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Liquid Oxygen Safety
By Joan Whetzel
Liquid Oxygen Safety
By Joan Whetzel
Earth's atmosphere consists of 78% nitrogen, 21% oxygen, 0.93% argon, 0.037% carbon dioxide, and traces of other elements. Oxygen, a major component of the air that we breathe, can be used for medically therapeutic treatments, for industrial uses, and in space sciences. These applications usually require a more pure from of oxygen that what is found in the atmosphere. Gas manufacturing companies create the higher grade of oxygen in a variety called Liquid Oxygen, also known as LOX. Patients on oxygen therapy receive liquid oxygen through the hospital's oxygen delivery system, or when at home, from a gas cylinder or anan oxygen concentrator.
The Physical Properties of Liquid Oxygen Physical Properties
Liquid Oxygen (LOX), like atmospheric oxygen, uses the molecular formula O2. LOX freezes at -222.65 degrees Celsius (-361.9 Fahrenheit),comes to a boil at -183 degrees Celsius (-297.4 Fahrenheit) and returns to a gas at -83.5 degrees Celsius (-118 Fahrenheit). In its frozen state, LOX takes on a pale blue hue and, because of its condensed state, it consumes less storage than oxygen in its gaseous state.
How LOX Is Produced
Producing LOX involves freezing the gas, reducing it to a temperature around -362 degrees Fahrenheit, which compresses, or concentrates, it into a liquid. One of three methods are used to produce LOX: 1) dividing the oxygen and hydrogen in water with an electric current and storing the gasses in separate containers; 2) creating a chemical reaction to separate oxygen from other chemical compounds; and 3) removing the oxygen from the atmosphere. In all three cases, once the oxygen is isolated, it is stored in its own container and exposed to a cryogenic distillation process that converts the gas to a frozen liquid.
For most uses, LOX is stored in thermos-like containers of varying sizes (small for home medical use, large for industrial uses). The larger, industrial storage tanks hold anywhere from 40 to 100 pounds of LOX. The smaller, portable tanks for home use contain about 6 to 11 pounds. The tanks are constructed much like a thermos bottle, consisting of an interior and exterior reservoir, with an vacuum layer between them. This construction technique insulates the LOX, keeping it cold and preventing warmer temperatures outside the tank from warming the LOX and prematurely returning it to a gas state.
The LOX remains a frozen liquid in the lower chamber, and begins the thawing process in the upper chamber. When needed, a flow control valve is opened, releasing the LOX from the tank, and it expands back as a gas.
Using Liquid Oxygen
Patients with chronic diseases benefit from LOX treatments. LOX in both hospital and home settings is used to treat respiratory and heart failure, to resuscitate patients in emergency situations, for preemies in neonatal ICUs, as a carrier for drugs used in anesthesia, and to help clear anesthetics from the patients' systems post-operatively.
In industrial settings LOX is used to produce breathable air in space stations and rockets, as a liquid propulsion system for rockets and ICBMs, and as a LOX binary explosive, which is a type of explosive that requires the addition of a second agent in order to create the detonation.
Liquid O2 Fire Hazards
Along with the wonderful uses for LOX, it comes with a few hazards. One hazard is the risk of fire. LOX, by itself is not flammable. However it can saturate flammable materials (fabrics, hair). At levels of 23% or higher, these materials ignite readily and are rapidly destroyed by fire. LOX, when exposed to combustible materials, like oil or grease, will explode. Placing LOX containers near flames or other heat sources can cause the frozen oxygen to thaw rapidly into its gaseous state which expands rapidly inside the small inner chambers of the tank. The tanks, which can't confine all that quickly expanding gas, will rupture, blowing shrapnel everywhere.
The Cold Hazards of Liquid O2
The extreme cold produced by LOX is another hazard. Oxygen, in its frozen liquid state, will cause severe freezing injuries - frostbite or cryogenic burns - to skin and eye membranes. Some materials, fabrics, plant life may become fragile, brittle, or even shatter, following exposure to LOX.
Health Hazards of Liquid O2
A third hazard of LOX is health related. Inhaling oxygen at levels below 50% doesn't usually cause any harm. However, at levels up to 80 to 100% for even 12 to 24 hours can bring about damage to the upper respiratory system. Neurological symptoms develop from inhaling pure oxygen at 2 to 3 atmospheres, ranging from dizziness to changes in mood followed by confusion, seizures and even coma. In addition, the low temperatures can produce cryogenic burns and frostbite to the oxygen delivery system within the lungs, which will lead to asphyxiation.
Tips and Warnings:
· Anyone living in or visiting a home where oxygen is in use, should not smoke within that home or near the patient who uses the oxygen.
· Oxygen tanks should be kept a minimum of 8 feet from stoves ,ovens, radiators, fire places, grills, heaters, water heaters, dryers and any other article that produces heat.
· Anyone whose clothing maybe saturated with oxygen should stay at least 5 feet away from the above heat producers.
· Oxygen tanks should be kept in well-ventilated areas. The oxygen canisters cannot keep the oxygen frozen indefinitely, so are set up to vent continuously. Because of this, oxygen will accumulate in high quantities if the tanks are stored in small or confined spaces like closets or behind draperies.
· To conserve oxygen as much as possible, and to lessen the threat of oxygen saturation and combustion, make sure the tank's valves are turned off when not use.
City of Tyler: Home Oxygen Safety
International Industrial Gasses, LTD: Liquid Oxygen
Minnesota Department of Health: Use of Liquid Oxygen
NASA: Oxygen Systems
Medox Healthcare: Liquid Oxygen (LOX)
Medical Search Dictionary: Medical Gasses --- Liquid Oxygen
All Atoms: Liquid Oxygen
How Products Are Made: Oxygen
Chemmie Bear: Liquifying Oxygen