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| NTPL - Isotech's Calibration Laboratory | |||||||||||||||||||||||
| NTPL - Comparison Laboratory | |||||||||||||||||||||||
| Lab News: Smaller Uncertainties for the Cal Lab Isotech’s Northern Temperature Primary Laboratory (NTPL) achieves even smaller uncertainties, again! A purpose of NTPL is to inter-compare fixed point cells and to calibrate SPRTs. SPRTs have definite limitations due to variations in the oxide state of the platinum. Changes of up to 1mK occur at the water triple point temperature after large temperature excursions of an SPRT. Reference Isotech Journal of Thermometry Vol 5 I Reference Isotech Journal of Thermometry Vol 5 Issue 1. However if an SPRT is used over a limited range, from minus 40°C to plus 30°C it can remain very stable. In reviewing our uncertainties we felt it was worth reducing the uncertainties at the Mercury Triple Point, the Water Triple Point and the Gallium Triple Point, since calibrations with uncertainties smaller then 1mK can be maintained. Our new UKAS Schedule, 31st March 04, reflects our desire to offer clients the best service available. At Mercury, Water and Gallium Triple points NTPL have uncertainties second only to NIST |
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Take a Tour: The Comparison LabFirst Stop: TTI 2 The TTI 2 is the ideal 1mK bridge. Can hold calibration data for up to 10 thermometers. Automatically averages up to 50 readings to a resolution of up to 0.000,01°C and calculates the standard deviation. Simplicity itself to use. Next Stop: Water Triple Point Cells In the bath are our water triple point cells, the uncertainty for our reference cells is +/-0.000,050°C at 1 sigma, our WTP UKAS accreditation is +/-0.000,070°C. Used here to check our many standard thermometers.  Next Stop: Gallium Standards A new plateau - all day, every day. Recently enhanced the Gallium Apparatus Model ITL-M-17401 is now fully automated.
Used to check and calibrate our SPRTs, our watchdog. Next Stop: Liquid baths Two models, 814 and 915 (pictured) give use from -80°C to 288°C. Uncertainties to 1mK. Our SPRTS connected to the TTI 2 are used as standards to which the units under test are compared. Next Stop: Fluidised Furnace Above 288°C we switch firstly to our Fluidised Calibration Bath Model 875. It circulates aluminium oxide for excellent temperature uniformity, the bath is sealed so the powder stays in the bath. There are no fumes; a problem with high temperature oil and salt baths. Used up to 700°C with uncertainties to +/-0.003°C at 660°C.
Next Stop: Spherical Furnace For high temperature thermocouple calibration, up to 1300°C, we switch to the Spherical Furnace model 877. Its concentric design gives performance in the order of 0.1°C at 1000°C. A platinum wrap reduces electrical noise and enhances performance.
Last Stop
Have you visited our primary lab?
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View UKAS Schedule
Tour the Primary Laboratory
Laboratory Training
For these temperatures we use our standard thermocouples. 
Along with the full range of comparison baths the Secondary Laboratory also maintains a set of Slim Fixed Point Cells. These cells have been used over the past 10 years during which time the design has been continually improved to offer the smallest uncertainties. But don't just take our word for it, PTB recently compared a set of Slim Cells maintained in Isotech POTTS against their own National Standards. The uncertainties assigned to the the cells in the apparatus is show below.