CONTROL OF METROLOGICAL CHARACTERISTICS OF HEAT METERS DURING OPERATION
The purpose of this article is to consider the features of calibration of single heat meters during operation.
Results of operation
Heat meters belong to the field of legally regulated metrology, as their measurement results are used in calculations between consumers and suppliers of heat for heating and hot water supply, so they are subject to periodic verification during operation and after repair. The so-called single heat meters have been widely used in the equipment of individual heat metering units for space heating. The peculiarity of single heat meters is that for them the error in measuring the amount of heat is normalized and experimentally determined without dividing it into the errors of the components. The physical quantities supplied to the heat meter inputs are reproduced тепло the heat carrier consumption and the heat carrier temperature. In this case, the water temperature in the flow unit corresponds to the ambient temperature, and the temperature in the thermostats to the temperatures in the supply and return flows. However, for heat meters based on ultrasonic method of washing the coolant flow with compensation of changes in the speed of ultrasound from the temperature of the coolant, this calibration technique cannot be applied due to a methodological error from replacing the variable speed of ultrasound with a constant value. To ensure the reliability of the verification results, a methodology was developed, according to which the verification is carried out in two stages. At the first stage, the error of the heat meter is determined when measuring the flow rate as the difference between the readings of the heat meter and the reference value of the flow rate reproduced by the spill unit. In this case, the temperature superheater of the heat meter is placed in a thermostat with a temperature equal to the temperature of the water in the pouring unit. This eliminates the methodological error from the temperature mismatch in the thermostat and in the pouring unit. In the second stage, the error of the heat meter is determined when measuring the temperature and calculating the amount of heat. In this case, the reference values in the thermostats and the readings of the heat cell when measuring the consumption of the heat carrier are taken as the reference values of the reproducible values. The total error of a single heat meter is defined as the sum of the errors obtained during the first and second stages of verification.
Conclusion Calibration of heat meters during operation contributes to obtaining reliable results of measurements of the amount of heat consumed in the housing stock, and the development on the basis of these results of measures aimed at the rational use of energy resources.
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