Diamond Light Source, the synchrotron complex on the Harwell Science and Innovation Campus, produces x-ray, infrared and ultra-violet beams of exceptional brightness. These highly focused beams of light are enabling scientists and engineers to probe deep into the basic structure of matter and materials, answering fundamental questions about everything from the building blocks of life to the origin of our planet. When Diamond opened in 2007, seven cutting edge experimental stations, called ‘beamlines’ were operational. Four more are now operational, with an additional 11 in various stages of construction and optimisation, bringing the total of operational beamlines to 22 by 2012.
Mains water (via laboratory breaktanks) is supplied to all the laboratories and ultra pure water is generated locally wherever it is needed, directly from the main supply. Diamond has so far installed 20 of ELGA’s PURELAB Option-Q 15 laboratory water purifiers to meet this duty, each capable of producing up to 15 liters/hour of ultra pure water. With such a wide range of user applications, each demanding specific water quality standards, Diamond set a quality specification (Table 1) that would satisfy them all. Meeting this specification from mains water means that the PURELAB Option-Q has to cram a lot of technology into a small, bench-top cabinet, as the process flow (Figure 3) shows.
An integral pump boosts the main water pressure and delivers it to a pre-treatment cartridge that combines particle filtration and granular activated carbon to remover residual chlorine, heavy metals and organic contaminants. It then passes through a reverse osmosis membrane. The latest generation of membranes provide up to 98% rejection of dissolved ionic impurities and over 99% removal of organics, particles and bacteria. The resulting water, typically better than distilled water, is then passed to the ‘polishing’ section. This consists of a storage reservoir from which water is continuously re-circulated through an 185nm UV lamp and ion exchange cartridges to produce ultrapure water at 18.2 MΩ.. Finally, a 0.2 μm point of use filter ensures virtually sterile water at the dispensing tap.
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