API 620Tank Design.ppt
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Never use metal enclosures for Cooking/Reheating Food in Microwave Oven (Not even Aluminium Foil) • Microwaves are radio waves. Radio waves in this frequency range have an interesting property: Water, fats and sugars absorb them. When absorbed they're converted directly into atomic motion heat. • Microwaves in this frequency range have another interesting property: Most plastics, glass or ceramics don't absorb them but waves pass through them without affecting them. • But what about metal? They Shield these waves by reflecting them out. Food in such metal containers will not get Cooked. • Sometimes it can be fatal. One should always avoid use of any form of metal in Microwave oven, especially tiny & thin metals (like Silver Foil). • The electric fields in microwaves cause of electric current to flow through metal. Substantial pieces of metal, like the walls of a microwave oven, can usually tolerate these currents without any problems. However, thin pieces of metal, like aluminium / silver foil, are overwhelmed by these currents and heat up very quickly. So quickly in fact, that they can catch fire. Plus, if the foil is crinkled so that it forms any sharp edges, the electrical current running through the foil will cause sparks & may cause microwave oven to totally explode. 23/1/2015 1
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Transcript of API 620Tank Design.ppt
Never use metal enclosures for Cooking/Reheating Food in Microwave Oven (Not even Aluminium Foil)
• Microwaves are radio waves. Radio waves in this frequency range have an interesting property: Water, fats and sugars absorb them. When absorbed they're converted directly into atomic motion heat.
• Microwaves in this frequency range have another interesting property: Most plastics, glass or ceramics don't absorb them but waves pass through them without affecting them.
• But what about metal? They Shield these waves by reflecting them out. Food in such metal containers will not get Cooked. • Sometimes it can be fatal. One should always avoid use of any form of metal in Microwave oven, especially tiny & thin metals (like
Silver Foil).• The electric fields in microwaves cause of electric current to flow through metal. Substantial pieces of metal, like the walls of a
microwave oven, can usually tolerate these currents without any problems. However, thin pieces of metal, like aluminium / silver foil, are overwhelmed by these currents and heat up very quickly. So quickly in fact, that they can catch fire. Plus, if the foil is crinkled so that it forms any sharp edges, the electrical current running through the foil will cause sparks & may cause microwave oven to totally explode.
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Induced Tensile Stress up to AllowableIs Safe
T1T1
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Induced Compressive Stress up to AllowableIs Safe
T2
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What If both exist together ?
T1 T1
T2
Combined Stress may exceedAllowable stress
will cause Failure !!! 23/1/2015 12
T1 T1T2
Allowed tensile for Induced compressive stress
T1T1
To qualify we need to find allowed stress for coexistent Induced stress Allowed compressive for Induced stress tensile
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Some Humour
Got Bored !!!
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! ! धन्यवा�दधन्यवा�द ! !
! ! 감사합니다 감사합니다 ! ! (Gam Sa Hab NI Da)(Gam Sa Hab NI Da)
! Thank You ! ! Thank You ! 23/1/2015 33
