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Hypobaric Chamber

Question asked by lhubl on Aug 13, 2018
Latest reply on Aug 25, 2018 by milt.werner


An existing hypobaric chamber is installed in an existing air force facility. The base fire marshal has determined that the existing facility is deficient without fire protection.


Can an existing hypobaric chamber (unconfirmed existing listings or fabrications per 4.2, equipment is estimated 40 years old) continue in operation and make the facility and room housing compliant per 4.1?


Can you please clarify D vs E chambers?


NFPA 99B 1.2.4

"Class D — Human rated, air atmosphere not oxygen enriched Class E — Human rated, oxygen-enriched atmosphere

(partial pressure of oxygen is above 0.235 ATA) (NFPA 99B Oxygen-Enriched Atmosphere (OEA).   For the purposes of this standard, an atmosphere in which the concentration of oxygen exceeds 23.5 percent by volume.)


Both Class D and Class E chambers are human-rated; however, chambers used for high-altitude training involving oxygen breathing are classified as Class D for the purpose of this standard."



In a class D chamber oxygen is only provided to breathing apparatus’ and not to the chamber environment? Are there limits on OEA from secondary introduction into the atmosphere from breathing apparatus exhale?


Class E chamber, OEA by oxygen supplied directly to the atmosphere?


The existing chamber is used for high altitude training with 100% oxygen supplied directly to masks, and per the user “Inside of chamber does have higher percentage of oxygen, sitting anywhere between 22% to 23.5%.”. Based on the code language and operations involving training with oxygen breathing apparatus' instead of an OEA over 23.5%, this seems to be a Class D chamber?