This arrangement is more expensive, since the filter housing is pressurized, but eliminates cavitation problems and protects the control valve from pump failures.
en.wikipedia.org The craft will have three versions, pressurized, unpressurized, and a combination of the two.
en.wikipedia.org The shrinkage pressurizes the core, helping to form the correct crystal structures.
en.wikipedia.org Such carriers include springs, electrical batteries, capacitors, pressurized air, dammed water, hydrogen, petroleum, coal, wood, and natural gas.
en.wikipedia.org