The requirements and safety guidelines for design and fabrication of Pressure Vessel for Human Occupancy (PVHO) windows is given by the ASME Association of Mechanical Engineers (ASME) PVHO-1 standard.  This Standard provides technical criteria for the user to establish the serviceability of a PVHO acrylic window under its specific environmental service conditions. Windows in protected environments as well as those in severe environments are addressed. Judicious use of this Standard will allow the user and/or the jurisdictional authority to determine when a PVHO acrylic window requires replacement.  The ASME/PVHO-2 Standard limits the maximum useful life of acrylic cylinders to 20 years or 20,000 cycles as there is no data to support the safety of the acrylic cylinders after this time.[1]

Each day prior to and following the delivery of hyperbaric oxygen therapy, the following inspections should be performed. The inspections should be performed and documented with the corresponding chamber serial number. Chamber cylindrical window blemish inspections are conducted to ensure the safe function of the chamber during hyperbaric oxygen  therapy.