GRAVITY DISPLACEMENT STERILIZER The metal construction contains two shells,either round or rectangular,to form a jacket and a chamber.Steam fills the jacket that surrounds the chamber.After door is tightly closed,steam enters chambers at the back,near the top,and is deflected upward. Air is more than twice as heavy as steam.Thus,by gravity,air goes to bottom and steam floats on top.Steam,entering under pressure and remaining above the air,displaces air both in chamber and in wrapped items downward,and forces it out through discharge outlet at the bottom front.The air passes through a filtering screen to wast line.A thermometer,located at this outlet below the screen,measures temperature in the chamber.When steam has filled the chamber,it begins to flow past the thermometer.Timing of sterilizing period starts only when the thermometer reaches the desired temperature. When air is trapped in chamber or wrapped items,the killing power of steam is decreased in direct proportion to amount of air present. Because the vital discharge of air from the load always occurs in a downward direction never sideways,all supplies must be prepared and arranged to present the least possible resistance to passage of steam through load from top of chamber downward.Also,air and steam discharge lines must be kept free of dirt,sediment,or lint. Most gravity displacement steam sterilizers operate on a standard cycle 121 0c at a pressure of 15 pounds per square inch(lb/in 2). Size of chamber and contents will determine exposure period;the minimum is 15 minutes.
Posted on: Fri, 19 Jul 2013 15:08:15 +0000
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