A typical cryogenic liquid cylinder is depicted in Figure 2. This is an insulated, vacuum-jacketed pressure vessel. They are equipped with pressure relief valves and rupture disks to protect the cylinders from pressure buildup. Liquid containers operate at pressures up to 350 psig and have capacities between 80 and 450 liters of liquid. Oxygen may be withdrawn as a gas by passing liquid through an internal vaporizer or as a liquid under its own vapor pressure. For more details on the construction and operation of cryogenic liquid cylinders.