Isotech milliK, User Maintenance Manual/Handbook

Page: 41 / 102

© Isothermal Technology Page 41 of 102 923 milliK manual - issue: 1.10
In the ‘Thermometer’ Window use the
↑ ↑ ↑ ↑ ↓ ↓ ↓ ↓
keys to select ‘Conversion’ parameter and then
use the
← ← ← ← → → → →
keys to select “IEC60751 (2008)”. This standard uses the Callendar Van Dusen
equation to convert resistance to temperature. To view the coefficients used in IEC60751
(2008), select ‘Coefficients’ and press the
↵
↵ ↵
↵
key. You cannot change these coefficient, but
you will be able to view the coefficients used in the IEC60751 (2008) standard:
3.9.3 Using a PRT with Callendar Van Dusen Conversion
PRTs and SPRTs can be calibrated individually (resistance-temperature characteristics
determined) in order to achieve low uncertainties. There are two algorithms used to represent
the thermometer’s characteristic (the Callendar Van Dusen equation and the ITS90
equations). The Callendar Van Dusen equation was developed first and was used as the
primary conversion algorithm for all PRTs up until 1990. It is still applicable for PRTs and
SPRT, although better uncertainty can be achieved by using the ITS90 equations (particularly
important when using higher accuracy SPRTs).
If your thermometer calibration is presented using Callendar Van Dusen coefficients (a,b,c or
α
,
β
,
δ
), use the
↑ ↑ ↑ ↑ ↓ ↓ ↓ ↓
keys in the ‘Thermometer’ Window to select ‘Conversion’ and then use
the
← ← ← ← → → → →
keys to select “Callendar Van Dusen”. Use the
↑ ↑ ↑ ↑ ↓ ↓ ↓ ↓
keys to select ‘Coefficients’ and
then press the
↵ ↵ ↵ ↵
key to open the ‘Callendar Van Dusen Coefficients’ Window: