WATER-COOLED CHILLER UNITS FOR HELIUM RELIQUIFIERS.

The mission of the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) is to conduct and support medical research and research training and to disseminate science-based information on diabetes and other endocrine and metabolic diseases; digestive diseases, nutritional disorders, and obesity; and kidney, urologic, and hematologic diseases, to improve people’s health and quality of life.

The Solid-State NMR and Biomolecular Physics Section (SSNMRBPS) of the Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases carries out research on the molecular structures and interactions of proteins and protein assemblies with important roles in biology and human disease.  This research depends on nuclear magnetic resonance (NMR) measurements that are performed in helium-cooled superconducting magnets.   To eliminate requirements for periodic helium refills of two NMR magnets, located in buildings 5 and 8 on the NIH campus in Bethesda, MD, SSNMRBPS is currently procuring two helium reliquifier systems.  These helium reliquifier systems require a constant flow of chilled water to remove heat that is generated in the helium reliquification process.  It is therefore necessary to procure two chiller units, which will be used in conjunction with the helium reliquifier systems.  The two chiller units must be water-cooled (rather than air-cooled) to avoid excessive heating within the rooms that contain the NMR magnet