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Methylhydrazine Part 2

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Encyclopedia of Liquid Fuels
This chapter is in the book Encyclopedia of Liquid Fuels
8 Materials of Construction for MMH4043Theself-contained atmospheric protection ensemble (SCAPE) suits used at NASAlaunch sites are made from a chlorobutyl-coated Nomex fabric. The fabric and its coat-ing is subjected to wear and tear and its integrity needs to be monitored daily [571].Splash evaporation tests of propellants spilled on space suit materials at threedifferent initial sample temperatures showed that most propellant spills freeze almostimmediately in vacuum [572, 573]. Hydrazine supercooled to 355K and then froze toice, which was near the triple-point temperature. The force needed to scrape frozenhydrazinefromthematerialsamplebyscrapingandthetimeneededtosublimefrozenhydrazine under one solar flux (simulated with a heat lamp) was measured. MMH didnot freeze but evaporated before much ice could form. MMH was the only propellantthat visually damaged the suit material. Aluminized Mylar layers were found to bedissolved in the area where the propellant had impinged on the fabric. SupercooledMMH dissolved the aluminized Mylar layers of the suit ensemble, and both hydrazineand MMH caused cracking in the polycarbonate helmet visor, but not in the helmetmaterial alone.Permeation resistance was determined by measuring the breakthrough time andtime-averaged vapor transmission rate of MMH through the fabric of two types of per-sonal protective equipment (PPE) suits [574]. The two types of PPE evaluated werethe totally encapsulating ILC Dover Chemturion, Model 1212 chemical protective suitand the FabOhio polyvinyl chloride (PVC) splash garment. Two exposure scenarioswere simulated:(1)a saturated vapor exposure for 2h, and(2)a brief MMH “splash”followed by a 2-h saturated vapor exposure. Time-averaged MMH concentrations in-side the totally encapsulating suit were calculated by summation of the area-weightedcontributions made by each suit component. Results showed that the totally encap-sulating suit provides adequate protection at the new 10-ppb Threshold Limit ValueTime-Weighted Average (TLV-TWA). The permeation resistance of the PVC splash gar-ment to MMH was poorer than any of the totally encapsulating suit materials tested.Breakthrough occurred soon after initial vapor or “splash” exposureCalculations showed that the maximum allowable permeation rates of hydrazinefuels through chlorinated polyethylene were of the order of 0.05 to 0.08ngcm−2min.−1for encapsulating suits with low breathing air flow rates (of the order of 5scfm or140L/min.) [575]. Above these permeation rates, the 10 parts-per-billion (ppb) TLV-TWA could be exceeded.8 Materials of Construction for MMHQuite often data for a particular material of construction may be available for one oftheotherthreepropellanthydrazines,butnotforthehydrazineofinterest.Toalimitedextent, it is possible to extrapolate metals compatibility data from one hydrazine toanother. For metallic materials, the extrapolation is easier than for non-metals. Metalsfound to be compatible with hydrazine are most likely to be compatible with MMH and
© 2022 Walter de Gruyter GmbH, Berlin/Boston

8 Materials of Construction for MMH4043Theself-contained atmospheric protection ensemble (SCAPE) suits used at NASAlaunch sites are made from a chlorobutyl-coated Nomex fabric. The fabric and its coat-ing is subjected to wear and tear and its integrity needs to be monitored daily [571].Splash evaporation tests of propellants spilled on space suit materials at threedifferent initial sample temperatures showed that most propellant spills freeze almostimmediately in vacuum [572, 573]. Hydrazine supercooled to 355K and then froze toice, which was near the triple-point temperature. The force needed to scrape frozenhydrazinefromthematerialsamplebyscrapingandthetimeneededtosublimefrozenhydrazine under one solar flux (simulated with a heat lamp) was measured. MMH didnot freeze but evaporated before much ice could form. MMH was the only propellantthat visually damaged the suit material. Aluminized Mylar layers were found to bedissolved in the area where the propellant had impinged on the fabric. SupercooledMMH dissolved the aluminized Mylar layers of the suit ensemble, and both hydrazineand MMH caused cracking in the polycarbonate helmet visor, but not in the helmetmaterial alone.Permeation resistance was determined by measuring the breakthrough time andtime-averaged vapor transmission rate of MMH through the fabric of two types of per-sonal protective equipment (PPE) suits [574]. The two types of PPE evaluated werethe totally encapsulating ILC Dover Chemturion, Model 1212 chemical protective suitand the FabOhio polyvinyl chloride (PVC) splash garment. Two exposure scenarioswere simulated:(1)a saturated vapor exposure for 2h, and(2)a brief MMH “splash”followed by a 2-h saturated vapor exposure. Time-averaged MMH concentrations in-side the totally encapsulating suit were calculated by summation of the area-weightedcontributions made by each suit component. Results showed that the totally encap-sulating suit provides adequate protection at the new 10-ppb Threshold Limit ValueTime-Weighted Average (TLV-TWA). The permeation resistance of the PVC splash gar-ment to MMH was poorer than any of the totally encapsulating suit materials tested.Breakthrough occurred soon after initial vapor or “splash” exposureCalculations showed that the maximum allowable permeation rates of hydrazinefuels through chlorinated polyethylene were of the order of 0.05 to 0.08ngcm−2min.−1for encapsulating suits with low breathing air flow rates (of the order of 5scfm or140L/min.) [575]. Above these permeation rates, the 10 parts-per-billion (ppb) TLV-TWA could be exceeded.8 Materials of Construction for MMHQuite often data for a particular material of construction may be available for one oftheotherthreepropellanthydrazines,butnotforthehydrazineofinterest.Toalimitedextent, it is possible to extrapolate metals compatibility data from one hydrazine toanother. For metallic materials, the extrapolation is easier than for non-metals. Metalsfound to be compatible with hydrazine are most likely to be compatible with MMH and
© 2022 Walter de Gruyter GmbH, Berlin/Boston

Chapters in this book

  1. Frontmatter I
  2. Foreword V
  3. Preface VII
  4. Contents XI
  5. Volume 1: Alcohols – Amides and Imides
  6. Alcohols 1
  7. Aliphatic Amines 55
  8. Alkanes 221
  9. Alkenes and Alkynes 367
  10. Alkylboranes 397
  11. Alkylhydrazines 433
  12. Amides and Imides 501
  13. Volume 2: Ammonia – Dimethylhydrazines
  14. Ammonia 703
  15. Aromatic Amines 845
  16. Aromatic Hydrocarbons 875
  17. Azides and Azido Compounds 879
  18. Boranes 973
  19. Boron 1131
  20. Cyano Compounds and Nitriles 1143
  21. Cycloaliphatic Hydrocarbons 1165
  22. Dimethylhydrazines Part 1 1333
  23. Dimethylhydrazines Part 2 1499
  24. Volume 3: Ethers – Hydronitrogen Compounds
  25. Ethers 1639
  26. Heterocyclic and Heterocycloaliphatic Amines Part 1 1673
  27. Heterocyclic and Heterocycloaliphatic Amines Part 2 1910
  28. Hydrocarbons 2181
  29. Hydrogen Part 1 2199
  30. Hydrogen Part 2 2416
  31. Hydronitrogen Compounds 2569
  32. Volume 4: Hydrazine – Jet Fuels
  33. Hydrazine Part 1 2587
  34. Hydrazine Part 2 2809
  35. Hydrazine Part 3 3084
  36. Hydrazine Part 4 3216
  37. Ionic Liquids 3397
  38. Jet Fuels 3497
  39. Volume 5: Kerosenes – Ramjet Fuels
  40. Kerosenes 3593
  41. Metals of the 2nd and 3rd Row and their Hydrides 3735
  42. Methylhydrazine Part 1 3879
  43. Methylhydrazine Part 2 4043
  44. Nitramines Part 1 4203
  45. Nitramines Part 2 4415
  46. Ramjet Fuels 4455
  47. List of Acronyms 4475
  48. Acknowledgments 4483
  49. Index 4485
Readers are also interested in:
https://doi.org/10.1515/9783110750287-034

Chapters in this book

  1. Frontmatter I
  2. Foreword V
  3. Preface VII
  4. Contents XI
  5. Volume 1: Alcohols – Amides and Imides
  6. Alcohols 1
  7. Aliphatic Amines 55
  8. Alkanes 221
  9. Alkenes and Alkynes 367
  10. Alkylboranes 397
  11. Alkylhydrazines 433
  12. Amides and Imides 501
  13. Volume 2: Ammonia – Dimethylhydrazines
  14. Ammonia 703
  15. Aromatic Amines 845
  16. Aromatic Hydrocarbons 875
  17. Azides and Azido Compounds 879
  18. Boranes 973
  19. Boron 1131
  20. Cyano Compounds and Nitriles 1143
  21. Cycloaliphatic Hydrocarbons 1165
  22. Dimethylhydrazines Part 1 1333
  23. Dimethylhydrazines Part 2 1499
  24. Volume 3: Ethers – Hydronitrogen Compounds
  25. Ethers 1639
  26. Heterocyclic and Heterocycloaliphatic Amines Part 1 1673
  27. Heterocyclic and Heterocycloaliphatic Amines Part 2 1910
  28. Hydrocarbons 2181
  29. Hydrogen Part 1 2199
  30. Hydrogen Part 2 2416
  31. Hydronitrogen Compounds 2569
  32. Volume 4: Hydrazine – Jet Fuels
  33. Hydrazine Part 1 2587
  34. Hydrazine Part 2 2809
  35. Hydrazine Part 3 3084
  36. Hydrazine Part 4 3216
  37. Ionic Liquids 3397
  38. Jet Fuels 3497
  39. Volume 5: Kerosenes – Ramjet Fuels
  40. Kerosenes 3593
  41. Metals of the 2nd and 3rd Row and their Hydrides 3735
  42. Methylhydrazine Part 1 3879
  43. Methylhydrazine Part 2 4043
  44. Nitramines Part 1 4203
  45. Nitramines Part 2 4415
  46. Ramjet Fuels 4455
  47. List of Acronyms 4475
  48. Acknowledgments 4483
  49. Index 4485
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