Oxygen & Other Gases (PDF)

Oxygen * Oxygen first appeared in the Earth's atmosphere around 2 billion years ago. * Oxygen was discovered about 1772 by a Swedish chemist, Carl Wilhelm Scheele, who obtained it by heating potassium nitrate and many other substances, Priestley pursued his investigations of gases. On 1774 he disc...

Oxygen * Oxygen first appeared in the Earth's atmosphere around 2 billion years ago. * Oxygen was discovered about 1772 by a Swedish chemist, Carl Wilhelm Scheele, who obtained it by heating potassium nitrate and many other substances, Priestley pursued his investigations of gases. On 1774 he discovered oxygen. * The word comes from the Greek "oxy" and "genes," meaning "acid-forming.“ * It makes up 20.948 percent of the atmosphere. * Oxygen is a gas at room temperature and has no color, smell or taste, not flammable, but involving in expansion. * oxygen manufactures : Various methods of producing oxygen exist including : air separation, chemical and electrolysis.  Oxygen * Storage of oxygen: either be stored in cylinders or manifold cylinder bank. * liquid Oxygen : - Vacuum Insulated Evaporator ( VIE ) is the most economical way to store and supply Oxygen. - it has a safety valve open at 1700kPa. - other valve is control valve open to allows liquid oxygen to evaporate when demand for oxygen is increased. - evaporation of liquid oxygen requires heat ( latent heat of vaporization )helping to maintain its low temperature. - cold oxygen gas is warmed once outside the vessel in a coil of copper tubing ( pipe line ). - at a temperature f 15C , liquid oxygen can give 842 times its volume as gas.  OXYGEN * oxygen concentrators : - Zeolites are hydrated aluminum silicates of alkaline earth metals in a powder or granular form. - Mechanism of action : * ambient air is filtered and pressurized to about 137kpa by compressor then this air is exposed to a zeolite molecular sieve column. * the sieve selected retain unwanted gases. * maximum oxygen concentration is 95% while Argon is the remaining constituent.  NITROUS OXIDE * N2O is a laughing gas. * colorless, odorless, nonexplosive and nonflammable. * only inorganic anesthetic gas. * gas at room temperature and can kept as a liquid under pressure. ** *Nitrous oxide Manufacture by ammonium nitrate (NH4 NO3 ) is heated to 250°C (NH4 NO3 + heat → N2 0 + 2 H2 0).  Entonox * Entonox is a compressed gas mixture containing 50% oxygen and 50% N2O. * medical uses are : - labour - dental extraction - causality * it is compressed into cylinder to a pressure of 13700kPa. * Poynting effect : temp. below -5.5C cause separation mixture , mean liquid mixture contain mostly N2O with 20% O2, flow constant rate cause high concentration of O2 first supply to pt. followed by liquid evaporate N2O ( hypoxic mixture ) * Dis advantage : prolong use , risky pt. ( bone marrow suppuration , pt. had operation for eyes, air embolism , pregnant lady )  OTHERS ** Compressed Air - medical air is supplied at a pressure of 400kPa - it is supplied from mainfold or economically from a compressor. - oil-free medical air is cleaned by filters and separators and then dried before use. ** Generalized Vacuum System - It is consist of a pump which is capable of creating a negative pressure of – 53kPa ( - 400mmHg ).