Replacement for Internal Active Thermal Control System Fluid Sample Bag Material

The International Space Station (ISS) Internal Active Thermal Control System (IATCS) uses a water based heat transport fluid with specific chemical parameters and additives for corrosion and microbial control. The fluid and hardware have experienced anomalies since activation of the United States Laboratory (USL), including chemical and possibly, microbial corrosion. The required sampling of the fluid has the crewmembers removing samples via an in-line sampling tool to perform real-time trace ammonia contamination tests using color change strips, and filling a 150 ml bag from each loop for the ground laboratory analyses. The former activity requires stable storage of the strips, and for the latter activity, it is highly desirable to return the ground sample as stable as possible.

This paper describes the process for materials selection, test methods/set-up, results, and final recommendation for a replacement outer bag. The test results showed the Pactech HD300 with an adhesive closure gave significant improvement over the barrier properties of the present polyethylene ziplock bag. New bags for use by the future ISS crews will be made of the Pactech HD300 material.