Compressed oxygen is oxygen gas that has been reduced in volume by being placed under high pressure inside a specialized container, typically a metal cylinder. This process transforms a large volume of atmospheric-pressure gas into a compact, transportable, and high-density form. Compressing oxygen allows a substantial amount of the gas to be stored and moved efficiently. This high-pressure storage technique makes oxygen a versatile substance, enabling its use across various sectors where a continuous, concentrated supply is required.
The Physics of High-Pressure Storage
The ability to store oxygen in a small space relies on the physics principle that gas volume is inversely proportional to pressure when temperature is constant. By using a specialized compressor to force gas molecules closer together, a large quantity of oxygen can be contained within a durable vessel. This compression allows a standard cylinder to hold hundreds or even thousands of liters of oxygen gas at normal atmospheric pressure.
Compressed oxygen cylinders are typically filled to pressures ranging from 137 bar (about 2,000 psi) up to 200 bar (around 3,000 psi) or more. To withstand these extreme internal forces, the storage vessels are constructed from high-strength materials, most commonly steel or aluminum alloys. Steel cylinders offer superior strength for high-pressure stationary use, while aluminum and composite-fiber cylinders are preferred for portable applications due to their lighter weight. The oxygen remains in a gaseous state at high pressure, as the cylinder is a non-liquefied gas container.
Common Uses Across Industries
Compressed oxygen is a foundational component in the healthcare sector, providing life-saving respiratory support. Medical-grade oxygen, often maintained at a purity of 99.5% or greater, is administered to patients suffering from conditions like pneumonia, chronic obstructive pulmonary disease, or heart failure. Cylinders are used in hospital settings, in ambulances during transport, and as portable units for home oxygen therapy, ensuring a constant and regulated supply.
In industrial settings, compressed oxygen is valued for its properties as a powerful oxidizer that vigorously supports combustion. Metal fabrication relies heavily on oxy-fuel processes, such as welding and cutting. Oxygen is mixed with a fuel gas like acetylene to achieve extremely high flame temperatures. This enhanced heat allows for faster and cleaner cuts through thick steel and enables efficient welding and brazing applications.
Specialized Applications
Specialized applications depend on the mobility and concentration of compressed oxygen for safety and performance.
- Commercial and recreational divers use compressed oxygen mixtures in their tanks for decompression and extended bottom times.
- The aviation industry relies on it for emergency breathing systems on aircraft.
- The chemical industry utilizes high-purity oxygen to increase the efficiency of oxidation reactions in the production of various chemicals.
- In wastewater treatment, compressed oxygen is introduced to accelerate the breakdown of pollutants by stimulating aerobic bacteria.
Essential Safety and Handling Precautions
Handling compressed oxygen requires strict adherence to safety protocols due to two primary hazards: the extreme physical pressure and the chemical risk of oxygen itself. The high internal pressure means that a damaged cylinder or valve can propel the container with significant force, posing a severe physical danger. Cylinders must always be secured upright with chains or straps to prevent them from tipping over, and they should never be dragged, rolled, or dropped when being moved.
Chemically, oxygen is a strong oxidizer, meaning it dramatically accelerates combustion, turning even small sparks into intense fires. The most important precaution is keeping the gas away from any oil, grease, or hydrocarbon-based material, which can ignite spontaneously in the presence of high-pressure oxygen. Regulators and valves must be kept scrupulously clean to prevent a dangerous reaction. Additionally, oxygen cylinders must be stored at least 20 feet away from any flammable gases or combustible materials, or separated by a fire-resistant barrier.