Testing of equipment according to the ATP is basically done in two phases:

(a) Measurement of the insulating capacity, that is, the K-coefficient, of the insulated body.

(b) Determination of the efficiency of the thermal appliance as installed in the insulated body. In the case of mechanically refrigerated equipment, the mechanical refrigerating appliance may be tested separate from the body.

The K-coefficient shall be measured according to the procedures in ATP, Annex 1, Appendix 2, paragraphs 1-28, and the following shall apply:

(a) The internal heating method shall be used.

(b) In ATP, Annex 1, Appendix 2, paragraph 8, last line, “about + 20 °C for the mean temperature of the walls of the body shall be interpreted to mean between +19 °C (+66 °F) and 21 °C (+70 °F).

(c) A report of each test shall be completed on a form corresponding to the pertinent test report model prescribed in ATP, Annex 1, Appendix 2. Report forms may be obtained by a request to the ATP manager.

In determining the efficiency of a thermal appliance with respect to maintaining a prescribed temperature inside the body, the procedures in ATP, Annex 1, Appendix 2, paragraphs 31-40 and 43-47 shall be used. A report of each test shall be completed on a form corresponding to the pertinent test report model prescribed in ATP, Annex 1, Appendix 2. Report forms may be obtained by a request to the ATP manager.