The purpose of this thesis was to fully evaluate the performance of "NDJ-1", an analog rotational viscometer of questionable manufacture and certification imported from China. In experimentation we focused on accuracy and precision in the range 1-100 mPas which we evaluated with the use of standard sucrose solutions and a reference device Anton Paar ViscoQC 300 – L. Results showed a combined uncertainty equal to the confidence interval of 〖CI〗_(95 %)/η=± 10 % η between 15-100 mPas. Low relative precision in the range between 3-15 mPas means that consecutive measurements should be taken to reach an acceptable CI. Under 3 mPas results are not reliable. We speculate that the ± 10 % uncertainty continues through the range of viscosity between 100-105 mPas. In comparing NDJ-1 to the reference device additional weaknesses like high minimum time between measurements (⡥ 16,2 s), low number of sped settings (4), lack of automatization and lack of spindles for low viscosity measurements were identified. Although the weaknesses lower versatility and potential for measurement of non-Newtonian fluids NDJ-1 is certainly a useful device. If precision, accuracy, productivity, and price satisfy the needs of a potential user and no comparable certified solution is affordable purchase may be justified. Concerns over the manufacturers of such devices and by extension their certificates make our results non-directly-transferable to devices of similar look and name. Thus, we deem NDJ-1 inappropriate for monitoring HACCP.
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