Flow meters aid research in ionisation and X-ray experimentation

Paul Boughton

Custom flow meter manufacturer and distributor Litre Meter has supplied Sierra Smart-Trak and Micro-Trak volume flow meters 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 infra red 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 (0.001 mm) in size, about the size of cells. However, to study smaller objects like molecules and atoms, light with shorter wavelengths like 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 incredible detail. The experiments performed at Diamond 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 to scientists and engineers at Diamond. 

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

The Micro-Trak101 series incorporates new, state-of-the-art sensor technology and a precision-engineered direct acting valve design to measure ultra-low gas flow accurately and reliably.

The instrument has been designed to operate at flow ranges under 4 standard cubic centimetres per minute (sccm) with a minimum controllable mass flow rate of 0.1 sccm. 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 that involve corrosive and toxic gases.

Smart-Trak and Micro-Trak incorporate Sierra’s Dial-A-Gas. Its internal microprocessor is pre-programmed with ten gases that are commonly used in biotech, pharmaceutical, analytical and research applications – others gases can be substituted to customise the flowmeter for applications. This technology allows the instrument to be used for multiple applications, creating great flexibility as well as helping to reduce spares inventory. 

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

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 which replaces expensive control and readout electronics, available mounted to the face of the instrument or in a convenient hand-held version. It enables a range of control functions including gas type, setpoint 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 like gas mixing and blending, batch control, leak testing and process monitoring at a fraction of the cost of complex programmed logic controllers (PLCs). A Compod, coupled with Sierra’s Smart-Trak mass flow meters and controllers, simplifies basic flow control installations and permits networking of multiple instruments using open source MODBUS RTU protocol. Two digital outputs and one analogue input can be configured by the end user for a wide variety of process controls. Unlike dedicated PLCs, a Compod is a small device that mounts locally to the face of the Smart-Trak MFC.

For more information, visit www.litremeter.com

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