Innovative Helical Screw Flow Meter

The VSE development department has combined this measuring principle, which by itself is not new, with the development of the new rotor sensor to yield a state-of-the-art flow meter. There was a considerable development potential because the measurement of the volume flow based on the the screw pump principle of the VSE series RS offers significant benefits:

• High degree of precision that is mostly independent of viscosity
• Pulsation-free measurement
• Lowest pressure losses
• Short response time due to innovative rotor profile and reduced masses
• Gentle fluid measurements
• Highest functionality due to intelligent sensor technology

The core objective of the new development initially was to create completely new rotor profiles, which had been adapted to the requirements for running an integrating motor using the latest design methods. These profiles ensure a low-resistance, high-precision measurement with optimally distributed masses that are also reduced by up to 45%. This results in a much better response characteristic in hydraulic applications- a big advantage over previously available devices.

Also in process engineering, these new types of profiles enable a low-resistance, high-precision measurement combined with the gentle transport of the measuring medium since many of the adhesives and sealants to be measured are sensitive to mechanical influences of the previously available devices.

In addition to the profile development, VSE also has optimized materials and technology concerning the bearings. The combined radial / axial roller bearing is shielded behind bearing supports shaped to be flow-optimized. Depending on size and intended use, either spindle bearings or precision ball bearings are used in tandem. Mounting is symmetrical, making it possible to operate the devices with the same loads in either flow direction. The bearings are made from tungsten carbide, and displacement flow meters are also made from silicon carbide (SSiC) for the first time. For poorly lubricated or dirty fluids, a radial / axial glide bearing made of ceramic materials is available. The combination with the corresponding rotor materials as well as optional hard coatings guarantees a long service life. The housing and rotor material can be modular graphite castings as well as roller bearing steel. All sizes are also available made from various kinds of stainless steels.

VSE also backs new developments in the area of signal formation. Based on the patented VSI high definition sensor system, a sensor module was developed that enhances the functionality of the RS flow meter significantly. The sensor itself features two GMR bridges (sin / cos) and is housed in a removable stainless steel cartridge case together with a signal conditioning and amplifier unit. It can be replaced when necessary without costly adjustment and configuration work. The sensor is adjusted automatically when being replaced.

The downstream electronics unit features a high-resolution sin / cos-interpolator, which can increase the resolution in increments up to a factor of 128 while maintaining exactly the same pulse lengths. The unit also has a variety of additional functions that significantly help users with the further processing of RS sensor signals. Among others, it features a programmable signal filter, which is able to offset unwanted, negative pulse sequences and detect and save values that exceed the indicated flow and temperature values. A separate directional signal is available for 1-channel evaluations.

It is therefore also possible to operate large-volume devices without the loss of frequency and accuracy while using low flow rates - a major advantage when operating with highly viscous or pasty as well as abrasive fluids. This means the frequency range can be adjusted and optimized for the respective measuring task. If required, flow-proportional output frequencies up to 100 kHz are possible.

Functionality can be further increased with other programmable options, for example, the flow meter can be adjusted to the respective measuring task without investing too much effort on the evaluation side.

The goal was to make a smarter flow meter to increase the functionality and lower the load on the corresponding electronic evaluation equipment of the user.

Additional functions still under development can be retrofitted subsequently using software upgrades, also on-site.

Various sizes for flow ranges of 0.1 to 1,000 l/min are available; the devices are designed for pressures up to 450 bar and suitable for temperatures of up to 120°C.