Pressure Vessel for Human Occupancy
vessel used for diving support
The American Society of Mechanical Engineers defines a Pressure Vessel for Human Occupancy (PVHO) as a container that is intended to be occupied by one or more persons at a pressure which differs from ambient by at least 2 pounds per square inch (0.14 bar). Since 1977, the ASME's PVHO committee has published standards governing the construction of a number of PVHO applications. The current design standard is PVHO-1-2023. The current code for maintenance and operation guidances is ASME PVHO-2-2019. Similar standards are published by a range of national and international standards organisations.
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
crewed 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.
The public source identifies “Pressure Vessel for Human Occupancy” as vessel used for diving support. This brief keeps that definition visible, then builds a research path around Pressure, Vessel and Human.
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The citation trail is more important than the brevity of the summary: it shows where individual claims can be examined in context. The source revision retrieved here is dated Mar 13, 2026. The linked authority identifier is Q7241744. None of the 0 selected statements returned an explicit reference. The first chronological checks are 1977, 2023 and 2019.
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