Foreword

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This document was prepared by Technical Committee ISO/TC 86, Refrigeration and air-conditioning, Subcommittee SC 4, Testing and rating of refrigerant compressors.

This first edition of ISO 18976 is a technical revision of ISO 917:1989 , which was withdrawn in 2015.

The main changes are as follows:

addition of two stage and economized compressors;
Clause 2 was updated;
Clause 3 was updated, additional terms defined because of, for example, refrigerant blends with temperature glide;
addition of the new Clause 4 “Uncertainty of measurement and test conditions”;
deletion of the list of measuring devices;
extraction of calibration of calorimetric methods into a separate clause;
addition of transcritical application;
addition of test requirements for inverter driven compressors;
addition of cyclic capacity control;
reference point numbering, symbols and indexes revised to allow for economised compressors and to simplify formulae;
former Annex B regarding the list of symbols was moved under Clause 3;
the text content of former Annex C was revised and is now Annex B “Estimation of errors”;
document was editorially revised.

Any feedback or questions on this document should be directed to the user’s national standards body. A complete listing of these bodies can be found at www.iso.org/members.html.

1 Scope

This document applies to single stage, two stage and economised refrigerant compressors. Selected test methods are described for the determination of the refrigerating capacity, the power input, the isentropic efficiency and where possible the volumetric efficiency. These test methods provide results of sufficient accuracy to permit consideration of the suitability of a refrigerant compressor to operate satisfactorily under any set of basic test conditions required for a given application.

NOTE Tests on complete refrigeration installations are dealt with in ISO 916 .

2 Normative references

3 Terms, definitions and symbols

3.1 Terms and definitions

3.2 Symbols

4 Uncertainty of measurement and test conditions

4.1 Uncertainty of performance data

4.2 Uncertainty of measurement

4.3 Refrigerant circuit state points

4.4 Test conditions

5 General requirements

5.1 Calculation methods

5.2 Requirements for the selection of a test method

5.3 Test period

5.4 Pressure and temperature measuring points

5.5 Oil circulation

5.6 Fractionation

5.7 Calibration of calorimeters

5.8 Source of refrigerant data

5.9 Kinetic refrigerant properties

6 Test methods

6.1 General

6.2 List of test methods

6.3 Choice of test methods for test X and test Y

6.4 Method A: Secondary fluid calorimeter

6.5 Method B: Flooded system calorimeter

6.6 Method C: Dry system refrigerant calorimeter

6.7 Method G: Water-cooled condenser/gas cooler on the discharge side

6.8 Method D: Refrigerant gas flow meter

6.9 Method F: Refrigerant flow meter in the liquid line

6.10 Method M: Energy balance on compressor

7 Determination of the power input by the compressor

7.1 Measurement

7.2 Calculation

8 Test report

8.1 General

8.2 Test results

Bibliography