Some Characteristics Of Cryogenic Gases

By Grace Rivas

Cryogenic gases or cryogens are gases that are maintained at a temperature of less than -150 degrees Celsius or 123 K. At these temperatures virtually all the gases have liquefied. There are 3 main types of cryogenic liquids. They include inert gases, flammable liquids and oxygen. The inert liquids are those that do not usually react. They include nitrogen, neon, krypton, helium and argon. The highly flammable types burn easily in air. An example is natural gas.

There are a number of applications for which these substances are used. Cryosurgery is the use of very low temperatures to destroy cancer cells. They are also used in the preservation of human and animal tissues in the field of medical technology. Cryogenic are extensively used in the maintenance of low temperatures in some chemical reactions such as those required for the manufacture of some drugs.

The use of cryogens is associated with several health risks. For instance, directly exposure to the cryogens may result in tissue injuries due to the very low temperatures. These injuries resemble those that are caused by thermal burns. The eyes and mucosal surfaces of the body are at a particularly high risk. The affected skin takes a waxy yellow appearance.

Asphyxiation is another risk than one should be wary of. Cryogens become heavier as they cool and tend to displace ordinary air. The accumulation of cryogens near the ground reduces the amount of oxygen available for respiration and this is what leads to asphyxiation especially in enclosed spaces. The other mechanism that contributes to this problem is the destruction of lung tissue by the cryogens.

Most of the cryogens are highly flammable especially if allowed to rapidly expand. Highly flammable gases include hydrogen, carbon monoxide and methane. The mixture between hydrogen and ordinary air is in particular very flammable and should be handled carefully. The other cryogen considered to be equally as dangerous in this regard is liquid oxygen. The liquid can cause combustion of materials such as carbon, stainless steel and cast iron.

Due to the many associated risks, one needs to take precautions. Proper thermal insulation prevents ignition. The insulation should be done to the containers and the pipes that are used in the delivery of the cryogens. Special flasks that are non-pressurised are available in the market. They have a loosely fitting cap that allows for the escape of excess pressure but keeps moisture out of the vessel.

It is important that put on personal protective clothing at all times. The clothes must also be maintained clean and dry at all times. They should be well-fitting and cover arms and legs. If the material penetrates your gloves, remove them as soon as possible. For protection of the eyes and the face, googles or a facial shield should be used.

Cryogenic gases have a wide range of applications. They are, however, very dangerous if not properly handled. Understanding the precautions required is very important. Ensure that you always read the instructions on how to use them. If anything is unclear, make sure that you consult.

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