly testing the limits of what is possible

KRACHT went right to the limits of what was technically possible when manufacturing and assembling the flow meter. For example, special production machines that are exclusively used for this product were used in the manufacturing process. Component production and assembly are also air-conditioned and closely monitored. It only takes the smallest particles to adversely affect the assembly of high-precision measuring instruments. With this in mind, a sophisticated process for component cleanliness and, in particular, the assembly workstations was also devised. In this way, the manufacturer achieves the highest possible component purity as well as ideal assembly conditions. For example, the process includes a special ultrasonic cleaning system that has been further developed exclusively for the new measuring instrument.

The world’s smallest gear type flow meter is assembled at special workstations in a clean air environment using ultra-fine air filters. Special calibration processes under stable climatic conditions compensate for even the most minimal tolerance fluctuations. Each individual device undergoes a final check and calibration – including creating a digital log – on a high-precision calibration test bench for low flow rates and low viscosities. This is how KRACHT ensures that every model that leaves the factory demonstrably meets the high application requirements.

So, KRACHT’s micro flow meter makes it possible not only to drastically reduce the lower limit for measuring fluids using gear type flow meters. The new device also makes test benches future-proof by enabling injectors to be tested using the latest injection technologies. “Winning the Best of Industry Award confirms to us that our intensive and complex development work has more than paid off and that we can offer an exciting and future-proof product that solves problems instead of creating them,” says Bernd Neidhardt, Chief Strategy Officer at KRACHT.

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We are a globally active medium-sized family company with about 450 employees. Our core competencies are the development, manufacture and sale of high quality technologies in the areas of pumps, fluid measurement, valves, hydraulic drives...

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