Belray 96 - Tube Head Thermal Characteristics

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[3] TUBE HEAD THERMAL CHARACTERISTICS
A. Interval between each exposure
The temperature inside of the tube head rises, when an exposure is made. The value of the heat
generated is measured in Heat Unit (HU), which is the product of tube potential, tube current and
exposure time. Excessive heat will be accumulated inside of the tube head, if the x-ray is used
without a proper cool down interval between each exposure. The excessive heat may damage the
x-ray tube, high voltage generator or both.
B. Duty cycle
To avoid the accumulation of excess heat in an effort to prolong the tube head life, a cool down in-
terval of 60 seconds or more must be allowed between each 1 second exposure. or a 30 second
cool down must be allowed between each 0.5 second exposure.
C. Tube head cooling curve
1. Tube Housing cooling curve 2. Anode thermal characteristics
3. Maximum rating chart
3
1
5
H
U
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S
2
5
H
U
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S
1
7
5
H
U
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S
TUBE MODEL D-088
ANODE THERMAL CHARACTERISTICS
Heat Storange (H.U.)
Time in Minutes
0 1 2 3 4 5 6
 20000
 18000
 14000
 10000
 6000
 2000
FOCAL SPOT 0.8mm
50 kV
60 kV
70 kV
80 kV
90 kV
Tube Current (mA)
Load Time (sec.)
0.1 0.2 0.3 0.5 0.7 1.0 2.0 3.0 5.0
 30

 20

 10
Tube Housing Cooling Curve
Heat Storange (KH.U.)
Time in Minutes
0 20 40 60 80 100 120 140
 250
 200
 150
 100
 50