What is compressed oxygen ?
Oxygen is stored in two ways. Oxygen can be frozen and stored in containers that resemble thermos bottles. Oxygen can also be compressed and stored in cylinders under several thousands of pounds of pressure. This section discusses compressed oxygen. The next section discusses liquid oxygen.
Compressed oxygen for medical use is stored in silvery aluminum cylinders with dome-shaped tops of green. If you use compressed oxygen, your cylinder is probably one of those pictured in Figure 1.
Two sets of names are used to specify cylinder sizes. The older set identifies them alphabetically from A, the smallest, to E. the largest. You may be most familiar with the lightweight B cylinder or the E cylinder, which is usually pulled along in a cart.
Each of the newer set of names starts with the letter M to denote "medical," followed by a number, which specifies the amount of oxygen in cubic feet that can been compressed into the cylinder. For example, the B cylinder is also called the M-6 cylinder.
Features :-
- Compressed Oxygen is typically supplied with a purity of 99.5% or better
- Colourless and odourless
- Does not burn but supports and accelerates combustion
- Non-toxic at atmospheric pressure
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Uses :-
One of the most common uses of compressed oxygen is to provide supplemental oxygen for someone who has breathing problems. The type of oxygen cylinder used for this is usually a small lightweight portable tank, although a person who uses supplemental oxygen in her home may have a rather large tank so that she does not have to keep changing smaller tanks out as she runs out of oxygen rather quickly. Compressed oxygen is also used in welding.
Applications :-
- Widely used with a fuel gas for cutting, welding, brazing and soldering. The use of oxygen gives higher flame temperatures than if air is used
- In oxy-cutting, an oxy-fuel flame preheats the steel to its ignition temperature. A jet of gaseous oxygen flows onto the red-hot steel, generating more heat and melting the steel. The steel in contact with the oxygen jet is oxidised, creating metallic slag which is blown from the cut, allowing more steel to react with the oxygen
- In plasma and laser-cutting steel, an arc or laser beam is used to heat the steel to its ignition temperature. Oxygen is then used in the same way as with oxygen-cutting to create an exothermic reaction and to blow away any metal oxide or slag
- Thermal lancing oxygen is used in conjunction with the steel lance to create a high-temperature melting process capable of drilling or cutting through materials such as concrete, brick, stone and most metals
- High-purity oxygen is used in the laboratories, process-control operations, metal analysis instruments and in semi-conductor production
- Used as an assist gas in lasers for cutting mild steel
Benefits :-
- Vigorously supports combustion. Introducing oxygen to conventional air-fuel flames increases the temperature of the flame
- Used as an ingredient in some shielding gas mixtures, due to its ability to help stabilise the arc and reduce surface tension
- When cutting, a 1% reduction in purity increases oxygen consumption by 25% and reduces the cutting speed by a similar amount