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Fazana
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| Joined: 21 Feb 2009 |
| Total Posts: 28722 |
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| 18 Jul 2014 09:31 PM |
lets test it on your pp
see if it works
~Another post by the pessimistic, cake munching Brit.~ @InsanityBrit |
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| 18 Jul 2014 09:33 PM |
any problem can be solved with enough liquid nitrogen
1. General precautions for all use of LN2 (liquid nitrogen) At all times, HAVE A PLAN of what you will do if.... a pressurized Dewar spontaneously vents? you freeze your watchband or wedding band to your finger? the funnel (which you should not be using) freezes and spews nitrogen upward into your face? 160 L of LN2 for whatever reason falls onto its side? (It happens. It's scary and unpleasant and could easily be quite disastrous.) Liquid nitrogen can cause terrible "burns." (Death of living tissue caused by the extreme cold.) Hand protection and goggles (not safety glasses) are to be worn when dispensing and handling liquid nitrogen. When handling large quantities, a full length apron will minimize the chance of a spill going into your shoes, where it might destroy some cubic centimeters of flesh before you can get your shoes and socks off. Persons using a tipper to dispense LN2 must wear a full face shield over goggles, cryo-gloves, full length cuffless trousers which completely cover the tops of the shoes (or a full length apron), and shoes which will not permit liqufied gas to enter them in case of a spill, and which are also quickly removable in case they do (allow liquid to enter). Do not use a funnel. Do not store container(s) of LN2 in a cold room or any other location where a person could physically enter an anoxic atmosphere. (Cold rooms have no air changes and a person entering a room with elevated nitrogen in the air can quickly pass out and then die within several minutes of entering. Liquid nitrogen will condense oxygen from the air. This is most alarmingly demonstrated if a person leaves his/her vacuum pump's coldfinger in a Dewar of liquid nitrogen overnight. In the morning the coldfinger will contain LIQUID OXYGEN up to the level of the nitrogen in the Dewar.
Guard against pressure build-up by using a pressure relief vessel or a venting lid. Remove metal jewelry/watches on hand and wrists. Glass Dewars must be taped solidly around the outside. The plastic mesh with which some small thermoses are sold protects the Dewar itself to some extent, but does not protect very well against injury from glass shards resulting from implosion. Asphyxiation -- nitrogen is not poisonous; the air is already about 78% nitrogen (oxygen makes up about 21%, and trace gases the remaining 1%). However, if sufficient liquid nitrogen is vaporized so as to reduce the oxygen percentage to below 19.5%, you are at risk of oxygen deprivation. Rapid venting can cause near-total displacement of normal air, leading to a local concentration of about 100% nitrogen. Simple asphyxiants such as nitrogen do not have good warning properties! (You might not feel "light-headed," you may simply pass out without any warning whatsoever. And then die without regaining consciousness.) Use only vessels designed for extreme cold. Not all Dewars are rated for liquid nitrogen. Always follow manufacturers' guidelines for use of cryogen vessels of any size. Do not carry liquid nitrogen in a passenger elevator. Never work alone with hazards, always have at minimum two people moving a large Dewar in hallways, elevators, and outside of buildings. Cryotubes containing samples stored under liquid nitrogen may explode without warning. Tube explosions are thought to be caused by liquid nitrogen entering the tube through minute cracks and then expanding rapidly as the tube thaws. Serious accidents have occurred around the country due to tube failures. A researcher in California lost an eye; numerous others have suffered plastic shards embedded in their hands and faces.
^^^ IGNORE THAT |
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