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PRESS RELEASE : Fluke Hart Scientific’s New Triple Point of Water Cells Contain VSMOW (Vienna Standard Mean Ocean Water)

AMERICAN FORK, UT — Fluke’s Hart Scientific Division, the world leader in temperature calibration, announces new triple point of water cells. The triple point of water occurs when water coexists within a single glass enclosure (typically glass) in all three of its phases: gas, liquid, and solid. It is defined within the International Temperature Scale as 0.01°C and is the most accurate device used to calibrate or verify thermometers.

Each of these new cells contains distilled ocean water which has an isotopic composition that is nearly identical to the international standard “Vienna Standard Mean Ocean Water” or “VSMOW.” Errors associated with poor isotopic composition can be as large as 0.00025 °C (0.25mK). The uncertainty contribution from VSMOW errors in these new cells is less than ±0.000007 °C (7µK).

Hart’s triple point of water cells are designed for use by commercial and military laboratories as well as in other settings requiring a check standard or calibration point for thermometers. The high level of accuracy of the triple point of water cells provides a way to identify unacceptable drift between calibrations.

Hart Scientific offers two series of cells. The 5901X-G series use a borosilicate glass shell. The 5901X-Q series use a fused silica or quartz shell. Research indicates that quartz is more effective at preventing the leaching of impurities than is glass. Each series has a variety of sizes to accommodate different sizes of thermometers.

Prices for these cells range from $800 to $1965. Cells ship 5 days ARO.

Fluke’s Hart Scientific Division designs, manufactures, and markets temperature measurement and calibration equipment. The Hart Scientific product line includes primary standards, thermometer readouts and probes, temperature baths, industrial calibrators and software. Primary and secondary laboratories, as well as a growing number of manufacturing companies who rely on precise temperature controls for manufacturing processes, use the equipment. These industries include pharmaceuticals, petrochemical, semiconductor, aerospace, food products and others. For more information contact Hart Scientific Inc. at 801-763-1600, visit their Web site at, or e-mail