RT 101 Chapter 7 TUBE FAILURE

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RT 101 Chapter 7 TUBE FAILURE Powered By Docstoc
					                                  TUBE FAILURE

                                       CAUSES

                               HEAT DISSAPATION

    RADIATION

    CONDUCTION

    CONVECTION

                                  Three causes

    1. Excessive exposure

          melting, pitting of anode

          tungsten can vaporize

                 causes coating of inside of envelope

                        filters beam

                        interferes with electron flow

    2. Long exposure time

          keeps anode @ elevated temps for extended time

                 excessive heat to rotor bearings via neck of anode

                        can cause envelope to crack

    3. Filament Vaporization

          Tungston atoms slowly vaporizing

                 coats inside of envelope

                        over heating of filament vaporizes filament

                        filament becomes thinner and eventually breaks

TUBE RATING CHARTS
Radiographer rating chart

Anode Cooling chart

HU (single phase) KVP x Ma X time

HU (three phase 6 pulse)1.35 x kvp x mas

HU(three phase 12 pulse)1.41 x kvp x mas

      Housing cooling chart

				
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