Valve aids subatomic investigation

Bruker BioSpin in Rheinstetten, Germany used Hoerbiger-Origa's Tecno piezo-controlled air pressure regulator to drive an air turbine with precise blasts of air.

A piezo-controlled pressure regulating valve is helping chemists and physicists examine matter at the atomic and subatomic level by controlling rotational speed in a nuclear magnetic resonance chamber built at Bruker BioSpin in Rheinstetten, Germany.

Nondestructive analysis of materials is a key technique for scientists working in a wide range of fields, with much of the current work being conducted at the atomic level.

Bruker BioSpin has developed a system for nuclear magnetic resonance (NMR) analysis in which a sample container, supported on an air bearing is turned using precision blasts of air.

During the design stages the Bruker engineers undertook an extensive search for a suitable high-performance valve and found only one that met all their criteria, the Tecno proportional valve made by Hoerbiger-Origa.

NMR works on the same principle as the medical procedure of magnetic resonance tomography.

A very strong magnetic field is created within the chamber and radio waves are directed through it.

This affects material in the chamber by transferring atomic nuclei to different energy levels as they absorb the radio waves.

Different substances absorb different frequencies of wave, and can be identified by their 'resonance frequency'.

Because of the magnetic field, conventional electric motors cannot be used in this application and due to the spin speed an air bearing is the best option for supporting the rotor.

These two factors combine to suggest that an air motor may be the best prime mover for the system.

However few air motors are able to offer the precision required.

The Bruker team found the answer in using Hoerbiger-Origa's Tecno piezo-controlled air pressure regulator to drive an air turbine with precise blasts of air.

Proportional pressure control is achieved using a tiny piezo ceramic lever that is bi-stable under the effect of a nanovoltage signal.

One of its main attributes to Bruker is that its switching is practically instantaneous, providing very good control of air flow.

Another is that the nanovoltage does not adversely influence the magnetic field.

The chamber uses a second Tecno valve, this time controlling the air bearing in relation to the total mass of the rotor plus its test pieces.

A test procedure may involve several hours of operation, during which time the rotor may be turning at up to 3.9Mrev/min.

Part of the design brief was such that the Hoerbiger-Origa valve control movement to +/-4 revolutions.

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