dimanche 23 septembre 2018

Useful Facts About Cryogenic Gases

By Laura Williams


Cryogenic liquids refer to gasses that have been liquefied and stored in their liquid state at extremely low temperatures. There are other names that are used to refer to these substances, which include cryogenic liquefied gasses, refrigerated liquefied gases, and deeply refrigerated gases. Cryogenic gases are usually formed from cryogenic liquids that have been vaporized. These substances have very many applications in industrial and commercial settings.

In one case, these gasses are used because of their low temperature properties. For instance, very low temperatures in the gases are used to contract components in machinery to allow them to form tight joints with other components. Another application is that freezing gasses makes it possible to transport it in extremely large quantities. For instance, between 690 and 850 liters of the gas only forms a single liter of the liquid, which can then be transported with much ease.

These gasses usually have a boiling point below -150 degree Celsius but this rule has a few exceptions. For instance, carbon dioxide and nitrous oxide are counted as cryogens even though they boil at higher temperatures. Carbon dioxide and nitrous oxide boil at -78.5 and -88.5 degrees Celsius respectively. Helium boils at -269 degrees with a lot more other cryogens boiling at considerably lower temperatures.

The properties of cryogens render them both dangerous and useful to animal and human life. These gasses for example trigger serious burns the instant they come in touch with bare skin and eyes due to their low temperatures. Tissue damage occurs immediately someone makes contact with un-insulated pipes or equipment used in transporting and storing cryogens.

One experiences tissue damage similar to damage generated by heat. Freezing will happen immediately if a stream of the gas is sprayed on the eyes or skin. Therefore, wearing proper protective gear while these gases are being handled is very vital. The bad impacts which these substances cause on the body can be avoided through wearing protective gloves and clothing.

Cryogens also have bad effect on carbon steels, plastics, and some types of rubber. When these materials are exposed to cryogens, they become brittle, making them susceptible to failure when exposed to the slightest amount of stress. On the contrary, some materials do not undergo brittle transition when exposed to low temperatures, allowing them to retain their ductility. Such materials include aluminum, copper, brass, stainless steels, and certain plastics.

Cryogens usually cause blockages in pipes, vessels, and equipment as a result of freezing of moisture and humidity inside. The freezing results from the cold nature of cryogens. As a result of the formation of ice, instrument lines, stop valves, pressure gauges, and safety valves among other apparatus may stop to operate correctly. If not corrected, this could cause a major safety hazard or accident.

Cryogens are known for causing catastrophic failure or rupturing of equipment and containers. The rupture is caused by a buildup of pressure caused by vaporization of cryogenic liquid. The liquid vaporizes as it absorbs thermal energy from the surrounding, causing a buildup of pressure.




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