The storage cylinders were placed in 149°C ovens for 28 days. The coupons were weighed and checked for appearance before and after testing, and the agent was analyzed using Fourier transform infrared (FT-IR) spectroscopy before and after testing. Peacock et al. concluded the following:

  1. "No new compounds, observable above background, were evident after 28 day, 150°C exposure of any of the candidate agents."
  2. "A possible decrease in integrated areas for selected spectral peaks was observed only for CF3I. This observation may be within experimental error, and was without accompanying formation of new compounds. An observation of a dark solid on metal coupons post-exposure for this agent may have been I2 which could result from either degradation or impurity in the original agent. Longer term study is warranted for this agent."
  3. "For the chemicals studies, stability in long-term storage and agent residue should not be major deciding factors in determining selection of appropriate agents for further study. As noted above, CF3I could be an exception."

In a second study, Harris2 examined FC-218, HFC-125, HFC-227ea, and CF3I more closely, that is, over a longer time and at more than one temperature (see Table C.3).

All agents were tested in the presence of Nitronic-40, Ti-15-3-3-3, C4130, and Inconel 625. The storage vessels were stored at the prescribed temperatures for as many as 52 weeks. At specific times the cylinders were removed from storage, cooled, and the contents analyzed by FT-IR. After conducting the study, Harris concluded:

  1. "The fluorocarbon agents FC-218, HFC-125, and HFC-227ea were stable at temperatures as high as 150°C for as long as 48 weeks. No by-products were formed."
  2. "CF3I degraded at 100°C and was accelerated at 150°C."
  3. "CF3H, CO2, and CO were produced in low levels as degradation products of CF3I."
  4. "The presence of moisture accelerates the degradation of CF3I."
  5. "The presence of copper accelerates the degradation of CF3I."
  6. "The presence of copper and moisture accelerate the degradation of CF3I."
  7. "An abundance band at 950 cm-1 was generated in the CF3I samples that may be from a fluorinated alkene; the presence of copper at 150°C caused the double bond to break."
  8. "Storage at ambient conditions of any of the four agents is feasible, but storage at elevated temperatures for CF3I needs more study."

Table C.3 Test Matrix for Harris Study

Agent

Temperature

FC-218

150°C

HCFC-125

23°C and 150°C

HFC-227ea

23°C, 100°C, and 150°C

CF3I (dry)

23°C, 100°C, and 150°C

CF3I with Cu (dry)

23°C and 150°C

CF3I (moist)

150°C

CF3I with Cu (moist)

150°C



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