Cool magnets enable viewing of microscopic structures
13 May 2008
Meeting the challenge of controlling very high flow rates, with differential pressures and to very high accuracy, were among the key factors in a successful ‘cooling’ application, recently completed using Samson Control Valves. The Diamond Light Source synchrotron in Didcot, Oxfordshire, is the largest science facility to be built in the UK for 40 years, the company states. The synchrotron can be described as a “super microscope” which enables scientists to see microscopic structures such as cells and atoms in great detail using X-rays, ultraviolet and infrared beams. The machine covers an area equivalent to five football pitches and within it are three accelerators, which can generate intense light beams 10 billion times brighter than the sun.
Electrons are fired out of an electron gun down a linear tube and into a small booster ring to increase their energy, and then into a giant storage ring where they zoom around at almost the speed of light. By applying a magnetic field, the electrons are then forced to bend and follow the path of the storage ring and in the process of doing so, they emit synchrotron light in the form of X-rays, ultraviolet light and infrared rays. This light can then be exploited by scientists to carry out their research. Over 450 magnets are used to generate the magnetic field required to drive the electrons around the ring.
A significant amount of heat is generated by the magnets, necessitating cooling to prevent overheating. The cooling is achieved using processed ionised water, which is pumped around the site by large pumps delivering over 200 lit/sec at pump heads of up to 10 Bar.
An important part of the process is to ensure that each magnet is supplied with the correct amount of cooling water at a differential pressure which will not cause damage to the sophisticated magnets.
The challenge given to Samson was to provide self-operated differential pressure regulators, which could pass high flow rates and control differential pressure to high accuracy. However, as self-operated valves are proportional controllers, they exhibit a degree of offset. Although this is not important in most applications, for the Diamond Light Source project, the typical offset would not be acceptable. Therefore, pilot and non-pilot valves were selected to suit Diamond’s flow / pressure tolerances. For the high accuracy circuits, Samson provided special type 2333 pilot operated valves made entirely in stainless steel to suit the processed ionised water application, along with more standard (but still all stainless) type 42-24 and 42-25 differential pressure regulators for the less demanding circuits. When commissioned, the Samson regulators ensured that each magnet received its allocated water supply, and no more, regardless of the amount of systems running at any given time.
Thanks to their modular design, sizes up to DN 500, pressure-balanced, multi-staged plugs and noise reducing trims, Samson Control valves are designed to keep everything under control, even when applications involve challenging conditions, such as high pressure drops and extreme temperatures.
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