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What is an Oxygen Generator?

oxygen generator

What does an oxygen generator do?

Oxygen generators separate oxygen from compressed air so that the gas can be fed into industrial processes in real-time or stored in pressure tanks. Oxygen generators are used in dozens of industrial applications ranging from gold mining to aquaculture. 

Normal ambient air is made up of 78% nitrogen, 21% oxygen and other trace gases like argon and CO2. In order to remove the nitrogen and trace gases, an oxygen generator is used.

The smallest oxygen generators are no larger than a soda can, while industrial oxygen generators can fill a room. However, all oxygen generators have the same purpose: to provide a safe supply of concentrated oxygen gas.

Businesses who need bulk oxygen gas often start by purchasing tanks of the gas from other companies who fill those tanks using an industrial oxygen generator. If their need for pure oxygen is large and ongoing, it may be cost-effective to purchase their own oxygen generator and produce oxygen on site. While the up-front cost of the machinery is significant, the cost per cubic foot of oxygen generated is 1/3 to 1/2 that of purchasing bulk oxygen, so over time, the oxygen generator can pay for itself.

One example of this is hospitals that pipe oxygen into patient rooms. Instead of using bottled oxygen, most hospitals have one or more industrial oxygen generators in the building. A system of pressurized pipes are used to flow oxygen to each room.

How does an oxygen generator work?

An oxygen generator works by separating oxygen from other gases in the air using various technologies. The specific method employed depends on the type of oxygen generator. Here are the main features of an oxygen generator and its operation:

  1. Air Intake: The oxygen generator draws in ambient air from its surroundings. The air typically contains approximately 78% nitrogen, 21% oxygen, and trace amounts of other gases.

  2. Filtration: The incoming air goes through a series of filters to remove impurities, dust, and other particulate matter. These filters ensure that the oxygen produced is of high quality and free from contaminants.

  3. Compression: After filtration, the air enters a compressor, where it is pressurized. This compression process increases the concentration of oxygen while reducing the concentration of nitrogen and other gases.

  4. Separation: The pressurized air moves into a molecular sieve bed, which consists of zeolite material. Zeolite is a substance with a high affinity for nitrogen. As the air passes through the sieve bed, the zeolite selectively absorbs nitrogen molecules, allowing oxygen molecules to pass through more readily.

  5. Oxygen Collection: The purified oxygen, now separated from nitrogen and other gases, is collected and stored in a reservoir within the oxygen generator.

  6. Delivery: The collected oxygen is then delivered to the user through a flowmeter and a delivery system such as nasal cannulas or a face mask. The flow rate can be adjusted according to the user's prescribed oxygen therapy requirements.

  7. Continuous Operation: Oxygen generators are designed to operate continuously, ensuring a steady supply of oxygen. They often incorporate cycling systems that alternate the adsorption and desorption phases of the molecular sieve bed, allowing for continuous oxygen production.

Overall, oxygen generators provide a convenient and cost-effective solution for individuals needing supplemental oxygen therapy, allowing them to receive the required oxygen concentration without the need for bulky oxygen tanks or frequent refills.

What is the difference between an oxygen concentrator and an oxygen generator?

An oxygen concentrator and an oxygen generator are two different devices used for generating or concentrating oxygen, but they are unique in the way in which they operate.

Oxygen Concentrator

An oxygen concentrator is a small medical device that takes in ambient air and removes nitrogen from it in real time, providing breathing air with a higher level of oxygen to the user. They are an alternative to replaceable oxygen tanks, and can be plugged in or portable. According to WebMD, about 1.5 million oxygen concentrators are used in the United States. 

Here are the key points about oxygen concentrators:

  • Operation: Oxygen concentrators use a process called pressure swing adsorption (PSA) to extract oxygen from the air. The air is drawn into the concentrator and passed through a series of filters, which remove impurities and separate oxygen from nitrogen using molecular sieve beds.
  • Concentration Levels: Oxygen concentrators typically deliver oxygen with concentrations ranging from 87% to 95%, depending on the specific model and settings. This concentration is sufficient for most therapeutic uses.
  • Power Source: Oxygen concentrators are electrically powered devices. They require a continuous source of electricity to operate and are commonly used in homes, hospitals, and other healthcare facilities.
  • Portability: While some battery-operated models are portable and designed for mobility, most oxygen concentrators are larger and must be plugged in.
  • Medical Use: Oxygen concentrators are commonly used to provide supplemental oxygen therapy to patients with respiratory conditions such as chronic obstructive pulmonary disease (COPD) or in other situations where additional oxygen is required.

Oxygen Generator

An oxygen generator, also known as an oxygen plant, is a device that generates oxygen by separating it from other gases in the atmosphere. Oxygen generators are typically used in industrial applications, but they can also be found in medical settings for large-scale oxygen supply.

Here are the key points about oxygen generators:

  • Operation: Oxygen generators employ various methods such as pressure swing adsorption (PSA), membrane separation, or cryogenic distillation to separate oxygen from air. The specific technique used depends on the scale and requirements of the application.

  • Concentration Levels: Oxygen generators can produce high-purity oxygen with concentrations ranging from 90% to over 99.9%.

  • Power Source: Oxygen generators can be powered by electricity or other energy sources, depending on the design and size. They are generally larger and more powerful than oxygen concentrators.

  • Portability: Oxygen generators are large, stationary units installed in industrial or medical facilities to meet the demand for large volumes of oxygen.

  • Industrial Use: Oxygen generators are commonly employed in industries such as steelmaking, chemical processing, water treatment, and aerospace. They are used for applications that require high-purity oxygen in large quantities.

Overall, the main difference between an oxygen concentrator and an oxygen generator lies in their operation, concentration levels, power source, portability, and overall applications or industry focus. While oxygen concentrators are primarily used for medical purposes, oxygen generators are larger devices primarily used in industrial settings to produce high volumes of oxygen.

Types of Oxygen Generators

1. Pressure Swing Adsorption Oxygen Generator

oxygen sieve filter

Pressure Swing Adsorption (PSA) is the most common method of producing oxygen at an industrial scale. PSA generators separate nitrogen from ambient air inside a pressurized tank filled with Zeolite. Zeolite is a natural or man-made mineral that acts as a “molecular sieve.” It is this ability to “sort” molecules by size that makes zeolite so useful. The larger nitrogen molecules are adsorbed by the sieve material while the smaller oxygen molecules drift past and are collected. Pressure is then released, the nitrogen molecules are vented to the atmosphere, and the tank is pressurized again.

Using PSA will result in 90-95% oxygenated gas. Further refinement can be achieved by repeating the process until over 99% “pure” oxygen is generated.

As a side note, the PSA process can also be used to generate nitrogen by collecting the nitrogen molecules and venting the oxygen. PSA is also used in the large-scale commercial synthesis of hydrogen used in oil refineries and in the production of ammonia for fertilizer.

2. Membrane Oxygen Generator

Membrane oxygen generators us a compressed air stream passed through semi-permeable materials that allow for the passage of specific molecules. Under pressure, smaller oxygen molecules pass through the membrane, filtered out and collected leaving a stream of nitrogen flowing out the opposite end of the membrane. While membrane-type generators are not as common, they are considered to be more reliable because there are no moving parts that can fail.

3. Chemical Oxygen Generator

aircraft oxygen generator

A chemical oxygen generator is a device that releases oxygen by a chemical reaction. A container of inorganic salts called “superoxides” or sodium chlorate are ignited. As they heat they give off oxygen until the compound is consumed.

Because of their long shelf-life, stability and small size (about the size of a can of soda) chemical oxygen generators are used in commercial airliners. Mounted over the seats, each generator can produce enough oxygen for 2-3 masks for 10-20 minutes. A similar device is called an oxygen candle. It works using the same principle of releasing oxygen with heat, and is used as a personal safety oxygen supply in mines, submarines and on the space station.

Oxygen Generator Uses

While there are dozens of uses for industrial oxygen generators, some of the most common ones are listed below.

Bulk Medical Grade Oxygen

Medical grade oxygen used in hospitals or for home health care is certified to meet the United States Pharmacopeia (USP) XXII Oxygen 93% Monograph. USP requirements are the oxygen level is between 90 and 96% pure with the remainder made up of argon and hydrogen. No more than 300ppm of CO2 or any other gases or molecules are allowed.

Portable Breathing Oxygen

The International Space Station, submarines and SCUBA divers all rely on oxygen generators to produce breathable air. Because they are closed systems, each work in conjunction with carbon dioxide “scrubbers” to remove the CO2 while bringing the oxygen level back to 20.9% oxygenated air.

Fish farms & Aquaculture

Like humans, fish and other marine animals required oxygen to survive. With the prevalence of fish farms, the “farmers” must insure their livestock gets proper oxygen to survive. Before fish farming was done on an industrial scale, the farmers would fence off an area of water at the edge of a lake to raise their catch. With industrial oxygen generators, farmers now have the ability to raise fish in man-made pools of oxygenated water. The benefit to the farmer is higher stock densities in a smaller area and faster fish growth.

Sewage and Waste Water Treatment

In waste water treatment plants oxygen generators are used to provide additional oxygen to the bacteria that enable biodegradation to occur. The bacteria break down the sludge into CO2 and water faster if supplemental oxygen is added during the process.

Steel Industry

Industrial oxygen generators are used in the steel manufacturing process in several ways. Oxygen furnaces are used for decarburization, the process of decreasing the carbon in the metals while in a molten state. Oxygen is also used to increase the melting rates in the furnaces and reduces scaling when reheating furnaces.

Gold Mining

Mines that extract gold on an industrial scale use oxygen generators during the cyanide leaching process. A sodium-cyanide solution is mixed into crushed gold-bearing rocks along with oxygen to release the gold from the rock.

Welding

Oxyacetylene cutting and welding of metals use liquid fuel and oxygen to increase the flame temperature so that the metal is melted at the point of the welding tip. This melting can be used to weld or to cut the metal.

Glass Blowing

Like welding, glass blowing requires high levels of heat to melt the glass. Oxygen is used to increase the temperature of the flames both in ovens and for torches used to shape the glass pieces.

Pulp and Paper Manufacturing

Delignification is the process of extracting lignin from the plant material in one of the steps required to make paper from trees. Large amounts of oxygen are required in this process, as well as several other later steps in pulp and paper manufacturing.

Oxygen Generator Safety

Enclosed areas with higher than normal levels of oxygen are typically not a medical hazard, but do increase the risk of fire. Even 2-3% increase in normal room oxygen levels when combined with fuel and a spark can result in a flash fire.

oxygen safety alarm

Industries who use oxygen generators rely on devices like our Remote Oxygen Deficiency Safety Alarm to protect workers around bulk liquid stored oxygen or where oxygen generators are used. This includes applications like steel manufacturing, welding and cutting, cryogenics, hospitals, diving tanks, underwater facilities and emergency air backup systems.

Where to Buy an Oxygen Generator

While there are dozens of types and uses for oxygen generators, there are only two ways to purchase them. 

Commercial Oxygen Generators are large pieces of industrial equipment that must be professionally installed. Because so many people search for "oxygen concentrator" they are difficult to find. We suggest searching for:

  • psa oxygen generator manufacturers
  • industrial oxygen generator manufacturers
  • chemical oxygen generator manufacturers

Thomasnet is where many of the top industrial oxygen generator manufacturers advertise online, so it is is a good place to start your research.

Because of the size, cost and output differences between industrial oxygen generator manufacturers there are no direct online comparisons between manufacturers, nor can we recommend which one to buy. However, a useful resource may be online discussion groups related to your industry where you can ask questions or see recommendations from companies like yours.

Home Oxygen Concentrators are small, lightweight units sold for home use through medical supply houses, retail outlets or online. Because they don't technically "produce" oxygen they can be purchased with or without a doctor's prescription.

Click the links below to gain more information on further solutions for nitrogen separation please visit:

Image used with permission from Rifair and Bubinek / CC BY-SA


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