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Litre Meter has supplied Sierra Smart-Trak and Micro-Trak volume flowmeters to research facility Diamond Light Source for use in ionisation and X-ray experimentation.

Diamond Light Source is a new scientific facility in Oxfordshire, called a Synchrotron, which generates high-intensity light beams across the light spectrum, from infrared to X-ray.

These light beams are then used in a range of scientific experiments by visiting researchers or users.

Optical microscopes can be used to study objects that are a few microns (0.001mm) in size – about the size of cells.

However, to study smaller objects such as molecules and atoms, light with shorter wavelengths such as X-rays is needed.

Synchrotron light can be as much as 10 billion times brighter than the sun.

This allows scientists to study minute samples in detail.

The experiments performed at Diamond Light Souce often require the use of gas-filled X-ray detectors and sample chambers operated at a range of flow rates and with different gas mixtures.

The measurement and control of extremely low gas mass flow is a necessity for the scientists and engineers at Diamond Light Source.

Scientists at the facility have selected Micro-Trak and Smart-Trak digital mass flowmeters to control the flow of gases used for various scientific applications.

The Micro-Trak 101 series incorporates new sensor technology and a precision-engineered direct-acting valve design to accurately measure ultra-low gas flow.

The instrument has been designed to operate at flow ranges of less than 4sccm with a minimum controllable mass flow rate of 0.1sccm.

According to Litre Meter, it is highly stable and delivers a measurement accuracy of +/-1.0 per cent full scale and +/-0.2 per cent repeatability.

Micro-Trak has a stainless-steel flow path and elastomer seals that eliminate the possibility of leaks.

It is suitable for use in most applications involving clean gases, including those with corrosive and toxic gases.

Smart-Trak and Micro-Trak incorporate Sierra’s Dial-A-Gas function.

Its internal microprocessor is pre-programmed with 10 gases that are commonly used in biotechnology, pharmaceutical, analytical and research applications; others gases can be substituted to customise the flowmeter for various applications.

This technology allows the instrument to be used for multiple applications, helping to reduce spares inventory.

Paul Quinn of Diamond Light Source said: ‘It is essential to keep a uniform flow of gas in our experiments as variations in gas mixture or flow rate can give spurious results.

‘We use the Smart-Trak and Micro-Trak meters to monitor the flow of the gases we use and to control the mixture of gases such as helium and argon.

‘Having a controller on the instrument makes it easier.

‘The Dial-A-Gas function is useful because it means we don’t have to recalibrate the instruments and recalculate flow rates when we want to use different gases,’ he added.

For higher flows, the Smart-Trak 2 has an accuracy of +/-0.5 per cent of full scale and can measure flow ranges from 0-10sccm to 0-1,000slpm.

Constructed in 316 stainless steel, the instrument features a fast-response control valve and primary standard calibration and National Institute of Standards and Technology (NIST) traceability.

It also has a pilot module that replaces expensive control and readout electronics, available mounted to the face of the instrument or in a handheld version.

The instrument enables a range of control functions, including gas type, set-point value and source, engineering units, output signal and valve state (open, closed or automatic).

These control functions are also available from a PC via RS-232.

Source code for RS-232 communication is provided but it has multi-drop RS-485/Modbus RTU capability using Sierra’s Compod.

The Compod enables simple gas processes such as gas mixing and blending, batch control, leak testing and process monitoring at a lower cost than complex programmed logic controllers (PLCs), according to the company.

A Compod, coupled with Sierra’s Smart-Trak mass flowmeters and controllers, facilitates basic flow control installations and permits the networking of multiple instruments using the open-source Modbus RTU protocol.

Two digital outputs and one analogue input can be configured by the end user for a variety of process controls.

Unlike dedicated PLCs, a Compod is a small device that mounts locally to the face of the Smart-Trak MFC.

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