ISO 916:2020 pdf free.Testing of refrigerating systems.
The following shall be subject to agreement: a) the condition of the cooled medium at the inlet and outlet of the evaporator or at two defined points of the cooled medium circuit; or b) the condition of the cooled medium at the inlet or outlet of the evaporator or at a defined point of the cooled medium circuit as well as the corresponding mass flow. The condition of the cooled medium does not only include its temperature but also its physical data.Conversion to warranty conditions The conversion to warranty conditions requires the indication of the compressor speed or the power supply frequency (for motor compressors), respectively, the refrigerant pressures in the evaporator and the condenser or the evaporation and condensing temperature, respectively, as well as the intermediate pressures in case of multiple-stage systems. For this purpose, the permissible deviations of the operating conditions for testing shall be specified.Methods for correction to measured performance to indicate performance at warranty conditions shall be agreed. See also 11.5.The tolerance refers to deviations from the assured property (e.g. refrigerating capacity, power absorbed, and COP) which are caused by the manufacturing process and shall be agreed separately. The permissible deviation of measured values from the assured property is the sum of the tolerance and the overall measurement uncertainty of the applied measurement method. In cases where zero negative tolerance has been specified in relation to manufacturing tolerances in 5.4, allowance for measurement uncertainty shall still apply.
6 Test preparation and procedure
6.1 The test shall be carried out with all values in steady-state condition and in addition particularly
with the compressor and the motor at operating temperature.
6.2 Prior to any measurement, it shall be ensured that heat exchanger surfaces not in contact with the refrigerant are clean. This applies, for example, to the cooling water side of condensers and the secondary refrigerant side of the evaporator.7.1 General
7.1.1 The condensing and evaporating temperatures are derived from the absolute pressure readings, where the sources according to 12.1 are used and the purging measures according to 6.10 are followed.
7.1.2 Only measuring instruments with fully verifiable indications shall be used. It is essential that the
measurement uncertainty can be determined by calibration and does not vary during testing. Measuring instruments whose condition may vary during the test shall be verified both before and after testing. The measurement uncertainty values indicated below refer to the extended measurement uncertainty with a confidence interval of 95 % corresponding to twice the standard deviation. 7.1.3 Besides the types of measuring instruments indicated below, other generally accepted measuring instruments or devices may be used provided they comply with the indicated measurement uncertainties. 7.2 Temperature measuring instruments The measurement uncertainty of the temperature measuring instrument shall be within the following limits while 7.1 shall be taken into account: a] for measuring the temperatures of cooled medium in the evaporator or cooling water in the condenser +0,1 K; a) for all other temperature measurements +0,5 K.The refrigerant mass flow can be determined for both the entirely liquid state and the entirely gaseous state by means of a flow meter in accordance with Clause 7 if the piping is provided with antipulsation devices or if it is free from pulsation and provided the measured values are not impaired by unacceptably large amounts of oil.ISO 916 pdf download.