Medical oxygen therapy is a treatment that provides supplemental oxygen to patients who cannot get enough from the air they breathe. This supplemental oxygen is delivered using specialized equipment that falls primarily into two categories: compressed gas cylinders, often called “oxygen tanks,” and oxygen concentrators. The tank itself does not need electricity to deliver oxygen. Oxygen tanks store pre-purified gas and rely on mechanical principles to release it, while oxygen concentrators are complex machines that must have a power source to function.
The Mechanics of Compressed Oxygen Tanks
Oxygen tanks, or cylinders, are metal containers designed to hold medical-grade oxygen under very high pressure, often exceeding 2,000 pounds per square inch (psi). This high-pressure storage represents a form of potential energy that is used to deliver the gas to the patient without any need for electrical power. The tanks are filled with pure oxygen that was typically separated from the atmosphere using industrial processes like cryogenic distillation or large-scale Pressure Swing Adsorption (PSA) technology.
The mechanism that controls the flow of oxygen is the regulator, which attaches to the top of the tank. This device performs the task of reducing the extremely high internal tank pressure to a safe, therapeutic pressure that the patient can tolerate. A flow meter, which is often integrated into the regulator, then allows the user or medical professional to set the precise volume of oxygen delivered per minute, typically measured in liters per minute (LPM).
This entire process of pressure reduction and flow control is purely mechanical. The system uses springs, diaphragms, and valves to manage the pressure differential, drawing entirely on the stored energy of the compressed gas. Because of this design, a compressed gas cylinder is an immediate and reliable source of oxygen that can operate completely independent of any electrical grid or battery.
Understanding Oxygen Concentrators and Their Power Needs
In contrast to tanks, an oxygen concentrator is a medical device that produces its own oxygen supply from the surrounding air and requires electricity to operate. Ambient air, which is about 21% oxygen, must be drawn into the machine and filtered to increase the oxygen concentration to a therapeutic level, typically between 90% and 95%. This separation process is achieved using a technology called Pressure Swing Adsorption (PSA).
The concentrator uses a motor and compressor to cycle air through specialized columns, or sieve beds, that are filled with a material called zeolite. The compressor uses electrical power to pressurize the air, which causes the zeolite to preferentially adsorb, or trap, the nitrogen molecules. By rapidly cycling the pressure between two columns, one column releases the trapped nitrogen back into the atmosphere while the other delivers the purified oxygen to the patient.
A continuous source of electrical power is mandatory for the concentrator to function because the compressor and the rapid cycling of the valves rely on mechanical movement. Stationary home concentrators typically plug into a standard alternating current (AC) wall outlet. Portable oxygen concentrators (POCs) are designed for mobility and use rechargeable lithium-ion batteries, which convert stored chemical energy into electrical energy to power the internal components.
Practical Differences and Usage Scenarios
The fundamental difference in power requirements dictates the practical application and logistics of each system. Oxygen tanks provide a finite supply of gas, meaning they will eventually run empty and must be replaced or refilled. However, their power independence makes them an excellent choice for immediate, reliable backup oxygen, particularly during a power outage.
Concentrators, provided they have power, offer a virtually limitless supply of oxygen, as they constantly draw from the surrounding air. This makes them highly convenient for long-term, continuous therapy at home, eliminating the need for frequent tank deliveries and exchanges. The stationary concentrator is generally larger and heavier, but it can provide a higher continuous flow rate than many portable options.
Portable oxygen concentrators offer the greatest mobility, often weighing significantly less than portable tanks and utilizing rechargeable batteries for use away from an outlet. However, the battery life is limited, and the user must always have a plan for recharging or a spare battery. Ultimately, the choice between a tank and a concentrator balances the guaranteed, power-free reliability of the tank’s finite supply against the continuous, power-dependent production of the concentrator.