A pressure vessel is a structure designed to contain a fluid at a different pressure to the pressure surrounding the structure without changing volume. A subset of the phases of matter, fluids include liquids, gases, plasmas and, to some extent, plastic solids. ... Pressure is the application of force to a surface, and the concentration of that force in a given area. ... Volume (also called capacity) is a quantification of how much space an object occupies. ...

Examples of pressure vessels are: diving cylinder, recompression chamber, nuclear reactor vessel, habitat of a space ship, habitat of a submarine, pneumatic reservoir and hydraulic reservoir. 12 litre and 3 litre steel diving cylinders A diving cylinder or SCUBA tank is used to store and transport high pressure breathing gas as a component of an Aqua-Lung. ... A recompression chamber is a pressure vessel used to treat divers suffering from certain diving disorders such as decompression sickness. ... Nuclear power station at Leibstadt, Switzerland. ... Ariane 5 lifts off with the Rosetta probe on 2nd of March, 2004. ... USS Los Angeles A submarine is a specialized watercraft that can operate underwater. ... Pneumatics, from the Greek πνευματικός (pneumatikos, coming from the wind) is the use of pressurized air in science and technology. ... Hydraulics is a branch of science and engineering concerned with the use of liquids to perform mechanical tasks. ...

In industrial sector, pressure vessels are designed to certain pressure and temperature, both technically referred to as "Design Pressure" and "Design Temperature". Because the pressure exceeds normal pressure which people can handle in manual operation, the design of pressure vessels are governed by design codes such as ASME (American Society of Mechanical Engineering), PED (Pressure Equipment Directive of the EU), JIS (Japan), and other international standards.

No matter what shape it takes, the minimum mass of a pressure vessel scales with the pressure and volume it contains. For a sphere, the mass of a pressure vessel is

Where M is mass, P is pressure, V is volume, d is the density of the pressure vessel material, and s is the maximum working strain that material can tolerate. Other shapes besides a sphere have constants larger than 3/2.

So, for example, a typical design for a minimum mass tank to hold helium (as a pressurant gas) on a rocket would use a spherical chamber for a minimum shape constant, carbon fiber for best possible d/s, and very cold helium for best possible mass/PV. There is no theoretical efficiency of scale to be had in a pressure vessel.