Hyperbaric chambers are used for medical applications and procedures at pressures above normal atmospheric pressure. Often, these treatments include the delivery of pure oxygen either direct to the patient or throughout the chamber itself. This combination of increased pressure and oxygen levels can present a significant fire hazard.
Hyperbaric chambers were traditionally used to treat compression sickness in divers beginning over 100 years ago. Since then, there have been a variety of other medical conditions treated with hyperbaric oxygen therapy. The most common use is now wound healing centers which may or may not be affiliated with a hospital. Both NFPA 99 and NFPA 101 contain requirements that apply to the facilities housing these chambers. Chapter 14 of NFPA 99 is dedicated to hyperbaric facilities and includes a great deal of requirements to ensure the safe installation and use of these chambers.
Here is an article in Today's Wound Clinic, that identifies many of the NFPA requirements applicable to hyperbaric facilities whether in a hospital or ambulatory care setting.