Pressure vessel for human occupancy

List of PVHO types

Types of pressure vessels for human occupancy include:

• diving chambers
• decompression chambers
• closed diving bells, also known as dry bells or personnel transfer capsules
• high altitude chambers
• hyperbaric chambers
• hyperbaric stretchers
• medical hyperbaric oxygenation facilities
• recompression chambers
• submarines
• manned submersibles
• atmospheric diving suits
• pressurized tunnel boring machines

A typical pressure vessel is not defined until there is at least one atmosphere (14.7 psig) of contained gas pressure. Less than that is typically a storage tank, even if there is some overpressure added by design. The rules for PVHO are invoked at 2 psig (13.8 kPa), per Section 1-2.1 "Application" of the ASME PVHO-1 code. This lower threshold is due to the potential for serious injury if a person under pressure as low as 2 psig is rapidly decompressed.

Section 1-3 "Exclusions" specify Nuclear reactor containments, aerospace cabins, caissons are not considered under the ASME PVHO-1 code. This is because each of those types of occupied pressurized chambers are under other jursidictions and therefore under other design codes. It is noted while "caissons" are under other applicable rules depending on the specific application, the Occupational Safety and Health Administration specifies the chambers in pressurized tunnel boring machines are under ASME PVHO-1 and any chamber used to decompress tunnel workers must meet ASME PVHO-1.