Preva Dental X-ray System User Manual, 00-02-1576, Revision ZA1
39
Instructions for the use of the Preva and precautionary statements
are part of this User’s Manual.
As described in the Recommended Maintenance section, the Preva
should be serviced on an annual basis to ensure proper
functionality. It is the owner’s responsibility to arrange for this
service and to assure that the personnel performing this service are
fully qualified to service Midmark Corporation X-ray equipment.
Leakage technique factors: 70 kV, 0.4 mA
Minimum filtration (half-value layer) in useful beam: 1.7 mm Al
The cooling curve charts for the anode can be found on page 40.
Please note that due to the integrated design of the Preva, there is
no meaningful separate cooling curve for the tube housing.
Since the Preva operates as a complete system in only one mode
as a high frequency X-ray system, there is no need to provide a tube
Rated nominal line voltage: 110 V – 230 V
Line voltage regulation: 10% of the nominal line voltage
1020.30 (h) (3) (ii) and (iii)
The maximum momentary line current (less than 5 s) of the Preva is
10 A when operated on 120 V (1.2 kW). Operation at higher input
voltage will reduce the maximum current (5 A at 240 V). The
technique factors producing the maximum momentary line current
Generator rating at maximum technique factor of 65 kV, 7 mA is
455 W. Duty cycle is 1:15.
Maximum deviation from indicated values:
a) Peak tube potential, maximum deviation: ±5%
b) Tube current, maximum deviation: ±1 mA
c) Exposure time: min 20 ms, max. 2 s, max. deviation: ±5%+1 ms
The measurement criteria for all technique factors used in
paragraphs (h) (3) (iii), and (h) (3) (vi) is 90% of the selected peak
tube voltage.
Statements and Information According to 21 CFR Sub Chapter
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