INGENIEUR
SETPOINT NO . 1 Setpoint Upper : 15.00 ° C Setpoint Lower : 40.00 ° C
Temperature Upper : 15.01 ° C CalibFactor Upper : 0.014827 Results Upper : 0.05857 W / mK HeatFlux Upper : 58.61 W / m 2 Temperature Lower : 40.03 ° C CalibFactor Lower : 0.013529 Results Lower : 0.06104 W / mK Percent Difference : 4.13 % HeatFlux Lower : 61.08 W / m 2 Temperature Average : 27.52 ° C Results Average : 0.05981 W / mK Resistance Avg : 0.4179 m 2 K / W R / unit Avg : 16.72 mK / W R-value : 2.373 Figure 8 : Test results for nitrile rubber insulation
MEASUREMENT UNCERTAINTY IN TESTING
The results from the steady-state thermal transmission properties testing are not 100 % accurate since there exist elements of uncertainty that may affect the measurement . Sources of uncertainty in measuring with a heat flow apparatus can be divided into three categories , namely ( a ) uncertainty in the precision of the standard reference material used as a calibrating specimen ; ( b ) uncertainty in the precision of the heat flow meter and other measuring devices like callipers ; and ( c ) uncertainty due to the fact that the calibrating specimen and the test specimen are not identical , thus they do not have identical heat transfer properties .
Therefore , it is crucial that the overall uncertainty is minimised . In the case of the testing done at the MRL , the maximum allowable uncertainty is 3 %.
TESTING AS PART OF ACCEPTANCE CRITERIA IN QUALITY ASSURANCE
The article has demonstrated the potential of the steady-state thermal transmission properties test for building materials as a quality assurance tool . The test could assist building designers and project supervisors in ensuring construction materials delivered on site comply with what is agreed upon in the contract prior to installation .
REFERENCE
ASTM Standard C518 , 2017 , Standard Test Method for Steady-State Thermal Transmission Properties by Means of the Heat Flow Meter Apparatus , ASTM International , West Conshohocken , PA , 2017 , DOI : 10.1520 / C0518-17 , www . astm . org .
74 VOL 89 JANUARY-MARCH 2022