Section 7. Installation
Eq. 1 and Eq. 2 yield approximations of the true linearity of a PRT. The
approximation error can be as high as several hundredths of a degree Celsius at
different points in the temperature range, and it varies from sensor to sensor.
Individual sensors also have errors relative to the ASTM E1137-04 standard.
These errors can be as much as ±0.3 °C at 0 °C and increasing away from 0 °C.
Purchasing high quality PRTs will minimize this error.
The best accuracy comes from calibrated sensors over the range of use.
Calibration factors are applied to one or more of the following PRTCalc()
parameters:
• Source
• Multiplier
• Offset
See the calibration sections in the previous PRT procedures for more information.
The following tables show sets of a, d, e, f, g, h, i, and j coefficients that are used
in the Eqs. 1 and 2, depending on the PRTType code entered in PRTCalc().
Coefficients are rounded to the seventh significant digit to match CR800 math
resolution.
PRTType codes depend on the alpha value of the PRT, which is determined and
published by the PRT manufacturer.
PRTCalc() PRTType = 1, α = 0.00385
1
Constants Coefficient
a 3.9083000E-03
d -2.3100000E-06
e 1.7584810E-05
f -1.1550000E-06
g 1.7909000E+00
h -2.9236300E+00
i 9.1455000E+00
j 2.5581900E+02
1
Compliant with the following standards: IEC 60751:2008 (IEC 751), ASTM
E1137-04, JIS 1604:1997, EN 60751, DIN43760, BS1904, and others
(reference IEC 60751 and ASTM E1137), α = 0.00385
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