The oxygen tank is a high-pressure vessel designed to safely contain gaseous or liquid oxygen, enabling its transport and application across various industries. Its invention was not a single event but the culmination of centuries of scientific inquiry and engineering innovation. Understanding its history requires examining foundational discoveries in chemistry and later technological breakthroughs in material science and gas compression. This progression transformed oxygen from a laboratory curiosity into a widely used medical and industrial commodity.
The Scientific Precursors to Storage
Before oxygen could be stored, its existence had to be proven, a process that occurred in the mid-to-late 18th century. Swedish apothecary Carl Wilhelm Scheele likely isolated the element earlier, around 1773, but his findings were not published immediately. The English clergyman Joseph Priestley independently isolated the gas in 1774 by focusing sunlight onto mercuric oxide, which liberated a gas he called “dephlogisticated air”.
Priestley observed that this gas caused a candle flame to burn intensely and allowed a mouse to live significantly longer than in common air. French chemist Antoine Lavoisier later recognized the substance as a chemical element, naming it “oxygen” in 1777 and describing its role in combustion and respiration. This understanding established oxygen as a distinct, highly reactive gas with potential applications, particularly in medicine, initiating the demand for effective storage methods.
Developing the Means for Gas Compression
The theoretical barrier to storing gases under high pressure was overcome by physicist Thomas Andrews in the 1860s through his experiments with carbon dioxide. Andrews investigated the relationship between pressure, volume, and temperature, demonstrating that a gas could only be liquefied below a specific temperature. He defined this threshold as the critical temperature, a point above which no amount of pressure could turn the gas into a liquid.
This discovery was fundamental because gases like oxygen, nitrogen, and hydrogen were long considered “permanent gases” that resisted liquefaction at room temperature. Andrews’ work in 1869 showed that to liquefy oxygen, its temperature first had to be lowered significantly. This theoretical foundation paved the way for the development of practical, large-scale gas liquefaction processes in the late 19th century. Carl von Linde in Germany and William Hampson in England independently developed the regenerative cooling process, known as the Hampson-Linde cycle, around 1895, which used the cooling effect of gas expansion to progressively lower the temperature until liquefaction occurred, making the commercial production of pure, compressed oxygen feasible.
The First Practical Portable Cylinders
The commercial availability of compressed oxygen created the need for durable, high-pressure containers, leading to the invention of the modern tank. Early attempts at storage used glass containers, but these were unable to withstand the necessary pressures and proved impractical for transport and safety. The invention of reliable, standardized steel cylinders for oxygen storage occurred around the turn of the 20th century, supported by advancements in metalworking.
These heavy, drawn-steel cylinders were designed to safely contain oxygen at pressures necessary for industrial and medical use. The demand for portable oxygen was accelerated by the medical field, with recorded use of oxygen for pneumonia treatment occurring as early as 1885. By the time of the First World War, portable oxygen apparatus, such as the John Scott Haldane equipment, was being used to treat gassed soldiers. These early 20th-century metal cylinders, first certified around 1917, established the physical form of the oxygen tank still recognizable today.
Contemporary Uses and Safety Standards
Following the initial invention, oxygen cylinder technology continued to mature, driven by the need for greater portability and reliability. Modern tanks use materials like aluminum alloys and composite fibers, significantly reducing weight compared to the early steel versions. This material evolution has enabled diverse applications, including home medical oxygen therapy, which became widely available in the 1970s, though the tanks were initially quite large.
Today, oxygen tanks are used in hospitals, aviation, deep-sea diving, and welding, each application requiring specific tank design and safety features. To manage the high pressure and reactive nature of the gas, safety standards are strictly enforced by regulatory bodies. These standards mandate secure storage, prohibit the presence of flammable materials, and require proper temperature control. Furthermore, high-pressure cylinders must have protective valve caps and be regularly inspected for integrity.