This standard defines qualification and acceptance requirements for two-phase heat transportation equipment (TPHTE), for use in spacecraft thermal control. This standard is applicable to qualification and acceptance activities of new hardware. However, acceptance requirements of this Standard can be used for existing hardware, which has been qualified previously to other requirements then listed herein. Requirements for mechanical pump driven loops (MPDL) are not included in the present version of this Standard. This standard also includes definitions and part of the requirements of ECSS-E-ST-32-02 applicable to TPHTE qualification. This standard may be tailored for the specific characteristics and constrains of a space project in conformance with ECSS-S-ST-00.